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A Russian Pass B1 FET Preamp/Buffer
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Author:  mwhouston [ 14 Oct 2010, 07:30 ]
Post subject:  A Russian Pass B1 FET Preamp/Buffer

I have started to build a Pass B1 preamp which uses the 2SK170 JFET. Two FETs are used in the cct. one acting as a CCS (constant current source).

I have used the Russian 1uf K409-Y PIO glass and metal encapsulated caps (input) and 10uf polies-ouput. With silver solder and Alps blue velvet pot and 40z solid brass black chrome knob. Tomorrow the PS: which is to be built on the same piece of the same vero-board.
Attachment:
PassFETPreampIIss.jpg

http://passdiy.com/pdf/B1%20Buffer%20Preamp.pdf
http://www.enjoythemusic.com/diy/0708/first_watt_b1_preamplifier.htm
http://www.enjoythemusic.com/magazine/e ... lifier.htm

Author:  dtsup1 [ 14 Oct 2010, 07:57 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

Very nice!! The Russian caps are surely going to add some lushness ! :mrgreen:

You must let us know how it compares with the Elliot P37A DoZ preamp !! :xfingers:

Author:  mwhouston [ 14 Oct 2010, 16:02 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

Yes far different caps than the P37A and fewer active components. FETs verses transistors. Still SS but in so many ways different. I may have it going by tonight. Short day at work for me.

The Hammond case I have picked out should really round off the build.

Author:  mwhouston [ 15 Oct 2010, 04:47 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

The completed Vero-brd. for the Pass B1. The only part I have added is a .1uf poly across the PS after the the 1R0 resistor. I used 2 X 10,000uf where Pass used 2 X 15,000uf caps.
Attachment:
PassB1ss_1.jpg
Attachment:
PassB1ss_2.jpg

Author:  Gio [ 15 Oct 2010, 18:35 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

Looking good Mark! What will you be using for a power source? I'll be looking forward to your impressions. ;)
Cheers

Author:  dtsup1 [ 16 Oct 2010, 01:04 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

I bet it will be some form of a battery PS . :mrgreen:

Author:  mwhouston [ 16 Oct 2010, 03:11 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

I cranked it up under batteries 2X 9V. Sound good with lots of low-end weight.

The final PS will be a SMPS of 20V.

Author:  dtsup1 [ 16 Oct 2010, 05:15 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

Wall wart SMPS ?

Can you write a bit more about the sound vs oatley / Elliot P37A / Woody headphone driver ?
:king:

Author:  mwhouston [ 16 Oct 2010, 16:46 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

19V Toshiba laptop power pack.

Not finished yet. Still drilling the case. Only a brief listen to this point to see it works.

Author:  Gio [ 16 Oct 2010, 17:28 ]
Post subject:  Re: A Russian Pass B1 FET Preamp/Buffer

From the Enjoy the Music review:
Quote:
My unit was outfitted with an Ault +18V (70W) Model MW116 switching power supply specified for medical applications. No complaints so far, but I'm very curious to substitute a linear DC power supply such as the B+K 1671A in the near future.

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