Demeter VTDB-2b DI

OrionManMatt · Post by **OrionManMatt** » 28 Apr 2012, 21:01

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.

Bernardduur · Post by **Bernardduur** » 29 Apr 2012, 09:54

Cool! Jensen transformer!!!

marshmellow · Post by **marshmellow** » 29 Apr 2012, 12:33

Doesn't mitigate the stupid circuit...

chicago_mike · Post by **chicago_mike** » 29 Apr 2012, 19:16

I think I have the ampeg tube DI schematic somewhere.

Thanks for the piccies!!

OrionManMatt · Post by **OrionManMatt** » 30 Apr 2012, 01:23

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.

marshmellow · Post by **marshmellow** » 30 Apr 2012, 02:32

- 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
- ...

Jarno · Post by **Jarno** » 02 May 2012, 11:47

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

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.