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[Kevin_Tisdall]

I volunteer at a local arts center running sound for their more complicated shows and also for some of teh open mic nights.   Most performers are very entry-level, unprepared, etc, etc.   But a few are quite good and do professional folky gigs all the time.  One of those guys showed up with a Boss Preamp/Loop pedal last time and all hell broke loose when it was connected.   There are no sound checks.  You connect whatever you are playing and do 15 min and get off.  No time to tweak.

So we moved a microphone connection to the voice out of the box, and used the same mic with a new wire to the box.  Guitar out went to pedal and then from guitar-out of pedal to a di.   Major feedback due to the gain and eq mismatch of the pedal.  I compensated at the board best I could but he gave up and did his last song without looping but with the box still in line.

We got together in the same space to work out the problems and were able to adjust the box gain and eq so that connecting it didn't feed back or otherwise change the sound of the vocal or guitar.  He saved those settings.  So at this point we have good sounding guitar and vocal, a reasonable monitor level and no feedback at all.

Then he started looping.   Guitar loops posed no problem aside from getting them into the box at the proper levels. He will work on that.   But the vocal loops (always done second) seemed to generate lots of 'artifacts' that eventually caused feedback or a ring in exactly the same place in each looped phrase.  1-2 loops was no problem but 4 loops (like 4-part harmonies) gave clear feedback in places.   

I expect that the vocal loop records some of teh guitar loop playback in the monitor output and any ambient room reverb and then amplifies it again as the next loop is recorded.  Until you have a loop of ringing tones and a vocal.

Anyone ever deal with this?  Solutions?  This is why God made bands?

--Kevin

[Robert Lofgren]

What mic were you using for the vocals?

I think that you are on the right track about the interaction between the looper and monitor. Any bleed from the monitor will just mess with the sound.

[Kevin_Tisdall]

What mic were you using for the vocals?

I think that you are on the right track about the interaction between the looper and monitor. Any bleed from the monitor will just mess with the sound.

SM58 when we were testing.  Also happened with Audix OM3 the night of the open mic session.

--Kevin

[Chris Grimshaw]

I've had similar problems.

The mic picks up some monitor bleed, and adds it to the loop. Layer it up a few times, and that's a whole lot of monitor in the looped sound.

IEMs are fine, or you'll have to reduce monitor levels down to basically zero while the loops are being built.

Chris

[Robert Lofgren]

TC- Helicon only sells super-cardioid mics to help reduce stray noise when using their loopers/harmonizers.

[Wes Garland]

Find your room modes and notch them out of the monitor super-hard with a PEQ.  Same freqs, cut from the vocal mic, just not as hard. NARROW. Q=10 if you can get away with it.  Shoot for 10dB GBF headroom, and do everything you can to improve placement, reflections, etc.

[Chris Grimshaw]

TC- Helicon only sells super-cardioid mics to help reduce stray noise when using their loopers/harmonizers.

That's unlikely to solve all the problems. IIRC I was using an EV N/D767a when problems came up, and that's also a supercardioid.

I suspect some of these loopers have compression baked in, which would certainly compound the issues.

Chris

[Guy Luckert]

  This is why God made bands?

--Kevin

this!

also why she made open mic knights lol!

[David Allred]

this!

also why she made open mic knights lol!

Per forum rules.  No religion.

I've dealt with  loopers on 2 occasions.  Not a hint of feedback either time, but mine was a vocal only, using one mic.

[Kevin_Tisdall]

Thanks all.  I may recommend he use a harmonizer for vocals and do the looping just on guitar.  The problem only arose when looping vocals and he will be in various places so optimizing for this one house won't be worthwhile.

--Kevin

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