How hard is it to rebuild an effects loop for an amp?

[TNJ]

I want to keep the Two Rock Emmie Pro amp I have...FABULOUS TONES!
The efx loop doesnt work, however. It has a loop with serial/parallel toggle.
Not sure what's wrong with the loop either, but it has never worked for me since I received it.
I have an email to Joe/Bill but havent heard back yet.

What's it gonna take to swap out, or rebuild?
Will it hurt the tone of the amp if done right?
Or should I sell and start again?
If I could keep this amp and get a workable loop, it would easily be one of the top 3 amps
I've ever owned.
Help a brother out...

S.
j

[scottl]

Mod the amp to only incorporate "in/out" jacks. Use an external loop, such as the TR, Glaswerks Matchbox, or Loopalator. Better tones than the built in unit. Call Bill, he has told me he always prefers external as well.

[JoeB63]

Mod the amp to only incorporate "in/out" jacks. Use an external loop, such as the TR, Glaswerks Matchbox, or Loopalator. Better tones than the built in unit. Call Bill, he has told me he always prefers external as well.

No, that's not the answer. Believe me, I have tried everything. But I do finally have the answer for you TNJ.

Two Rock's that have buffered loops (EPro, Custom Reverb, Topaz) really only have half-buffered loops. The return is buffered, but the send is not --- which is dumb.

The problem with using a Dumblator device, as Scott suggests is those have a slight smoothing effect on the tone, which can be nice on OD (or not), but sucks on clean tones ---- on these amps. These half-buffered-loop amps don't need the Dumbleator to control the high-end (as do some D-style amps with non buffered loops). Plus those devices are expensive and just unnecessary with these amps. (Note that I tried this; it's not conjecture).

I have tried everything over the past 6 years to solve this problem on 3 TRs that I've owned. Once you realize that the return is buffered but the send isn't, the obvious solution is to attach a buffer (or any buffered pedal in bypass, like a Boss pedal) to the effects send of the amp with a short cable (e.g. a one foot cable), then go out to your pedal board, then back from the board straight into the effects return on the amp.

However, that doesn't work either. The reason is that unity gain buffers in used that way in TRs increases the signal level and screws with the tone and feel of the amps. Trust me on this, I've tried several buffers in this way and it's always the same thing. It's a weird thing in the TR's loop implementation.

I found a temporary solution, with a permanant one on the way. I took my RC Booster and used it as I suggested with the buffer above. With the booster set on, I turned the gain all the way down, the tone controls on neurtral, I then set the volume where it needs to be to be in unity gain with nothing in the loop. That gives me a level-matched buffer. This works perfectly (again, you gotta trust me on this) -- no tone or feel change at all. But it's not a good use of a $185 booster pedal.

I have a dedicated buffer with a 25K volume pot in the mail to me now. This should work as a permanent solution (it's small and cheap - $58). Right after I ordered that buffer, I found this: http://bargeconcepts.com/glzbv.html
which I'm sure will do the trick. If the buffer that's on the way doesn't work, I'll get the Barge one (the 3 knobber).

[TNJ]

O.K. Joe,
Thanks for your thoughtful response.
I have this pedal....

http://cusackmusic.com/?page=showFiles&type=Products&item=More%20Louder

http://www.cusackmusic.com/Manuals/More%20Louder%20Manual.pdf

When I use this pedal in buffered bypass mode, do you think it will do the job with the loop?

And should I use this in serial or parallel mode?

Thanks!

S.
j

[JoeB63]

O.K. Joe,
Thanks for your thoughtful response.
I have this pedal....

http://cusackmusic.com/?page=showFiles&type=Products&item=More%20Louder

http://www.cusackmusic.com/Manuals/More%20Louder%20Manual.pdf

When I use this pedal in buffered bypass mode, do you think it will do the job with the loop?

And should I use this in serial or parallel mode?

Thanks!

S.
j

I don't think that pedal will work. I believe what you'll find is that the signal level out of that pedal will be higher than when you've got nothing in the loop. Of course, you can bring the loop level down (in serial mode) with the rear loop master control on the amp. But I found that even doing that, the tone and feel of the amp is different (in a bad way) with a buffer in the loop. You need a buffer (or buffered pedal) that allows you to bring the signal level down below unity gain (because the output of the TR loop is above unity gain (vs. having nothing in the loop).

But you should try that pedal. You'll find that it will bring back the lost high-end when you're using the loop --- that's a good thing. But it will also increase the volume in a not so good way.

I'll keep you posted on my $58 pedal that's on the way. It might be here today.

Also, I've never had any luck getting effects to work in the TR loop in parallel mode (even delays, which should work fine). And even in parallel mode, that unwanted signal boost is a problem -- it seems to occur just from putting anything in the loop (serial or parallel).

[AudioGtrman]

Not familiar with the topology of this amp. Is this a tube driven loop or FET? I have a schemo for a tube drive circuit if you want it......and have room or inclination to add one.

[jay42]

Maybe I should stay out of this, but it occurs to me that we should know what the OP wants in the effects loop and whether he want series or parallel -- rack equipment or foot pedals? The idea of adding an external buffer is good, however, if it runs off of a 9V battery, there's not much headroom compared to +/- 15V. It would be good to know at what level the send output peaks.

[TNJ]

I want to run the serial loop, with either line or pedal level effects.
With no tone suckage, please. :)

S.
j

[TNJ]

Well,
I tried the DD6 into the loop...nothing.
This loop is dead.
In serial mode, there is no sound...PERIOD...from the amp.
In parallel mode, there is only sound when I crank the loop level and amp level to the max...again, no effect is heard (except for the amp's reverb, which drenches the whole sound).

I'm totally frustrated and confused with this thing... :confused:

S.
j

[jay42]

Have you stuck a tuner on the Send? You need that to determine where the failure is. The other test is to run a pre-amp out...a POD will do...into the Return.

[JoeB63]

Well,
I tried the DD6 into the loop...nothing.
This loop is dead.
In serial mode, there is no sound...PERIOD...from the amp.
In parallel mode, there is only sound when I crank the loop level and amp level to the max...again, no effect is heard (except for the amp's reverb, which drenches the whole sound).

I'm totally frustrated and confused with this thing... :confused:

S.
j

It's either a bad tube (V3 or V4, but likely V4) or the amp needs repair.

[TNJ]

Well,
Mac from Two Rock emailed me, and I just got off the phone with him.
He said to ship the amp back, and they WILL fix the problem.
There you go...

Thanks for the help everyone...back to the source with this one.

S.
j