Upgraded Stereomour? Paul?

[samoore]

I read some old posts about development of an upgraded/more refined Stereomour.  Is that still underway, or have you dropped that project?  Just wanting to know before I pull the trigger on a stock Stereomour.

Regards,

Steve

[Paul Joppa]

Not ringing any bells. Are you sure it was the Stereomour? Maybe if you can find one of the posts I can elaborate on it.

The only upgrade I can think of is possible Magnequest transformers. See the nearby thread on that. I see nobody has started a thread at Mike's forum yet, so maybe the interest level isn't actually very high?

I've explored a few oddball ideas, but all are just daydreaming at this point. I don't think I have had any ideas so far that have actually been designed enough to be confident they are actually possible.

[samoore]

Hi Paul,

Here are the links to your posts about a shunt-reg 45.

http://www.bottlehead.com/smf/index.php/topic,24.msg2994.html#msg2994 [nofollow]

http://www.bottlehead.com/smf/index.php/topic,24.msg2995.html#msg2995 [nofollow]

Here is the relevant text from those posts that I was curious about:

"I'll just add a bit about levels. I see the Seduction and SEX amp as entry level, with Eros and Paramount as our high end. The Stereomour, both 2A3 and 45, will fall in between those levels. The shunt-reg 45, if it becomes a product at all, will be at a higher level than the Eros and Paramount. (Quickie is kind of an oddball, but on average I'd call it entry level.)
As to "levels", I would say that the SEX amp and Seduction are our entry level products, with the higher end products being Eros and Paramount. The Stereomour (both 2A3 and 45 versions) will fall in the middle between those products.

Earlier in this thread I mentioned a project I am working on, which is a fully shunt-regulated 45 amp - this will be at a level above the Eros and Paramount, and I don't know if there will be enough demand for it to become an actual product. It was probably a mistake to mention that in this thread, and I apologize for any confusion it might have produced. We always have a bunch of projects going on, and only some of them make it to the actual product stage."

Steve

[Grainger49]

Bottlehead has had one limited run of a SR 45 that I was aware of in recent years.  It was a short offering and sold out in a week or two, IIRC.  But that was never a full time product. 

PJ might have that in mind. 

The question is can you live with the power output of the 45?  If so you might lurk till a SR 45 run is offered.  If not it isn't a problem.

[Jim R.]

Paul,

Astroimage did start a thread over on the mq forum and I bumped it and sine then two others have replied.

Folks who want to see an iron upgrade from  MQ should go over there and post their own reply in that thread.

Mike has not responded to that thread since April or so, when he said the ball  was in your and Doc's court.

-- Jim

[samoore]

Why couldn't one just order custom output transformers from Electra-Print for the Stereomour?  Is it just a matter of them fitting on the chassis?

STeve

[braubeat]

Magnequest makes upgrade transformers for the Paramour. These will work fine for stereomour but will not fit in the chassis. So fitting the chassis is indeed the issue.


Michael

[samoore]

So, I have to ask, and excuse me if this sounds ignorant.  But, why didn't Paul design the Stereomour so that the Paramour Magnequest Transformers would fit, knowing that people would want to upgrade?

Steve

[InfernoSTi]

In my opinion, by designing the Stereomour to be upgraded to the Paramount, one would have to compromise the size and cost perimeters to the point that it would not be appealing to the "middle" market...i.e. someone like me.  As it is designed, the Stereomour not just meets my expectations, but it exceeds them every single time I listen.  Others have had this same experience (Ed..ebag4...comes to mind), so the product design goals are successful "as is."

From my standpoint, the Stereomour represents the best amplifier I've ever owned. Perhaps if I had more experience and suitably matching speakers, source, and listening room (w/treatments), I would step up to the Paramount.

However, I appreciate the price point, the integrated design in a manageable size, and the tweaks I have made really have impressed me as to what the Stereomour is capable of producing (Mundorf Silver In Oil caps, upgraded driver and power tubes, and upgraded power cord).  I think bypassing the volume pot would be my next project but that involves developing a preamp with a suitable volume control...I'm still considering my options. In the end, room treatments are adding a lot more value to my system as it stands today.

I would think that if the sound quality improvements that could be gained from the addition of MQ transformers was critical, then the Paramount monos might be a better place to start.  For me, the improvements to my listening room are having a much greater impact dollar for dollar than I ever would have imagined (perhaps 30-50% of my sound quality is from the room interactions).

Just giving a "non technical" response.  I'm sure there are other, more practical, considerations, like the exposure to HT voltages and the like.

John

[Paul Joppa]

Well, it's all very complicated!

Just an example, the Paramour upgrade choke is not the same size as the output transformer, so they can't be mounted on the same bolts, which is necessary to fit two sets on the same chassis efficiently. Also, both parts have exposed terminals and should not be mounted above the chassis plate for safety reasons. So new parts are needed in any case.

[howardnair]

paul!! how could you not think of everything?--actually putting the stereomour on a wood chassis with the rca's on one adjacent surface and the controls on another and the tubes and trannies on a third makes me really appreciate pauls component layout-even using the top plate as a template for each component it takes me a couple days to go from prototypes in plywood to actual assembly-couple that with owning and restoring/troubleshooting  several hh scott amplifiers-i can not say enough about the intelligent and  simple layout of bottlehead gear

[Grainger49]

One of the things I was impressed with when I started building Bottlehead kits is the tight layout.  The signal path is kept to a minimum, the AC is isolated and the layout makes sense.  Those 1uF caps on the Seduction and Eros tube pins is a trick to get there but it is part of keeping the Bottlehead kits quiet.

It is unusual that kits are as quiet as most Bottlehead builds are.  That is the result of the layout and wire routing that Doc and Paul are so careful about.

[kphelan]

I am a newbie, a lurker, and not in any way a builder, so sorry if this is an inappropriate response.  I have read in this thread and others multiple queries about possible MQ upgrades for the Stereomour.  Ummm... has anybody considered Hashimoto output transformers?  I just had my Fi 2A3 stereo amp rebuilt (not by Don), and in the process replaced the original Magnequest OPTs with Hashimotos.  The Hashimotos are noticeably smaller than the Magnequest units, thus the reason for this post.  I thought perhaps the Hashimotos might fit on the Stereomour chassis.  I bought a pair of these from the US distributor:

newbielink:http://www.obsinc-products.com/servlet/Detail?no=19 [nonactive]

I have only had the amp back for a couple of days, but the sound is better, fuller, tighter bass, and bigger soundstage.  I was lead to the Hashimoto site when I read that Don Garber now uses Hashimotos as stock on his amps.  BTW, the president, Mr. Isao Asakura was a delight to deal with. 

I have no interest in Hashimoto or any other audio company.  Just thought I'd pass this along.

---Kent

[Paul Joppa]

A quick look did not turn up suitable plate chokes for 2A3 (20+ henries 50+mA) or any parallel feed (interleaved core) output transformers. There was one choke (30H, 40mA) that would do the job with 45s, though I can't find the mounting dimensions. All the output transformers seem to be potted. Some mechanical re-design would be necessary to accommodate transformers that do not correspond to the stock units, which are horizontal channel frames with EI75 cores.

The Stereomour uses a 4K primary impedance, so the 3.5K units would be suitable from that standpoint.