Fx loop Op-amp Coupling Question

[chrisaxeman]

Hello all!

Hope the amp related question is not a problem,but it does concern fx.

What is the best method for coupling op amp stages from the same input signal-what cap values?

To cut to the chase,I want to reconfigure the fx loop of an amp to have a pair of sends-Y-cable I here you say?-Hang with me,please.

I need one to be line level(rack effects),and the other adjustable for instument level(line level pedals).

I've been padding down the instument level pedals with a dual Adjusticator(works great),but on the schematic of the amp(Laney GH50L),there is a slave out jack(never used it)that has exactly the same Op-amp config as the fx loop send,except this slave out's input is tapped from the output leg of the master volume pot(easily removed PTP connection),while the fx loop send is tapped from the normal tone stack output position.

I'd like to take advantage of this "spare" op-amp set,by inserting a pot into the R2 position to reduce it's gain for pedal interfacing.It's already in the amp,and makes for less patching and stuff.......

Do I have to then use coupling caps to isolate the two identical stages from the same input signal before their respective input resistors(R1's)?

Cheers and thanks in advance.

Chris.......

[davebungo]

I shouldn't have thought so, especially if the first stage, which is already connected, doesn't have one.  It appears as though the input is already referenced to ground anyway, so there is no need for a DC blocking cap.  Bear in mind though, that the input resistor to the second stage will add extra load onto the tone stack.  Probably not a big problem but look out for it.

[chrisaxeman]

I shouldn't have thought so, especially if the first stage, which is already connected, doesn't have one.  It appears as though the input is already referenced to ground anyway, so there is no need for a DC blocking cap.  Bear in mind though, that the input resistor to the second stage will add extra load onto the tone stack.  Probably not a big problem but look out for it.

Thanks Dave,

When you say extra load,what do expect I might be up against sonically?

I would of imagined it was not too critcal being that this part of the circuit is line level,but I,m all eyes and ears.

Cheers

Chris.........

[davebungo]

All I'm saying is that I don't think you should notice any difference, but it's always a good idea to listen to the amp before and after the mod just to make sure there aren't any unexpected side effects.  Good Luck.

[chrisaxeman]

Thanks Dave!

C..........