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6AS7 headphone amp with Sophia Electric Mesh plate rec. tube
http://www.diyaudioprojects.com/Forum/viewtopic.php?f=9&t=4632
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Author:  mwhouston [ 16 Dec 2013, 22:21 ]
Post subject:  6AS7 headphone amp with Sophia Electric Mesh plate rec. tube

I may have made these comments else where or even started a threat but I can't find it so here is a new start. Ever since I had a quick listen to a Woo HP amp with some $900 HPs I knew I had to build one. BUT what sucked me in big time was the Sophia Electric Princess Mesh plate rec. tube (274B) flattening out the HT ripples. It looked stunning and the HP amp was gorgeous looking and even better sounding to say the very least.

I have a good schematic which I found on this site which uses a E88CC (Tesla gold pin) and 6AS7, direct coupled with capacitive output. The core to any good tube HP amp is an ultra-quiet PS. Add this a separate PS and amp build and add big fat Sophia Electric (expensive) rec, tube and you have the power and the glory.

I thought I would start with the PS. Here is my layout on a heavy cast Al chassis. Things are going to get tight here but I'm hoping to build the amp on a similar chassis. Two XLR sockets will provide connection points for the amp section. The choke (20H\100mA) and power tranni Hammond. The Sophia tubes are allergic to surge so a 4uf PIO cap is number one followed by choke, 100uf electro, limiting R then 180uf cap. Should be quiet? I hope so. Here is an early layout idea.
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Author:  thehoj [ 16 Dec 2013, 22:43 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Do these fit in a standard octal tube socket?

Author:  mwhouston [ 17 Dec 2013, 00:24 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

thehoj wrote:
Do these fit in a standard octal tube socket?

The Sophia 274B is for octal and 274A for 4 pin.

Author:  mwhouston [ 19 Dec 2013, 03:43 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Funny how when the brain is under pressure it may deliver big time. I had a lunch date in Melbourne: 30min bus ride, 60min train and then 20min walk. I got up early but wanted to sand and prime the chassis of the PS for the HP amp. I had not decided on a colour or name for the appliance.

In the next two hours I had the drilled cast Al chassis prepped and primed and had a colour and name selected. Colour: White, I'm thinking cream but I have yet to see the selections. Name: Sanguine. There are four emotional states identified in human nature (look up the others). Sanguine is the social or pleasure state. Hard to be sociable with headphones on unless there are at least two outputs. Yes there will be two outputs which will always present at least 70omhs to the amp regardless. But pleasurable has to be easy. You have some high-end cans clamping the head, gorgeous sounding and stunning looking (God I better deliver on that promise) tube headphone amp and your fav. tracks on a high end player. That's pleasure!!

Top coat goes on tomorrow and the the amp chassis????

Author:  mwhouston [ 20 Dec 2013, 20:46 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Layout ideas for the amp section and the chassis for the PS after a visit from Mr Drill Press and Mrs Spray Can. There was some nice whites, light greys etc. to choose from. I went for a bright white. Hope to have the amp section drilled, primed and top coated today.
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Author:  mwhouston [ 21 Dec 2013, 01:08 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Being outside and fearful that at any moment it was going to poor down (rain) I hurriedly drilled, prepped and primed (acid etch heavy spray) the amp section. Tomorrow the white top coat goes on. Due to our very warm weather of late the PS top coat is drying fast. In the next few days I may get the chance to start assembly.

The layout changed slightly from the photo. I have brought the two phone outputs beside the single input and move the volume control to the right. I think this will be better. Also at the rear where the two power lines come in from the PS, I have put them on top of each other. I just thought it may look better. I haven't started collecting passive components yet for the amp section but fortunately there is not s lot to collect.

Author:  mwhouston [ 23 Dec 2013, 04:01 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

The PS is assembled but only partially wired. I have completed the mains wiring, wiring to the power filter and power tranni. Of course also the filament wiring to the Sophia rec. tube. A big job ahead and a long way to go. The chassis for the amp section is drying. Tomorrow I may get the PS finished.
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Author:  mwhouston [ 26 Dec 2013, 02:14 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Here is an image of the PS and amp section assembled but not wired. The two XLR connection will carry the HT and filament current (DC) to the amp section. Being different se!xs you cannot put the a XLR in the wrong socket. Now to wirer it up.
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ASSII.jpg
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Author:  Geek [ 26 Dec 2013, 05:51 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Great work! :beerchug:

Author:  mwhouston [ 26 Dec 2013, 06:51 ]
Post subject:  Re: 6AS7 headphone amp with Sophia Electric Mesh plate rec.

Geek wrote:
Great work! :beerchug:

Long way to go buddy.

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