I'm fairly certain I've asked folks before and gotten a big "No that
would be too difficult" (i.e., expensive).

How easy or difficult might it be to add an effects loop (after pre,
before power) to guitar-type amps which were never designed with one?
I'm thinking specifically of MusicMan heads which are usually available
for cheap; for me their only drawback is the lack of a loop. Any tips
much appreciated.

It depends entirely on the specific circuit and the type of
construction. You just have to look at the schematic and see if
there's a reasonable place to pick off the signal and send it to a
"normalled" switched jack (or pair of jacks). If you can find a good
spot to do it, you then have to look at the amp's circuitry and see if
it's reasonable to do it there. With point-to-point wiring it's pretty
easy to do but if it's a tight spot on a messy PCB, it may be
difficult.

What you're looking for is a buffered, AC-coupled connection between
stages. Some amps don't have any such thing. Can you post a link to
an online schematic of the amp in question?

Unless the amp is already incredibly undesirable, you have no business
drilling holes in the chassis to accommodate the jacks. Don't make any
mods to a decent guitar amp that can't be completely un-done. It's
only going to **** off somebody who might own the amp later. Chopping
up guitar amps is kind of like cutting down the rainforest. It's
incredibly inconsiderate of future generations.

ulysses


Adam Gottschalk wrote:

I'm fairly certain I've asked folks before and gotten a big "No that
would be too difficult" (i.e., expensive).

How easy or difficult might it be to add an effects loop (after pre,
before power) to guitar-type amps which were never designed with one?
I'm thinking specifically of MusicMan heads which are usually available
for cheap; for me their only drawback is the lack of a loop. Any tips
much appreciated.

You can often break into the circuit right before the phase inverter for the
send, then return to the same place...just breaking the circuit for a
send-return. Buffering is important. London Power has schematics for this
type of thing, and a kit for a tube buffered loop.

As Justin said, do it without butchering if at all possible. A separate box
for the jacks and some new cables through existing holes in the chassis
ought to do the trick.

George Reiswig
Song of the River Music
"Justin Ulysses Morse" wrote in message
m...
It depends entirely on the specific circuit and the type of
construction. You just have to look at the schematic and see if
there's a reasonable place to pick off the signal and send it to a
"normalled" switched jack (or pair of jacks). If you can find a good
spot to do it, you then have to look at the amp's circuitry and see if
it's reasonable to do it there. With point-to-point wiring it's pretty
easy to do but if it's a tight spot on a messy PCB, it may be
difficult.

What you're looking for is a buffered, AC-coupled connection between
stages. Some amps don't have any such thing. Can you post a link to
an online schematic of the amp in question?

Unless the amp is already incredibly undesirable, you have no business
drilling holes in the chassis to accommodate the jacks. Don't make any
mods to a decent guitar amp that can't be completely un-done. It's
only going to **** off somebody who might own the amp later. Chopping
up guitar amps is kind of like cutting down the rainforest. It's
incredibly inconsiderate of future generations.

ulysses


Adam Gottschalk wrote:

I'm fairly certain I've asked folks before and gotten a big "No that
would be too difficult" (i.e., expensive).

How easy or difficult might it be to add an effects loop (after pre,
before power) to guitar-type amps which were never designed with one?
I'm thinking specifically of MusicMan heads which are usually available
for cheap; for me their only drawback is the lack of a loop. Any tips
much appreciated.

A. & G. Reiswig wrote:

You can often break into the circuit right before the phase inverter for the
send, then return to the same place...just breaking the circuit for a
send-return. Buffering is important. London Power has schematics for this
type of thing, and a kit for a tube buffered loop.

I would have said it's only worth doing if the buffer is already in the
circuit, but I hadn't realized there are kits available for doing this
sort of thing. It sounds like a nasty mess to me, but if you want it
badly enough it apparently can be done.

As Justin said, do it without butchering if at all possible. A separate box
for the jacks and some new cables through existing holes in the chassis
ought to do the trick.

If it's some horrible amp that's bound for the dumpster, it's not such
a big deal but it's always sad to finally lay my hands upon some cool
old amp I got for cheap, only to discover some slick **** had his way
with it before it got to me.

ulysses


George Reiswig
Song of the River Music
"Justin Ulysses Morse" wrote in message
m...
It depends entirely on the specific circuit and the type of
construction. You just have to look at the schematic and see if
there's a reasonable place to pick off the signal and send it to a
"normalled" switched jack (or pair of jacks). If you can find a good
spot to do it, you then have to look at the amp's circuitry and see if
it's reasonable to do it there. With point-to-point wiring it's pretty
easy to do but if it's a tight spot on a messy PCB, it may be
difficult.

What you're looking for is a buffered, AC-coupled connection between
stages. Some amps don't have any such thing. Can you post a link to
an online schematic of the amp in question?

Unless the amp is already incredibly undesirable, you have no business
drilling holes in the chassis to accommodate the jacks. Don't make any
mods to a decent guitar amp that can't be completely un-done. It's
only going to **** off somebody who might own the amp later. Chopping
up guitar amps is kind of like cutting down the rainforest. It's
incredibly inconsiderate of future generations.

ulysses


Adam Gottschalk wrote:

I'm fairly certain I've asked folks before and gotten a big "No that
would be too difficult" (i.e., expensive).

How easy or difficult might it be to add an effects loop (after pre,
before power) to guitar-type amps which were never designed with one?
I'm thinking specifically of MusicMan heads which are usually available
for cheap; for me their only drawback is the lack of a loop. Any tips
much appreciated.