Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: rodgre on October 07, 2020, 12:25:28 pm

Title: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: rodgre on October 07, 2020, 12:25:28 pm

Hello there.

I have a Red Bear amp in for a tune up and I'm wondering if it's worth it to convert it to use standard 12AX7s in the preamp, instead of the Russian 6N2P. I was wondering if anyone has done this and could walk me through what needs to be rewired on the sockets and if anything else needs to change.

I realize that 6N2P tubes can be gotten pretty cheaply online from Eastern Europe but if it doesn't make much sonic difference (does it?) it might be way more convenient to have the amp use standard tubes that can be gotten anywhere.

Thoughts?

Thank you!
Roger

Title: Re: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: sluckey on October 07, 2020, 12:37:31 pm

According to this link all you have to do is plug it in. No wiring changes required.

     http://oldradio.qrz.ru/tubes/russian/short/6n2p.shtml

Title: Re: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: knebiter on October 07, 2020, 01:09:28 pm

I think the heaters are different.
6.3V only.
Across 4 and 5 on 6N2P.
9 is not used.

Title: Re: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: PRR on October 07, 2020, 02:35:25 pm

(https://tubes-store.com/images/6n2p_rewire.jpg)
?

https://tubes-store.com/product_info.php?products_id=1114
"6N2P tubes are a replacement for 12AX7 in any typical amp application, but they have 6.3V heater voltage and would need a different wiring than stock 12AX7's."

https://ebayhickoks.com/images/eBay/eBay_De/OROSZ%20csovek/=%20Datasheets/6N2P-(EV)%20Datasheets/Datasheets%20-%2001.jpg

Title: Re: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: PRR on October 07, 2020, 02:45:56 pm

https://en.wikipedia.org/wiki/6N2P

Title: Re: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: rodgre on October 07, 2020, 03:12:44 pm

Thank you so much! That's perfect.

Roger

Title: Re: Converting Red Bear amp from 6N2P tubes to 12AX7
Post by: tubeswell on October 07, 2020, 09:51:00 pm

DTSP option for 6N2P/12AXY heaters on Valve Wizard site http://www.valvewizard.co.uk/heater.html (http://www.valvewizard.co.uk/heater.html)


(I haven’t tried this but it seems handy)