Altec 604E Infinity RS-1B ARC D90B 6F8 vs 6SN7

Click pics to enlarge. Bell 2122C atop the 604E. Note the contraption in front of the added tweeter, an imitation of the passive Xinshe 597. On the shelf Chinese Preamp with 6F8G, next to Conar SE EL84 amp (not used).

Letter from NYC (23-13): Labor Day Weekend+, Part IV (Tuesday), Escape from NY!

Written in Shenzhen

(Continued from Part III (Monday)) Now, I had not planned anything for this day, as I had to fly back to HK middle of the night. It was a busy day. As usual, I woke up early, and did laundry. Then I started to move the various gear back to their storage. Turned off some power banks. Closing up shop. Then the building superintendent came to inspect the balcony. And then the Telephone Rang...it was Kevin...

Kevin had some uncooked stuff left over from a BBQ party the previous day and wanted to invite me and Andy to listen to his recent endeavors (see below). I was hesitant, but how could I refuse? So I galvanized myself and did as much as I could have before Kevin picked me up around 12:00. We then picked up Andy, who had a big surprise. His friend had gone fishing and gave him a Fluke from his crop. This we took to Kevin's house. Dead but fresh Fish...

Altec 604E And so we listened to the latest iteration of Kevin's Altec 604E. I don't write about every one of our meetings - how could I? Suffice to say, over the 2 months in NYC, I came here a few times. I shall take this opportunity to explain it a little. The modern crossover is likely not bad. To balance the sound, Kevin had tried adding tweeters. The last round was with EV (the ones used in Klipsch) but he had settled on the ones in the pic (L-pad used). We don't even know what they are but they do help to raise the image height and impart a little more openness. More interestingly, sometimes Kevin adds a Diatone fullrange (mounted in the center of an LP). One time before, I listened to each, connected or not, and concluded it did make a difference for the better. This round, we listened to them being driven by Bell 2122C, but with a Chinese Preamp in front. This one employs 6SN7 and has regulator tubes. In a previous round, it sounded superior to its sibling without the regulator tubes. 6SN7 vs 6F8G Kevin had been running the preamp with the 6F8G (with adaptor) I gave him a long time ago. On this day, at his asking, I brought a pair of RCA 6SN7, and sure enough, it outperformed the 6F8G. The 6F8G has more oomph, but the 6SN7 is more subtle. Interesting, as many on the net professes the superiority of the ST 6F8G. Andy chipped in, and said from his own experience he prefers the 6SN7 too. This round of the 604E was the best I have heard, and really quite decent, but I still say, with A5/A7 around, why bother? They are all equally difficult (a way of saying: impossible) to get perfectly right, but the A5/A7 are for sure better endowed.

During all this time, Kevin was in and out. The dead fish took over and he prepared half of it for us in the upstairs kitchen. Perhaps you don't know this: he was a trained cook!!! Instead of steaming, he poached the fish and it was excellent, aided by some Chinese broccoli. Of course, Andy's wines helped!

Infinity RS-1B and Audio Research D-90B Kevin's Infinity had featured in the blog more times than I can remember (should you care to peruse). Previously, like Andy, he had used the VTL MB-450. He swapped in the ARC D-90B and it made a surprising improvement. There seemed to be enough power, and with the added benefit of a more refined sound. The D-90B (arcdb) is a somewhat unusual one from relatively earlier times. Instead of 6550, the B version sports 5881, at a slightly lower power. Driver tubes are different too, no 6CG7 and introducing 6922. Kevin's unit was bought from Leo and has good tubes in them. Russian 6L6WGC and nice Hungarian Tungsram 6922s. So it seems that the ribbon panel of the Infinity is not that hard to drive! Good news. It is interesting that the same ARC 90B sounded lean with the B and W M801 (Kevin preferred his CJ MV-75 there). And so, finally, the Infinity had come into its own this time around. We happily listened to Prokofiev's Cinderella Suite (OSR/Ansermet, London STS). Very good. The Infinity is perfect for Prokofiev, and it recalls listening to Romeo and Juliet (Cleveland/Maazel, London) upstairs at Andy's (it's been ages).

 

Kevin dropped me back in Flushing around 3:30. I returned some magazines to the library and ran some errands. Back home, I frantically mopped up and packed. Around 9:30 pm Kevin picked me up and drove me to the airport. Thus concluded this round of mad dash and my return to NYC. I had the feeling that I had escaped, far from the madding crowd.

 

Poached Fluke and Chinese Broccoli

Another occasion, authentic HK style food in a restaurant

Another time, cheese from NJ Amish Farm

Below Halal Food Take Out

A bit of the silver ARC D90B can be seem on bottom shelf

This Ultra-Analog Classe DAC is excellent. CJ MV75 below (meters added)

Wild assortment of Decca cartridges and accessories

TT Galore

Can someone give some info on this driver?

Yamaha B2 NS1000X ARC SP10

From Our Readers (21-3): Roy C on Yamaha NS1000X with Yamaha B-2

Ed: As a longtime admirer of the NS1000 (which I'd gladly re-own any day given the right circumstances), and having penned many articles in this blog on these legendary loudspeakers, I enthusiastically welcome this article from a fellow reader, and it's a delight to encounter the equally legendary B-2!

BACKGROUND

Yamaha NS1000M & NAD 3020B has always been my favourite combo in the small 100sf audio room. I enjoyed the sound so much that I finally got hold of the bigger NS-1000X from Hifido Japan… & then the journey began!

ABOUT THE YAMAHAS
Yamaha NS1000X speakers (84'~88'), heavier (42kg) & newer model of the well known NS1000/1000M series. Similar high/mid BE drivers with 12" fibre carbon woofer. The In-line drivers layout is a copy of the higher model - NS2000. NS1000X was used by Luxman Japan as reference speakers up to 1979, along with a pair JBL K2 M9500! Some recognition there… at least in Japan domestic market. [Ed: see vintageknob)

Yamaha B-2 power amp (76'~80') uses 4x VFET per channel, 2x100w (8 ohm), dual mono design, separate transformers & twin volume pots. Some feel that VFET is the "most emotional" power transistor and having triode-like character similar to 300B. The VFET had ceased production since 80's due to its high cost. [Ed: see vintageknob]

THE SYSTEM
Power amp : Yamaha B-2
Preamp : ARC SP10 and Preamp section of NAD 3020B
Digital : Sony SR200P<DAC (Sparkler S306 or Micromega Mydac)
Analogue : Kenwood 600<Jelco<Denon DL301ii
Cables : Gotham & Belden

THE JOURNEY
My original NS1000M/NAD 3020B combo was musical and non-solid state sounding. Though different, it was as enjoyable as my other SET tube system. However, when I got the NS1000X and paired the 3020B with it, the magical synergy disappeared. Perhaps the NS1000X 6-ohm design and carbon fibre woofer calls for higher power than the 20w/ch 3020B is capable of. [Ed:1]

Next came Luxman SQ507X. Someone in Japan had great success with 1000X after auditions against various amps. Having 60w/ch, modeled after the highly acclaimed Luxman SQ38FD, the sound was more powerful, more 3D, but warm & soft just like old tube amp… but to my ears, it was just OK [Ed:2]. As the preamp section of the vintage NAD 3020 series has been praised by collectors [Ed:3], I was convinced to use 3020B as preamp with the power amp section of the Luxman driving NS1000X…Things seemed settled. But searching for ways to improve 1000X has always been on my mind.

In early 2021, a mint & reasonable priced Yamaha B-2 came on board. Paired with the preamp section of the 3020B, with the Yamaha B2 Vol pots arbitrarily set at 12 o'clock, there were more low level detail; mids/high have faster transients, and mico-dynamics had improved…the system appeared very much modern sounding. Still, to someone exposed to years of tube & SET, I felt something was still lacking – musicality.

I then tested B2 with my old ARC SP10 preamp, with the B2 gain pots set at the same 12 o'clock. It was an obvious mismatch (maybe impedance?) as there was unwelcoming high freq edge that was wearing, even with short listening sessions. The 3020B was then back as preamp. Sounded good again with some CDs, just OK with others, but still not as great as I have hoped from a B2/1000X combo.

The breakthrough came about when I recalled how we tested the B2 for function at the dealer's place: no preamp was used, DAC directly connected to B2 & gain pots set at 8 o'clock, A full range sound was audible in the big 350sf showroom. This implies the B2 works well even at low gain pot setting!

I then reconnected SP-10, lowered B2 gain pots to 9 o'clock & upped the volume control of SP-10. The sharp high frequency gone, hall sound & imaging came back, background noise lowered, more space in-between instruments. I felt the energy of piano keys & vibration of drum skin. Transients, attack, rhythm N pace all improved!

CONCLUSIONS

Ability to use power amp gain pots with preamp volume control adds a wonderful new dimension in system fine-tuning. [Ed:4]

Tube preamp SP10 improves musicality for sure. Maybe high-end SS preamp like Spectral DMC-12 or Krell KBL could do likewise or even better with B2, but that has to be tested. [Ed:5]

Tube Pre with SS power is exciting and rewarding. However I still gladly return to my other full tube SET setups for totally different sonic enjoyment. I am very fortunate and delighted to have different setups for different music & listening moods.

Footnotes
{1} Yamaha 1000X placement is of great importance. Huge Improvement achievable by mere repositioning. Great patience and muscle needed. Unlike conventional speakers, 1000X (2nd order X'over sealed box) has to be placed closer to a solid front wall, no toe-in.

{2} Yamaha B2 generates lots of heat. To protect and prolong the VFET lifespan (great pity not replaceable), suction fans are placed on top of B2 casing and ON after 30 mins into operation.

Editor's Postscripts: [1] Both rated at 90 db, the lower 6 ohm rated impedance of NS1000X is certainly less benign than the 8 ohm of the NS1000M. That said, the 20 wpc of the NAD is marginal even for the NS1000M, though the synergy is surprising indeed, as I had enjoyed this combo in a smallish space for 6 years; [2] Luxman usually sounds softish; never consider their preamps - no dynamics; [3] actually, I think few use the preamp section only. I am one who had praised it, as did my friend Hoi. That said, the standalone 1020, which is basically the same, does have a good reputation; [4] your results can be used to argue by some that a passive preamp will work just as well, if not better, though I don't think so. The B2 is likely of high input sensitivity, which is why it does not work well with the high gain SP-10 (a whopping 26 db just for linestage) initially. Then, there is the issue of the volume knob of the preamp, which at low settings besides not tracking stereo linearly often does not sound so good. It should be noted that many preamps, including the ARC SP-11 (but not the SP-10) have both Level and Gain controls, allowing one to finely tailor. That said, when 2 components both have volume knobs, it always pays to experiment with settings; [5] I doubt it. Certainly Krell has never made an outstanding preamp.