Saturday, February 15, 2014

Tube Review: The Valve Art 350B pentode

The original Western Electric 350B - which I've only heard in a few rare instances - has become one very expensive output tube.  Valve Art, through Shuguang, currently makes a "reproduction" that is extremely affordable and has a nice vintage "G" bulb shape that would look quite good in a pair of Quad II monoblocks or any other vintage amplifier that can handle the extra filament current of the 350B over the more pedestrian 6L6GC.

I purchased a pair of Valve Art 350B from Antique Electronic Supply.  Price is less than $40 a pair, which is quite inexpensive compared to the majority of NOS and even new tubes.  Construction quality is quite high with  welded plates, good looking mica, two vertical support rods, and white ceramic spacers.  No, it isn't anything like a 1940s 807, but it looks pretty close - perhaps if you rubbed off the Valve Art logo it could fool some of your more tube savvy friends... or not.

I plugged the 350Bs into my Multi-Valve amplifier which has adjustable fixed bias.  I dialed them in at a healthy 60mA, perhaps 50mA would be a safer bet for long life, but at this price I'm willing to give up a little longevity for a few (and I mean a very few) extra watts.  After all, I'm not running horn tweeters in a multi-amp system, but a pair of full-range speakers that can take whatever I can dish out.  At this bias setting there was no sign or red plating and the tubes have been working perfectly after a good solid 100 hours or more.  So much for the myth of poor Chinese tube reliability. 

The first record up was Neil Young - Live At The Cellar Door.  Detail - audience coughs and  hall ambiance were all there - perhaps lacking compared to the best NOS I've heard, notably the Philips metal base EL34s and vintage Tung Sol 6550s.  However no frequency aberration stuck out and there didn't seem to be any of the "solid state in a bottle" bleaching that is often the hallmark of new production tubes.  This recording, however, is not the most dynamic so it was time to move on to something else.

My Japanese pressing of The Police - Synchronicity is an exciting and bouncy album requiring plenty of power to unravel everything that is going on.  With the Valve Art 350Bs, I noticed that the bass didn't go as low as the vintage Tung Sol 6550s.  The 350B sounded compressed and confused on the big peaks - perhaps hitting the edge of their power envelope in this single-ended amplifier.   A more efficient speaker could perhaps ameliorate this issue.  I also noticed a touch of dryness - though maybe this is a function of the recording itself.

Pink Floyd - Animals is a perennial favorite of mine - my German pressing is very dynamic with tons of detail.  With the Valve Art 350B, I noticed a murkiness to the sound as if a layer of gauze was making the finer detail and attack of the songs.  Sure, the music was still there, but I found my mind wandering.  The "swirl" - as I call it - was missing; this is the moment when the notes become visual, engrossing the mind with music.  Depth also become shorter and the soundstaging less enveloping than normal.

I tried a few other albums - Roxy Music, Dr. John, an Agalloch CD - and found that the quieter cuts fared better.  Once the dynamics cranked up, the bass would become plodding and the music unrefined, bringing down the system sound quality down several notches - turning my pride and joy into a sonic mess.  Adjusting the current down to 50mA didn't seem to make any difference either.

I really, really wanted to like these tubes.  I mean they look great and I'm usually a champion of Chinese tubes, but - at least with this amplifier - I cannot recommend the Valve Art 350B.  Perhaps in push-pull or with a different transformer load, voltage, or current, or even cathode bias they would shine.  Or maybe I was asking too much out of them, but the SED 6L6GC in the same circuit sounded much better.

Review System:
VPI Aries with JMW 10.5i tonearm and SDS Power Supply
Dynavector 10X5
Cardas Cross 1M interconnects
Quicksilver preamplifier with Mullard short-plate 12AX7s, RCA 12FQ7s, Amperex 12AU7
Cardas Quadlink 5C 1M interconnects
Multi-Valve Stereo amplifier
Cardas Hexlink speaker cable
UREI 813A monitor speakers
VTI BL503 equipment rack