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cdwitmer 27th March 2008 05:48 AM

The days of wine, roses & WE205D
(A Japanese friend's WE205D SE amplifier)

Because I started to get some queries about my friend's amplifer over here, I decided to start a new thread (not that I expect it to grow very long) to avoid cluttering up the thread about Feastrex speakers. So here is a quick look at what he has done:

And his comments about it:

"It is with a sense of awe that I undertook to build an amp around this classic output tube -- a real world treasure. I decided to keep things extremely simple and easy on the tubes, going from a triode connected pentode first stage to resistance load, coupling, grid choke, and then to output stage. The grid choke was also used to take good care of the WE205D tubes. Output is about 1W. (For my cloistered existence, 1W is more than I need.)

"I did try to use excellent quality parts, such as the Noguchi Transformer "Finemet" (nanocrystalline) core OPT and choke, a stainless steel chassis, KM capacitors (cathode bypass), Vitamin Q (coupling), Dale resistors, WE capacitors (output stage cathode) Western Electric wires, etc. Back when I built this amp, I still had a job and some spending money.

"I played around with voltage amplification tubes in all stages, trying out the 6SJ7, 5693, WE717A, WE409A, etc., but it was the WE409A's overwhelming power of musical expression that surprised me. The sound of the recording venue is completely different from other tubes. I found this difference to be amazing. Ever since then I have been in love with the WE409A.

"I like the pure, tight bass and a superior vibrant midrange of push-pull amplifiers, but the unique tone of this single-ended amplifier, with its smooth harmonies and silky touch seem to grow on me as the years go by. And the years are going by . . . "

-- Chris

Serge66 27th March 2008 10:16 AM


gary s 27th March 2008 10:35 AM

Hi Chris.

With parts at one's disposal like these, it is no wonder the amp looks quite magnificent. I can only imagine what it sounds like with these truly amazing speakers.

Your friend should be proud of his achievement.

Absolutely beautiful. Thanks for sharing it with us.


korneluk 27th March 2008 02:01 PM


Very well executed. I like the socket adaptors to try different pentode drivers.

How about a schematic?


-- josť k.

cdwitmer 28th March 2008 05:43 AM

Ask and ye shall receive . . .

Follow-up comments from my friend:

"Some people say that if you're going to use the WE205D, you might as well use the 45. I'm 100% in agreement with that. The WE205D costs 10x-20x what you would pay for the 45, but the sound character is almost the same. The 45 is a wonderful tube and a great value. (Speaking of RCA here.)

"Another apparent alternative is the TJ FullMusic 205D, in a new shape without the pointy head. The pins too have been changed to the same easier to use UX type as found on the 2A3. When the power comes on, the filament lights up attractively through the mesh plate. It's a delight to the eyes . . . but not to the ears. It might be DullMusic or NullMusic, but "FullMusic" is a misnomer, unfortunately.

"The WE205D's pins are unusual, and the heater voltage is also unique at 4.5V. And on top of that it is expensive, but its sound is just ever so slightly harder than that of the 45 -- and a wee bit more refined, in my opinion."

L to R: RCA-45, TJ FullMusic 205D, WE205D

The TJ FullMusic 205D has a beautiful mesh plate

Note the TJ FullMusic 205D's more conventional UX 4-pin configuration

kmaier 28th March 2008 09:35 PM

Chris, thanks for the schematic post and the feedback on the TJ 205D, etc. It would seem many people have the opinion that the RCA 45 is preferred variant... while I'm not going to disagree, I will point out that many branded 45s out there are not manufactured by the manufacturer labeled on the base, RCA included. The pair of 45s in the pic appear to have different internal construction, and from what I can see, neither is a "real" RCA made 45. I actually have a NOS pair of RCA branded 45 triodes in the original boxes with matching date codes on the base. One is RCA made and the other is not. Note that this was common practice between manufacturers to re-label tubes... simple economics of setting up the manufacturing line for a particular tube type.

I'm lucky enough to have pretty large collection of 45s... many different brands, mostly ST-glass (which I prefer) and some balloon types. I'll try and get some decent pics of the internals and post them with some descriptions. Granted, I do not consider myself an expert on the 45, but I probably have more of them to experiment with than most people. I can show at least 5 different internal constructions in ST glass and 2 internal constructions in Balloon glass that are different. I also find there are some sonic differences between them. As for my personal (current) favorite, I'll put that in the post too.

Regards, KM

cdwitmer 30th March 2008 07:14 AM

How about that . . . I guess tube amps are like potato chips, you can't have only one. Now my friend is ready to start on his next project, 50 watts single ended out of the RCA 805 . . . here are a good 10+ kilograms of transformers to get him started --

I'm glad I can vicariously enjoy all this through him, because my wife would have me living in the dog house if I started building tube amps . . .

-- Chris

limono 31st March 2008 03:38 AM

I built Yamamoto inspired S-08 pair of monoblocks .No as pretty as the one pictured but also using penthodes 717A as an input stage .While I have RCA 45s and other brands too VT-52 is just head and shoulder above 45 even with filament DC supply .
I should not post that but the prices are so inflated already that I can't afford them anyway :
Regards, L

astouffer 31st March 2008 04:48 AM


I should not post that but the prices are so inflated already that I can't afford them anyway
That reminds me of why I stopped subscribing to Vacuum Tube Valley. One page details the history of the 45 tube and the last paragraph says they recommend people conserve to keep the supply around as long as possible. The next page is a project using eight 45s!

limono 31st March 2008 05:13 AM

There are still plenty of 45 tubes around . The thing is just unless you have 104db speakers and use the amp from 200hz up there is no use for 45 Set. (IMHO of course)
Regards, L

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