Define "true bypass"

[miner49er11]

What, exactly, is true bypass? Why does it appear to be so difficult to design a pedal with true bypass?

[moose23]

It's not that difficult and it's not always the best solution. HAve a read of this:

http://www.tech21nyc.com/technotes/index.html

[fu22ba55]

True Bypass: plug directly into your amp and throw all your pedals away.

[bongomania]

"True bypass" means when the effect is switched off, your instrument signal is prevented from continuing to run through the effect circuitry, and it is also not running through buffers or other active components.

This can be achieved with a mechanical switch (most common), or with relays (electronic switches that perform a mechanical switching function), or with some novel circuit designs using electronic "tricks" to force the signal to travel on a path that avoids the rest of the circuit.

It's not difficult at all, but it is more expensive to manufacture than the type of electronic buffered switching used by Boss, DOD, etc.

And, as noted above, it's not always "better".

[fu22ba55]

An additional benefit with mechanical true-bypass pedals is that they don't deplete the battery if you leave them plugged in (like Boss pedals). But most people choose true bypass for its sonic properties. (The battery thing is just a bonus.)

[gnasher1993]

Originally Posted by fu22ba55

An additional benefit with mechanical true-bypass pedals is that they don't deplete the battery if you leave them plugged in.

Do you have a source for this? As far as I know, that isn't true

[line6man]

Originally Posted by fu22ba55

An additional benefit with mechanical true-bypass pedals is that they don't deplete the battery if you leave them plugged in (like Boss pedals). But most people choose true bypass for its sonic properties. (The battery thing is just a bonus.)

That isn't true.
I'm not a pedal guy, but AFAIK, pedals are switched on and off by the insertion of a guitar cable to the input jack, connecting the battery's negative to ground.

True bypass switching allows you to route the input directly to the output, bypassing all active components, however, the battery still powers the circuit as long as there is a cable plugged into the input jack.

[fu22ba55]

Originally Posted by gnasher1993

Do you have a source for this? As far as I know, that isn't true.

Originally Posted by line6man

That isn't true.
I'm not a pedal guy, but AFAIK, pedals are switched on and off by the insertion of a guitar cable to the input jack, connecting the battery's negative to ground.

I'm thinking mechanical, true-bypass, not just true-bypass circuitry.

My sonic research turbo tuner works (as an on/off switch) with no 9 volt in it whatsoever. What does that mean? (I honestly don't know.)

http://www.turbo-tuner.com/pages/manual-st2.htm

I'm assuming that that means no load on the battery when disengaged, but I could be wrong.

Whereas, I've had other "true bypass" pedals (MXR Bass Envelope, Fat Sandwich) that eat batteries while still plugged in.

Is there a difference between mechanical bypass and true bypass? or does the Sonic Turbo Tuner use another means to engage the battery?

[line6man]

Originally Posted by fu22ba55

I'm thinking mechanical, true-bypass, not just true-bypass circuitry.

My sonic research turbo tuner works (as an on/off switch) with no 9 volt in it whatsoever. What does that mean? (I honestly don't know.)

http://www.turbo-tuner.com/pages/manual-st2.htm

I'm assuming that that means no load on the battery when disengaged, but I could be wrong.

Whereas, I've had other "true bypass" pedals (MXR Bass Envelope, Fat Sandwich) that eat batteries while still plugged in.

Is there a difference between mechanical bypass and true bypass? or does the Sonic Turbo Tuner use another means to engage the battery?

Again, I'm not a pedal guy, so I'm not real familiar with various circuit designs, but a true bypass should be the use of two switch poles to route the input and output either to the effects circuit, or directly together.
There may be a third pole on the stomp switch to toggle the LED on and off to indicate if the effect is on or bypassed.

The battery is always in the circuit if there is a cable in the input jack.

It wouldn't be wise to kill the power when you switch the effect on and off, because then you would get a big pop when switching.

[bongomania]

The Turbo Tuner may have its own thing going on, but I 100% guarantee it has nothing to do with true bypass in any other pedal. TBP in general has nothing to do with battery drain. Again though, the Turbo may have its own special system.

If you re-read my previous post, you'll see the answer to the question about mechanical switching.

[fu22ba55]

Just found this article too:

http://www.stinkfoot.se/andreas/diy/articles/bypass.htm

excerpt:

-----------

If I take the battery out and it still works in bypass mode, it's true bypass, right?
Nope. Sorry. What the battery-out test will tell you is if your pedal has a mechanical switch that carries signal or not, and if there are any active electronics in the main signal path. Take a look at one of the SPDT diagrams again - when the effect is powerless, the bypass line will of course still function as intended, but the effect input is still attached to it. No true bypass there, then. If your pedal has a buffer stage in front of the switch, or if it has electronic bypass switching (such as in Boss/Ibanez-type pedals), it will of course not pass any signal when powerless. But - again - you can not use this test to verify that a pedal is true bypass, only that it isn't.

-----------

This is why I'm not a pedal guy. Too much brain hurting with reading thinking. I defer to my original post. Throw your pedals away.

[blastjv]

Yeah, what I think is happening is that when you use your pedal with no battery in it, in the 'bypass' position the signal passes right through, when you hit the switch, the signal is being routed to the tuning circuit and therefore acting as a mute switch as the signal can not pass through the circuit when it is unpowered.

Another related phenomenon is when I have accidentally plugged in a pedal backwards and found it worked fine in bypass, but then muted the signal when I turned it on as it was not meant to move the signal in that direction...stupid mistakes...


-JV

[Jaco D]

Very interesting. Whatever is "lost" due to the pedal. etc. not being true bypass, is that what is called "tone suck" (been hearing that term a lot lately)? Is there a way of objectively measuring whatever is lost? So far, from what I've been reading the "lost" part is aurally perceived. Just wanted to know if you could measure it objectively.

[bongomania]

Yes and yes. Yes absolutely the signal loss we're talking about is what's known as "tone suck". It can be measured, although it's tricky because you have to measure several parameters--but it can be done.

[warwick.hoy]

True Bypass: marketing propaganda to make pedal noobs think one brand of pedal is superior to another.

This is a topic that will generate a lot of debate. I think that a lot of people will demand true bypass from all their pedals without really knowing what that means and then wonder why their TBP pedals POP the first time they step on them after powering up.

I'm certainly not anti-TBP and the relay based designs are pretty swell,...but I'm also not anti-buffer. I don't have any tone suck with the 4 BOSS buffers on my pedal board,...at least not anything that I can't deal with via EQ.

[McSpunckle]

There should be no debate at all on this subject. Period.

True bypass is when your signal is 100% disconnected from the circuitry of the pedal. Both the input and output jacks are connected directly together, and neither is connected to any portion of the pedals circuit. It is exactly as if the pedal was not in the chain at all.

In the old days, pedal makers would just use a switch to connect the jacks together, but some portion of the circuit was still connected. They'd either disconnect the input or output. Some of the circuitry is still attached, resulting in either some filtering (usually in the high end) or signal loss. This is what's known as "tone sucking." Some designs can handle this better than others.

Newer, buffered bypasses will basically send your signal through 2 buffers, and use some electronic switching to disconnect the effect circuit. Lots of buffered pedals would eventually result in a loss of high end. Also, a lot of pedals are designed for the signal that comes from a guitar. A lot of fuzz pedals, for instance, don't work well with active signals. They can sound harsh since they were designed to load down the guitar signal. If you have an active bass, don't worry so much about this. Your signal is already buffered.

True bypass is a good standard if only because the maker of the effects can't possibly know what you're going to be using their effects with. Buffers are extremely simple circuits, too, so you could make one pretty cheap.

[grygrx]

I still like this article for clarity on bypass details.

http://tonfaktor.blogspot.com/2008/0...s-methods.html

[warwick.hoy]

Originally Posted by McSpunckle

There should be no debate at all on this subject. Period.

True bypass is when your signal is 100% disconnected from the circuitry of the pedal. Both the input and output jacks are connected directly together, and neither is connected to any portion of the pedals circuit. It is exactly as if the pedal was not in the chain at all.

In the old days, pedal makers would just use a switch to connect the jacks together, but some portion of the circuit was still connected. They'd either disconnect the input or output. Some of the circuitry is still attached, resulting in either some filtering (usually in the high end) or signal loss. This is what's known as "tone sucking." Some designs can handle this better than others.

Newer, buffered bypasses will basically send your signal through 2 buffers, and use some electronic switching to disconnect the effect circuit. Lots of buffered pedals would eventually result in a loss of high end. Also, a lot of pedals are designed for the signal that comes from a guitar. A lot of fuzz pedals, for instance, don't work well with active signals. They can sound harsh since they were designed to load down the guitar signal. If you have an active bass, don't worry so much about this. Your signal is already buffered.

True bypass is a good standard if only because the maker of the effects can't possibly know what you're going to be using their effects with. Buffers are extremely simple circuits, too, so you could make one pretty cheap.

To clarify,...I'm not one to debate the merits or de-merits of TBP or BBP. I have pedals with both on my board but there are pros and cons to both. FWIW the type of bypass a pedal has has no bearing on whether or not I desire it, and I've never encountered any pedal that "tone suck"ed so bad that I couldn't fix with an EQ tweak.

There is also something to be said for having a buffer somewhere in your chain for long signal chains and long cables. I'm not an expert on how this works,...input impedance or whatever but the addition of at least one buffer gives a passive signal the umph it needs to make it through a long signal chain.

EDIT: I will say I'm not particularly found of the bypass in my Moogerfooger,...but rather than give up on it (because it's an amazing pedal) I can have it modified to be TBP or I can have put in a TBP loop. Again the bypass type had little bearing on whether or not I wanted this pedal because in there end,...there are ways of working around it. Now if MOOG would just shield the MFers better.

[RCCollins]

Originally Posted by grygrx

I still like this article for clarity on bypass details.

http://tonfaktor.blogspot.com/2008/0...s-methods.html

thanks for that

here's one point of interest from his summary of buffers (which is regrettably brief):

"Cons: Requires power for any signal to pass through, loss of high end tone when multiple pedals are in series." (my emphasis.

This should probably say "potential" loss of tone, and is really of much greater importance to guitar players. It should also be pointed out that, like long cables, a long chain of true bypass pedals ALSO tends to result in loss of high end - as he points out in his summary of "true bypass" as commonly understood (and used in his own designs):

"Cons: Costs more to implement, can’t drive long chains, possible switching ‘pop’. When many true bypass pedals are chained together and there are long cables from the pedals to the guitar and amp a large capacitance can build up from the long cable runs (including all those little patch cables and the wires in the pedals themselves) causing substantial high end loss."


I guess it's good thing we play bass!

[blastjv]

Yeah, but it's still a problem for those of us who keep a lot of trebble in our tone. I am really loving the sound from my new rig, but my Morley PWB is a HORRIBLE tone sucker (but an AMAZING wah), and I'm surprised to find that my Aguilar Agro seems to be eating a bit of the liveliness of my sound as well. I hadn't noticed this with the Agro with other rigs I've rotated through recently (the Morley always sucked). I do plan on upgrading cables very soon, but may end up just throwing both of them in a loop.

-John