Weird Squeal with True Bypass Loop Pedals--Please help

Discussion in 'Effects, Pedals, Strings & Things' started by TooManyToys, Jun 16, 2006.


  1. TooManyToys

    TooManyToys Guest

    I'm stumped with a pedal mystery, and I was hoping the many gear gurus on this board could help me out. Let me say in advance I'm thankful for any help that will be offered.

    I've built up a couple of pedalboards in the last few months, and one finishing touch I wanted was a true bypass looper so that I could activate different groups of pedals with just a click or two rather than several. After reading several reviews, I ordered a couple of loopers from Loop-Master.

    Brian at Loop-Master is great to deal with, and he had my custom pedals delivered in a very reasonable time at a fair cost. I set up the boards, and things seemed to be going swimmingly. On my "main" board, I have a Wah, Volume, Keeley Comp, Keeley BD-2, OCD, and H20 with everything post Volume Pedal going in through the looper (Comp, BD2, OCD, and H20).

    I noticed a few days after that when I cranked the controls on the BD2 (just to see how nasty it could get) that it would get this nasty squeal. The squeal would oscillate depending on how I turned the controls (including tone, level, and distortion). Turning the guitar's volume knob would control the pitch/volume of the squeal as well.

    So, I tried to narrow down the culprit. I noticed that I would NOT get the squeal when it was just the guitar plugged into the BD2 and then into the amp. It would feedback Nugent/Hendrix style, but it wouldn't have this weird squeal. However, if I plugged the BD2 into the true bypass looper, then it would squeal when turned up.

    I tried eliminating various components. I tried different cables, amps, guitars, batteries, and power supplies. At first I thought it might be the BD2/Loop-Master combo, but I tried a Keeley DS-1 with Keeley Comp, a Visual Sound Jeckyll and Hyde, and the OCD, and I would get the squeal from them as well. Every time, the one constant was the Loop-Master looper.

    Well, this depressed the heck out of me because Brian's loopers are really cool and obviously very useful. Still, I thought the units must have been defective. I contacted Brian and he offered to let me send the back so he could check them out.

    I never did that because I wanted to try some other true bypass loopers. I ordered the Keeley model (the Japanese apartment) and, sure enough, the squeal was still there. Guitar into cranked overdrive into amp=wild feedback. Guitar into Overdrive (in the loop pedal) into amp=nasty squeal.

    I thought "what the heck?" and tried yet another true-bypass loop pedal, the Radial Bigshot EFX. Yes, the squeal is still there. Obviously, these loop pedals are not all defective, but I'm stlll clueless about what's causing this issue.

    I'm not an electronics genius by any stretch, and I sure as heck couldn't (and can't) figure out what would cause one of these pedals to squeal like this. I have tried to replace every variable I can think of. I typically use George L cables, but I've tried other brands, and the squeal is there. I've tried six electric guitars, three different amps, and it just doesn't matter. I've tried batteries and power supplies, and it doesn't make a difference.

    I'm stumped. Is there anything about a True Bypass Loop pedal that would cause this behavior with Overdrive/Distortion pedals?

    There are people on this board that know a lot more than I do about such things. Please, help me figure out what the heck is going on here.

    I'm also curious if anyone has had similar experiences. For all I know, this behavior is normal. However, it's not one particular looper or one particular overdrive. Are there variables I haven't considered?

    Thanks, everyone!
     
  2. cbpickin

    cbpickin Tweed Supporting Member Silver Supporting Member

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    I have experienced a similar problem with my micro looper. I use just my TU2 in a loop by itself. I thought I could just use the send side since I didn't need the return signal since the tuner is in mute mode when engaged. But, if I don't run a cable on the return side also, I get a squeal. If I run a cable, no squeal. I don't understand it either, I just know how to stop my problem.
    Do you have the send and return loops completed? I wasn't sure from your post. It sounds like it though if you are running several pedals, but just checking if all four jacks on your looper have a connection.
     
  3. enickma

    enickma Member

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    What are you powering them with ? I have run into this problem, and found the culprit to be a Visual Sound 1Spot. I tore everything apart like you did, and was perplexed before I caught it. I have 13 pedals on my board, so I am using a pedal power 2 plus, and the 1Stop + 5 connector plugged into the PP2 to power them all up. I also have a Loop Master from Brian, and thought it might have been the culprit. I took 5 pedals and powered them up with the 1Stop ... I'd get that cycle squeal/hum. I switched pedals, order of pedals, true bypass and non true bypass ... same result. I took just one pedal ... noise. I unhooked the 1Stop from the PP2 and directly into the wall. Noise. Then I did the same thing with the Pedal Power 2 .... silence. Now, I have the older version ( 1000mA ) of the 1Stop, and have read where there were noise problems on some. A few buddies of mine have the newer version ( 1700mA ) and theirs are silent. An ebayer screwed me misrepresenting it as a new one .... no wonder the jackhole sold it. It sounds to me like it's a power issue

    p.s. another variable might be your outlet you are using. Some outlets aren't properly grounded and will give off noise.
     
  4. John Phillips

    John Phillips Member

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    It sounds like 'coupling' in the looper causing the pedals to self-oscillate. The components in there may have enough capacitance to pass a tiny signal back from the output to the input, which then gets reamplified by the overdrive pedal.

    Try a buffered looper - the Boss Line-Selector is probably the cheapest.
     
  5. TooManyToys

    TooManyToys Guest

    First, thanks to everyone who's posted so far.

    To give some more details here, yes, all send and return loops are completed. I have a single looper that I've been testing things with, so that can't be it, I'm afraid. This problem occurs with other single loopers I've tried (Radial, Keeley).

    Regarding power, I too have a One Spot (one of the newer ones) and thought it might be the culprit. However, to take that out of the equation I powered the pedals with batteries, and the squeal is still there. I even tried it with a battery powered amp (a Micro Cube) so as to take my apartment power completely out of the equation, and it still does it.

    I haven't tried the Boss Unit yet. I downloaded the manual and saw that it's really not what I'm looking for (you can use the two loops in parallel, but not in series), so I'm just about ready to give up on True Bypass Loopers altogether.

    Forgive a potentially stupid question, but the only thing I haven't changed is where I'm trying these things out (i.e. my apartment). Could something here be causing that sound with these looping pedals?
     
  6. 6789

    6789 Member

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    I had a pedal squeal because the edge of the battery was touching the output jack. It was a real tight fit inside the pedal, so I couldn't just reposition the battery. I stuck a piece of paper between the two and the squeal went away.
     
  7. TooManyToys

    TooManyToys Guest

    Sorry, but that's not it. I've tried it with both batteries and power supplies (and the battery doesn't touch the output jack anyway). Thanks regardless.
     
  8. drbob1

    drbob1 Silver Supporting Member

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    I'm with John, you're getting some coupling between the looper and the pedals that creates positive feedback. I don't think there's going to be an easy fix for this. How about this option: don't put high gain pedals in the loop. Sounds stupid, but hear me out-the main reason for a TB loop is to get NON-TB pedals out of the signal chain when not being used. If you buffer your signal so that capacitance from jacks and cables isn't too overwhelming, you could safely run the signal guitar->buffer->OD/fuzz->Looper->amp. The other thing that might be interesting would be to try a buffer before the looper and see if that fixes it? BTW, did you try changing guitars? I've had some problems with my vintage style stuff with nasty feedback using high gain pedals from the unpotted pickups (squeal, not musical feedback).
     
  9. jamison162

    jamison162 Member

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    Open Ground on one of the loops possibly???
    I always wire my boxes so that ALL Inputs, outputs, etc. are wired to a common ground when not carrying a signal. Noise, hum, capacitance, etc., etc. is not allowed to build up and should always have an escape if wired correctly. No dropdown resisitors should be needed either. Except for voltage regulation on your LED's. Totally passive and transparent.
     
  10. TooManyToys

    TooManyToys Guest

    Again, thanks to everyone for their input. The problem has been partially solved.

    It seems that Dr. Bob and John were both on to something. One thing I hadn't done is try some different pedals in front of the looper, so here's what I did.

    I plugged my guitar into a Boss DS-1, which has a buffer built in. I then plugged that into one of the TB Loopers that had a Boss Blues Driver running through the loop. That, of course, went into the amp.

    I hesitantly engaged the loop pedal with the Blues Driver cranked. No squeal! Just high gain feedback that would make Nugent proud.

    I wondered if a non-buffered pedal would have the same effect, and so I then replaced the DS-1 with a Fulltone OCD. The squeal returned.

    So, for some reason I don't understand yet, having a buffer (even in the form of a buffered pedal) before the loop pedal eliminates the squeal.

    Please, can someone explain to me why this is the case? Remember that this squeal was present in True Bypass Loop pedals from Loop-Master, Keeley, and Radial. So, it's not like the loop pedal is defective. None of these pedals use buffered loops.

    Also, I'd rather just have a dedicated buffer for the pedalboards. Can anyone recommend one? I'm considering just putting a Boss Tuner at the beginning of the chain in hopes that will solve it as well.

    Thanks for all of your assistance!
     
  11. John Phillips

    John Phillips Member

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    It's very simple - the output impedance of the buffered pedal is extremely low - I think the Boss DS-1 is 1Kohm (it might be 10K, but it doesn't make much difference either way). This is far lower than the input impedance of any pedal, including the one in the loop (typically in the 500Kohm region), and enough to completely squash the tiny leakage signal at the loop input that's causing the problem.
     
  12. TooManyToys

    TooManyToys Guest

    John,

    Thanks for the quick reply. I'm curious--is my experience standard fare for people who use TB Loops to switch groups of effects? I didn't get the looper because I wanted to turn non-true bypass pedals into true bypass pedals. I got it because I wanted to turn groups of pedals on/off easily.

    I ask only because I scoured the Internet for answers before I posted here, and I did hear of anyone else complaining about this.

    Just curious if anyone might know the answer. Thanks.
     
  13. drbob1

    drbob1 Silver Supporting Member

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    You can build a buffer into the looper (or get it built in there), I think there's a schematic for a simple one in Anderton's "Electronic Projects for Guitarists".
     
  14. John Phillips

    John Phillips Member

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    I haven't actually heard of it before either - I just knew what the cause was likely to be for theoretical reasons :).

    One problem I have noticed on quite a few pedals is a tiny (but irritating) leakage of the distortion sound into the bypass. Again, running a buffer in front usually cures it, for the same reason, it's a spurious signal leaking through via capactive coupling.

    The Boss TU-2 will definitely work, BTW - regardless of its 'tonal' qualities as a buffer (which I find perfectly fine, although some people don't like it).
     
  15. GuitslingerTim

    GuitslingerTim Member

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    When building a DIY bypass strip I wired the switches logically with a design worked out with an ohmmeter. The design produced a lot of noise and squealing. I changed the design so the effect loop input jacks are grounded when switched out, and the output jack disconnected. The design works great.
     
  16. enickma

    enickma Member

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    Only problem with that is the TU-2 is an absolute tone sucker. I've noticed huge differences in tone when a Boss pedal(s) are in the signal path. Running multiple Boss pedals in a row is tone suicide. The Barber Launch Pad is a great buffer pedal ( actually has a lot of functions )
     
  17. Bob Sweet

    Bob Sweet Member

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    I'm taking a total stab in the dark here as I'm not familiar with any of the pedals mentioned but here goes.
    On your hi-gain device (sorry can't remember what model it is), my guess would be the in and out jacks are on opposite sides ? Am I correct? If so I would think maybe the jacks going to the in and out of the looper are very close to each other, is that right? If that's the case my guess would be that they are too close to each other and you're getting cross talk which is causing the feedback. Hi-gain devices sometimes (most of the time) should have their in's and out's as far from each other as possible. I'm not sure you can remedy this with the looper short of modfying the location of one of the jacks. Maybe go inside and on the section you are using the hi-gain box rewire it using shielded cable, just make sure you ground the shield well.
    That's my guess for what it's worth, good luck.
     
  18. John Phillips

    John Phillips Member

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    Interesting. I get a great tone with my Boss pedals (three before the amp, plus a Dunlop - and a DOD and then another three in the amp's loop, on my main board) in line... better than the straight-in tone in fact :).

    FWIW, I don't hear the huge 'tone suck' from the Boss TU-2 - it does change the tone slightly, but actually it's quite a good buffer. I do hear a massive change in tone from running multiple 'true' bypass pedals in a row though. I'm not sure I would describe it as 'tone suicide' either, but it does very definitely lose top-end and detail.

    (I also just posted a reply to your other question on the other thread, BTW - you may want to change the position of your buffer if you're worried about 'tone suck'.)
     
  19. enickma

    enickma Member

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    Interesting how each persons experiences can vary. I used to have multiple Boss pedals in a row, and it was horrific how crappy each pedal sounded. That was a huge reason for me going out and investing in better quality pedals .... I bought better everything actually. Better cables, and a looper plus a buffer would have worked well too I am discovering. I threw my old Blues Driver into the mix the other night and it sounded fantastic ... I couldn't believe it. It sounded like garbage before.
     
  20. TooManyToys

    TooManyToys Guest

    It is pretty funny how the smallest change can make a big difference in the sound.

    In my experience, true bypass pedals sound more "pure" if you're using maybe 2-3 pedals. However, as John rightly points out, people who are true bypass nuts will find out that hard way that once you have a pedaboard full of true bypass pedals you have a new slew of problems, ones that can be solved by a good audio buffer. Buffers, if well made, do not by definition have to rob you of tone.

    I imagine that many of us have both buffered pedals and true bypass pedals in our setups. Since I've heard so many people (famous and local) use buffered pedals (e.g. Boss) well, I find it hard to believe that they are necessarily, always and forever bad for one's sound. However, enickma's experience was obviously negative. Maybe the changes in cables made the difference.

    I initially started this message because I was having problems with a true bypass loop pedal and overdrive/distortions in the loop. Oddly enough, the easiest fix it seems is to place a buffered pedal before the loop; however, I'm looking into other options, particularly the Axess Electronics Buffer.

    A great read on true bypass business, FYI, can be found at the Pedalsnake website (a super product, by the way): http://www.pedalsnake.com/page.aspx?pid=2

    Jody Page, the founder of Pedalsnake, is an engineer who used to work for NASA, so methinks he's qualified to speak on such things.

    I guess in the end the goal is just finding a setup that both the player and the listener can enjoy. My pedalboard has everything from Keeley and Fulltone to Boss and Ibanez on it, and it's starting to sound pretty good, now that the squealing is gone :)

    I think good sound is always going to involve some compromise. I hear a bit of coloring with a few Boss pedals, but having only true bypass pedals (including all the cabling) can cause some serious high end loss as well. We just have to pick our compromise, I suppose.

    Do you guys think Hendrix ever thought about true bypass?
     

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