Issue with TC pedals in Rect-o-verb loop

[anders.blomberg]

So I've got this issue with my TC Electronic Hall of fame reverb and Nova repeater pedals in the loop of my Rect-O-Verb 50 mk II combo. What happens is basically that some sort of noise gets feedbacked in the pedals and it sounds horrifying. The problem occurs when I turn up the volume on the pedals. I've uploaded a video of the problem here https://www.youtube.com/watch?v=0wJp5bATdxc.

I've tried other pedals (tremolo and overdrive) in the loop and have no problem with them. I've tried the pedals before the amp and there's no problem there. I've tried the pedals in the loop of a Mesa in the local store and no problem there either. I've changed all cables without any success. I've changed the FX loop tube without noticing any difference. I can't even figure out if the problem is in the amp or the pedals. Please help!

 

[elvis]

Sounds to me like you are overdriving the pedals. Mesa amps tend to run really hot signals in the loops because the master volume is PRE-loop, so the full signal to the power section runs through the loop. I generally have to attenuate the FX send and then add gain after pedals in the loop if I want full volume out of the amp. You can use a LLS or a buffer with gain for that.

 

[mandoismetal]

It's probably because the amp has a parallel loop. Even when set to the maximum value (90%-100% depending on the amp) for wet signal, there is still a little dry signal bleed in the circuit. Because of this, there is a a millisecond(s) delay between signals and although almost imperceptible to the human ear, it is enough to cause phase issues. My RoV did the same thing when setting my delays too high. You can try to mod your loop to series. Good luck!

 

[elvis]

I disagree. Having a parallel loop causes a comb filter, which sounds like a flanger effect. It wouldn't affect the delays, for sure.

 

[mandoismetal]

Elvis, not trying to argue with you, but I had the same amp and pedal combination and that happened to me. I took my amp to a local tech and the nodded the loop. That solved my problem. It happened with my chorus and delays. Reverb was not affected.

 

[anders.blomberg]

Mandoismetal, did you get the same kind of feedback as I do? From what you describe with signals being out of phase, I do not understand why the signal goes into this digital feedback-like noise? Also, since I tried the pedals in the loop of a Dual Recto head in the shop without problem, I'm thinking it might be a problem with my amp. Doesn't all rectos feature the parallel loop? But I might just be wrong. I'm just not to fond of the idea of fiddling with the amps circuits to make it series.

 

[mandoismetal]

Yes. I had exactly the same problem you're having in the video. I know it happened with my flashback delay and my chorus. I never cranked my reverb that much so I don't know if it would've caused a problem too.
Some of the very first Rectos had series loop as well as the newer reborn models. You can try replacing the tube that buffers the loop to see if that helps, but I'm pretty sure it is a parallel loop design flaw.
I hope this info helps out a bit.

 

[anders.blomberg]

Guess that's it then. I'll leave a report if I get down to modding the amp.

 

[elvis]

Mando, thanks for the consideration. But you're SUPPOSED to argue with me. :twisted:

By any chance did you have anything else done when getting your loop modded, like adding a buffer or lowering the send level? I've done loop mods on my own amps, and the tech could have gone a lot of different ways with it.

 

[mandoismetal]

Elvis, lol I'll keep that in mind for future forum trolling.
As far as the mod, nope. He just swapped a couple of leads from the loop mix pot and tied down another one. I got the schematic straight from Mesa.

 

[KiwiJoe]

Patient: "Doc, it hurts when I do this."
Doc: "So, don't do that."

It sounded fine to me until he tried to crank the levels. Too much "send" from the amp going to the pedal for that much level from the pedal? I thought that's what level knobs are for.

 

[anders.blomberg]

I disagree on that it was working fine until I cranked the level. I see the reverb as an effect rather than just a spice in the background. When I turned up the level to what I consider a usable level, things got nasty.

So I went for my soldering iron, whipped it around for a bit in the amp, and now the loop is series, and effects are working like a charm. No downside to this! Easy as pie. Although I don't understand why the parallell loop funked things up. Thanks though!

Here are picks before and after the mod:

 

[mandoismetal]

Very neat and tidy work! I'm glad you got everything working fine for you.

 

[elvis]

I am really struggling to explain how this could have been the cause. Glad it worked for you, though!

 

[anders.blomberg]

I agree with you. I've sent the question to Mesa, but am still awaiting reply. Guessing it's not coming. Anyway, I'm really happy with the serial loop. Turned out it wasn't just the TC's that disagreed with the parallell. I never understood the Sonic stomp until now, after the mod. Having always destroyed my tone, it now really enhances it. And for general tone degradation from having the full signal go though the loop, I haven't noticed anything.

 

[Guitarmiester]

I'm having this same issue with a Series 2 Single Recto I just bought, except I have to max the pedal levels and turn the loop mix to at least 60% to have the delays and reverb be more than just subtle background noise. Doing so causes that rumble of doom. I can back off the pedal levels but then I'm back to square one of barely even hearing them.

Sounds like the mod is the only way to remedy this.

 

[TRENCHLORD]

I've always thought that you should activate KILLDRY on the pedal when using time-based effects with a parallel loop.

On killdry the pedal only secretes the wet signal instead of the wet/dry mix, then you use the amp's mix knob to dial in the ratio of wet-dry desired.

I'm fairly sure it even says that in the manual of the TC pedals (run killdry for parallel loops).

 

[anders.blomberg]

I had no success with the kill dry.

 

[Guitarmiester]

Same here. Activating kill-dry only provided the ability to max out the volume level of the TC Electronic delay without getting that booming sound. Other than that, it really didn't make much of a difference. Wasn't even close to a miracle cure that I was hoping for.