1974 Ampeg v4 "ext. amp out/ ext. amp in"

[TheGreatDepression]

I read that the "ext. amp out" lets out a line-level signal after the preamp for use with a slave amp. i also read that for amps where these jacks do not exist, you're supposed to use the effects loop if you want to use a slave amp...so does that mean i can run my effects through the "ext. amp out" and "ext. amp in" as if they were labeled "FX send" and "FX return"?

i'd really like to have an effects loop on my v4, but i don't want to fry it or my effects with a harebrained scheme. someone help?

[Diablo]

That's not going to work.

[TheGreatDepression]

well, thanks for letting me know before i went and did something stupid.


is there any way you could explain why it wouldn't work? i'd really like to have a better understanding.

[Diablo]

Take a look at this preamp schematic. The two jacks marked Ext. Amp are connected together - there is no "in" and "out". If you are clever, I think you could rewire the jacks so the hot leads don't connect to each other and you could use your effects in between.

http://www.drtube.com/schematics/ampeg/v4pre-jp.gif

[Rob Mercure]

Unless I'm mistaken - I'd have to check my V-4 - the power amp in breaks the circuit using the jack and it will allow in/out. The posted schematic is one of the ones from the net done by Joe xxx(can't remember) but I'm got the Ampeg factory schemo - not with me, darn - and I believe that it's set up that way. If not it would be easy to simply use switchcraft type switching jacks and just make sure that there is a load on the "out" as well as a grid return/leak resistor on the "in."

Rob

[tboy]

I'm not sure when the change occurred, but older V4s did have it wired as shown on Joe's schematic, and newer amps had it wired (and labeled, I think) as a loop. It may have been a line-level loop though, which would be too hot for many stompboxes. On the old version, that 100k resistor in the bottom of the output voltage divider also served as the grid resistor for the next stage, so that would have to be dealt with if the jacks were re-wired as a loop.

[Dave Curtis, dB AudioTech]

Here's the schematic from mine.