Fender Schem Question

[C Moore]

http://support.fender.com/schematics/gu ... _Rev-A.pdf

Can you explain, generally, how the effects loop works on this amp.?
I am not really sure what all the symbols mean, or what the SS Devices are for.
Are those TRS Jacks.?
Is that loop designed to shunt around the Reverb.?
So the preamp out grabs the signal before the Verb, and then mixes it back in with the Verb on its way to the PI. You can choose to keep the Verb out of the mix if you turn it Down/Off I guess.?
I suppose I am mainly confused about what type of jacks those are, and what is going on with the SS "stuff".
Thank You

[martin manning]

The pre amp out/power amp in jacks are TRS, each with two isolated make/break switches.
In normal operation (nothing in the loop) the preamp output is split, with one leg going to the reverb and the other bypassing it, and these are mixed back together at the input to the PI. There is a FET that can be used to ground the wet signal before the mixer, killing the reverb.
The preamp out is a send buffer tapped off the last preamp stage, and using it does not change the signal path.
Using the power amp in (return) jack connects the loop return signal to the input of the return recovery amp. It also disconnects the preamp output from the reverb wet/dry split point, and connects the output of the return recovery amp in its place. The reverb parallel paths are after the loop return, so reverb is always available.

[C Moore]

Thanks Martin -
When you say the Pre Out is buffered...is that what makes the use of pedals easy.?
Is that what the whole Dumblator (sp) thing is about. Guys have a stand alone buffer so they can use (with better results) pedals in their series loops.?
Thanks

[martin manning]

Yes, driving long cables and an FX board is better done from a low-impedance output because the signal loss is lower. The Dumbleator uses a cathode follower (low Z out) for the send combined with a standard (high Z in) gain stage for the recovery. Very similar to what you see in the BD RI, except Fender is using op-amps.

[C Moore]

I see...Thanks.
Do you (or anybody) have a link to a schem that shows a Parallel Loop.?
I understand the basic Difference/Reason for having one, but I am just wondering what a Parallel Loop looks like schematically.
Thank You

[martin manning]

The reverb part of the BD RI is a permanently wired-in parallel loop, as it is in most fenders.

Some stuff here too: https://tubeamparchive.com/viewtopic.ph ... highlight=