Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Stereomour => Topic started by: faithintruth on January 02, 2015, 06:54:44 AM
-
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
-
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.
-
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.
-
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.
-
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
-
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.
-
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.
-
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.
-
Got it. Thks
-
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
-
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.
-
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.
-
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.
-
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.
-
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.....
-
I've not tried the Stereomour. I've had a Fi-X, Bugle and had a JE Labs Simple 45 and another 45 amp in my system. I owned the first two.
There are things a 45 tube does well in my opinion. For full range, it isn't my first choice. The Stereomour configured for 2A3 may work better but you should give a 45 amp a listen in your system before committing to one. There is probably someone near you that has one you can try.
In my experience, it wasn't a matter of power output but of tonality of the tube.
-
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.
I have Paramour II -45's, much the same circuit as the Stereomour, but mono blocks and no input selector/volume pot. My main speakers are EV Sentry IV-A's, 102dB/1W/1M. The 45's are wonderful, BUT, they do not control the bass as well as my Paramount 300B's or 2A3 Paramours. I agree that the 45's are best as mid/treble amps. That being said, I still use the 45's as the full range amps and they are so sweet I soon forget the less than stellar bass.
I agree with the recommendation to quit the internet queries. You said you have 45's.....it's simple....use them!! The only ears that you need to please are yours.
Cheers,
Geary
-
One of the reasons for bass difficulties with 45s is that they have a relatively high plate resistance, so you get less damping of the speaker. This is clearly speaker-dependent, of course. It is possible to tune a speaker for a low damping factor but it is almost never done because it will then sound wrong with a normal (high-feedback) amplifier.
-
Paul,
Can you provide any advice concerning tuning a GPA 604-8H-II driver in a 9 cu ft vented box for optimum damping factor with a 300B Paramount?
Jim
-
Paul,
Can you provide any advice concerning tuning a GPA 604-8H-II driver in a 9 cu ft vented box for optimum damping factor with a 300B Paramount?
Jim
If you can provide the Thiele-Small parameters, I can run some calculations for that.
-
Thanks Paul. Great Plains Audio published the following Thiele-Small Parameters:
Xmax (inch) = 0.20
Re (ohms) = 6.80
Vd (cu. in.) = 19.20
Fs (Hz) = 30.90
Vas (cu. ft.) = 16.35
Ref. Eff (%) = 4.87
Qts = 0.261
Qms = 8.49
Qes = 0.270
Vid (cu. ft.) = 0.24
Jim
-
I'm getting 10CF tuned 36Hz; with a sand amp it would be more like 5CF - looks like the box is already well tuned for SETs.
-
The box is tuned to about 42 Hz. I will experiment with restricting the air flow through the port (2.5"x11"x0.75" slot) with foam or some fibrous material to lower the tuning a bit.
Could you describe how you calculated the box size and tuning for the high(er) impedance amp?
Jim
-
I increased the speaker's QE in proportion to the effective source resistance.
Roughly, the tube plate resistance is about 700 ohms; add in the transformer primary resistance plus the secondary DC resistance times the turns ratio squared to get about 900 ohms. The nominal reflected load resistance is the primary impedance rating, 3000 ohms. Multiply QE by 3900/3000 = 1.3 times, and run some software (I'm lazy!)
You can lower the tuning by making the opening smaller. Most speaker design free software will have a calculator. Measurements are better, but it's easiest to measure if you have a 2-channel oscilloscope.
-
Thank you Paul. If I understand this correctly you used Qe=0.270x1.3=0.351 in a typical speaker design software to adjust for the higher impedance of the amp.
Jim
-
Exactly.
-
By the way Paul, is the iron used in the Stereomour supplied by Magnequest? Any brand name parts?
-
No boutique parts - we choose the parts carefully, including listening comparisons, but also try to keep the cost down. The transformers are my own designs.
In another thread the question of a suitable Magnequest output transformer and plate choke came up. The question is at present still unanswered.
-
Like galyons I have Paramour II's set to run 45's. In addition I have the SEX/Stereomour iron installed. I ran the system for a couple of years with 2A3's. Then a friend gave a pair of 45's and I decided to try them. Lets just say that the 45's never came out. There are arguments for both tubes. But for me, my listening room, speakers (Orcas/Subs) and music taste, the 45 was preferred. As they say YMMV.
As mentioned here previously the 2A3 tube can safely operate in the 45 configuration but NOT the other way around. So if you wire it for a 45 you can tube roll 2A3 and 45's for comparison. Just make sure that the amp and tubes have been given ample time to burn in before doing any critical listening.
-
Any brand name parts?
You will find the same level of parts quality in our products that you would find in many Stereophile class A rated components. This includes the coupling capacitors, resistors, diodes, sockets, and switches, etc.
We select our parts for reliability, good in-circuit performance, and ease of acquisition. Our high end Tube Repro uses a lot of botique parts, and it can take me days chasing down multiple vendors to find what I need to complete the build.
-PB
-
...In another thread the question of a suitable Magnequest output transformer and plate choke came up. The question is at present still unanswered.
Now it's answered, Mike is not going to do a suitable transformer.
-
That the Stereomour is configurable as a 45 amp but 2A3's can also be rolled in is a huge option for me. Thanks to everyone for sharing.
-
PJ,
Here is a quote from you:
"The design is optimized for the 2A3; to run a 45 the power supply voltage is dropped about 30 volts by increasing a power supply resistance. This resistor gets pretty hot! Significantly increasing the heat under the chassis is not recommended without changing the layout, and perhaps increasing the ventilation area - i.e. to do so reliably is not a minor alteration.
For conservative operation, I recommend running the 2A3 as if it were a 45 - much easier to do."
(The above is exerted from a January 2015 posting)
I think I'll avoid the major alterations and go for the Tucker 45