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REVIEW: Tube Audio Lab WE91 300B Monoblocks Amplifier (Tube)

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Model: WE91 300B Monoblocks
Category: Amplifier (Tube)
Suggested Retail Price: $2500
Description: Custom-made WE91 monos, 6C6 driver,
Manufacturer URL: Tube Audio Lab
Model Picture: View

Review by Paul Folbrecht on February 12, 2009 at 09:55:28
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for the WE91 300B Monoblocks

I first came across Tube Audio Labs via an ad on audiogon advertising a pair of custom 300B monoblocks using the venerable and revered Western Electric "91" circuit of theater amplifier fame. The amps were built on square metal chassis painted a matte gray and had a beautiful (to me) "1930's industrial" type look (as Min of TAL calls it).

I have been through a lot of amps and a lot of women in my audiophile career. On second thought, there have been indeed a great many amps but actually only one woman. A lot of amps indeed. I first caught the SET bug about three years ago now and, really, once bitten, have been hooked - SETs just always, in general, sound better than the competing topologies to me. I've owned at least a dozen SET stereo amps, integrated amps, and monoblocks in that time, from many manufacturers. I think I've developed something of an ear in distinguishing different output tube types, drivers, rectification methods, output transformers, and parts.

My previous experiences with the 300B valve were less than thrilling. Like many others, I came to the conclusion that other, lower-power values were intrinsically superior: they were faster, and more direct, in general, never suffering from the 300B plague of slow or thick sound. I'm talking about the 45, 2A3, PX-25, and PX-4.

So, I decided that my Audio Note AN/Es would be happier with a bit more than the 3-4 watts I'd been feeding them (in my large room), and decided that the 300B was *probably* the best bet (if the aforementioned weaknesses, which are unacceptable to me, could be avoided). After all, to do a 211 amp really right costs a fortune, and they generate a scary amount of heat. Furthermore, I was and am still a believer in 'the simpler, the better' in terms of circuit - the fewer stages the better. (A 300B can be built with two stages but I'm pretty sure a 211 cannot.)

Research led me to the WE91 300B circuit, which has many followers, it seems. They claim that this circuit produces an amp with a powerful, smooth, yet highly resolved sound. It's my (far from expert) opinion that there is something very positive about a pentode driving a triode - as is common practice in Japanese circles (Yamamoto, Kurashima). For one thing, the extra gain makes a second gain stage unnecessary, but in addition to that, this configuration seems to offer that 'powerful yet liquid' sound that such amplifiers tend to exhibit.

To cut this long story down a bit, I eventually started chatting with Min, and decided to order a pair of amps. The ones advertised on audiogon seemed an absolute steal at $1650/pr, using quite respectable parts, including all Hammond iron. Partly because my AN/Es have amazing bass extension I did want premium output iron and opted for Hashimoto. Min said he preferred to use the 6C6 as driver (as opposed to the more typical 310A) and a 5R4 rectifier. Other parts included ASC oil caps, Sprague caps, PIO coupling caps, good carbon & film resistors. (While I may do some cap rolling at some point, up to now I've had no inclination to mess with anything.)

Min finished the amps on time (unlike, well, a number of custom builders) and packed them extremely well. I received them the week before Christmas. I'd ordered mine in a matte black finish and they looked great, with that lovely 'industrial' look with bare trannies (except for the covered Hashimoto) and the giant ASC caps protruding from the chassis.

To describe the sound I would say that it is very close to what I was hoping for, but frankly exceeds my expectations in the areas of refinement and nuance. I _no longer believe_ that the 300B is an inferior value to the 45 or 2A3 in any way, I will say that. Despite DC heaters, the amps are extremely resolving of detail and nuance.

And yet very liquid indeed, and enormously dynamic. Now, any well-made SET, with a proper power supply, will be very dynamic within its power limitations, but I must say these amps seem to be extremely muscular indeed. In terms of overall SPL, they are capable of driving my HE AN/Es far louder than desired at any time - which is to be expected.

Do the amps display the slow/fat midbass that is (stereo)typical of the 300B? No, not at all - if they did, I'd convert them to 2A3! The bass is extremely taut and extended. Stand-up bass, as in Evan's amazing Village Vanguard, displays no bloom beyond what's on the recording. (I do have my AN/Es about 18" out from the corners, which is not completely typical for these speakers, but to me they are simply sound better there and are capable of precisely sculpted bass, sounding as articulate as any sealed cabinet.)

In closing, despite going to virtually all Audio Note Kits electronics (DAC/pre/phono pre), I am keeping these amps at least for a good long while. They give me the musical, smooth, dynamic sound I crave, with abundant nuance and musical information, and have essentially no weakness I could point to as anything significant.

Product Weakness: None
Product Strengths: See above

Associated Equipment for this Review:

Amplifier: Tube Audio Labs Custom-Made WE91 300B Monos
Preamplifier (or None if Integrated): Eastern Electric MiniMax
Sources (CDP/Turntable): Audio Note Kit DAC 2.1C Sig/Acoustic Solid Classic Wood, RB300, Blackbird
Speakers: Audio Note Kit 3 AN/E
Cables/Interconnects: VH Audio, Anti-Cables, Morrow
Music Used (Genre/Selections): Jazz/rock
Room Size (LxWxH): 30 x 30 x 15
Time Period/Length of Audition: 1.5 months
Other (Power Conditioner etc.): Running Springs
Type of Audition/Review: Product Owner

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