True By Pass (TBP)?

BluesJr

New member
What is True By Pass (TBP)? On pedals that have TBP the whole circuit is passed when the pedal is switched off, the signal goes from input-jack to output-jack true switch. There is practically no signal loss and no tone colorization. Most modern mass-produced pedals don´t have TBP, like Ibanez, Boss, DOD and most hand made "boutique" pedals have it, like: Austone, Budwah, Fulltone, Roger Mayer Rocket Series pedals, Voodoo Lab....



Why not every pedal have TBP if it is so good? First, it is more expensive to make, you have to use more expensive switches like DPDT or even 3PDT if you like to have True By Pass with LED. Second, the switching is not always noiseless, these switches sometimes make small "clicking" sound when kicked on or off. This happen mostly on few first time you switch after connecting the pedal between your guitar and amp. You can switch the pedal on and off few times before the gig and often get rid of the noise. You can connect a resistor between switch and ground and help with the noise or you can just live with the "vintage" problem. Some amps are more sensitive to this than others.



There is also one problem with many pedals and lots of cables, they will weaken your signal. The guitar signal from passive pickups is not very strong and it is high impedance and that makes it very sensitive to cable capacitance. The worse (cheaper) your cables are and the longer they are the bigger is the capacitance and you will loose your high end clarity and also get some phase shift because of the difference in time the higher and lower frequencies travel in a high capacitance cables.



You should always use best quality cables like Spectraflex (very strong great on stage) or George L (great in studio and on pedal board) they have low capacitance and sound great even with few extra meters.



Some of these problems can be solved with pedals without True By Pass, it is true many companies don´t use TBP because it is so expensive and requires some hand soldering, but also because there is no noise when switching and if done properly can also help with the capacitance problem.

Almost all pedals without TBP take in the high impedance guitar-signal and send out a low-impedance signal that is not sensitive to cable capacitance, so you can use lot´s of high capacitance (cheap) cable after this kind of pedal without problems about loosing your signal. Of course these kind of cheap cables have other problems like more noise and I do not recommend using these.



Almost all better pedals are made with True By Pass and it is almost like a standard in the better pedals and it do have many advantages I will tell later. But some high-end "boutique" pedal companies like Roger Mayer and Klon do make also pedals without True By Pass but with Buffered Output. This Buffered output is low impedance and Roger Mayer has takes more advantage on it by having dual buffered outputs on his Voodoo series pedals. This way both signals are as strong as the input signal also when bypassed, this would not work with TBP.



Here is what Bill Finnegan, the man behind Klon pedals say about Buffered Output:





"I designed the Centaur with a buffered output, not true bypass, BY CHOICE - true bypass is a very simple thing for any circuit designer to achieve, and the fact that the designers of most "boutique" pedals choose it has more to do, in my opinion, with their acceptance of conventional wisdom in this regard than it does with any concentrated thought on their part about how to achieve the best, most sonically transparent results in the real world.

The reason, in essence, is cord capacitance. Cord capacitance is a fact of life - all guitar cords, even the low-capacitance types such as the George L´s cable, for example, are capacitive: an 18-foot generic guitar store guitar cord (Rapco, etc.) will have anywhere from 1500 to 2000 picofarads of capacitance, and a low-capacitance George L´s cord of the same length will have perhaps 500 picofarads, or one-quarter to one-third of that. This capacitance not only robs the signal encountering it of high-frequency response, especially the overtones that are integral to the distinctive sonic signature of every electric guitar, but in my opinion it also wreaks havoc with what I will call the harmonic structure of the signal, the precise way in which all of the signal´s high-frequency components fit together to create an important part of that sonic signature.

True bypass, by definition, does nothing to address this real-world problem: the capacitance of the cord following any true-bypass unit in a signal path remains fully able to do the damage described. With a well-designed buffered output, however, the capacitive effect of the cord following the unit is essentially negated; with the Centaur, for example, you could run hundreds of meters of the cheapest, most capacitive guitar cable from the output of the unit and suffer no loss of high-frequency response and no damage to the signal´s harmonic structure due to capacitive loading. It is important to emphasize that a buffered output, if it is well-designed (not an easy thing to do), does not add anything to the original signal - it merely prevents the loss of important components of that signal.

When you get the chance, try a simple test: with the regular-length cord you are accustomed to using, play for a while with a guitar and into an amp that you are intimately familiar with, typical settings on both. Then turn off the STANDBY on the amp, so that all of your amp settings are untouched, and substitute a very short cord, say 1 meter, for the regular-length one. When you start playing again, you will almost certainly notice that all of the sudden what is coming out of the amp seems not only brighter than you are used to hearing with those settings, but also louder. You will then have gotten a sense of what cord capacitance has been subtracting from your signal, and as your ear develops further, you will begin to hear more of the subtleties, not just "brighter" and "louder". It´s like having a good hi-fi system for listening to recorded music, and then spending a ridiculous amount of money on a GREAT system - once you´ve heard the great system, you´ll never be able to go back to the good one."



I have talked with Roger Mayer and his thoughts are very similar (Roger makes also pedals with True By Pass; all his Rocket Series Pedals are with TBP).



Bill Finnegan also told me: "The Centaur, almost always, belongs AFTER any and every other pedal in your signal path and DIRECTLY in front of your amp."



This will lead us to the biggest problem with buffered outputs:

You can´t put a pedal without True By Pass in front of vintage Fuzz (or remake) or YOUR TONE WILL BE HISTORY!!!!!

Just place a Tube Screamer in front of Fulltone ´69 or Vintage Fuzz Face and the tone is gone even if the Tube Screamer is bypassed!!!

Those Fuzz pedals that uses discreet (often germanium) transistors, want to see the high impedance signal from your guitar. You have to be very careful where to place pedals with buffered outputs and when using lots of those you often get radio interference (that can happen also with some silicon transistor Fuzz´s with True By pass).



What if you love your vintage Ibanez pedal that don´t have TBP and love to have it bypassed without buffering? It is not easy nor cheap to modify the Vintage Ibanez to 3PDT switch and I would not recommend that to a vintage TS-808. You can connect your pedal (or pedals) to a True By Pass Box. That is a box with switch and four jacks, one to connect your guitar (input) then one for your amp (output) in between there are input and output for the effect or effects chain. Then you can switch between the true by pass and the effects. This kind of box can be also with LED, then you need battery and 3PDT switch (like the Fulltone switch). I have these made for myself by my tech, if you are interested about getting one, e-mail me.



Rule #1: Don´t place any pedal without True By Pass in front of your Fuzz, she likes to see your pure high impedance guitar signal.

Most Fuzz pedal don´t even like if there is a buffered signal after them, I don´t know why it is like that but it just is. Try it with Fulltone ´70s pedal, put a Boss (these are worse than Ibanez) after it and the Fuzz is thinner and kind of ugly.



Rule #2: Experiment. The pedals with buffered outputs often love to be the last one just in front of your amp (Klon, Roger Mayer Voodoo-1). You can also tailor the tone of your pedal if you put a pedal with buffered output in front of it, it now sees the low impedance input and often sounds different. An example: The great Austone Soul-O-Stomp pedal boost your signal and makes it bigger and fatter, that is great most of times, you get more output, more body and don´t sound too shrill. But you also loose some high-end and with cleaner settings this is not always desirable. Now if you place an effects with buffered output, like Ibanez Tube Screamer in front of Austone S-O-S the tone is brighter and very transparent, it sounds very close to Klon at clean boost to my ears. So if you like rounder fatter boost use it with True By Pass pedals and if you want transparent clean boost use it with TS-808 or TS-9, it makes a great pair with one of these. Some players use two TS-9´s or TS-808´s in series, but the TS with Austone makes a much better pair and more versatile because you get three tones: Austone, TS and both at the same time, the last one is a killer combination.



Some other experiments I have made: Roger Mayer Stone Fuzz likes to have an boost pedal after it, you can kick in a "turbo-mode" for extra big tone if you have the Austone S-O-S pedal after it. Quite funny, but the Austone Textone Fuzz Nutz and Austone S-O-S combination don´t work at all!!!

Klon and Roger Mayer Voodoo-1 like also to sit after Fuzz as a boost.



Most Fuzz pedal and many overdrives sound best in front of slightly overdriven tube-amp. I have found out that it is best if it is power-amp distortion but that makes it often very loud. The amp distortion makes the fuzz fatter, smoother and more tube-like. Try a Fuzz in front of ultra clean Fender Twin and it sounds errr... different!!

The boost in front of amp help simulate the "Fuzz meets the loud tube-amp a´la Jimi" tone.



But Experiment, that´s what Jimi did!!



Happy Tone Hunting.

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