Pedal Impedance and "True Bypass"

The Moog Forum Moogerfooger Forum
1

Does anyone know anything about this stuff, or interested in it?

I’m trying to assemble a pedal board and maintain my tone as close to 100% as possible. But strange things are happening, including the tone being adversely affected when I introduce a “true bypass” pedal into the chain.

I’ve been looking at this:

http://www.muzique.com/lab/imp.htm

And this:

http://www.muzique.com/schem/mosfet.htm

I’ve also got a pair of moogerfoogers isolated via an effects loop – that seems to be working well. It’s adding effects on either side of the loop that’s causing problems. Right now it’s a two loop box…would one solution really be to just to get a bigger effects loop?

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I know lots. Been through it all, and have implemented a solution in my rig with MOOGERFOOGERs included - lots of 'em.

Please explain your set-up. Specific pedals, order (or potential orders) of pedals, instruments and amplification and any power supplies you may have. The reason for this is that there is just so much to explain that it’s best to see what you have and the order you use it in to understand the potential glitches encountered. I hope you’re patient :slight_smile:

If you are having tone changes with a “true bypass” pedal in your chain when the pedal is in bypass mode, you could have a number of things that cause it. First being that the pedal is in fact not true bypass, and rather some marketing ploy to indicate that 80% of people won’t notice the difference when it’s bypassed. If the pedal is in truly true bypass, you should not notice any change in tone, unless something has gone wrong - like a broken switch, broken wire etc. Don’t worry yet.

Further, if you are also adding a new cable into the chain along with the true bypass pedal the tone change could be caused by the cable, and not the pedal.

Further still, if you add the true bypass pedal to the chain, and are powering it from a common power supply, you may be robbing some power from another pedal that isn’t true bypass. The stolen power could be causing a change in tone as well.

As you can see it gets quite involved quick - but it’s not hard to source issues, and I can help you do so.

Firstly, try plugging your instrument into the true bypass pedal in question, and then directly into your amp. See if the change in tone is still there. Next put that true bypass pedal in your true bypass effect loop, and compare the bypass sound of the pedal in the loop and the loop off. You shouldn’t hear a difference. Try different cables if you do hear a difference - use short and good quality cables. See if you can eliminate the change in tone this way first. Start there and let me know your results.

Aside to this, the best way to keep tone present (in a guitar rig) is to have a master bypass that allows a direct connection between the axe and amp. Short cable runs are essential between pedals as well, along with decent quality cable. A lot of this is subjective too depending on your hearing ability.

3

Oh, good. Thanks for your reply.

Here’s what I’ve got:

I’m going from my guitar (well, actually a piccolo bass) into an EHX Hog, into the 2 loop switch (Loop-Master), and then out the switch into a Boss RV-5, and then into the amp. All cables are Monster Bass cables. So far, all is well. Sounds great. The Hog seems to pass the signal well.

The pedals that are giving me troubles are EBS – the multicomp and the unichorus. I really like the sound of these pedals, but I’m pretty sure I’m not hallucinating when I notice signal degradation even when in bypass mode. The sound seems less “transparent” or “open,” suggesting that the very top of the high-end is being rolled off.

I’ve troubleshooted by going straight into one or the other of the EBS pedals, bypassing the HOG but still going into the Boss before the amp, and it still sounds like the signal’s being degraded. Putting one of the EBS pedals into the effects loop does seem ok, though.

This leads me to wonder whether I should just get a bigger loop switch, basically one loop for every pedal I want to add. Ultimately, I’d like to add four to what I’m currently running: the two EBS pedals, a third Moogerfooger, and a fuzz. Were I to buy a bigger loop switch, I’d definitely order one with a master bypass. But before I plunked down the money for the order, I’d like to know in advance if this was gonna work.

The other thing that’s sort of weird is I’m hoping to alternate using two instruments through this pedal board: a modified Jazz bass with passive pickups, and an Alembic custom bass with active electronics. It sounds like one of the issues involved is the way pedal resistance works backwards to affect the output of the pickups, and I wonder if it’s too much to ask for a pedal board to work the same way on two very different instruments, electronically speaking.

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And I’m running the EBS pedals on batteries. I just tried my fuzz factory in the chain after the Hog before the loop switch, and that seemed ok. Specific EBS problem? How can that be?

5

Just tried one of the EBS pedals using a power supply and – it seemed better, even in bypass mode. Running on a battery but otherwise turned off, there’s a brittle edge that isn’t there when the power supply’s plugged in.

Is this the answer?

And I’m curious how you incorporated your Moogerfoogers. The built-in preamps worry me…is this a realistic concern?

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For your information:

http://www.petecornish.co.uk/case_against_true_bypass.html

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You know, I was just going to post that link. That’s one of the things that got me worried.

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True bypass pedals are best used when placed after a pedal with buffered input like a Boss pedal so as not to overload your pickups. Additionally, if you isolate pedals in loops, each loop should have a buffered pedal before a true bypass pedal if you don’t have a buffered pedal before the loop itself.

Just because you run a number of TB pedals, consider the additive length of cables between your pedals which increase capacitance & therefore subjects your signal to tone loss. Keep cables as short as possible & make sure you use a quality buffered pedal at the head of the chain.

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Thanks. I’d be curious to hear from don’tbelievethehype, who, as I recall, has a zillion pedals, or anyone else who’s got a huge setup like that.

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Would a “high-quality buffered pedal” include…dare I say it…a Moogerfooger?

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ARGGG! I had this huge post typed up that answered all of your questions, then my login timed out!

So it sounds like the EBS pedals are not completely true bypass - meaning that something in the way the circuit is wired depends on external power to be present for the signal to properly ground. Quite common. So yes, one answer is to power those with a power supply, and yes the other answer is that you could put them in a loop of their own. Use your ear to decide.

The EHX HOG is probably the best TRANSPARENT buffer you can find in a pedal. The BOSS RV-5 is okay, but tends to kill some of the dynamics that tone has… I always find BOSS pedals make the sound sterile, too clean if you will. They take away organic.

Yes MOOG pedals have awesome buffers too, that you can use to control and shape sound a bit. They do add color however, and if that color is unwanted when the effect is off then you will need to use a true bypass loop pedal like you have to bypass it. Don’t let the built in pre-amps worry you at all, they are fantastic tools that you can use for many different purposes such as distortion, limiting, boosting and coloring.

The master bypass pedal is a neat function because you can essentially preset an effect sound, then hit the switch and melt faces. It would be a convenience item to having a large strip of true bypass loops. I use one.

I’ll post about my rig a little later… but the MOOGS are in their own true bypass loop… I even use a small single TB loop pedal to bypass the 101 sometimes because it’s noisy.

I think the Pete Cornish article is a perspective, one that you could find some information in to assist you with troubleshooting your sound. By no means is it a rule or should it be followed - don’t limit your sound and creativity, use your judgment to create what you want.

Cable is subjective, however long runs can change the tone of a passive pickup instrument - long runs being 50 ft plus of medium quality cable. Active instruments do not suffer from this because the output is low impedance, which is what every pedal with a buffer outputs too. Optimize cable lengths, don’t blow the bank on cable, it’s just not worth it. Always remember this when things get out of hand: Jimi Hendrix, The Beatles, The Band all did it without today’s technology, why do we have to. It’s all marketing, and every time one of their songs gets mastered someone takes out all of the recorded “imperfections” and rebalanced the EQ anyways :slight_smile: If we bought food like some people buy cable we’d all be eating organic free range fat free top of the line quality food. Money better spent IMO - makes the brain work better, thus playing better.

Back on topic… I’m running 18 pedals loops included, and have no issues with planet waves cables robbing tone. I have a mix of true bypass and buffered and I (ab)use my amps FX loop.

Buffers vs true bypass is a subjective topic. Try this: Plug your passive bass into the Fuzz Factory, then into your amp. Set the gate at 3 o’clock or more. Let a note ring out noting the sound of the decay. Now plug the same bass into the HOG, then the fuzz factory. Run the HOG in bypass mode and play the same note and let it ring. Note the difference! Now take the HOG out and use your Active bass into the Fuzz, and note the sound. You will be able to hear what a buffer and active pick-ups can do to the sound quite clearly. What works for you is your sound :slight_smile:

I have some pedals in a specific order because the buffers mess with what I want the pedal to do - like react to the pick-up organic qualities.

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There’s a lot there I’m gonna experiment with, so thanks. But just checking quickly again, it still sounds like the EBS is degrading the sound, even running on the power supply, unless it’s in the effect bypass loop – then it seems ok. So I guess I’m gonna get a bigger effects loop thing, even though it feels slightly absurd to be placing a true bypass pedal in a true bypass loop. Is this the electronics equivalent of double-bagging it?

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If the pedal is degrading the sound when in bypass mode it isn’t true bypass. Simple as that.

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How can this be? They’re Swedes – they’re supposed to be good at this sort of thing. Were they too busy having affairs with other professor’s wives and complaining about the “silence of God”?

So what have we learned. First, “true bypass” as a term is suspect for at least a couple reasons. Second, it seems to be largely a question of trial and error, which necessitates some waste.

The tone through the Hog–>loop–>Boss is working. So I’ll go with that, and get a bigger loop. New paranoid thought…would a larger effects loop also cause problems?

And do the guys who run a million effects at a certain point just go, “fuck the bypassed signal, I’m never using it anyway”?

15

The use for True Bypass arose when players realized that their passive pick-ups when connected directly to a pedal make a desirable sound. IE a fuzz pedal, or distortion, wah etc. So does everyone need true bypass? Heck NO!

BUT

If you want your true pick-up sound to get to the pedal or amp of choice so that it has a specific dynamic tone, AND you require another pedal or two to be in front of that pedal in the chain, then you do need true bypass to allow that to occur.

Don’t forget that once the pedal is not in bypass mode, you now have a buffered output (in most cases).

In my case I have all of my FX pedals before my OCD drive pedal - some have everything before their amp drive channel. This means that if you don’t want mud distortion, or you want to keep your dynamics when your effects are off, then you need to have pick-up direct to input to achieve the desired tone.

Do you need a bigger loop? NO! You could put two moogerfoogers in one of your loops and the EBS in the other, or some mix and match combination thereof. If HOG to loop to RV-5 works, then stick with it, just place the EBS somewhere in the loops.

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One of the reasons I’m worrying about this is I’ve got a show coming up in a couple weeks where the audience will be pretty focused on me. And I’m not gonna be able to get a bigger loop pedal by that time anyway, so yeah, first things first, put the EBS pedals in the loop with the moogerfoogers. And actually, they do sound good that way. It means some extra stomping, I guess, but no big deal. I do love the concept of these long strips at the bottom of the board where every pedal can be activated. And ultimately it’d be cool to have a master bypass so you can turn everything, or almost everything, on and off with a single switch…

17

Well if you could come up with a good reason to turn off a 104Z I’ve got to hear it! :laughing:

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Check this out: (a sleeper true bypass module for foogers!)
http://cusackmusic.com/wp/?page_id=22

19

Vot the hell?

Anyway, that gig I was getting prepared for was indeed undermined by electrical problems, but not the ones I was worried about. My EHX HOG was NOISY. There’s something about that particular pedal – it’s very sensitive to current irregularities. Too much power on the circuit and the harmonies start playing by themselves.

The Moog stuff did great, though :smiley:

20

Besides tone-sucking effects, tone can suffer when an effects-chain isn’t properly buffered like a guitar w/passive pickups for instance. Most of the passive true-bypass loopers are best for isolating a chain of effects to minimize tone-loss but if they don’t incorporate FET or optical switching, you can experience pops or clicks when switching from one loop to another.

When incorporating true-bypass effects it is important to realize that the capacitance in the cables between them contribute to high-frequency loss. If you have a 21’ guitar cord running into 6 pedals, a 6" cable between each, & a final 12’ to your amp, the loss of clarity definately becomes discernable as you have over 35’ of cable. The longer the cables, the more capacitance, the greater the inherent signal loss depending on the quality of construction & materials from which your cables are made. Just because all your pedals are boutique, true-bypass doesn’t mean tonal heaven.

If you have 40’ of cable between your guit & amp, That’s it.. you’ve got 40’ cable & all the capacitance that comes with it. Perhaps you can boost the treble to compensate but of course if you boost any signal, you also boost the noise within that signal & quite obviously the S/N ratio drops as the noise floor rises. The solution is one buffer before all the true-bypass pedals in each loop.

Always choose quality cables & try to incorporate true-bypass side chains of effects. Buffers are sometimes good, true-bypass isn’t always the right answer for a given configuration, & proper impedance matching is paramount to good tone.


Smolskitech loopers are excellent; I like their Mini Loop!
http://www.smolskitech.com/products.html

ToadWorks Roundabout lets you switch the order of the two loops in relation to each other which is unique.
http://www.toadworksusa.com/RT.html

Loopmaster offers the greatest configuration options in custom looping.
http://www.loop-master.com

Lehle makes some of the best true-bypass loopers available.
Their Little Lehle offers stereo capability, noiseless switching, & variable power.
http://www.lehle.com

The Boss LS-2 Line Selector is buffered & offers a Mix knob for each loop.
http://www.bossus.com/gear/productdetails.php?ProductId=150

I have spoken.