Strange clipping only with FX loop

[Addictedtokaos]

Hey,
I just picked up a Gstring for my rectoverb and I noticed when I hooked it up I get a strange clipping.
-only happens when I have a pedal in the loop.
-I tested all my cable - no issues.
-No issues when no loop connected
-clipping on CH1 happens when master is around 12:00 or gain around 9:00-10:00. Clipping starts earlier when Master is set higher.
-clipping on CH2 only happens when master is set to 3:00 and higher.
-cleaned input, send and receive jacks. no improvement.
-checked the tubes/changed out tubes. no improvement.

I recently did the FXloop serial mod myself. Is it possible I either:
a) have a bad solder?
b) maybe damaged a trace?

Ive also read in another forum that the rectoverbs was prone to this issue with certain pedals anyone else here this?
http://www.seymourduncan.com/forum/showthread.php?t=141237 (see post #7)

 

[94Tremoverb]

Test it with a plain cable in the loop. If it clips it's something in the amp, and if it doesn't it's the pedal(s).

 

[Addictedtokaos]

Yeah, I tried just a patch cable going directly from send to receive. There was no issue. I agree too, if it was the amp the symptoms should still be there with the send/receive jumped.


So you think both my Sniper modded Boss GE7 and Gstring are both causing clipping?

 

[UnderJollyRoger]

Can you set the input gain of your effects ? maybe you are overloading them with too much volume ... i think the g-string should have an option to do that.

 

[94Tremoverb]

Try the pedals one at a time.

Some Boss pedals do definitely have a problem with the loop level in a Rectoverb - but only just. A friend of mine has the same problem and to fix it I ended up adding a couple of resistors to the MV pots to drop the level by 3dB, which was enough to stop it. You just have to turn the Output Level up a tiny bit further to get the same volume back. In theory you could just do the same thing by turning down the MV pots slightly, but he found that took it into the 'cutoff zone' on Channel 2 where it loses a lot of tone.

 

[Addictedtokaos]

Thanks for the suggestion, but I was only using one pedal at a time.

Yeah, so far my workaround has been to raise Output and lower MW. I dont want an overdriven tone for my CH1 so that works, but I do like a little on CH2 + gain. But I can live without.

I'll have to verify this later but I think when I had my output to approx 9-11:00 and change channels I would get a pop sound sometimes, which I dont remember every happening when not using the loop

How much of a volume difference was there between CH1 and 2 by adding the resistance, if you can remember.

 

[94Tremoverb]

3dB. I added a resistor of the same value as the pot, in series with the top of the track. This halves the signal level for any given pot setting.

But if you have your Output Level at only 9-11 o'clock that's *way* too low - try raising it to about 2-3 o'clock and reducing the MVs accordingly. The problem with loss of tone on Ch 2 only occurs when the MV goes below about 10 o'clock.

 

[Addictedtokaos]

I did my research and built a "signal pad" myself with an old 500k pot i had laying around. It worked but I found it too sensitive to get the exact adjustment I wanted. I found I could remove the clipping but suffer tone loss.

After researching some more most amp and pedal manufactures use a 25kOhm linear pot as a level send. It supposedly is a good balance between being able to trim line level and not lose tone. So I have one coming in the mail.

I also came across this http://www.jt30.com/jt30page/potfix/

Using these instruction I attached a 100k resistor to my pot and it really added the flexibility the pot needed to get that exact spot where there is NO clipping AND NO tone loss. It was nice to be able to listen to the signal and as I would lower the level be able to hear the slightest loss in tone and know to raise it back to that spot. I was informed that I could have saved some trouble and just purchased an Audio Taper vs a linear.

The only thing I noticed in my testing is that it (the signal pad) has to be connected to your first pedal in the loop with a short jumper type patch cablel. If I placed it just out of the send jack and connect it to my first pedal with a longer patch cable it doesnt work. My guess is that due to being a passive circuit it cant amplify the signal long distance.

Anyways I cant wait to get my 25k pot in and see how it differs to the 500k.