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|For Sale Ads|
|Model:||WE91 300B Monoblocks|
|Suggested Retail Price:||$2500|
|Description:||Custom-made WE91 monos, 6C6 driver,|
|Manufacturer URL:||Tube Audio Lab|
|Review by Paul Folbrecht on February 12, 2009 at 09:55:28|
IP Address: 22.214.171.124
|Add Your Review|
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 Strengths:||See above|
|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|
How did it compare to the Wavelength and Art amps that you had.
Get those gruesome "russky caps" out of the circuit and replace them with some dignified capacitors!
Read your review on the Lux 91 on 6moons. Like to hear your views on how it compares with the TAL WE91 that you have reviewed here. Also wonder if you have a chance to compare with the sophia Electric 91-01 300b that Jeff Day liked so much. Appreciate very much if you could share your experiences.
"Live free or die"
Great review, Paul! Very nicely written, especially when it's in my favor. I do like the WE91A design. It definitely has a very distinct sound (interesting and old), partially thanks to the pentode driver and 2:1 plate to screen grid suppressor voltage ratio. It is an acquired taste for some. I'd liken it unto finely aged Kimchi. Some hate it, some love it.
If any of you are going to build a WE91A with the 6C6, I'd suggest extra caution be taken about the value of caps used for the screen grid (suppressor) of the 6C6. To get more refined bass, I'd recommend 2uF - 2.8uF oil caps. Anything outside this range or different material of caps will give you a slight upper midrage glare that nobody wants.
AN makes some great amps, but I am not too sure about their dogmatic approach to detailed-oriented sound. Most of SE amps that I have seen by them have a driver in SRPP stage using high mu tubes. Sure it brings out more details, but it seems to lack musicality and warmth. That's just my 2 cents.
"The only thing I know is that I know nothing"
I have to say that I would never refer to Audio Note sound as 'detail-oriented'. It is detailed, yes, but in a perfectly musical way (like, say, Shindo).
I like your amps, dude, but DON'T MAKE ME CHOOSE BETWEEN YOU AND PETER!!!!
[runs from room in tears]
Just a small correction or two,
1.) We go for anything but a detail oriented sound, what we voice our products to achieve is a balance between all elements of the sound, in my view too much direct focus on any facet of the sound is highly undesirable, as it draws too much attention to itself, which is why,
2.) we generally use the circuit configuration most suited to the job, which includes, anode follower drivers in most products, and at the upper end of the range driver transformers, in fact the only amplifier we make that uses shunt regulated push pull driver stage is the MEISHU and the Kit One (which is based on the MEISHU circuit anyway)
So you cannot have seen too many of our amplifiers, if your impression is that SRPP features as a mainstay in our circuit choices.
Have you compared the sound of the 6C6 vs the EF37A or other pentodes?
I haven't tried the EF37A, but I did try 6J7s and 5693s. The 6J7s seems to have that midrage glare, which made me to look elsewhere. I like 5693s in Raymond Koonce's WE91A clone circuit. They are a very refined and proportional sounding tube, at least in the WE91A circuit. -Min
"The only thing I know is that I know nothing"
Have owned over 30 SET amps. Most all types and I keep coming back to 300b DC.
Direct coupled or DC on the filaments (as per the reviewer's amp)? I am guessing direct coupled.
I've never heard of a direct-coupled 300B.
Didn't think it could be done. Well, yes, if you use 3 stages (Fi), then yes. But not two.
The Lux is a 3-stage amp.
I could have sworn the Fi 300B was 3 stage as well.
A three stage directly coupled 300B amp would probably require a 1000 volt power supply. There are a few directly coupled designs floating around out there that are two stages, which keeps the power supply voltage reasonable.
The newest Fi design has a coupling cap between 6SN7 and 300B.
Yep, there are a fair few 2-stage directly-coupled 300B amps out there. Quite a few in the DRD style. I have been thinking about direct coupling to a lowish dissipation 300B (300V, 50mA, 5k-ish load), tho could proabably use a 2A3 for less $$$ and similar power. Sonically?...
Hifi Collective's 300B and Brian Cherry's Lux 300B both use 5687, directly-coupled to the 300B ... about 10mA in the former, about 20mA in the latter. am sure there are others ...
Well, you beat me there, John! :)
I would think with all your other Audio Note gear that you would go for something with their iron.
I don't if others have heard this, but their (AN's) high end transformers just don't sound that good replacing "ordinary" transformers in ordinary gear.
"Live free or die"
different operating point into a different primary impedance.
Did you notice that I didn't buy a version with Hammond output iron?
Ah, Hashimoto, good call on that one!
Seriously though, it seems to me a touch disingenuous to list for $1 and not sell for $1.
I *like* the loudness button!
Nice review. You described much what I am looking for in music reproduction (at the moment) very well. Your comments here and others I have read recently suggest that I may have to look into this topology (which I had previously decided to pass over).
From the various comments I have read and some listening many years ago it seems that the 300B character can change considerably with alterations to the operating points...
Do you know if the 6C6 tubes are being used as pentodes or triode-strapped?
Pentode! It would not be a WE91 if the driver were not a pentode - right?
(I believe Min dislikes the 310A as he doesn't like the new-prod and the NOS, of course, are very pricey.)
It would not be a WE91 unless it was made by WE.
Nobody would argue with that, I don't think.
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