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12AX7 as a substitute for 12SL7/adapter from ebay

PostPosted: Sat Feb 15, 2014 1:25 pm
by kku
I must be daydreaming. Is it really possible to successfully and prolongedly use 12AX7 using this adapter? In a Darling circuit?

http://www.ebay.com/itm/1pc-12AX7-12AU7 ... 2ec92a7d15

Re: 12AX7 as a substitute for 12SL7/adapter from ebay

PostPosted: Sat Feb 15, 2014 3:12 pm
by Geek
*bangs head*

Uneducated n00bz! >:o

6SN7 == 6FQ7 != 12AU7
6SL7 == 5751 != 12AX7

A very "Sheldon-esque" (as in Big Bang, not SDS (lol) ) pet peeve of mine (sick)

Re: 12AX7 as a substitute for 12SL7/adapter from ebay

PostPosted: Sat Feb 15, 2014 3:54 pm
by kku
Geek wrote:*bangs head*

Uneducated n00bz! >:o


If I was "educated" about tubes, I would not be asking questions around here...would I? I know that 12ax7=12sl7=5751, but I do not have any more knowledge beyond that. I do NOT know if they are 100% electrically identical substitutes or not.

I guess what I meant to ask was, would there be any adjustments/tweaks be needed to be made in the PCB circuit?

Re: 12AX7 as a substitute for 12SL7/adapter from ebay

PostPosted: Sat Feb 15, 2014 6:45 pm
by Geek
Hi kku,

I didn't mean you :$ I meant the seller.

As for circuit mods for 12AX7, it depends on the topology. If a straight voltage amp, have an anode load resistor typically 100K and choose a cathode resistor for B+/2 (usually 820R for a healthy tube).

Cheers!

Re: 12AX7 as a substitute for 12SL7/adapter from ebay

PostPosted: Sat Feb 15, 2014 8:05 pm
by kku
Asked the same question to the seller. Got this reply.

"hi,if your amp original tube is 12SN7/SL7 can direct plug my adapter.
thanks!

- xulingmrs"

Sounds too good to be true.

Going back on the hunt for 12SL7s. (lol)