Peavey EDI box

[Mick Bailey]

If anyone has an old MK1 Peavey EDI box, would you mind plugging a lead into the 'amp in' socket and measuring the DC resistance from barrel to tip (which gives the primary resistance)?

I rediscovered my unit and the output seems to be very much lower than I remember. My primary reads 33k ohm, which seems to be high for such a tiny transformer.

[The Dude]

I don't have an answer to your question, but you are feeding the unit from an amp's speaker output?

[Jazz P Bass]

EDI pdf file

[Mick Bailey]

Yes, it connects between amp and speaker. I haven't used it for years and maybe my memory has faded, but it used to work pretty well.

Its just a transformer inside that connects across the amp and has a simple speaker emulator LCR circuit and trimpot for timbre.

It does have a fair loss due to being able to take 35v RMS and there's no compensation for lower signal levels, so it does normally need a fairly healthy signal to get much out of it.

EDIT: The pdf say it all. That's a mk2 but I think they're identical other than the enclosure.

[The Dude]

I figured you knew how it worked, Mick. The reason I asked is because, back when those things came out, I used to occasionally get them in with the symptom "low/no output". It was because people were trying to use them as a regular DI with an instrument or line level input and not understanding the purpose of the box.

[J M Fahey]

If anyone has an old MK1 Peavey EDI box, would you mind plugging a lead into the 'amp in' socket and measuring the DC resistance from barrel to tip (which gives the primary resistance)?

I rediscovered my unit and the output seems to be very much lower than I remember. My primary reads 33k ohm, which seems to be high for such a tiny transformer.

Interesting.
Never heard of them or seen such a specialized DI, but from comments above I *guess* there is a strong input attenuator, say 33k/1k to turn 35V RMS into more standard 1V RMS or so and from then on a more or less standard DI transformer.

Meaning I would open it (wink wink) and if true (or something similar) I would add an extra switching jack straight into transformer primary.

It would lose bells and whistles but could double as a regular direct box if needed.

jm2c

[Helmholtz]

EDI spec sheet says:
"Drain on speaker signal: Less than 1/2W at 30Vrms."

As P = V²/R or R = V²/P this means an input impedance >= 1.8k.

I'd also measure input AC resistance to see if some part of the input resistance is hiding behind a cap or a transformer