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December 12, 2019, 08:57:34 AM

Author Topic: New Stereomour II  (Read 3197 times)

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Offline Alonzo

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New Stereomour II
« on: December 11, 2016, 07:50:24 PM »
Just finished the Shunt Regulator and DC Filament install.  Initial power test worked, got filaments lit for all 4 tubes and all 8 LED's on.  Saw wisps of white smoke from around 13U so shut it down for tonight and I'll troubleshoot it tomorrow.  Since the fuse didn't blow I'll poke around and check the wiring in that area, solve it before going on to the voltage checks.
Some pics of the build.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800

Offline denti alligator

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Re: New Stereomour II
« Reply #1 on: December 12, 2016, 03:16:31 AM »
Nice colors!
- Sam

Rega P3-24 (w/AT 150MLX) w/Groovetracer upgrades / C4S Seduction / FLAC -->J.River -->DSD256 -->Gustard X20 / Stereomour II / Klipsch Forte II w/Crites upgrades / C4S S.E.X. 2.0 +Nickel MQ Iron / Speedball Crack / Sennheiser HD600 w/Cardas cable

Wish list: Eros / Crackatwo / Tode

Offline Alonzo

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Re: New Stereomour II
« Reply #2 on: December 12, 2016, 06:09:51 PM »
Thanks,
The base has 3 or 4 more coats of stain before finishing. The pale grey is just the bottom coat. The darker stains first layer is on.  I'm hoping to get the grey to come thru, I'm going for a weather beaten sand scoured beach wood look for the base.  If that doesn't work I'll get a Blumenstein case to match my other amps.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800

Offline Sugar Man

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Re: New Stereomour II
« Reply #3 on: December 13, 2016, 05:50:38 AM »
Interested as to your thinking on using 10uF capacitors - isn't that quite a bit outside of PJ's design parameters? I'm using 1.5uF Jupiter Flats in that spot, which is at the low end of his range.  I went a little lower, so I could also try them in the Eros, which shipped with 1.5uF Solens.
« Last Edit: December 13, 2016, 05:55:47 AM by Sugar Man »
Mike "Stein" Ayotte

Current Gear:

Elekit TU-8600 300B w/Lundahl Trannies
Audio Note R Zero II Phono Pre
Rega RP8 w/ Audio Note IQ3 (MM)
Audio Note E Speaker Kit-04 w/ AlNiCo drivers

Stereomour II w/ Jupiters
Eros w/ Mundorf Silver Oils
Paraglows (retired)
Quickie w/ PJCCS
Blumenstein Orcas & Subs

Offline Alonzo

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Re: New Stereomour II
« Reply #4 on: December 13, 2016, 12:15:01 PM »
The circuit is in the middle of a configuration change.  I changed the output transformer to a BH5 Ni which is 3K impedance.  I remember a formula from here of 2*L/R*R where L is the plate choke Henries and R is the impedance of the output, with a range on either side of the micro farad solution of half to double.  A standard Stereomour (stock) would be 2.5uF (supplied with a 3.3) so when I changed the outputs I put the final value I'm going for in place.  My setup will be BCP-15's at 40H and TFA-2004 pinstriped Sr at 3K so 80/9 (throwing out the zero's) for 8.8uF.  So I should be good for a range of 4 to 17 or so.
I think I got this right (if not someone please correct).
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800

Offline Doc B.

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Re: New Stereomour II
« Reply #5 on: December 13, 2016, 12:53:52 PM »
I hate to keep saying this, but the theory is only good up to a point. The proper way to determine the value is measure the amp's bass into the intended nominal speaker load and look at the bass response. Too small a value and there will be a hump in the mid bass. Too big and you won't get the nice little knee that extends the bass response smoothly, you will see a dip and a hump below it. If you don't do the due diligence and measure the response you can use any value you want, because you won't really have a clue what it is doing anyway.
Dan "Doc B." Schmalle
President For Life
Bottlehead Corp.

Offline Jamier

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Re: New Stereomour II
« Reply #6 on: December 13, 2016, 05:29:18 PM »
I'm asking this question from a position of complete ignorance: I know that the BH-5 was an aftermarket part designed for the Paramour. Is it appropriate for use in the Stereomour II? If so do you also need to change the plate chokes?

Jamie
James Robbins

Offline Alonzo

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Re: New Stereomour II
« Reply #7 on: December 13, 2016, 06:06:18 PM »
There aren't any approved upgrade outputs for the Stereomour.  I like to experiment and if it sounds good I keep it, whether or not it is scoped and measured.  It's not hard to trace the genealogy from the Paramour, Paramount, Stereomour to find items that may work but are not in the business scheme of Bottlehead.  The stock outputs aren't bad but if you want to try nickel or pinstriped metals you have to go to other companies.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800

Offline Paul Birkeland

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Re: New Stereomour II
« Reply #8 on: December 14, 2016, 08:23:36 AM »
The original Paramour monoblocks used off the shelf parts for the plate choke and output transformer.  This helped us keep the price reasonable for these amplifiers, and upgrading the iron brought about a huge jump in performance.

Luckily for us, and ultimately for our customers, those off the shelf parts became no longer available.  This brought about a major improvement in the stock iron, taking the plate choke from 10H in the Paramour to 40H in the Stereomour (same inductance as the MQ choke mentioned in this thread).  The output transformers were also designed from the ground up and absolutely bury the Speco units used previously. 

There are lots and lots of aftermarket transformers that you can try in our amps.  As Alonzo mentioned, if you want to try exotic lams in your transformers, you'll have to contact Magnequest or Sowter.  Other than those two companies, I would expect any other transformer substitution to be a journey in the wrong direction. 
Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man

Offline howardnair

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Re: New Stereomour II
« Reply #9 on: December 14, 2016, 12:53:48 PM »
Alonzo. It a little late for this advice for the weathered look unless you sand the paint off. You take primer and paint it on and wipe it off   In your case you would use grey then you can finish over it it's a simple process akin to Pickeling. The stain over may work I would be tempted to try a solid stain maybe wiping it off or use a stiff brush and give it some grain
Sanding until the wood starts showing through may work also

Howie

Offline Alonzo

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Re: New Stereomour II
« Reply #10 on: December 14, 2016, 02:44:41 PM »
Thanks Howie,
I have a sander so it won't be that much of a problem removing the paint.  I'll have to look up Pickeling, only done that with jalapenos or cucumbers.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800

Offline Paul Joppa

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Re: New Stereomour II
« Reply #11 on: December 14, 2016, 03:02:23 PM »
I'm asking this question from a position of complete ignorance: I know that the BH-5 was an aftermarket part designed for the Paramour. Is it appropriate for use in the Stereomour II? If so do you also need to change the plate chokes?

Jamie

PB's history summary is accurate. I'll just add the Magnequest part of the history.

The BH-5 is a 3K impedance part, actually a variant of the TFA-2004 Junior with some special internal touches. It was built for the Paramount. The Paramour/Stereomour is designed around a 4K impedance, originally because that was what was available as an off the shelf 70v PA system line transformer (the Speco). I never could talk Mike into making a 4K transformer, and I didn't want to change the operating points, so for a short period we had a custom unit made for upgrades. We had some quality control issues with the custom winder, so I accepted the BH-5 as close enough, counting on the high inductance of the BH-6 choke to provide enough bass goodness to make up for the modest impedance mismatch. It is clearly an upgrade from the Speco.

We were also using the Speco in the stereo SEX amp, so when it went out of production (actually the design changed but kept the model number, which kind of blindsided us), I elected to design our own transformer and choke for the SEX and the Stereomour.
Paul Joppa

Offline Alonzo

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Re: New Stereomour II
« Reply #12 on: January 07, 2017, 11:24:47 AM »
Latest update;  TFA2004's installed.  Tight fit.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800

Offline Paul Joppa

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Re: New Stereomour II
« Reply #13 on: January 07, 2017, 12:56:34 PM »
Latest update;  TFA2004's installed.  Tight fit.
The TFA-2004 transformers' coil axes are aligned with the power transformer, and thus likely to pick up a good deal of hum. If you rotate them 90 degrees, the hum will null out, and it won't be such a tight fit either. Two birds, one stone!
Paul Joppa

Offline Alonzo

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Re: New Stereomour II
« Reply #14 on: January 07, 2017, 02:34:27 PM »
Thanks Paul,
I looked at that 3 times trying to figure it out and still chose wrong.
Alonzo B
BeePre, Kaiju, some Stereomours (I's and a II) to DT150 tweeters, GPA 802-8G's on Jabo horns, Altec 414z's, Eminence 15A's open baffles, Seductor to Altec 299-8A with MRII horns and a Mainline with HD800