JM Signature recording preamp

[Mat Cortex]

In my thinking the Edcor trannie and the direct box are sort of the same kind of thing.

I'm thinking the same way. I choose the EDCOR Xfo to have line level output for mainly headphone use. But i wanted the amp to be as polyvalent as possible: used with power amp, recording interface, bar's PA system, etc. Kind of do-it-all preamp.

As JazzGuitarGimp said, that circuit was used back then for studio equipment.
I firmly think that we can make it work without removing the so-called OT.

I think the XLR and 1/4 output needs modifications: ground lift, switch to chose the output, resistor for rectifying the mismatched impedance. Worth trying. Do you think so ?
I'll draw a new output schem this week and post it.

Regards
Mat

[10thTx]

I think the XLR and 1/4 output needs modifications: ground lift, switch to chose the output, resistor for rectifying the mismatched impedance. Worth trying. Do you think so ?

Yes, I think it would be good to try those things.

With respect, 10thtx

[Mat Cortex]

i'll order the components this week, so no mods before at leat the next week. Be sure i'll come back with the result.

Regards
Mat

[JazzGuitarGimp]

Pulling up a chair and watching with interest.....

[Mat Cortex]

Hi,
Here's the new output schem. I decide to omit the grounding on the XLR and to use the 1/4 for headphone only. No need for ground lift anymore.

Is R61 and R62 OK or do i need a 560R on both stereo end ?
The EDCOR Xfo is 2,5 W rated. Is 3-5W resitor needed ?
I doubt that the output section of this amp is above 3/4W.

Regards
Mat

[M Fowler]

Handy reference for ground problems.

[Mat Cortex]

Handy reference for ground problems.

Thanks,
Very interesting document. I'll take a deep look at it

Best regards
Mat