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flyinglemur 2nd October 2007 11:01 PM

First foray into tubes!!
So I figured I'd start simple.

Excuse the sideways-ness of the schematic :).
I'll be building the two sides, so good for about 10w, ample through 91dB speakers.

Just curious - exactly how interchangeable would a 12AU7 be with the AX - I've known them to be swapped over in guitar amps with no problem and producing favourable results...

Should be commencing at the end of the year (college project), and some interesting addons, like a remote controlled motorised volume pot etc.


flyinglemur 2nd October 2007 11:38 PM

I must apologise for the immense picture - I had no idea this forum didn't autothumbnail :p. And there appears to be no ability to edit, so please accept my red faced apologies

planet10 2nd October 2007 11:39 PM

Actually the image has been replaced by a generic "imaged hosted by AngelFire" graphic.

If you can't shrink the image to fit (1000x1000 and <100kB) mail me and i can help out.


SY 3rd October 2007 01:05 AM

In a hifi amp where gain and distortion are more important than in MI amps, a 12AU7 and 12AX7 should not be interchanged. Despite the same pinout and heater ratings, they're vastly different tubes.

Welcome to the world of thermionics!

flyinglemur 3rd October 2007 08:21 AM

:) Point taken, the AX7 stays! Can one edit posts here?!


ray_moth 3rd October 2007 08:51 AM

Editing posts works OK, providing you don'r leave it too long before you do so. A useful tool is the preview button, which helps you get it right before posting.

A bit more about the 12AU7: this is not a very linear tube and there are better 9-pin alternatives, like the 6CG7 and 6FQ7. They're not quite so easy to find and may cost a bit more, but they are quite linear - true miniaturizations of the 6SN7. They're not able to sub successfully for a 12AX7, though, anymore than the 12AU7 is, and their pin-outs are different anyway.

flyinglemur 3rd October 2007 08:59 AM

12AX7 stays so...It's more of an experiment than anything


Sal Brisindi 3rd October 2007 02:22 PM

Here is a resized jpg of the 6v6 amp above. I also turned it 90 degrees.

Sal Brisindi

flyinglemur 3rd October 2007 02:51 PM why couldn't I edit my post and do that? :) I'd resized it and all :(!!


I see now that I can edit my posts, now that I've come out from being under moderation?! Cheers! :)

Jeff Yourison 3rd October 2007 03:06 PM

You can edit your posts if you're logged in; you'll see the button on your post just below and to the right of your text once it's been submitted.

Perhaps you logged out and then went back in to read your post without logging on?

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