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Demeter VTDB-2b DI

Posted: 28 Apr 2012, 21:01
by OrionManMatt
I wasn't exactly sure where to post this; so, I'm taking a shot and posting it here. If it belongs elsewhere, feel free to move it.

Here are some internal shots from my Demeter VTDB-2b.

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Re: Demeter VTDB-2b DI

Posted: 29 Apr 2012, 09:54
by Bernardduur
Cool! Jensen transformer!!!

Re: Demeter VTDB-2b DI

Posted: 29 Apr 2012, 12:33
by marshmellow
Doesn't mitigate the stupid circuit...

Re: Demeter VTDB-2b DI

Posted: 29 Apr 2012, 19:16
by chicago_mike
I think I have the ampeg tube DI schematic somewhere. :)

Thanks for the piccies!!

Re: Demeter VTDB-2b DI

Posted: 30 Apr 2012, 01:23
by OrionManMatt
marshmellow wrote:Doesn't mitigate the stupid circuit...
I'm unfamiliar with the circuit design part of electronics, since I'm still sort of a paint-by-numbers guy with this stuff. Would you mind educating me on why the circuit is stupid? Thanks so much.

I'd love to make a few nice DIs one day too. Some just to always have around and some that also sound great.

Re: Demeter VTDB-2b DI

Posted: 30 Apr 2012, 02:32
by marshmellow
- The basic topology doesn't make much sense
- ECC83/12AX7 is a rather bad choice for a line driver
- UKF is dangerously high with the ground-referenced heaters
- ...

Re: Demeter VTDB-2b DI

Posted: 02 May 2012, 11:47
by Jarno
Can someone post a schematic of this thing? I do agree that ecc83 isn't the best choice to drive a tx but given the space constraints they probably didn't want to use two tubes.
For anyone building something similar, you could go for ECC832, which has a high mu and low mu triode in a single tube.

Edit:
Found the circuit :oops:
Wouldn't be too hard to lift the heaters a bit, right? Only a couple of parts.

Edit2:
The schematic Analag posted later in that thread is pretty simple, and ECC832 is def. a candidate for such a application.