Bottlehead Forum
Bottlehead Kits => Stereomour II => Topic started by: Alonzo on December 11, 2016, 07:50:24 PM
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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.
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Nice colors!
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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.
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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.
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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).
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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.
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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
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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.
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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.
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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
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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.
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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.
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Latest update; TFA2004's installed. Tight fit.
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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!
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Thanks Paul,
I looked at that 3 times trying to figure it out and still chose wrong.
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Yes, I have to scratch my head for a while too - every time! Those beautiful end bells hide the information you want.
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Iron reinstalled, minor cap and resistor problem fixed, voltage checks passed. Setup with 2A340's on 4ohm tap of the pinstripes to MMG's.
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Hi Alonzo,
Did you ever use that chromed top plate with the transparent copper powdercoat?
I'm seriously considering a Steromour II and will probably do the same transparent copper color scheme. I plan to use my spalted birch base for the stereomour and will make a custom base out of some teak I have for the s.e.x. 2.1.
The s.e.x will be almost exclusively a headphone amp for my modified Meze 99 Classics, and the stereomour II will most likely be built as a straight power amp as I have a killer 1 in and 1 out 5670 based preamp with noise figures in microvolts at full scale, which is far more than either of my amps can use. It also has a great volume pot.
For the stereomour II, I would probably only add the shunt reg upgrade -- I just like AC filaments on 2A3's.
Which horns are you using -- Frugal horn or Horn Shoppe?
-- Jim
P.S. -- love the Tolkien quote in your sig. :-)
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Hi Jim,
Right now it's sitting in the garage, 3/4 built. I'm trying to convince Mike L. to make some different 45 parafeed transformers for a it. It is simply gorgeous so I won't use it for one of my experiments. I had a Koa base built for it, the combination is dark and lovely.
Who did the plating work for you, I have a Mainline that is a plain Jane compared to my other amps, it could use an upgrade.
Using Frugal horns MK III with FE126 enabled speakers. Once Dave gets back on his feet will try out some of the Mark Audio speakers or maybe a XL pair of horns.
My youngest son is a bit of a wanderer, if you don't keep his attention he will find something else to focus on. For his 30th we took a road trip and had some silver cuffs made with the Tolkien quote; "All that glitters" on the outside and the "Not all those who wander" on the inside. It's a nice reminder of an adventure we shared and a great quote!!!
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Hi Alonzo,
Wow, the koa base sounds like it would be really nice with the "copper mirror" as I used to call it. If I do get another stereomour I'll most likely do the transparent copper again, but leave Doc's "brush work" untouched. Should look really nice, not to mention, very different.
I don't remember the name of the chrome platers except that they were based in Connecticut somewhere. They were good guys to deal with -- unlike the guys who brass plated some transformer endbells for me. Don't remember who they were either.
So, what's with Dave G.? I've been away from the whole audio thing -- except for listening, for a good while, but as my health slowly improves I'm being a bit more active on a couple of the forums -- this one being my favorite, of course.
I have one of those last 6 s.e.x. 2.1 kits still sitting in a box and as soon as the system is back online following some upgrades to my Orcas and some homebrew interconnects and the addition of the iFi Micro iTube 2 buffer/preamp. Take care,
Jim
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Yeah, it looks great, thank you for the sale. My system is a mish mash of colors and stained BH bases and Blumenstein bases. My final upgrade will be to get them all in Koa bases and either copper or black chrome coated top plates. Nothing matches now (blue Stereomour II, blue BeePre, hammered copper Stereomour, black and brass Stereomour, red Stereomour , naked Mainline and naked Smash and the copper one waiting to be finished. I wish I had the skill (and patience) of someone like Leeland, he makes some great looking gear.
Dave was hospitalized for an internal issue, infection and system failure. The details are on his forum. He's now home recuperating. Hopefully he has a full recovery.
Good to see you back on the forum, hope your health keeps improving.
Alonzo
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Today Imoved my rack out from the wall as I'm having the trim in my listening room painted -- a greyish sage green to complement the battleship grey accent wall and the sandy beige that covers the other walls. The chair cushions are a sage color and so is the area rug that will go down once the speakers are placed. Yeah, I can't see a bit of it, but like the gear, I want the room to look nice too. There are two ficus plants in the front corners in pots and sitting on black lacquered 2" thick platforms. Then it will either be the bamboo Orcas and baby benthic subs and amps for a two-tone look, and the Abbys will match the rack when I put them in. So, I'll be alternating speakers as the spirit moves me. Of course the current el-84 amp is a bright Porsche Racing Ruby Red, and the stereomour II (if I decide to build one) will go in the birch box, and I may build a base for the s.e.x. 2.1 that matches the walnut earcups on the Meze 99's. Oh, and the main floor is carpeted with a beige burbur -- all wool so as to minimize static buildup.
At this point I can only manage 3-4 hours a day to work on things, so I try to get as much done every day, that I possibly can. Today, when I pulled out the rack I did all the wiring to connect the sub amps to the main amp, so the only thing left to do there is to run the speaker cables to the subs themselves, which isn't very practical nowat this time. Whatever I end up doing on the amps, I promise they will look and sound great. Time to start oiling the birch stereomour II base...
Just have to have it all looking good. Of course I'll send pics when it's all together.
Your son sounds a good bit like me. :-)
Take care,
Jim
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Hi Alonzo,
Are you also using the EXO-003 in your SII? What are your observations of the change from the stock configuration?
Jamie
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Hi Jamie,
Nope, currently it has Mike's BCP15+ in it as plate chokes. Had those on hand in another amp so I swapped the stock PC-3's for them.
I've changed a lot from stock, only was stock long enough to do the voltage checks and a quick sound check. And I changed plate chokes at the same time I changed outputs so I couldn't truthfully tell you which made the great sounds I hear now. I can say I like the combination of 3K transformers and the BCP15+ chokes even though the specs aren't perfect to the design of the Stereomour II.
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Hi Alonzo,
So, with that OPT/plate choke combo are you essentially running the set-up that PJ descibed in Greg's thread, 300V (plate to cathode)/ 60mA / 3KOPT with the JJ 2A3 -40 ?
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But with Full Music Meshplates now. Moved my pair of 2A3-40's over to my Stereomour I with Dowdy chokes (and 3K outputs). Still mixing and matching tubes - amps - speakers to find out which is best.
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Hi Alonzo,
So, with that OPT/plate choke combo are you essentially running the set-up that PJ descibed in Greg's thread, 300V (plate to cathode)/ 60mA / 3KOPT with the JJ 2A3 -40 ?
The BCP-15 is limited to 50mA current. That would be the stock operating point at 300v plate to cathode.
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Thanks Paul! I should think before I type, don't know where I got that number.