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.