Bottlehead Forum
Bottlehead Kits => Legacy Kit Products => Topic started by: MickeySmile on November 17, 2010, 05:47:36 AM
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Hi all,
I just bought an used one 2A3 paramount amp., I think it could be very old version and it has some bad capacitors. The seller lost the schematic and assembly instruction. I would like to upgrade and clone another one to pair with it. Hoping to get advice and information how to proceed.
Thanking in advance for your help.
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Post a picture. The Paramount is not that old. The Paramour is much older and also uses 2A3 tubes.
Another way to tell is the size of the base. Measure the width and depth, meaning front to back. Then post.
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Here are the pictures of top and bottom. The amp. base dimension is 6x10
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If memory serves me right [I don't have my Paramours any more] what you have is a Paramour amp.
Check the Bottlehead products page to see what a Paramount looks like
http://www.bottlehead.com/sc_images/paramountunderside.jpg
Bryon
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Yes, that's an original Paramour. Any idea what happened to the other one? They were only sold in pairs.
What leads you to conclude it has bad capacitors? Anything else you know about it?
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I don't know why the seller has only one and I didn't ask. In attachment is the picture of the capacitor that I see the bottom cap pops up, so mu guess the other one will be bad soon. Beside that everything else look intact.
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You are spot on. A cap like that needs to be replaced. That is the capacitor on the cathode. The resistor that is in parallel with it should be checked also.
The transformer for this amplifier is not made by Bottlehead today. Neither is the metal top plate. All the other parts you could source from a supplier and assemble. Well, maybe not the output transformer. You might find a pair of those from someone who has upgraded theirs and kept the parts.
A little woodwork will make the base.
So what I'm saying is that since you seem inclined to rebuild the one you have and build another this is the place to help you. (the Bulletin Board)
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Correct me if I'm wrong but I think the output transformer on that is the speco still used in the quickie (headphone version)?
And Eileen was kind enough to custom order some PT-2 power transformers for my SR-45 project last year. Don't know if they can still be ordered but can't hurt to ask.
Not sure on the availability of the chokes though.
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Yes, it's a Speco. Regarding the PT-2 - the way transformer winders work is that there is not a minimum order, there is instead a minimum price. This price is that same for one unit on up to about 10 units. So for example if we ordered 10 PT-2s (which we are not going to do, since we don't use them) the total might be $600, or $60 each. But if we order just one PT-2, the price is still $600.
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Actually, your amp appears to have the Hammond custom power transformer, which we used prior to the PT-2. I am not aware of any substitutes that would not require circuit modifications.
It is possible that the output transformer is also the one we used prior to the Speco, so it may be difficult to source a matching one - but a pair of Speco's is still quite inexpensive. (The Speco bears the legend "SPECO T7010.")
The 10-H plate choke appears to have the nylon bobbin, not the earliest layer-wound design, so the current version should be a good match even though the actual manufacturer has changed again. (All three versions bear the same part number, C-7X.)
I agree with Grainger, the electrolytic caps should be replaced; the amp is getting old and it looks like that one is already failing.
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It is possible that the output transformer is also the one we used prior to the Speco, so it may be difficult to source a matching one - but a pair of Speco's is still quite inexpensive. (The Speco bears the legend "SPECO T7010.")
Oops, yeah you are right. I forgot that we used a different one before the Speco and that looks like what this one is - there is kraft paper on the coil rather than yellow plastic.
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OK, if I want to upgrade to improve sound so what are mods should I need? Beside the speco T7010 are there other candidates can be substituted for output transformer? Also, I need the schematic could someone post it up for me please!
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Correct me if I'm wrong but I think the output transformer on that is the speco still used in the quickie (headphone version)?
And Eileen was kind enough to custom order some PT-2 power transformers for my SR-45 project last year. Don't know if they can still be ordered but can't hurt to ask.
Not sure on the availability of the chokes though.
Who is Eileen? Could you introduce me to her?
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We seem to have lost a few replies. Eileen is Dan (Doc B)'s wife and business partner; she handles customer service because she's a total sweetheart. Dan is not dumb!
I'll check this thread again tomorrow to see if any posts have been restored...
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Here is the contacts page:
http://www.bottlehead.com/contu/cntu.html
Since you are new here you probably don't know the secret handshake it takes to find it. Just to let you in on it... every page has a badge in the upper left corner. Click on the badge and you go to an index and Bottlehead news page. At the top of that page is the badge with some links next to it. Contact us is the bottom link.
If you look down that index/news page you will find a picture of Doc/Dan with an odd look on his face looking at a blond woman. She isn't Queen Eileen, but is Jacqui Naylor, a Bottlehead friend and recording artist.
I suggest you call for fastest service. Since you are new you are not aware that Bottlehead is still moving and constructing their shop where they will pack kits and assemble special orders.
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Don't know if my post temporarily disappeared or what, but I see it now. Basically it will cost a ton to get a couple of PT-2s made, just as much as it costs to get 10 of them made. Ditto with the laser cutter and a chassis plate. It would probably make more sense to get some plates made by Front Panel Express. Actually by the time you get through with all of the special orders and tracking down of parts it probably makes more sense to sell the amp and build a Stereomour, which already incorporates upgrades that you would be considering for that single Paramour, like better transformers.
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Dan,
I was going to suggest that but had no handle on the costs. The OP seemed to want to build another Paramour. The Stereomour would be a considerable upgrade.
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Thank you Doc B. & Grainger49 for the advices. More likely I have to wait for awhile to do the Stereomour upgrade. In the mean time, do you have the schematic of this paramour amp.? I like to fix this one first.
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I have a schematic of the latest generation of Paramour just before it was superseded. It is different from yours in that it has different transformers and plate choke. That isn't likely to be the problem your amplifier has.
But I would like Doc's permission to send it. It is his intellectual property.
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I have a schematic of the latest generation of Paramour just before it was superseded. It is different from yours in that it has different transformers and plate choke. That isn't likely to be the problem your amplifier has.
But I would like Doc's permission to send it. It is his intellectual property.
I respect that and am hoping he will give the permission. By the way, I am thankful for your hospitality.
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But I would like Doc's permission to send it. It is his intellectual property.
Actually it's PJs design originally and he should have some say in it too. It's OK with me if it's OK with him. My hunch is it will be prudent to replace all the electrolytic caps, and possibly the UF4007 rectifier diodes if that bad cap is shorted. Other than tubes possibly being a little tired everything else is probably working to spec.
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OK, if I want to upgrade to improve sound so what are mods should I need? Beside the speco T7010 are there other candidates can be substituted for output transformer? Also, I need the schematic could someone post it up for me please!
OK, I didn't see my post re-appear so I guess it's lost; I'll try again.
The first recommended upgrade is to a C4S current source plate load on the driver. This was first offered as an upgrade, but shortly after it became a standard part of the kit. It improves the sound quite a bit, and also reduces the hum somewhat. The currently-listed SEX kit C4S upgrade is very similar, and I'd be happy to look over the manual and advise of any changes.
There was, back in the day, an iron upgrade kit that included a Magnequest BCP-15/50mA plate choke and a custom output transformer made for us by another vendor. The original 10-henry plate choke was recycled to replace the 270 ohm resistor in the power supply. The BCP-15 is still available (though Mike at MQ is not taking orders right now due to some health issues). I expect him to come up with a 4K impedance transformer eventually, to upgrade the Stereomour which is basically the same circuit. So far I am not aware of a fully satisfactory substitute on the market; the MQ TFA-2004Jr probably comes the closest.
The coupling cap (0.1uF/630v) and the parafeed output cap (3.3uF/630v) are the most significant ones to replace with better parts - "audiophile caps of your choice" as we say, since favorites change frequently.
The schematic was in the manual, and manuals have been available, however I don't know if there are any manuals that old still around. Doc B will have to address that question.
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Bwahaha - Doc B and I are cross-posting! Apologies for the confusion. I have a sketch of the schematic after the C4S upgrade - send me a PM with your email address and I'll forward it.