Music Man sixty-five 112, 1-channel: post-preamp-effects

[AristoTele]

I have a Music Man "Sixtyfive RD 112" one-channel type of amp probably from early 80's. There is a low gain and high gain input and then there are two jacks titled "input/output" with different voltages in the front panel.

Can this input/outputs used as an effect loop for post-preamp-effects (delay, chorus) and, in that case, how they should be switched? Does the power lo/high-switcher something to do with this?

Please no comments of the possible results of this experiment. I only want to know the technical basis in this solution. And if possible with very simple terms, like "put this switch to that position and plug in the effect output here".

I would appreciate any info on this issue.

[Enzo]

The jacks are insert jacks, which would be used as effects loops, or any other insert function. look at page 2 of this file: http://www.schematicheaven.com/newam..._&_2100-rd.pdf

The two jacks have a gain stage between them. The earlier one is the low level one, and the later one is high level. The low is just before the gain controls and the high is just before the volumes.

As a single TRS jack, you need a breakout Y-cord.

As to switching it, you would switch the effect on and off at the effect. These are simple inserts, not switchable.

[AristoTele]

Thanks!

So basically there are two different stages to put the loop. Input/output comes to same jack and the loop is generated by Y-cord, like:


input/output (low)
|
|
|
/...\
/..... \
/.........\
/............\
__> effects >

or, if I bypass the gain section
input/output low input/output high
| ....................|
| ....................|
| ....................|
| ....................|
| ....................|
___-> effects__> ?

[52 Bill]

If you look at the schematics, the low level break jacks come right after the basic preamp stage. The high level break jacks come right after the distortion/gain channel.

If you take the output from the low level jack and send it to your FX and then you take the output from your FX and feed it into the high level return, you will bypass the distortion/gain channel of the amp.

The set of two jacks were supposed to allow the use of low signal level guitar pedals as well as high signal level rack mount FX with the amp.

[AristoTele]

Now I got it

Thank you very much Bill. Now I'm back on the track.

AristoTele