Stereomour vs. Tucker 45...?

[faithintruth]

Hello everyone. I'm new to the forum and fairly new to tube building. Not sure if here is the right place but my question is about the Stereomour. I have been wanting to build John Tucker's Simple 45 from '97 but almost immediately started comparing it to the Stereomour. My next integrated will be a stereo 45 tube project because I have many. Can someone comment on two circuits....Perhaps only Paul or Doc B. are able. I look forward to your persoective (s).....Sean

[Paul Joppa]

The Simple 45 differs from Stereomour in that it uses direct coupling, which is a sonic advantage. It is more similar to the Paramount in 2A3 form; in fact that is a direct descendant of the Simple 45 circuit - there have been a number of improvements over the years.

A few have converted the Paramount to run 45s, though this is not a supported modification. Be aware that direct coupled circuits tend to be high maintenance and fussy. If it were me, I would personally go for the Stereomour and spend some $$$ on a really good interstage capacitor, such as a V-Cap teflon. That will address many of the issues with cap coupling.

[Paul Birkeland]

I would add to PJ's commentary that having adjustable plate voltage on the driver stage really improves consistency of a directly coupled amplifier, especially as the driver tube ages.  In the design from Oct. 1997, you could get some adjustment by using a variable resistor as the cathode resistor.

JT, Doc B., PJ, and I would all certainly agree that the C4S active load is more developed than the active load presented in 1997. 

[Doc B.]

From a sonic standpoint a lot of the difference is going to be about bass dynamics and weight. The Stereomour simply has more because of the cap coupled circuit andm the 2A3. Running a Stereomour with a 45 will definitely give it more of the lightweight bass presentation of a 45 amp if that is what you seek. The Simple 45 is a very nice sounding amp that I would be inclined to use as a tweeter amp in a multiway system because its forte is resolution and a black background, at the sacrifice of bass punch.

[xcortes]

Hello Doc,

My concern about using different amps on each driver is the potential phase issues. Can you comment on your views/experiences?

Lo mejor para 2015

[Doc B.]

Do you mean multi-way drivers being out of phase due to biamping? In that case, the only reliable thing to do is measure the system and adjust the speaker polarity and/or crossover slope, time aligment, etc. If you just mean does a Stereomour flip phase relative to a simple 45, no. They both have two inverting stages and thus just two phase flips (assuming the transformers are wired right), so they are both non-inverting amps.

[xcortes]

Are there no other phase changes in an amp due to coupling caps, different transformers, etc? If the answer is no then using different amps per driver makes sense.

[Doc B.]

There can be all sorts of stuff affecting phase to a larger or smaller degree. But there can also be major phase differences between a tweeter and a midrange at the crossover point. That's why I'm saying you need to measure the system as a whole.

[xcortes]

Got it. Thks

[faithintruth]

Thanks Guys for your responses. I have certainly liked the few videos of the Stereomour with 45 tubes that I've seen on YouTube. Through the video cam mic the exact response of the amp is not really discernable but one gets a real sense of the amp's character, clarity and pace.

Doc, with regards to bass response I've read many places including from Bill Epstein himself that the 45 was capable of good bass extension and tightness. Azzolina says people should not be fooled that a 45 amp lacks any bass slam or impact (his is a transformer coupled design). I'm not trying to criticize the Stereomour just learn about the 45's potential in it's circuit.

Is there a ccs I could buy separately? 5k OPT's ?

Best
Sean

[Doc B.]

It appears that you really want to love the 45 tube. I think the Stereomour will give it a very good environment to do what it is known for. Beyond that my advice is simply to try it yourself, and form your own opinion. You will just make yourself crazy reading a bunch of opinions on the interweb.

[Paul Joppa]

The SEX 2.0 C4S upgrade kit is basically two current source plate loads. The 5K transformer in the Tucker 45 is from Magnequest, and still available. If you should decide to do the Tucker, it might be best to start a thread at the Magnequest forum:

http://www.audioasylum.com/forums/magnequest/bbs.html

I am there semi-regularly and can offer some help.

Another source is the Legacy Products forum here - the Simple 45 is the parent (or perhaps sibling) of the Afterglow which became the Paraglow I and II (all were Tucker designs), and eventually Paramount 2A3 (my take on that venerable design).

As I said, I'd do the Stereomour 45 myself. Parts, support, and community are much easier to get hold of that way.

[johnsonad]

Give the 45 a try but I'm with Dan. After trying it twice I've given up on it outside of a tweeter amp.

[faithintruth]

Aaron, Did you try it in a Stereomour?  Did you have efficient speakers like Klipschorns? I also worry about its ability to control a woofer. I'm not poaching here...The Stereomour is 850.00 and I'm in Canada so it's more like 1100.00 right now because our dollar sucks.

[faithintruth]

Thanks Paul and Doc. Lots to think about. Support is very important to me as I'm not an expert by any means and you guys are heavy weights.....