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Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Tue Feb 09, 2016 12:30 pm
by symbolique
Got these mini JJ12AU7 & JJ12AX7 that was planning for a mini guitar head project.
Anyone know of any good builders or old models that can make some use out of these unused tubes?
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Tue Feb 09, 2016 11:38 pm
by symbolique
No 1w ro 5w builders?
Was a Frequency Central UK project before he went euro rack...
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 1:28 am
by crochambeau
I'd save 'em for rolling in amps or what-have-you, or consider a preamp build, the 12A#7 dual triodes are very common and highly supported.
They are, by themselves, not really well suited to make power.
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 1:32 am
by waltdogg
Hang onto them for an emergency. You never know when you or someone you know will need 'em but cant wait for an order from an online retailer. Those gold pin JJs are very common and fairly cheap. Nothing worth building an amp around but a nice upgrade for an amp that comes with regular JJs or Sovteks in the preamp. And yeah 9 pin 12A#7 tubes don't have much output and don't put one in an EL84's socket either. Great way to kill your amp.
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 1:46 am
by lordgalvar
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 7:53 am
by Uncle Grandfather
lordgalvar wrote:http://www.cgs.synth.net/tube/noise.html
magnets

Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 11:39 am
by crochambeau
You need the Thyratron tube as the noise source though, the AX is just doing standard preamp service in that scheme.
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 11:46 am
by lordgalvar
I know. But it's something to do
Just thought it was neat.
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 11:59 am
by crochambeau
lordgalvar wrote:I know. But it's something to do
Just thought it was neat.
Yeah, it is neat. I've been meaning to building those Eric Barbour circuits for years, even have a perfect enclosure collecting dust in the garage... one of these days.
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 3:21 pm
by culturejam
waltdogg wrote:And yeah 9 pin 12A#7 tubes don't do output
You can do push-pull output with a 12AU7. Check out the Firefly circuit by Doug Hammond:

Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 3:22 pm
by waltdogg
Oh nice.
Re: Mini Gold 12AU7 & 12AX7, what to do with them?
Posted: Wed Feb 10, 2016 6:49 pm
by symbolique
This is similar to what was going to use the Minis for.
