Artemis Labs LA-1

Click pics to Enlarge. Note the Kondo-like Split-Level chassis with holes for cables to go through.

Review: Artemis Labs LA-1 Preamp, Part II
7119 vs 5687

LA-1, Part I

Artemis Labs, now long defunct, was headed by John Atwood, former Technical Editor of the much missed Vacuum Tube Valley publication of Charles Kittelson. Its first products in 2004 were this Preamp and the companion PH-1 Phonoamp. It was much later that I saw and heard them at the AV show in HK, though as usual, given show conditions, the sound did not register with me.

In HK, their products, though receiving wide praise, never sold well. I suspect that had something to do with the aesthetics. These products have the form of a bulky brick with a V(or U)-shaped trough in the top center, where the tubes are seated. The aluminum face plate looks rather Gothic to me. I actually don't quite like the look, but some reviewers seem to like it. Unusual shapes usually is not a good idea in the conservative world of audio consumerism. Second hand prices are low, even when I got it in 2010 (even lower now).

Construction This preamp is definitely not run of the mill, and is intriguingly constructed. There is a lot of technical information in the 2006 positive-feedback and belated 2010 dagogo reviews.

My interest in the LA-1 lies in its use of a single 5687 for amplification. The use of this tube in a preamp was initially developed by Kondo (I have yet to see one of these as he then moved away and used other tubes) and later much emulated in DIY circles. The split level construction of the LA-1 is also Kondo-like, but on a less luxurious level. Parts quality is superb. The coupling cap is Auricap (personally I harbor doubts about Teflon caps). The potentiometer is stepped Goldpoint and Chokes are used for Loading (somehow I was not able to get the front cover off but at the bottom there is a pic from the net). I popped open the back cover though and that overbuilt power supply is fit for an amp! BTW, see that black wire used for the signal (lower right corner)? It is Belden 8450, the solid core version of the 8451 that I use!

Ergonomics Excellent. Stepped volume can sometimes be trouble, but it is well designed here. I always get the exact volume I need. The two level knobs also come in handy in balancing the stage. And the Mono switch is a luxury.

Sound There is something very direct about the sound, and a presence that some of the reviewers had alluded to, but I find it difficult to exactly pin down the sound. What I find significant are:

• Simplicity Despite its realization, this is as simple as a preamp can be. Just a triode section capacitor coupled to the output, with very little feedback. One can hear this simplicity.

• Dynamics and Headroom There is definitely something outstanding about the headroom of this unit. It is never fazed. It is not ultra-dynamic in the usual sense. Its gain is modest at 13db. It doesn't immediately impress one as punchy as, say, a preamp based on the SRPP circuit. But the way it follows the dynamic is exceptional. No stress, no matter what. It is not reticent, it just gets out of the way. It is good with all manners of music.

• 5687 vs 7119 The 5687 was made famous by Kondo. Since then it has been used widely in DIY circuits, as well as in some mass products such as the iconic Audio Note (UK) Kit 1, which I used to own. It is a very good amp, and better than its then much more expensive commercial brethens Conqueror and Conquest. But still, I could not get over its trace of brightness. I rolled 5687 and 7119 but thought the 7119 sounded quite off. Fast forward to now. The LA-1 is completely different, and highly amenable to both tubes. The 5687 has a more airy sound, but the 7119 is definitely more corporeal sounding, and that is my preference. 

• A Steal At current price, this is a steal. If your system is kind of laid back, this may not provide you with the jump factor you need. But, if your system is in ship shape, the Artemis can be a big surprise and make you re-evaluate what you think you know about dynamics.

Beefy Power Supply!

Bottom pic from here. LA-1 to the Left. See the Chokes (there is better pic here)

FX Audio TUBE-01 Scythe Kama Bay Mini Pro Bluetooth HDMI Linear Power Supply

Click pics to enlarge.  The Dynamic Duo on top of Artemis Labs Preamp. Note the Volume Knob Positions. Also note the left edge of the Scythe's Front Plate, with its beveled curve (not a chromatic aberration).

Review: FX Audio TUBE-01, The Mouse that Roared!
Review: Scythe Kama Bay Mini Pro D-Amp, Spinach'ed Popeye! 
New York Diary (20-17): Streaming on the Cheap; Bluetooth, Part II; via HDMI, vs USB; iPad vs Chromebook, Spotify Redux 

The more I stream, the more I stream. This is a continuation of my last article (just roll down). Like all addictions, it can be hazardous to one's health. I am probably streaming music at least 10-12 hours a day, and on the computer for about as long. Not very good. But, what is good now, I ask? Worldwide, Ugly Politicians are using this window for their own gain. No wonder I am becoming more unhealthy!

During this pandemic, another bad thing, though far less harmless, is that we give ourselves reasons to buy things. In the US, alcohol consumption is up 50%, but I am actually consuming less (though I stock up).  I have at least several audio things on my mind. The big word now is "essential". No, they are not, for sure. I fight the expensive ones off, and then I am still curious. What better consolation than to buy a few cheap and cheerful things?

FX Audio TUBE-01
Given my positive experience on what a good tubed buffer has on Bluetooth Playback (in my last installment, but my iFi iTube is not exactly cheap), just for journalism's sake I started looking for a cheap buffer that would do the trick, and soon my attention was focused on the FX Audio Tube-01, a well liked el-cheapo unit that has over a long time been much vaunted over the internet. This long-running and informative Audiokarma thread is testament to that. Somewhere it mentioned the tube is connected in triode. Looking at the board it seems there is no opamp in the signal path but there is an area that is not accessible to the eye so I cannot be sure. Also, keep in mind the same device is also offered under several different brands. There is also a version with tone controls but it adds a pair of NE5532 opamps to accomplish the task. So, better stay with the simpler version, I'd say. The funny thing about this thing is the confusion over whether it is just a buffer or a preamp with gain. There is no question, the spec states a maximum output of 3V, much higher than a buffer's usual 2V, so this is a preamp with gain, not just a buffer. Given the very low price, it is quite well built and good looking. Power Supply is a 1A 12V DC Wall Wart. Ergonomics Little. One in, one out. Tubes Stock, it runs a Chinese 6J1 in each channel. Warning! This is a miniature 7-pin tube, and the socket is very tight in its grip. I cracked one of the stock tubes during installation. Fortunately I had bought some used old 6AK5's (equivalent tube), but installing them was difficult. If you have a tube straightener it would have been easier. If just one pin is a little skewed it would not go in. It took me many attempts to get my Sylvania's in.

Scythe Kama Bay Mini Pro D-amp (SDA35-2000)
This was solely an accidental diversion. While researching my Dayton BTR-01 I somehow discovered the TNT 2009 Rave Review of Scythe SDA-1000 Kama Bay D-amp that uses the Yamaha YDA138 chip to produce 10 wpc. As an occasional student of cheap and cheerful T and D amps (Lepai and SMSL), I mopped it up. I just loved the looks of it, but it is unfortunately long unavailable. Then I discovered the (?2000) Mini Pro (still available but in short supply) that uses the Maxim 98400A chip to produce a higher 20 wpc. This Italian Review (translated) is the only one, but it is good in relating the history of Scythe audio products. See, Scythe (a Japanese company, products manufactured in China) has long ago abandoned making audio products, and that is a shame, as they were not run of the mill. This is a little like Elekit, which makes toys and AI type stuff for kids; audio is just a sideline. As one who cares about aesthetics, I just love their industrial design, something that most Chinese products are seriously lacking in. Even this little thing, though not as striking as its illustrious predecessor, still sports subtle details (see top pic); additionally, it has only 3 feet, surely audiophile thinking. Power Supply is a Switch Mode Computer type brick capable of 3A (that is generous). Unusually, it also comes with a bag of cables and mounting brackets for installation in a desktop hard disc drive! Ergonomics For such a small thing, it packs a wallop. In the back there is an RCA input; in the front, a Minijack Input and a Headphone Output. Internals See bottom pic for the jam-packed interior.

System Used:
BT: Dayton Audio BTR-01 Bluetooth Receiver (S/PDIF out; Belden 1694)
DAC:  Micromega M1yDac (Kimber KCAG)
Preamp: FX Audio Tube-01
Amp 1: Scythe Mini Pro
Amp 2: Akitika GT-102
Loudspeakers: LS3/5A (Audiomaster 15 ohm)
Linear Power Supply: MW122A

Round 1: Scythe Solo I first connected just the Scythe. I was totally surprised by how well it drove my 15-ohm LS3/5A. In this respect it definitely outpaced my Lepai and likely my SMSL (but then it has a larger 3A PS). It has pretty high gain and I didn't need to turn the volume knob beyond 10:30-11:00 O'clock. Sound was just what I expected, neutral and clean. Importantly, it was in total control, amazing for such a small thing. It benefited a little from running in. If I were to set up a desktop, this would be my amp (and you can mount it inside the hard disc drive if you have an extra slot).

Round 2: Scythe + FX Next I inserted the FX between the source and Scythe. Note that as one of my stock Chinese 6J1 went south, I used a pair of old stock Sylvnia 6AK5, which is just as well. Right off the bat, I was astonished by how much gain the FX has - buffer it is not! And by how much the Sound gained in Presence and Allure. Volume Settings The system has too much gain, and I set out to find what setting is best. I tried both extremes: Maxing out the Scythe and using the FX to control volume; and vice versa - neither was optimal and resulted in less presence or coarser sound, respectively. Empirically I had both around 10 O'clock. But I wanted to know at what position does the FX outputs the normal 2V. vs Elekit TU-8500 As the Elekit has a Unity Gain setting (here) and is nearby, I recruited it for use. I maxed out the Elekit and determined the volume level of the Scythe (around 10:30). Then I substituted the FX and dialed in the same volume by listening. I was shocked that the FX reached 2V around 10:30! This tiny thing has more gain than some of my active preamps! In terms of sound, in this system I prefer the FX for its more open sound. I listened happily to this duo for many days.

Round 3: Linear Power Supply In the Audiokarma forum, there were a lot of discussions on how a linear PS improves the FX, so I dug out my little used el-cheapo 2A regulated PS (on sale now; if you buy one make sure you get the plug kit too). FX TUBE-01 I first tried it on the FX. There was definitely a difference; a somewhat weightier sound, but I thought I preferred the pacier sound of the stock SM PS, so I switched back. Dayton BTR-01 Again, there was definitely a difference, but this time in the other direction - the sound seemed just a little airier, so I kept it in. I wanted to test the Scythe too, but couldn't because it has a special male plug (with a pin inside) that I don't have in my plug kit.

Round 4: FX + Akitika The FX pleased me so much that I resolved to further test it out as a preamp. I was writing at the dining table but the sound stopped me dead in my track. What the hell! The sound is GREAT! The soundstage doubled and there was bags of air. For the last few days I just stayed with this combo, which did everything well. For this article, I performed a reality check. FX vs Artemis Labs LA-1 I have been using the Artemis before the dynamic duo's arrival. The change in sound after I swapped in the Artemis was quite subtle, definitely not night and day. Perhaps the Artemis was just a little more solid in its foundations and had even sweeter treble. The diminutive FX emphatically did not at all shame itself, particularly with BT material. Most astonishing!

Round 5: Streaming HDMI Using a generic HDMI cable, I connected my Chromebook to the $10 Wiistar convertor, (which has to be powered by 5V USB). I then connected the Wiistar to the Micromega MyDac via optical or coaxial and compared the sound to USB. I clearly preferred the HDMI to USB, warmer and smoother. Of course, the connection is highly impractical for a laptop but if I have a desktop this may be an alternative to USB (which also benefits from being converted to S/PDIF).

Round 6: iPad vs Chromebook During the Memorial Day sales, I got a good deal on the current iPad 10.2". I streamed NML through it. I don't know why, the volume is definitely lower by at least a couple of notches; the sound is more sluggish and lacking in sparkle; and the soundstage is a little more constricted. For sure the Chromebook is preferable.

Spotify Reconsidered After my last article I actually surfed Spotify quite a bit looking for things that are not in NML. For me, it is actually a useful supplement. e.g. it has quite a few Doremi albums. This is a label specializing in historical reissues and live performances. An example, one of my favorite pianists is Reine Gianoli, whose wonderful Mozart sonata cycle, originally on Westminster LPs, can be found on Spotify but not NML. Of course, Spotify is also good for Jazz and Pop. I listened to a few cuts of Cantopop (like my favorite Shirley Kwan) and they sound great on the LS3/5A.

Comments

• FX Audio TUBE-01 This thing is unbelievably good! Good enough to use in your main system.  Highly Recommended. 6J1 Variants This tube is derived from 6AK5, a tube with an excellent lineage (here). Developed by Western Electric (403A/B), the 6AK5 is excellent sounding. I just bought a few used ones from Ebay and they are cheap and sound great. There is good reason why a lot of Chinese gear use 6J1 and 6N3: both of these tubes have good sounding US precursors (5670 and WE396A/2C51 in the case of  6N3). On the other hand, avoid those that use 6N1, as there is no exact equivalent.

• Scythe Kama Bay Mini Pro It is a good little amp but will be difficult to get. Of course, it is still not as good sounding as the Akitika!

• Linear Power Supply Traditionally a Linear PS is regarded as better than Switch Mode. But my experience with Switch Mode power supplies have been largely positive. My LTA and Micromega sound great with their SM power supplies, as do this round's dynamic duo and the Dayton BT. No reason to lose sleep over it.

Dayton BTR01 FX AUDIO BL-MUSE-01 Aukey BR-C1 HK008 Bluetooth Receivers vs USB Streaming iFi iTube Naxos Music Library Spotify Youtube

Click pics to enlarge. Dayton BTR01 in action. Aukey BR-C1 in foreground; iFi iTube and Micromega Mydac in left background.

NY Diary (20-16): Streaming on the Cheap; Bluetooth, Part I
Review: Three Bluetooth Receivers, Dayton BTR01, Aukey BR-C1 and HK008, vs USB
Review: iFi iTube, Part II
Streaming Naxos Music Library (NML) (with Chromebook)

This is a very long article that follows my Bluetooth Journey chronologically, not a more categorical presentation. I chose this way because it would tell more of the joys and frustrations of the journey.

Getting the NML through you NYPL account

This is picking up where I left off in the last Diary Entry on Streaming NML (here). Since writing that, I haven't stopped streaming but have done some adjustments, and some of the results surprised me, to say the least. I'll start with a bit of re-cap.

BEFORE: Ancient Dell Laptop + Unitek USB Cable The Unitek is my go-to USB cable (better than the Belkin Gold, see here; but it seems available only in HK). The Dell was a loaner, pre-Windows 10 but running the 10 (I also tried my even older XP Dell; it displays but cannot run the NML Player). Sound With the Micromega DAC, sound was quite good. The treble was surprisingly detailed, but sometimes with a steely tinge on period instruments or when the going got rough. Cable Swaps I dug out more cables and toggled them, resulting in a somewhat warmer, but just as detailed, sound. So the updated system:

Bluetoon Receivers: Aukey BR-C1 and Dayton Audio BTR01 (chronicled below)
DAC: Micromega MyDAC (DIY 47 labs)
Preamp: Elekit TU-8500 (Gotham GAC-2111)
Amp: Akitika GT-102 (Acrotec 6N-1010)
Loudspeakers: Audiomaster LS3/5A (15 ohm)
Stands: el-cheapo Energy stand used without spikes
Blue Ray Player: Sony S-5000ES (Audio Out; Canare 2T2S)
Turntable: Audio-Technica AT-PL120/Denon DL-301ii

My New Chromebook (skip this part if you have no interest in Chromebook) As described in Diary (20-8), some time ago I irrevocably crippled the browser of my 2012 Macbook Pro and computing on ancient laptops has been a patchwork. Finally I couldn't stand it anymore and impulsively bought an entry level Acer Chromebook 14 for $200, before tax. Considering that computer prices have shot up with increased demand during the pandemic, that was a comparatively good deal. I ordered it from BJ's and was shocked it showed up the next day. I guess it was available at my local store and they delivered it together with other people's groceries. Nonetheless, efficient and deserving of praise! Basic but has Flaws Opening it up surprised me - a nice carrying bag is included. This is my first Chromebook, and it is a very basic one. I liked the fact that it has an aluminum chassis (of course at the cost of additional features). The screen is large, but images, though fairly good, lack some contrast  (Apple it ain't). Working on it feels remarkably like working on a Macbook Air. I use the computer to mostly read the news, write (obviously) and watch a little youtube, certainly no gaming and high demand stuff, so this basic model is good enough for me, and I can sit and write with it on my lap for hours. I open multiple tabs when I write (sites with relatively little ads and pop ups) and stream music at the same time, and the speed is acceptable (not with some youtube videos though) and happily the battery lasts forever. I/O's are few, 2 USB and a HDMI but regrettably no SD card slot. I also tested the earphone out and it was acceptable (no worse than Apple). Drawbacks There are a few, some unforeseen by me. It's not the price, but the ecosystem. Keyboard It is a little different, but adjustment is easy. I do miss several keys that I use a lot (Pg Up/Dn, Home, End and Delete) and hence cannot yet execute some DOS commands (but these keys on an external keyboard work). There are Chromebook shortcuts for these but it will take a little time to learn them. Input Sometimes I have to type in Chinese (not that often). With Apple, it is the best. With a PC or Android Cell Phone, I use the very good Google Pinyin Method, which can easily toggle between the Traditional and Simplified Chinese characters. So I was really surprised the Chromebook cannot; it's one at a time (reason here). And the Fuzzy Logic is not as good. This is a minor gripe though. Wechat This is the Social Media almost all Chinese use. On my Mac and PC, I like to install the Wechat app and use it when I type a lot. But despite some unofficial attempts, this is basically not possible on a Chromebook. As for Wechat's web edition, it can be displayed but fails to login even after scanning the QR Code. This may not be surprising as anything Google is not available in China. So for those who have to interact a lot with Chinese friends and associates, the Chromebook is not a good choice. This is not my case, so it is good enough for me.

Round 1: Initial Woes USB Aargh! I plugged the USB in, and NO sound from my Micromega. MyDAC requires a driver for Windows, but this Chrome ecosystem is apparently different. Next, I thought of my Meridian Explorer but could not find it. Anyway, that was a disappointment (but there is a surprise later). So, I grudgingly continued to use the ancient Dell. Bluetooth (BT) A day later, I decided just to try out Bluetooth. Last year I tried out some cheap Bluetooth stuff with my then-functioning Macbook Pro, and I had great difficulties (here). So I got them out. Well, the Chromebook proved better in this department. The Dayton BTR-01 was detected but would not pair, (surprise later too) but I was glad the Monoprice BHS-839 Headphones paired (it will see some use in the kitchen). When all seemed lost...

Round 2: Aukey BR-C1 Bluetooth Receiver This is a tiny (2") el-cheapo Rechargeable BT Receiver with a mini-jack analogue output. I bought it from Amazon soon after I wrote the Bluetooth/Monoprice Earphone article. Make sure you read the purchasers' feedback (that was what I did when I tried to decide which one to buy). The top one from a tech-savvy guy is most interesting, and I will quote him below.


Two changes and this goes from mediocre to nearly perfect "audiophile"
Reviewed in the United States on March 22, 2017
Verified Purchase

Upon first play using one of my reference pieces I use, 1.618 by BT, I knew something was off about this gadget. Being a bit electronics and audio proficient, I opted for an autopsy.

1st image: 65-second, 20 Hz to 20 kHz logarithmic sweep at -3 dB and half system volume w/ 85-86 uF stock output capacitors & filters.
2nd image: 65-second, 20 Hz to 20 kHz logarithmic sweep at -3 dB and half system volume w/ ~290 uF output capacitance.

I set up the wrong multiplier for the scope between both sets of measurements. Please compare shape, not the measured values.

The micro responsible for driving this entire device is the ISSC IS1681S made by the Microchip subsidiary ISSC. It's a Bluetooth 3.1 + EDR device that supports a mic and stereo sound. The power source, aside from being plugged in via USB, is a 2YL6 "jellybean" Li-Ion SOT-23-5 charging regulator and a 250 mAh, 0.9W lithium battery. ISSC's site change that this IS1681S can live for 10 hrs on a 120 mAh battery. I didn't map the schematic, but 2x A2SHB-marked transistors, also a jellybean part, drive the left and right channels though 2 caps in parallel-ish and one inductor. The capacitance of each channel on the board is 85-86 uF, which is where I make my point.

A crude linear intensity sweep showed roll-off for everything below 650 Hz. The 3dB point is dead on 51-52 Hz, and the 6 dB point is at 20 Hz. This means that any low mids and high bass is easily being attenuated. As the capacitance is driven by MLCC caps, 0805's being the largest used here, which suffer from letting DC through at higher loads, the isn't enough for driving any decent speaker setup. Even at half volume I was getting a significant DC offset.

I had some 220 uF's sitting around from another project, specifically EEU-FR1C221, so I cut the leads of two of them and soldered them on. Away went the DC offset. Away went the 3 dB & 6 dB low-mid & low frequency attenuation And up went the peak-to-peak amnplitude. I can go louder now along with only a 0.82 dB roll off from 97 Hz to 60 Hz, which is good enough for me. My monitors go down to the mid 50's. Frequency response is flat from 97 Hz to 20 kHz.

Why does this matter? Aukey spent the time and money to inlay 4 steel pieces and 2 screws holding them in to add 20 grams of mass to this device. I'll admit that the thick-walled ABS case and rubber foot coupled with the texture of the plastic are spot on for the feeling of quality. I didn't expect perfect audio, but I didn't expect +6 dB attenuation in bass. The range of the bluetooth transceiver is great, despite the steel blocking a good part of the antenna on the left. However, if they remove the steel and minorly adjust the PCB layout, they will be able to accommodate similarly spec'd electrolytic caps and provide *excellent* sound for bluetooth device that costs $20.

Aukey, please remove the weights and use the cost differential to fix the frequency response. you do this, you'll get 5 stars from me. 2 were taken off because that roll-off starts/stops pretty high up in my opinion and physical presence was prioritized over function.

Amazon gave me a discount for leaving this guy in my cart for a few days (doesn't mean that it will or won't happen to you) so I got bluetooth audio that sounds equivalent to a shielded line-in input to my monitors for $12 so this was a fun experiment that netted me a very capable device I'll want to keep. I want to buy more, mod them, and share them.

And They Lived Happily Ever After? When I first got it last year, I tested it briefly and it did not work with my Macbook Pro either. I almost forgot about it this time. In the early evening, I brought it out for a trial. Connection SURPRISE! It paired easily with the Chromebook! The connection is fairly stable, though at times it'd stutter a little, though overall it is acceptable. Sound Level At first, the sound level was quite low and I had to crank the volume up. Then I realized and checked the Chromebook's volume, which was at my usual low setting (I usually work almost silent, preferring to listen to music from my real systems). I maxed it out and, voila, the level became more normal, though I am certain it is below the standard 2V. Ergonomics For this price, don't expect that much! It has a lot of features for car and earphone use, which is useless to me and irrelevant here. Battery There is a Lithium Battery inside, and USB charging is easy and quick. Once charged, it lasts forever. If you don't want to do recharging, of course you can have it permanently hooked up with a USB charger (not included). Audio Output There is only a stereo Minjack. I used a generic adapter for RCA. Weight It is so light that it tends to be dragged back by the interconnect (and adaptor). The Vibrapod gives more traction as well as control vibrations. Sound I mostly streamed NML. Initially, I was a little unsettled. It seemed more generalized, less detailed. On the other hand, it seemed rather pleasant, not much treble glassiness. Cable swapping made only a small difference (I settled for the Kimber KCAG). Anecdotally, the sound reminded me not a little of my 2018 Bluetooth session with my HK friends icefox et al (here). Then, as I gradually grew more and more acclimated to the sound. I started to suspect I might find it on par with the USB streaming before. I found that hard to accept, as Bluetooth, especially non-Apt X and low-end ones, are universally regarded as way inferior and not fit for audiophiles. It took another day of constant streaming to sort out my impressions. All that remained was switching back and compare (which I did two days later to the same conclusion). Yes, in this system I prefer the Aukey Bluetooth. It's too bad my other BT devices don't work (surprise later). In the next bullet, I shall dwell on its virtues. Radio I spent some time enjoying Radio Garden (link set to Italian Radio Emilia-Romagna). I roamed over the globe, stopping by in Africa and India for some stirring music, finally checking in to RTHK4, Hong Kong's classical (and jazz) radio. Around the World in one hour! I urge you to explore this site but warn you that it can be addictive! :-) Pro's Some of you will no doubt question my high end credentials for preferring BT. Although it is hard to isolate the various elements, a few words to explain my preference are in order. Organic It is about the whole, not the components. There is something holistically right about the BT/Aukey. It breathes naturally and gets to the heart of the music. Now, as mentioned in my first article on NML streaming, its free feed is not even close to CD standard, not to say hi-res, though it is good enough for me (and mrgoodsound, though as a subscriber he may have a slightly better feed) to enjoy the music. Smoothness Compared to the USB streaming before, the Aukey BT is smoother, which is why initially I had to undergo a period of adjustment for what I first perceived as loss of high frequency content and detail. After more listening I became aware that there is about as much detail there, but the distribution is different. With USB, the images are smaller and the edges are sharper; with the BT, images are more fleshed out. I can imagine in the wrong system (say a less resolved one) the BT could come across as more muddy or bloated. But in mine the massed strings certainly sound more real. Soundstage and Hall Sound In terms of depth, the Aukey extends a little further back, but that is not significant compared to its surprising ability to convey the Recording Venue (Hall Sound). In my opinion, accurate Hall Sound goes hand in hand with Listening Comfort. Years of listening to classical music in audiophiles' system taught me the vast majority have no idea of what the hall sounds like - what they hear is a cardboard cutout. Case in point: I went through the excellent Beethoven Symphony Cycle by the Vienna Academy under Martin Haselbock (Alpha). They were recorded in different venues (each deliberately matched with the venue of each work's premiere) and I definitely hear the different halls. Another example: Remy Ballot's Bruckner Cycle was recorded in St Florian Cathedral, where Bruckner was based, and I can hear the reverbs. For a 16-bit aficionado (I am confident the 16-bit chips have the best hall sound, bar none), that's quite something to say! The small orchestra is clearly heard; the vibrato-less strings never grating, very exciting! If you have a streaming service, try it! The cushion of the hall sound lets me hear the really big symphonic works with comfort. Con's Effective Distance It is not very much; long distance champ it is not. But, are you kidding? For $15, I have no complaints. Also, here I do want to address the question raised by the technically minded Amazon commentator concerning the stock unit's roll-off under 670 Hz (-3db at 50-52 Hz; -6 db at 20 Hz). In my opinion, the very gradual rolloff to -3 db at 50 Hz is nothing much to worry about (unless your system is really lean in the lower midrange, midbass and bass) - not a few tube gears probably do that, and cable changes are able to help. In my case, I worry even less as the LS3/5A has a signature midbass bump that will flatten out the curve some, especially since I am using wood-based stands (without spikes) that probably make bass yet a little fatter. Indeed, I am not lacking in bass. I don't feel the need for a sub.

Round 3: Extra! + iFi iTube Late one night, I was playing Bruckner. I was actually contented but the idea of adding a Buffer came to me. I pulled out my little used iFi iTube (my review) and connected the Aukey (with KCAG) to it, using the Belden 8451 to connect to the preamp. Wow! It's not just better, it is significantly better! As Buffer (0 db Gain) I was not surprised that the Buffer sweetened the strings and brass a little, but I was happily surprised by Greater Ease and even more by the Enhanced Dynamics! That adds a lot to the big symphonic experience (like Bruckner)! Aukey has no spec's so I don't know whether there is an impedance issue, but the buffer surely improves things. As Buffer (6 db Gain) Even though the volume knob on the preamp had not even reached 12 o'clock, over the next few days I also tried out the 6 db gain setting. Unlike the previous round, I heard a little difference. Perhaps because I feel the Aukey is low in output volume (or perhaps the compression of the BT plays a role too) the additional 6 db gain adds a little more spice. I A/B'ed some: this is different from cranking up the preamp by 6 db; the attack is a little better. This is the setting I now use. As Preamp (6 db Gain) I briefly tested this, eliminating the Elekit preamp altogether. Just like before, the iFi did not cut it - the perspective is flatter and there is less presence. Maybe good enough for the desktop (which is what some of the reviewers use), but not in a real system. vs Chromebook Audio Out At the end of my comparisons, using the same cable and adapter I connected via the headphone output. I had tested this a few nights ago with my Grado SR-80 and it was par for the course, no worse than my Macbook Pro (not saying much). In this system, the sound was acceptable but not as wholesome as the Aukey. The tinny treble (strings) though was much improved; surely the iTube has helped!

Round 4: Miracle 1, Dayton BTR01 Revived!  + Micromega MyDac The Dayton is a Parts Express Product. It is a BT 3.0, non-AptX Receiver. As I was finishing the article, I opened it up and took a pic. The Chip used is CSR 57E6-87CG. The Op Amp NE5532P is seated on a socket, so should you like you can do some rolling. I googled the chip and guess what I found? A pic of FX Audio BL-MUSE-01 which looks exactly the same. I investigated further and found the innards are identical too! So, The Dayton is OEM'ed by FX Audio, which is a reputable Shenzhen enterprise. Dayton is out of stock right now, though more are due in imminently, whereas FX can be bought anywhere on Amazon and Ebay (the cheapest I have found is this). However, should you be interested, personally I'd pay a few bucks more and buy from PE, because they have a 5-year Warranty and are famous for their service. During this covid crisis, Parts Express must be hurting and they have lowered their free shipping requirement from $100 to $49, and you can include a few adaptors or whatever you need with your order! Of course, those near Hong Kong I am sure can easily purchase the FX from Taobao for even less. Connection As mentioned, first I had trouble; it was detected but would not pair. This was when I was using the Aukey. I moved it further away and plugged it in and forgot about it for about 2 hours. After a while I saw the blue light blinking and I was suddenly able to pair it! I moved it back into the system and it maintained the connection (I turned off the Aukey). As a matter of fact, it has been almost 3 weeks; every night I broke the connection when I turned off my Chromebook and it would re-connect with no problem the next day. The connection is super-stable (visible direct line) I suspect the initial impasse was due to too many devices around. Now, another strange thing: I tried again with my old Macbook Pro and, unlike before, it paired! Go figure! I have no idea why the Dayton works now with my Macbook but not before. Perhaps the 2 hrs of "warming up" did something? Ergonomics This is a small but quite well-built device, with great ergonomics. Power Supply is via a 12V wall wart (Linear PSU is a possible upgrade path). There is a stereo pair of Analogue Output as well as a pair of S/PDIF Outputs (Coaxial and Toslink). The Digital Outputs allow me to use a DAC of my own choice in lieu of the onboard one. I wasted no time. Sound I first used the Coaxial Output (Belden 1694A) into the Micromega MyDAC (iFi not used). A big smile broke on my face! The sound has everything the Aukey has, and significantly more. Retained is the musicality. Improved are the resolution, dynamics, even treble smoothness. In fact, the punch, and bass heft, sometimes surprises me. Brass and Massed Strings have sheen, no etching on most discs; no easy task! Fabulous! Toslink Actually I knew from before: with the Micromega, Toslink (Monoprice) is almost indistinguishable from Coaxial, and so it proves here (I think there must be some re-clocking inside). Analogue Out I connected it with the KCAG to the preamp. No surprise, sound was still quite good, but a little flatter and not as dynamic. I even added the iTube buffer (+6 db) to beef it up, but the sound was naturally still better with the Digital Outputs. However, just like the Aukey it is pretty decent and would be satisfactory without an A/B Comparison.  Lossy NML vs lossless AIFF I played my lossless AIFF files on iTunes. At first, they stuttered kind of badly, though not disconnecting, but that went away after I turned the BT off on my chromebook. Streamed over BT (lossy itself), the difference is there, but not by as much as one would think. Previous Review When I bought it, there were only user reviews. Imagine my surprise that there is now a TNT Review. Damn! I could have been the first! :-( But, wait a second, I just finished reading it. It is a complicated and crazy review, which I completely disagree with (rare in my experience with TNT), so maybe this review will right things!

Round 5: BT vs USB On my Macbook, I have almost 1T of music stored as AIFF in iTunes. In there is an AIFF file of Concerto Italiano's recording of Bach's Goldberg Variations (orchestral transcription) which I love and have previously recommended. So I played the lossless file via USB and compared it to Chromebook playing the lossy NML file with BT. Suffice to say, as an audiophile, I think the USB is still better, but, being a direct connection, not by as large a margin as I'd imagine. Somehow, despite the better resolution of the USB, the wholesomeness of the BT still came through and it is not shamed (I can see with certain music it might even be preferable).

HK008 dangling on the DIY minijack cable. Aukey on Keyboard.

Round 6: Deja-Vu (HK008) After 2 weeks of thorough immersion in streaming, a few days ago I finally fired up my horn rig because, as is my custom, I wanted to test again the TU-8800VK before shipping it out. This is a much more efficient system, so I didn't use the iFi and just inserted the Aukey via the amp's Minijack input, and it played delightfully. System:

BT: Aukey BR-C1 or HK008 (DIY Mogami 2534 with Rean Minijack connectors)
Amp: Elekit TU-8800VK (Belden 9497)
Loudspeakers: Klipsch Heresy I
Subwoofer: Pioneer SW-8

A few hours later, the Aukey ran out of battery and had to be recharged. I substituted the even smaller $10 "HK008" (Amazon), which paired instantly. Amazing! The sound is virtually indistinguishable from the Aukey, so I am not going into details. I continued my streaming with the HK008 as I wrote, until...

Round 7: Miracle 2, MyDAC USB Revived! This is truly amazing (to low tech me). I had almost finished the article when I wanted to find out the cost of a used MyDAC. I poked around and ended up wasting some time reading old reviews, one of which reminded me that there is a small switch behind the MyDAC that switches between USB 1.0 and 2.0. For Windows, 1.0 does not require a driver but 2.0 does. I looked behind my unit. It is set at 1.0. My heart sank but I connected my Chromebook anyway. No sound, as before. What the heck, I thought, and tried out the 2.0. Success! I think that may be because my Chromebook's USB is 3.0 and it won't work on the 1.0. As for the Macbook Pro, may be the USB is 2.0 and that works on 1.0? I have always thought it was from 2012, but I just checked it, and it says "Late 2011". The 3.0 came out in 2011, but maybe my Mac still had the 2.0. BTW, my Unitek Cable and the Extension are 2.0. Anyway, that teaches you again the well-worn lesson - don't give up until you have tried everything! Sound Now I am able to use the same NML lossy files and make a direct comparison between USB and BT. There is no question the USB is still better (in bass heft particularly) but the BT is not far behind. For the small difference, until I have a dedicated computer in my audio system (may never happen) I am staying with BT.

Comments

• Chromebook I don't make much demand on my computers, so my cheap and cheerful unit is welcome. Its ecosystem reminds me of Apple more than PC. It is not an ecosystem of choice for those who have to interact a lot with Chinese friends and associates. More relevant for here, from my limited experience above, in terms of streaming, BT seems OK. As for USB, I think it is OK too. As USB 2.0 came out in 2001, before Computer Music has taken off, I doubt there are many old DAC's with only USB 1.0 input. Because the USB didn't work earlier, I bought a $12 HDMI to S/PDIF Converter (also has a Minijack out) which has just arrived. I shall stream via the HDMI output. I might also reclaim from a friend my Musical Fidelity V-Link (a good USB to S/PDIF convertor that does re-clocking) to try out. As I believe S/PDIF to be better sounding, that would be interesting, but it will have to wait as I'd not like my friend to worry about my knocking on his door during the pandemic. :-) :-(

• Akey BR-C1 and HK008 You can add streaming to your main system for peanuts. With some care, the sound is not bad at all, even good enough for this jaded audiophile. Despite their limited ergonomics, they punch above their weights, literally. Recommended. Also, make sure the distance is not too great and avoid having multiple BT devices on at once as it will cause pairing problems. AND, they are so portable that you can take it to your audiophile nemesis' place to embarrass him (I do that even to my friends, and certainly my HK friend icefox does too)! And good for a gift! The HK008 is not available right now but any generic one will likely be an equivalent. I regard BT as a bona fide Music Server! For those who do not already use a DAC in their system, these are reasonable choices. Given the somewhat lower output, use of a buffer, especially one with gain, will significantly improve the sound.

• Tube Buffer The iFi I use is now in its Mk II iteration, and it is not exactly cheap, certainly not commensurate with the prices of the BT devices. But there are very cheap ones available, and I intend to try out one of these soon (FX).

• Dayton BTR01 as vilified by TNT reviewer I completely and wholeheartedly disagree with the TNT reviewer I cited earlier. That reviewer basically worked in an obstacle course, and, unforgivably, he did not test the digital outputs of this fine device. Had he used the digital output options he would have been surprised. If you ask me, that reviewer's own home limitations disqualify him as a reviewer, no matter how good his ears are/were. His must be the most incomplete review I have ever read on TNT - in the end, that review is more about HIM and his HOME than about the device. Sigh...TNT, you can, and usually, do a lot better! The corollary is, think of BT as a cheap Streamer, not something to send audio over long distances. This is important conceptually. If you want more distance, I am sure it is not impossible but be prepared that implementation will take more trial and error, not to mention more money and possibly frustrations. 

• Dayton BTR01 as I Hear It The Dayton is a GREAT device, and a great bargain, whether you use its analogue out or, much better, its Digital Outputs into your DAC of choice. Or you can get the FX Audio BL-MUSE-01, as it is exactly the same. It is musical and, at least with lower-res files (like the NML), does not even shame itself against the standard USB. Grant you, its Distance of Operation (the only thing the TNT reviewer was concerned about) I cannot assess, as here in this room everything is within sight. But, based on Features and Sonic Attributes, HIGHLY RECOMMENDED! For those who already has a DAC in their system with an unused Coaxial or Toslink Input, this is a no brainer - downright FUN!

• BT vs USB As mentioned above, the USB resolves more and is more audiophile oriented. However, there is also something wholesome about the BT, perhaps a subtractive virtue. It sounds best when it is digitally extracted. With a suitable DAC, like the crazy bargain but highly musical Micromega MyDAC, BT is highly satisfying! As I don't have a computer in my audio systems (that may someday change), the BT is now my choice for Streaming. This is because I don't work at a desktop and literally have the laptop in my lap. I'd use the USB if I do work at the desktop but as it is I'd not like to be tethered to a USB cable.  The price of this, ultimate resolution, is an acceptable price to pay. The most important thing is, it can be musical.

• Audiophile Phenotypes and the Good and Bad Things about Computer Music Today in computer music, there is little question purchasing hi-res files (once so touted) is rapidly waning and Streaming is already Mainstream, even for audiophiles (not so good for musicians). If you consider youtube a form of streaming (which it is) it is astonishing how many audiophiles partake in that experience (my friends all do it, and think of those Ken Micallef clips mentioned in the last post). The great thing about computer music is that so much of it is available free or for a small fee. I think all can agree on that, but audiophiles differ greatly in how to receive (retrieve) the stuff. For people like me (and likely my colleague mrgoodsound), with streaming, as long as the music sounds good enough, absolute sound is of no concern. The important thing is to explore music, and when we are listening to something new and exciting, analyzing the sound is the last thing on our minds, and that is why I think one does not and should not need to spend too much on Streaming Equipment. I also think, people like us are likely to buy the music we discover (especially hard copy; I know mrgoodsound does). But I know many audiophiles have a different mindset, and they demand "the best" when they stream, which is why in 2 consecutive recent issues, Stereophile's JVS (kind of an audio Decameron figure; even his prose smacks of it) reviewed 2 Music Servers (Innuos and Wolf) with base prices of USD 13,750 and 9,295, respectively. And you still need to provide the DAC! I am afraid the only people well served at these extreme prices are the manufacturers and the reviewers. If I go with Aukey or HK008, my Music Server + DAC is less than $15! What I am saying is, I doubt these will turn around a piece of music that I do no take to. Maybe you ask, when is "good enough" good enough? Well, for me, proof of Good Enough (my motto) is that I have listened happily to BT Streaming for more than two weeks on my LS3/5A. Seriously, I don't even feel like I need my big rig, such a game changer it is! During this long period, I had gone through many Symphony Cycles: 3 Beethoven, 1 Brahms, 2 Bruckner and a Prokofiev, and that is just symphonies! I even thought that I should not have shipped some of my favorite CD's back from HK when I relocated - they are mostly available on NML.

• BT Upgrade? Another proof of how much I love BT is that after my experience with the Aukey but prior to the successful pairing of the Dayton I was contemplating taking a risk and getting the Arcam rBlink BT Receiver (AptX), which has been discontinued and is now on sale for $150. I have always liked Arcam and had their first-generation rDAC. The Arcam is obviously better built and ergonomically similar (no optical out though). After my success with Dayton I banished the thought, as its digital output is probably not that different and I don't really need the DAC part of it. But if you don't have a DAC and want BT, you may want to consider it. As for on the cheap, I am actually tempted by many Amazon/Ebay offerings that promise long distance BT for $50. Not many of these though have Coaxial Out. For me, a good BT digital Output is now a requisite, that is all I need. Also, I haven't yet tried a better PSU. I do have a 3A Multi-DC-Voltage Linear PSU around but, being easily satisfied, I somehow never put it into use with my numerous wall wart devices! Good enough is good enough for me, but I think this time I shall try it out. As I am streaming day and night, any improvement will be welcome.

• My Doubts about Computer Music Corollary, despite its strengths, I suspect there is something not entirely wholesome about USB Streaming. Grant you, I am not at all the last word in Computer Music, but I continue to harbor doubts. Cheap and cheerful is where I draw the line, and this round of BT experience is supportive. I think back about my HK friends, icefox and his cohorts, all uber-experienced audiophiles (and audio wanderers, even vagabonds) used to auditioning big and megabuck systems (which include expensive Music Servers)  - perhaps I now really know what they were experiencing. There are so many bad computer audio setups out there (including at shows and dealers) that I completely distrust writers who wax lyrics about them. Remember: Cheap is good, but Cheerful is even better! Since when has our audio hobby become a big technical mess? BT is just Simple, Unadulterated Joy, a rare phenomenon in audio today!

• NML Youtube Spotify Mind you, lest you wonder, for a very serious classical listener who wants the broadest coverage of music, Spotify is out of the question, and even Tidal and Qobuz are not in the equation (they have hi-res files but are way behind NML in coverage). But then, even NML is not perfect. There are quite a few esoteric labels not under its stable, and even for those that are, selected albums can be missing. As an example, Vikingur Olafsson, the trendy Icelandic pianist whose Bach track below notched around 8 million views on Spotify, is a DG star, yet his other DG albums are not on NML. I suspect this may be a calculated move on the part of the label. CD Recommendation All of my recommendations come from Streaming. For each one you see I'd estimate there are 20 albums that I decide not to include. This is not at all because they are not good, but because I deem then not generally recommendable (e.g. esoteric, difficult or sonically compromised). Quality The NML Free Feed (likely 64kbps) is good enough for me, and my listening experience is so much the richer for it. I'd not mind listening to Tidal or Qobuz too, but where'd I find the time? vs Youtube Using BT, I listened to the Bach Youtube below (official); it is virtually identical to the NML feed, so I may listen to the occasional Youtube through BT in the future. vs Spotify This gets fascinating. Spotify says its non-premium stream is 160 kbps, which should sound a little better than NML's 64 kbps. So I used the same Bach track as comparison. It sounds no better, so I think 160 is likely the maximum. BUT, this is crazy: it sounds different, and worse for it! I went back and forth, and the Spotify definitely is louder, has less treble definition and more bloated bass. I also compared Spotify with Youtube by using Carla Bley's Live 3 Blind Mice Track, which features as drummer Billy Drummond, one of the Musician Audiophiles in Ken Micallef's series, and the result is the same. I am certain Spotify equalizes the sound for more bass, like the "Loudness" function of yore. In its Android app, there is an equalizer function which one can use to remedy, but the web player offers no such facility. Nonetheless, I shall explore a little more of Spotify for what is not on NML (like Jazz). I searched for one of my favorites, Bruckner's 8th Symphony, and while there were few, I was surprised to find a 2014 live New York Philharmonic performance under Alan Gilbert. I listened to the whole 80 minutes (excellent performance).

Basic Repertoire Any Bach keyboard music, especially when it is played so well by Vikingur Olafsson, is Basic repertoire. While we are on the keyboard, I am a fan of the eclectic keyboardist Carla Bley.

Linear Tube Audio MicroZOTL MZ 2.0: A second opinion

By mrgoodsound

Editor: This is indeed a Milestone for this Blog! Readers should examine the two distinct views and think philosophically! Perhaps Leave a Comment? Have Fun!

Today's article will be very unique, in some ways a first for the blog, and my most ambitious yet since doctorjohn invited me to start writing a column some months ago.

For context, over two months ago I exited my loudspeaker purgatory by acquiring a pair of 1978 La Scala's. I absolutely love these speakers and mean to provide something of a write-up on them, but several adjustments to my listening room need to be completed first. In the interim, I was searching for a low power (<10 watt) amplifier I could replace my Lance Cochrane 6550 amplifier (50 watts) with to fully exploit the La Scala's efficiency. I was very intrigued by doctorjohn's praise of the microZOTL2 and after some deliberation placed an order for my own unit, with the intention of using it as an integrated amplifier.

I will spoil the conclusion of the article now: the sound did not work for me and I made arrangements to return my unit to the manufacturer. What follows below is hopefully a coherent analysis of why that is and how I reached my conclusion. Please note I do not really consider it a 'review', nor do I consider myself an 'audio reviewer'. The term makes me cringe, as it has been bastardized by the mainstream audio press and their casual relationships with industry manufacturers. However, it will be a unique opportunity to provide a second opinion to my colleague doctorjohn's on the microZOTL, something which we rarely (read: never) see from the 'professional' audio reviewers. And why not? Multiple perspectives are necessary to reach critical consensus, and infinitely more useful than just one. Sadly, you will not see this from the advertiser-relationship driven audio press. It would not make much sense having two writers tell you how great one component from one manufacturer is when they could each be busy telling you how great two different components from two different manufacturers are.

In recent memory, I can think of only one mainstream review which offered a second follow-up opinion, and that was the BorderPatrol DAC in Stereophile. Unfortunately, it was offered for entirely the wrong reasons: disingenuous journalism to push a predefined agenda, at great cost to the integrity of Stereophile's staff. The original review and follow-up are linked above, though you can read more about the context of the situation in this article from Part-Time Audiophile.

My System

I have never really described my playback chain in detail for the reader, as it has been in a state of constant flux for the last 6 months. I will lay it out now for the context. I currently only use a digital source as my 6 (six!) turntables are all in various states of disarray. This front-end consists of a HP laptop running Windows 10, feeding USB to a USB/SPDIF converter, which feeds S/PDIF to my abbasaudio DAC. The DAC is TDA1541 based and has a low-impedance triode output stage capable of a healthy 4.0V RMS. It can drive an integrated amp directly. My pre-amplifier is The Truth which provides volume control and source switching for the Lance Cochrane 6550 amp. I would like to state I am not really dissatisfied with any aspect of the Cochrane amp's performance. In fact, I am surprised time and time again at just how good it is. However, I did want to see what was possible with lower power, fewer active stages, etc. to really bring out everything my source has to offer. Call it the audiophile's curse. The La Scala's are placed in the corner of the room, angled in 45 degrees to the center, in accordance with Paul Klipsch's placement instructions. Once I tried this placement I stopped considering in-room placement, despite having a good amount of space. Belden 9497 speaker wire is used, my interconnects are all random, nothing fancy, only copper or tinned copper wire.

Options Power supply I ordered the Switch Mode PSU. This is because I really wanted to see if the unit worked in my system before investing in upgrades (in hindsight, a very wise choice) and doctorjohn's praise was sans LPS. Besides, I could always upgrade later. Tubes I requested the NOS upgrade tubes. While I agree with doctorjohn that current production tubes have gotten better, I still avoid them any which way. They always sound coarse and lacking in refinement to old production. I also avoid tube rolling, I prefer when the manufacturer can just supply me with 'the good stuff', like they did in the old days! Remote Yes for me. Remote control for volume adjustment is so important for me. I do not want to be enraptured in a performance and glued to my seat only to feel the volume is one tick too quiet or too loud. I do not want to get up between recordings of varying gain levels. Most importantly, I tend to stand up and pace around the room when listening. This is a weird trait of mine, I don't really know anyone else who does this, but I like to have the remote in hand and be able to adjust the levels as I walk around.

Day One

Impressions of build quality, finish, pride of ownership are all very high. It feels like a premium unit and I love the see-through top cover. I had already waited three weeks for the unit to ship, so when it arrived I immediately finished work and set it up, connecting my DAC to its RCA input. I did not listen to my system as it was (generally, this is an evaluation mistake) and fired up the MZ2. There was no background even with my ear against the tweeter, which cannot be said for every other amp I have tried with the La Scala so far. The manufacturer had advised no burn-in required, so I began listening right away with a live recording of Glenn Gould live in Moscow Conservatory (1957), streamed from YouTube. (I think another article detailing my obsession with Gould is soon due).

I was taken with what I heard right away! The benefits of removing active stages and output transformer were evident in increased immediacy and physicality. The notes were sharper, each individually more distinct, lending to an impression of increased intelligibility and drive. I recall cheering internally, that the microZOTL was a success and that this was the best piano playback I had yet heard. I listened enraptured to the rest of the recording, which unfortunately is incomplete and ends abruptly in the middle of Fugue #4. Desiring more Gould, I put on Haydn Sonata no. 3 from Columbia ML 5274 (the YouTube link I provided is unfortunately 'remastered' and neutered compared to the local file I have). This was just as exhilarating as the live Moscow recording and I felt rather confident after just two recordings that the microZOTL was the bee's knees.

Unfortunately this confidence would be short lived. I began to explore pop/rock favorites and grew rather concerned about what I was hearing. First was Joan Baez's cover of Fountain Of Sorrow. This is a very typical mid-70s pop production from A&M on early transistors. Very clear and distinct vocals with some light overdubbing and snappy accompaniment. What stuck out with the microZOTL was not pleasing, the snappy accompaniment became annoying and sharp; Joan's voice was thinner than expected and a bit detached, despite piercing clarity and forwardness. Technically, the sound was impressive, all the stereo pop record tricks were highlighted like fireworks, the bass was 'tight', but the sound had an unnatural insistence to it not unlike servo-controlled direct drive turntables. I was disappointed and put on a few other pop records, wondering if it was a fluke, but unfortunately heard more of the same. I decided the unit needed break-in and left it to run signal overnight.

Day Two

I returned after the unit had 24 hours of play time and ran through the same recordings as yesterday as well as new ones. I cannot say the sound character changed at all, and I heard the same traits. The playback was too damped; similar to what I would expect listening to the raw multi-tracks of a pop record in a studio on an analytical monitoring system. There was a lack of weight or gravitas around the middle frequencies, voices in general seemed shifted a pitch up. I played all sorts of 60s pop/rock such as Hendrix, The Mamas & The Papas, Jefferson Airplane, etc. hoping to hear a baggier or fuller sound, but it did not come. I did not have a strong desire to listen and decided to return after the 100 hour mark had passed.

Day Five

I returned after the unit had 100 hours of play time and ran a loop again through all the same recordings, listening acutely for improvement in my areas of concern. One thing is for sure, the sound character did not change at all with break-in! I had watched the Johnny Cash biopic Walk The Line (2005) the previous night and decided to run through some of his catalog with the microZOTL. This was the final straw, Cash's voice was lacking its smokey Southern chestiness and I found the rockabilly tunes repetitive and fatiguing, despite impeccable 'timing'. This was especially shocking considering I had just been enjoying them on my Vanatoo desktop speakers the night before.

At this point, I shut off the microZOTL and switched back to the Truth + Cochrane combo. After 15 minutes of warm-up I played the same Johnny Cash tunes. Instant relief! The body returned to his voice, the accompaniment was certainly a little more smeared and not as lithe but certainly played with more warmth and communication of musical intent. If anything, the little bit of smearing contributed to a greater sense of 'human' playback. An analogy can be drawn to the 'quantization' of modern pop/rock records which removes all human elements in favor of perfect transients and timing. The effect here is not so drastic but easily felt when switching back and forth.

I went in a complete backwards cycle, playing through every record from the past week and with each felt more relief, less annoyance, more enjoyment and relaxation. I came full circle to the same 1957 Gould recording from day one and realized that I preferred that too on the Truth + Cochrane. The recording was actually transformed, as if I was hearing an entirely different interpretation of the same piece. Gould's playing was less frantic, the individual notes stood out less but their relationships and melodies a hundred times easier to absorb. Intonation especially in the low-end came through clearer. Despite having four cascades (6SN7 input, 12AU7 voltage gain, 6CG7 phase inverter, 6550 output) and an overkill power rating for my speakers, the Lance Cochrane amp scored higher where it mattered.

At this point, my thoughts on the MZ2 must read as very critical and fairly negative. I want to be fair to it as a component and provide a description of its sound, in my system, absent from the feelings experienced or recordings played in the past week. To do so I will use the framework for all aspects of sound provided by Anatoly Likhnitsky's 7 Words About Audio Examination Errors (2001) to dissect the MZ2's sound character.

• Sound proportions (include tonal balance, spatial impression, clarity of sound and dynamics).

Tonal balance is linear, although slightly devoid of euphony or saturation. Spatial impression is distinct with regards to stereo effects as aural objects are thinner, sharper, less stuck together. Clarity of sound as it relates to absence of veil and electronic masking is very high. Dynamics are sharp but the sound is lacking in satisfactory fullness in the LF which in turn affects the dynamics.

• Soundness of sound (includes vividness, saturation, brightness and naturalness of sounding of music tones).

Saturation is lacking. Voices, wood instruments have a slight pallor, lack of rosiness. Many musical tones take on a frantic, insistent characteristic that can be distracting. Brightness and vividness are present in that the sound is forward and un-obscured, but is more like monitoring a direct mic feed than playback of a finished record.

• The emotional content of the “sound” (energy, emotional mobility, emotional diversity of the sound of music).

At first confusing and paradoxical, why the emotional content of sound is absent despite the presence of technical excellence as it relates to timing, rhythm and articulation. Ultimately, the sound is stripped of emotional content for the above reasons. 

• The spiritual content of the “sound” (a sense of the appropriateness of the distribution of musical sounds, the nature of their sound production, intonation, dynamics, rhythm, etc.).

The highest level of perception, which is inaccessible due to the shortcomings listed above. The greater sense of intelligibility from the microZOTL is false, as it is technical and not spiritual or emotional in nature. I really wish this wasn't the case, as for me it is the ultimate damnation of any audio component.

Conclusion

So, you can tell by now the microZOTL is not for me. The technical reasons behind this I can only hypothesize about. You will probably notice that I have not referenced anything from doctorjohn's initial post about the MZ2. This is because I don't actually disagree with anything he said, though obviously our conclusions on it diverge. I could have read his post 100 times and still not have been prepared for what my experience was, but this does not make his review a bad one. Just the same, you may read my impressions and be largely discouraged from trying this amplifier, but you might really like it! When I get curious about something, I try it for myself and form my own conclusion, that's that. Victory or Defeat? I know a lot of people get discouraged when they get a new component and it is not 'the one', and treat the experience as a defeat to recover from. I do not regret at all trying the microZOTL. I have eliminated a curiosity, gained experience, and perspective on where to go next.

Output Impedance The ZOTL amps all have very low output impedance specifications. For the MZ2 it is 2ohms. I have a hunch this is largely to blame for the 'over-damped' character, stripping the sound of its emotional mobility and diversity. I know that when it comes to headphone amplifiers, there is a trend towards a very low OI (<1 ohm) being the most desirable and 'accurate'. This is horseshit, and in my experience these amps sound the worst of them all. Perhaps this issue is only exacerbated by the 16 ohm La Scala's. The Circuit In Sound Practices issue #15, editor Joe Roberts slips in this paraphrased quote: "Sure the Loftin-White was a great amp but if it was that great why isn't everyone listening to Loftin-Whites?". I believe the same can be said of the ZOTL circuit. The transformer is being replaced in the circuit by an impedance matching network of surface-mounted resistors, which will bring its own sound compromises like everything else. For me this was not preferable to transformer coupling. The Evil Output Transformer Actually, the entire basis of ZOTL is that output transformers are a source of distortion which should be eliminated. I will not try to argue with what the scopes say. I will say that there are schools of thought which view the output transformer as a necessary randomizer of sound. The curious and intellectual reader may learn more from Anatoly Likhnitsky's Formula of Sound. With Pre-amp Something that I am not able to try, which doctorjohn did, is use the MZ2 with an active line stage before it that would have a complimentary sound character. I only have The Truth, which does not have much character to speak of, and didn't help the situation when placed before the MZ2. I will say that I never felt the MZ2 was running out of steam or drive with the La Scala's, output power and gain were definitely not concerns.

doctorjohn also asked me to assess the MZ2 as a pre-amp and headphone amplifier. The two components I have for these categories, The Truth line stage and the abbasaudio OTL headamp, I already consider to be 'best in class', and the odds are stacked highly against the little ZOTL amp. I did try it as a pre-amp in front of my Lance Cochrane 6550 and as a headphone amplifier driving my modified HD600s. My conclusions are in-line with what I wrote about it as an integrated amplifier, although its primary shortcomings (lack of euphony, damped sound character) were more apparent listening with headphones as I am particularly sensitive to these aspects there. I will note that the MZ2 performs all three functions and costs the about same as just one of the dedicated units it battled against.

Lastly, a bit of an easter egg in the film Walk The Line (2005). In one scene Johnny Cash (Joaquin Phoenix) is in a radio station ready to debut his first single, when the operator asks him to flip the record. Given that this scene was supposed to take place in the mid-50s, the broadcast equipment is very accurate! You can see a Gray Research 106SP tonearm in action, mounted to what must be a Gates or Rek-O-Kut 16" transcription table. Good attention to detail from the Hollywood set designers!

Linear Tube Audio MicroZOTL Elekit TU-8150 Klipsch Heresy

Click pics to enlarge. Bottom, wires from RCA to TP3/4. Note the disabled resistors (under the red wire).

Review: Linear Tube Audio MicroZOTL MZ 2.0, Part III, as Preamp
Review: Elekit TU-8150, Part IV
HiFi Basics XI: Pre-amp or not to Pre-, That is the Question
Review: Klipsch Heresy I, Part IV

Linear Tube Audio, Part I (mostly as amp, with my 104 db YL horns), Part II (used as amp in the Living Room with 97 db Klipsch Heresy I).

Elekit TU-8150: Part I (Basic Info; 6AQ5 vs 6V6), Part II (Pentode vs Triode; Input 1 vs 2), Part III (tested with bookshelves).

Klipsch Heresy, Part II, Part III, Part IV (this includes the important comparison with the Elekit TU-8800VK)

Elekit TU-8800, Part II

Minor Modification of TU-8150
After rather exhaustively testing the TU-8800VK and given my fondness of the 6V6 tube, I finally summoned the energy to perform small modifications to my TU-8150.

In TU-8150, Part II, I discussed the topology of this amp. To quickly summarize, compared to the TU-8800, this is a modestly endowed amp, with a much smaller transformer (which is not necessarily a bad thing). It is a sibling of their popular TU-8200 but designed to run the low powered 6AQ5 and 6V6. It is also apparently designed for the desktop. Input 2 (RCA in the back) is routed to the minijack input in the front before going to an op-amp (for amplifying weaker sources like cellphones) and then the 50K volume pot. I removed the op-amp for purer sound. I wrote this:

1) The long signal signal path of the RCA Input 2 is certainly not ideal, but looking at the schematic one can disable R101 and R201 and solder a jumper wire between the RCA terminals and TP (Test Point) 3 and TP4, thus bypassing the Op Amp stage altogether; 2) Even if the Op Amp is removed, because of the associated circuit the signal still passes through 2 more resistors before reaching the 50K main volume pot - the 4.7K resistors (R102 and R202) before pins 6 and 2 of the Op Amp and the 22K resistors (R103 and R203) connecting pins 6 and 7 and pins 2 and 1 before the 50K main volume pot. That is 26.7K (22K + 4.7K) of resistance that can be bypassed if TP3/4 are used. If one uses the RCA Input 2, even with the Op Amp removed, there is a total of 36.7K of resistance before the 50K volume pot, making a total resistance of 86.7K if the main volume is maxed out. One notes that in SET amps the line level signal usually directly goes to the main volume pot, and 100K is the more popular value. One can use jumpers and eliminate those 4 resistors (R102/R202 and R103/R203).

As you can see in the pic above, I did (1) by disabling R101/201 (lifting one end) and wiring the RCA directly to TP3/4 (just before the potentiometer) using the conductors of Belden 8451 (just as I re-wired my TU-8300). For the moment I did not tackle the R102/202 nor R103/203, so if the minijack is used the signal will still see 26.7k of resistance before the potentiometer.

Used in Ultralinear Unlike before, given the somewhat lesser sensitivity of the Heresy I, I opted for Ultralinear Operation.

TU-8150 Used as Integrated Amp I have actually never tested the amp before like that. Suffice to say it played well but volume had to be turned way up and so it was not the most dynamic. Clearly a preamp would benefit it.

LTA MicroZOTL MZ 2.0 + Elekit TU-8150
System used is the same as testing TU-8800VK, except that now the LTA is inserted as a preamp (with Gotham and Belden as interconnect, see below). With the volume knob of the Elekit TU-8150 maxed out (something that cannot be done with the TU-8800), the volume knob of the LTA is around 1 O'Clock:

Turntable (stereo): Thorens TD-124 Mk I with Thomas Schick 12" arm and Goldbug Clement II MC Cartridge.
Turntable (mono): Technics SL-1200 Mk II with Denon DL-102 Mono Cartridge。
Phonoamp: Arcam rPhono (to Gotham GAC-2111 interconnect)
CD Player: Magnavox CDB 262 (to Gotham DGS-1 interconnect)
Preamp: LTA MicroZOTL MZ 2.0 (Gotham GAC 4/1 or Belden 8451)
Amp: Elekit TU-8800 (Belden 9497 loudspeaker cable)
Speakers: Klipsch Heresy I (alnico)
Subwoofer: Pioneer SW-8 (connected to amp with generic cable)

• Bass As soon as I played something (it was Nick Cave's The Boatman's Call)), I was really taken aback. Surely, there was more bass! I dialed back the subwoofer volume a little and listened again. Now, the balance was about right, but it was apparent it is not just a question of loudness, as the bass is even cleaner, better delineated and a little deeper! This is likely attributable to the LTA, which has phenomenal speed and bass (read my LTA, Part I).
  

• Air and Detail Also, given that I had come off the excellent upgraded Elekit TU-8800VK, I was very happy that the combo yielded little to the former here (using 6V6). As a matter of fact, there is a somewhat deeper soundstage, more air around instruments and more minute details.
  

• Transient, Microdynamics and Flow The system's faster transient means enhanced microdynamics and more truthful timbers. Whether it is Nick Cave or Dvorak 9th (Detroit/Paray, Mercury), it is exciting, but never strident and always with enhanced musical flow.

• Power Despite the somewhat more refined and sparkling manner of the LTA + TU-8150, the combo does not sound quite as powerful as the TU-8800. People with less efficient loudspeakers may have different conclusions.

• vs TU-8800 In some ways this is a non-comparison. Elekit vs Elekit Although under the same roof, the 2 amps are quite different, especially in gain structure. The TU-8800 basically cannot be used with an active preamp (particularly if one plays vinyl) whereas an active preamp is needed to max out the TU-8150's performance. Of course, if I install the Op-amp back into the TU-8150 (as initially tested in Part I)  I'd have more gain but it is still likely not as high as the TU-8800 (or 8300 for that matter). That said, I'd think the TU-8800 is better built and more versatile, though for someone who prefer lower-powered tubes like 6V6 it is likely an overkill. LTA vs Elekit TU-8800 Let me clarify this. There are 2 facets to this: We are pitting 1) the LTA (as preamp) against the preamp section of the TU-8800. Now, I don't have the schematics of the TU-8800 so I don't know whether it has an active preamp gain stage or is just an amp with a passive volume knob (latter more likely). But the result is clear - I prefer LTA + TU-8150 to TU-8800(VK) on its own, but this is because I can get away with 6V6 (not many can), and the LTA preserves its own sterling attributes used as a preamp; 2) LTA as amp vs TU-8800 I think I prefer the more subtle sound of the LTA, but it loses out in sheer grunt. Contributing Factor of the Active Preamp To my thinking, part of this is due to the contribution of an active preamp. I have written extensively about this - unless I am faced with an amp with very high input sensitivity, I prefer to have an active preamp (especially since I am a vinyl addict). The "scientific" basis is not certain (just as "science" is used as a refutation of vinyl), but that's what my ears tell me. For more on this, read the HiFi Basics part that finishes this article.

• Note: I do think a little more power will not be remiss. The LTA will be staying in the system as preamp. I am going to rotate some amps more powerful than the TU-8150. Next up will likely be the AES AE-1 300B amp. 

HiFi Basics XI: Pre-amp or not to Pre-, That is the Question This is excerpted from a very long previous article. Regular readers may want to skip it. I am just using this opportunity to turn this into a HiFi Basics Article for indexing purposes.

DIY, Preamp, Passive Volume Control, First Watt and Low Powered Amp

• Is an Active Preamp necessary? Audiophiles are divided into the pragmatics and the theorists. The former will try anything if it makes the system better. The latter believes in numbers and have strong beliefs on many issues. There can be no more contentious issue than whether an active preamp is necessary. Take the standard CD player output of 2V, if you run that directly into your amp, it will be ruinously loud. So the preamp actually attenuates the signal going into the amp. The classic active preamp has gain, sometimes a lot, but in the end the signal is also attenuated before going into the amp. Many people take this to mean a passive preamp is all one needs. Why amplify and then attenuate? In theory this is correct, but in practice things are very different - the setups I have heard with passive preamps (including my own and those with source going directly into an amp with a passive volume) easily number more than a hundred, and in no more than a handful of instances did I not long for an active preamp. Let's look at this in detail.

• Passive Volume Control (PVC) Basically this is a volume pot. You can easily build one with a cheap volume pot, or you can spend thousands using boutique parts and ultra expensive resistors. My Audio Synthesis Passion V (a pic from the net to the right) costs a lot, and the cost of the parts add up to more than the second-hand price! Here are some factors influencing performance: Amplifier Sensitivity Amplifiers with high input sensitivity, such as Leak, works well with PVC, whereas those with low sensitivity, like Quad, would not. Source Output Most CDPs output a standard 2V, but there are exceptions. The vintage Muse Model 2 was supposed to be a very refined sounding DAC, but it has an unusually low 1V output. I heard it once many years ago in Opera Audio in HK. The late Stanley Chu had it in a system with 300B amp and Klipsch La Scala, but I just found the sound dull. On the other hand, Audio Note UK is known for the very high output of its DAC's. My vintage DAC-2 (here) has a monstrous 10V max. It was designed to be able to drive AN amps (those with volume knobs) directly. High Source Outputs work better with PVC. This is why imho people who play vinyl should NOT use PVC. Signal Loss and Buffer One reason why preamp with gain drives the amp better is that a PVC by nature can only use a short interconnect. Preamp with gain can drive much longer interconnects. Even more important, many active preamps actually buffer the output, which has a great advantage in impedance matching. Transformer Volume Control (TVC) This is now all the rage. Since a transformer naturally "buffers" the output, it has advantage in impedance matching with the amp. Some can even have gain, which is a plus, especially for those who use analog sources. But TVC's are not without problems: 1) expense - all are very expensive, more so than a very good active preamp; 2) non-linearity - I don't care what they claim; ALL of them cannot be linear across the range due to the compromises in winding; in fact, non-linearity can be severe. All the claims for better cores, wires etc are exaggerated. It is ironic that the DIY enthusiast can put so much faith into TVC, as they cannot easily measure the TVC's performance under dynamic condition. That said, some do sound reasonably good.

• First Watt I am a firm believer of First Watt, which has to be: 1) of good tonal quality; and 2) of good dynamic capability. The former is not hard to achieve, but the latter is often ignored. In forums I see many DIY people using flea powered amps with PVC for "pure" sound, but most of those setups are severely lacking in dynamics. There are many people who like the "economy" of an integrated amp, but in almost all cases their "integrated" amp is just an amp with a PVC, incapable of a glorious first watt. There is a reason why a company like Audio Note, which specializes in low-powered amps, use high-gain everywhere else, be it a CDP, preamp or phonoamp (I am actually not a fan of their sound, but I know why they do what they do).

• DIY Woes This is too big a topic for this article, so I shall be brief: I have literally come across hundreds of DIY people in my audio life and, sorry to say, much of the experience is a waste. Too much trust in science and material, too little cognitive insight, too much reliance on internet opinions, too little equipment to compare with. I don't care what you DIY, have a good source (say, an old 16-bit CDP or turntable), integrated amp (say, the cheap NAD 3020) and loudspeaker (say, the Yamaha NS-10M) on hand to compare, and be honest with your failures.