Do i need to buffer the post preamp signal if i put an effects loop in my amp?

[SimpleLeo]

That's pretty much it.

If i have a pretty straight-up amp do i need to buffer the signal from the preamp if i'm sending it to an effects loop?

This Q comes up cos of a discussion where it was mentioned that the high impedence of the post preamp signal is not good for long cables? Can you tell how much i just don't know?!

FYI: while i'd normally like to not buffer the signal (probably because that's what everyone tells me not to do, despite having a bunch of pedals which buffer the signal anyway), in this situation it might be advantageous on circumstantial grounds. More on this later....

Thanks. L

[Rosewood]

It depends somewhat on the effect device. Try it unbuffered to see if the signal level drops. What amp are we talking about?

[donnyjaguar]

The short answer is yes. If for no other reason than the impedance you will be driving is a mystery. In audio its perfectly fine to go from low-Z to high-Z. I notice that some amplifiers use Opamps instead of a tube for this part of the circuit so that could be an option if you don't want to get into punching more holes in a chassis. You'll need about 12Vdc for the op-amp, but you can put a voltage doubler on the filament winding and use this for a +/-6Vdc supply. Very easy as you won't need much current. You configure the op amp for unity gain so the output is tied directly back to the inverting input. The output impedance will be appreciably lower than 1 Ω and will drive anything. Most opamps are dualies so you can use the second one for recovery and work a gain adjustment in if necessary.

[SimpleLeo]

Ok, for the details. This is the lowdown:
Taking tiny epiphone VJ head, adding much tweakery goodness. Finally and importantly: inserting effects loop with stereo return to feed two pwr amps. yum.

This stereo return is made possible by mono in/stereo out effects.

I am minded that buffering is the way forward for dealing with the mono/stereo mismatch when the loop is not in use. That is, when loop is off one still needs to get the now mono signal to two pwr amps.

Finally finally: I am a complete outsider to the build. I am investigating what is possible so men more clever than what i am can go do the clever stuff. Believe me, I want to make something that is totally awesome, but think this is best way. for now.

L