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Converting 300b SET amp to 2a3 SETAmp

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Converting 300b SET amp to 2a3 SETAmp Empty Converting 300b SET amp to 2a3 SETAmp

Post by mgf Mon Oct 27, 2014 11:23 pm

Hi,
I have a pair of used 300b monoblock which I hope to convert to 2a3 amp,any diy expert who can advise and help or recommend someone who can do it for a fee? Thanks in advance.Schematic here :-
http://users.otenet.gr/~athsam/audio_note_conquest_power_amp.htm

mgf
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Converting 300b SET amp to 2a3 SETAmp Empty Re: Converting 300b SET amp to 2a3 SETAmp

Post by vt4c Wed Oct 29, 2014 10:18 pm

Hi mgf,
    No DIY expert but just providing recomendation....study

    To convert to a 2A3 PSE amp, the simplest approach will be to...

1.) Increase resistor R10, R11, R12 & R13 to 8.2K ohms
2.) Increase resistor R6 (power supply section) to 1.5K ohms.
3.) Change the filament supply to 2.5V (might be a concern as 2A3 need more current)

   The other snag to this is that the gain might be a bit on the high side for a 2A3 PSE. Going passive volume control might be a good idea.

   If your intention is to have a major revamp; then, you might want to ditch the 2 stage cascade 6SN7 for a single stage driver....plenty of of tubes that will work well here...The Russian 6E5P is one good candidate
vt4c
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Converting 300b SET amp to 2a3 SETAmp Empty Re: Converting 300b SET amp to 2a3 SETAmp

Post by mgf Thu Oct 30, 2014 7:49 am

Hi,
Thanks for your kind advice and modesty. I was told that among others the reliability of the transformer will be affected after the conversion so I'm having second thoughts now. Anyway all inputs and discussions are welcome because these are part of the fun of our hobby.

mgf
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