explanation of buffers vs. true bypass

  • Thread starter Thread starter hthomas
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I have read this before, but thanks for sharing. I wish all pedals had the option to either have true bypass or add a buffer. Too many buffers is not great either, anyone who has used a lot of boss pedals in their chain has found this out.
 
From Custom Audio Electronics' website:

3. What are buffers and how are they used?

Buffers are extremely important in a multi-component system. They are often misunderstood and often get a bad rap by those who are uninformed. In a CAE system, a buffer is a unity gain (input level equals output level) impedance converting circuit. It essentially protects your high impedance guitar output (or any other high impedance source, such as an amps' effects loop send) from being loaded down by the input it is connected to. In effect, it converts high impedance to low, which means subsequent stages are then driven by a low impedance source (the buffer's output). High impedance sources such as your guitar's output (assuming you have passive pickups) has very little current drive capability and it's signal is subject to a harsh environment once it leaves the guitar. You already know the adverse affect a long cable has on your tone. Same thing happens if you pass your signal through a bunch of effects pedals. Even if they have "true bypass" (an ugly, over-used term), each one will suck a little more of your signal along with the cables and connectors, mainly due to capacitive loading of your high impedance guitar signal. The end result is a muffled weak signal that lacks clarity. But once your high impedance guitar signal hits a properly designed buffer with a high input impedance, the buffer takes over, and uses its higher current capability (remember, its an active circuit that requires a power supply) to drive all subsequent stages, thus preserving your instrument's tone. This brings us to buffer quality. Buffers come in all types of designs, from discrete transistor, op-amp, to esoteric tube designs. All have their own unique sonic stamp. At CAE we use the op-amp approach. It has served us well for years, is low noise, and is extremely transparent to our ears. Buffers often get blamed for causing an overly bright sound, but we feel if its designed properly, any perceived "brightness" is because now the guitar is not being loaded down by subsequent stages!

Buffers can cause problems, too. There are some effects devices that don't like to see the low output impedance of a buffer. These are typically discrete transistor designed fuzz circuits (such as the Dallas Arbiter Fuzz Face). They react better to the high impedance output of the guitar. In fact, the guitar output, cable and input stage of the Fuzz Face complete a circuit that is highly dependent of those 3 components to work correctly. Fuzz Faces clean up nicely when you roll back the guitar volume control... not so if a buffer is between the guitar and Fuzz Face input. So if you have a pedal board with a Fuzz Face on it , put it first! Other pedals may react the same way. Experiment to see what works best for you. Keep in mind all active pedals (such as Boss, Ibanez, etc...) act as buffers and will impart their own sonic stamp even when bypassed. This is what started the whole "true bypass" (ugh! that term again) craze. See? Too much of a good thing can be "bad". Which brings us to how we utilize buffers in CAE custom switchers. We only use buffers where absolutely necessary. Typically, in a pedal based system we will not buffer until after the first 4-5 loops, which is usually just prior to sending the signal down to the pedal board (via a long cable run, hence the need to buffer) to hit the wah/volume pedals. Any more than 4 or 5 loops, and the guitar signal may be affected by capacitive loading. So the first few loops is where you would put any impedance sensitive effects. This also means your guitar will go through fuzz, overdrive or distortion pedals BEFORE the wah. We prefer this order because the wah then has a more harmonically rich signal to filter. Try it yourself. Of course, if a specific order is required, we will do everything we can to make it happen. Buffers are also necessary to drive isolation transformers, since the relatively low primary impedance of the transformers may be detrimental to whatever circuit is feeding it. This is also why amp splitter circuits must be buffered. You can't drive multiple amps with a relatively high impedance source. So there usually is a buffer somewhere in the output stage of your custom switcher. That's usually it. 2 places minimum. There may be more active stages depending on your system requirements.
 
I've read interviews with Pete Cornish where he talked about the Buffer vs. True Bypass debate. This really got my attention though.
"Some players go to great lengths to preserve their unbuffered tone, including expensive low-capacitance cables; but using a good clean buffer avoids all this."

Really? So you can use mediocre cables as long as you have a decent buffer in your chain such as a Buff Puff? How about the buffers built into the RJM switchers? Good quality?
 
I remember getting the dirt first hand from some cats at Eventide or EHX or somewhere like that... Basically, this whole "true bypass" concept is great, in theory, but it's more of a marketing buzzword that helps move product - and it's not necessarily the best thing for the signal, or, your ears (or your audiences ears...!!). I know there's also a bit on YT about this... Lemme see if I can drum it up:



This is what I do know, from personal experience... TRUE BYPASS in the sense of gold plated snake oil soaked relay is great - so long as it's bypassing a circuit that's direct and not complex. However, it's a break in the chain - another joint, another connection, another link in the chain added. I've gone the route of "true pure relay bypass", and on a board with few stomps - dyno... No problemo. Easy.

However, get into a board with 10+ stomps??? I'll take clean, buffered, boosted outputs along the way ANY DAY!!!!!

But in short, to the OP's question...
Buffering tries to reorganize the signals girth, width and breadth (for lack of a better term) as it passes through a non-activated stomp or effect. It can be done primitively, or very sophisticated - either a signal boost, or a complete restructuring via pre and post DSP.

True Bypass means, when inactive, the stomp or effect has a dead hard relay cross the path of the guts of the stomps (the circuitry) and simply melds the 2 ends of the cable going into either side, together. That is a true bypass via hard relay.

The caveat to this is that true bypass has been used for stomps that aren't relay based, but moderately hard wired...again, it becomes a buzzword.

I've used both, and will take quality buffering hands down, every time.

Peace,
V.
 
glassjaw7":6e75hz3m said:
I've read interviews with Pete Cornish where he talked about the Buffer vs. True Bypass debate. This really got my attention though.
"Some players go to great lengths to preserve their unbuffered tone, including expensive low-capacitance cables; but using a good clean buffer avoids all this."

Really? So you can use mediocre cables as long as you have a decent buffer in your chain such as a Buff Puff? How about the buffers built into the RJM switchers? Good quality?
Click to expand...

It's not as simple as that statement makes it. There is such a thing as too much buffering. What buffering does is run your guitar signal through a clean amplifier stage which is designed to show a large impedance to the input signal. From there, that boosted signal into an out amplifier stage designed to show the output a low impedance. The impedance shown at each stage determines the overall effect of the buffer. First stage too low and the sound is warm and bubbly. First stage too high and the sound is too bright and flat sounding. Second stage too low and it can sound weak and starved. Second stage too high and it can sound harsh and brittle. It's balance that's key.

It annoys me when people say things like 'such and such buffer steals all my low end!' :facepalm: nope! It's just preserving too much high end!

Further, I find that having two buffers in the same chain makes my guitar sound weird. I only run one at a time. Maybe it's just me :dunno:
 
Good info Jake...!!

As well, cables get into the category of concern once they pass the 20 foot mark... Vovox cables are the biz, but I use standard every day 12 foot cables in the studio. Nothing fancy. But for stage use and long leads in and out to the front and back (say, 30 foot plus each way), this can definitely be a consideration.

But buffering in moderation and with quality is banger. Seriously, 100% banger.

V. :yes:
 
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