When is it true bypass

[Vitrolin]

i have been wondering what are the limits of the term true bypass.

is it any unbuffered bypass.

does it have to be with mechanical switch or relay

what about a analog latches, opto-couplers, mosfet relays

what are you thought on these components for bypassing, any experiences would be great

[Tony Forestiere]

"True bypass, often referred to when discussing effects pedals, can be thought of as a straight wire connected from the input to the output of a pedal. With a true bypass pedal, when the pedal is in bypass mode (off), the guitar signal is routed directly to the guitar amplifier without any of the interference, loading, or buffering effects that are often caused by the pedals that are in-between."

From this by Peter Janis: http://thehub.musiciansfriend.com/tech-tips/tech-tip-true-bypass-pedals-and-buffers

[R.G.]

Welcome to the hobby/pursuit/mania.

You could read some of the foundation documents at geofex.com that would help you with a lot of the basics.

For this question, you would probably like "The Ins and Outs of Bypassing" http://www.geofex.com/Article_Folders/bypass/bypass.htm

You might also like the whole "Technology of" series: http://www.geofex.com/fxtech.htm

[GibsonGM]

Yes, what Tony posted is the GREAT definition.

Many, many other ppl would be totally satisfied with 'semi true bypass', too....like how Boss pedals' buffer is always connected...generally, that's fine for most.

The key point (IMHO) to think about if NOT doing true BP per the definition, is that all components will have frequency limitations...optocoupling being a good example...they are awesome tools for some uses, but could suffer at high frequencies.   This is true even for WIRE, but we don't care about any freq's so high that we'd ever hear any difference!   

After all, 99% of the reason for TBP is to avoid the "interference, loading, or buffering effects" of in between effects.   If your method does this, you will probably be happy.     To-date, TBP seems by far to be the easiest way to achieve this, tho.

Welcome to the forum

[R.G.]

I'm fond of the "Clinton Bypass". Quoting one of my favorite historical figures, "I don't think you can find any evidence that it's not true."

[R.G.]

I really should insert my favorite true bypass comment here.

True bypass is a solution to a problem we mostly don't have any more. Two problems, actually.

One was the problem of needing the guitar to not be badly affected by the pedal if the pedal's battery died. Seriously - who uses batteries any more?

The other was "tone sucking", the problem of the pedal eating away treble even when the pedal was not engaged. Today we understand that this is caused by the pedal input loading down the guitar. And most pedals are not driven by a guitar, because they're in the middle of long chains of pedals.

It's worth noting that many highly-regarded vintage pedals did not have true bypass, and were perhaps better for not having it. This is because the pedal actually caused a drop in signal level. The "cancel" inside the pedal that was not true bypass preserved an even engaged/cancelled volume, but putting a true bypass switching loop around it showed up the pedal for the volume drop it caused.

Remember - true bypass is not the solution to every pedal switching problem, and not even the highest performing one. It just gets a lot of forum-attention from those who don't understand a whole lot about bypassing.

[chuckd666]

Most people who buy things don't really know what to get and that is why marketing exists.

[R.G.]

And aren't the marketers happy about that!   

[chuckd666]

I think they're also happy about that "TGP" page or whatever they call it

[Magnus]

Hello,
for me true-bypass is the mechanical switched variant,
where the input is connected directly to the output and to nothing else.
Anything else isn't a "true" true-bypass...

There are other good working variants, but I prefer true-bypass.


Greetings
Magnus

[amptramp]

I would define true bypass as the use of switch contacts only (including relay contacts) to send a signal from the input to the output without having it go through any of the internal circuitry.  True bypass has some advantages and disadvantages as listed below:

Advantages

1. Negligible signal distortion in bypassed mode
2. Exact unity gain in bypassed mode
3. Negligible frequency response deterioration, connected or bypassed
4. Minimal noise addition
5. Minimal interaction with effect circuit
6. No power required for switch function
7. No other circuitry required except switch pop reduction resistors

Disadvantages

1. Expensive 3PDT alternate-action switch required
2. Introduction of switch pops unless circuit modified
3. Different behaviour depending on order of contact transfer
4. Low reliability and life of switch
5. Difficulty in adding remote switching capability
6. Cannot be initialized on turn-on
7. Advantages not necessarily applicable to delay functions

[R.G.]

Let me reiterate:
True bypass is a solution to problems we no longer have, in general.

[Vitrolin]

it isn't because that i'm obsessd with true bypass, I just wonder what is the opinion on non-mechanocal components that would give same result is.

opto couplers could easely be wired so that it would be bypassed when the pedal isn't powered.

[Electric Warrior]

Let me reiterate:
True bypass is a solution to problems we no longer have, in general.

The problem is that we want to deactivate our pedals sometimes. I still have that problem. 

[R.G.]

it isn't because that i'm obsessd with true bypass, I just wonder what is the opinion on non-mechanocal components that would give same result is.

I design pedals for a commercial-pedals company. We have used non-mechanical components for bypass for ... um, fifteen years now, about. We used to use mechanical switches to tell the electronic signal switching what to do, and then designed ordinary footswitches out when we noticed that a big part of warranty work was the mechanical switches. Mechanical components are a reliability problem.

One thing that works really well to eliminate the issue of the pedal circuits is to put a really high input impedance in front of the pedal circuit itself. If the input to the pedal does not load down the signal from the input jack, it is really, really hard for the circuit to "contaminate" the bypassed signal, which is one of the issues claimed as an advantage of true bypass.

That can be improved on by putting a semiconductor switch in front of the whole pedal circuit and simply opening up the path into the pedal electronically. That's the essence of the "Clinton Bypass" - I don't think you can find any evidence (external to the pedal) that it isn't true.   

My opinion is that electronic switching, done well, is every bit as good as mechanical switching, as well as being more flexible and generally cheaper. If it's not done well - well, why would you do that?

Let me reiterate:
True bypass is a solution to problems we no longer have, in general.

The problem is that we want to deactivate our pedals sometimes. I still have that problem. 

Oh, say not so!!   

[MrStab]

a pedal is considered True Bypass when people run out of things to complain about in the input stage.

[Hatredman]

To-date, TBP seems by far to be the easiest way to achieve this.

Pete Cornish would disagree.

[GGBB]

Let me reiterate:
True bypass is a solution to problems we no longer have, in general.

But don't we have a new problem? "Buffer build-up." I have an always-on pedal (reverb) at the end of my chain that serves as my buffer, and I sometimes have a buffered bypass pedal at the start (compressor). But when I am playing clean, I don't want my signal passing through another 10-15 buffers.

[PRR]

> when I am playing clean, I don't want my signal passing through another 10-15 buffers.

When you record to wax/CD and someone plays it on their system, there may be *hundreds* of bufferish stages between the mike and the listener's ear.

[thermionix]

Seriously - who uses batteries any more?

LOTS of players still use batteries in pedals.  Especially those of us who use very few pedals.  Wall warts and extra wires are just an annoyance to us.  Obviously a different scenario for those with big pedal boards, wouldn't want to do that with batteries.