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tropicalmuz 19th September 2012 10:09 AM

Tube ID help please.
Hi Guys, I recently went through my older tubes and found a couple I received in a mix box ages ago.

I didn't notice the Telefunken diamond on the base when I bought them.

Could I have a hand IDing them please?


Tube 1: (4 pics)

Tube 2: (3 pics)

Thanks again. :)

tropicalmuz 19th September 2012 10:22 AM

Larger photos:
Tube 1:

The base is the same on both tubes:

tropicalmuz 19th September 2012 10:27 AM

And, better resolution for tube 2:

DF96 19th September 2012 10:51 AM

They are both dual triodes, of conventional construction (so definitely not ECC88, for example). You probably already knew this, though.

You can work out the pinout by looking closely at the base connections. Then use a valve tester or lash-up circuit to see what they are.

tropicalmuz 19th September 2012 11:16 AM

Thanks DF96, I have a vague recollection of them being somehow labelled 12au7.

I have no tube tester (I'd love to get in touch with someone who does here in Tasmania).... so I just tried them in the preamp socket of my amp (meant for a 12ax7) and tube 1 (red top) needs a volume boost to compare with the Raytheon blackplate I have in there but does sound pretty good. The other one (no red top) seems to have the same gain as a 12ax7 so maybe that's what it is?

mctavish 19th September 2012 12:50 PM

Yup, look like telefunken 12AX7 or 12AU7, red usually means they were screened for microphonics or low-noise ect.

tropicalmuz 20th September 2012 11:26 AM

Thanks guys.

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