Difference between BUFFERED and True Bypass......

[guitarSQUIRELL]

What does it mean when pedals say that the signal is buffered? I understand the true bypass which has no tone coloration, but never have understood what the purpose of a buffer does to a pedal. Educate me and others that may not know about this question plz......

[blueman335]

Re: Difference between BUFFERED and True Bypass......

There's lots of opinions, even the experts don't agree, and some experts are against the true bypass obsession. True bypass lets the signal pass thru the pedal and not the effect circuit board, but with too many effects or too many cords and jacks, the signal gets progressively weaker with passive PU's (passives only generate a 1/4 watt of power to begin with, or less). Buffered bypass boosts the signal, some say only replacing what was lost, others say they color the sound, but the quality of the buffers make a difference. Buffered bypass is not the bad thing some make them out to be. Plus cord quality and length are also potential culprits in frequency loss.

The biggest offenders of 'tone suck' (loss of frequencies when a pedal is off) are wahs and fuzzes because of the way their boards are designed. Lower-priced wahs are usually non-true bypass (GCB-95, 845, 847, etc) and some guys rewire theirs for true bypass (as I do to mine; there's online instruction). Wahs are generally recommended to be first in the pedal chain, and ironically, fuzzes usually don't work well after a wah unless the wah has a buffered output (there are wahs that come with this feature, or you can mod them yourself; my solution is to avoid fuzzes).

Sifting thru various online advice, many recommend using true bypass when you can, and putting a buffered bypass pedal at the front on the chain to keep the signal at full strength (and some say to also put a buffered pedal at the end of the chain). It helps to use cords no longer than they need to be.

[Darg1911]

Re: Difference between BUFFERED and True Bypass......

A good buffer is transparent, or almost so. Tone leaving the buffer equals the tone coming in. You may hear the difference with a "transparent" buffer but that difference is relative to the sonics due to signal loss. In other words, plugged straight in to the amp with a very short cable versus plugged in through the pedal board chain, you may hear a change in tone, most noticeably the high end rolled off so the tone can sound darker, in the extreme, even muddy. With a good buffer, the sonic difference between plugged straight in to the amp and through the board would be, if not unnoticeable, very subtle, but it depends on where the buffer is placed. If the tone is already affected, the buffer is just going to pass that on, assuming it's a transparent buffer. So, its not necessarily the buffered bypass pedals that are a "problem", it's how transparent the buffer is. That's my problem with buffered bypass pedals ... they aren't all transparent. Even some of the expensive pedals. I personally don't want a bunch of different buffered bypass pedals on my board, because one or more of them is bound to color the tone. I recently got rid of a J. Rockett pedal because I hated the buffer (and wasn't doing the surgery to make it true bypass). Gigging, I probably wouldn't notice it, but just hearing how it altered the tone drove me nuts. On the other hand, I have an ABY with switchable buffers and the buffers are pretty much transparent.

Not an electronics whiz, but I think the biggest issue is cable capacitance. The longer the cable, the higher the capacitance and the more the high end is rolled off. The output from passive pickups is high impedance and combined with the capacitance of long cable runs, that contributes to the high end roll off. A buffer takes the high impedance signal at the input and outputs a low impedance signal which is less susceptible to the high end roll off caused by the capacitance of the cable. On the flip side, some pedals, like fuzzes, generally don't "like" a low impedance signal at the input. So placement of the buffer and pedals like a fuzz are important. Also, when an effect pedal is on, the signal is buffered. So if you use any always on pedals, you have a buffer already. But, it too can make a difference where it is placed. And another reason why placement of some pedals, like fuzzes, is particular.

So I guess the basic difference is a buffered bypass pedal is doing the "conversion" from hi z to lower z when it is switched off. A true bypass pedal just passes whatever signal is coming in, right on through, without electrically altering it. I stick with true bypass pedals and if I experience a degradation of tone between plugging straight in and plugging through the pedal chain, or if long cable run is hurting my tone, then I'll add a dedicated buffer or use a pedal that I know has a transparent buffer. But take my comments for what they cost you ... I'm mostly a bedroom player these days and when I do plug into my pedal board, it ain't a long chain of effects.

There are probably lots of good articles or videos on this topic. I think Pure Tone (I was looking at their ABY a while back) has a good video on the topic of buffered and true bypass pedals. Maybe try checking it out.

[jimijames]

Re: Difference between BUFFERED and True Bypass......

So from an electronics perspective the reason we use buffers is due to how passive guitar electronics work.

The magnets in pickups magnetize your guitar strings which vibrate when you strike them. This vibration creates a current in the copper coil - it's more complicated than this (I'm pretty sure at least) but the more copper you have the stronger the output signal. Resistance has something to do with it as well, as does magnet strength.

The flip side of this is that for these copper coils to generate enough electricity you need massive amounts of actual wire which means massive amounts of resistance.

The what happens with high resistance signals is the phenomenon of cable capitance... Essentially the more cable a high resistance signal passes through the more treble frequencies aka detail that is lost.

Now the thing about resistance is that it is additive... A circuit has a single resistance which is why you see input and output buffers for many pedals. But on either side of the buffer the resistance is uniform.

I am not sure as to how op amp buffers work (though I suspect the principal is similar) with a transistor buffer the signal is replicated (though in opposite phase I'm pretty sure) in a low resistance environment. Essentially there's one resistance on the left of the buffer and another on the right.

So in terms of "signal purity" there are a lot of variables... While in theory the input signal is identical (aside from phase) to the output/buffered signal things like tubes and even transistors to some degree don't perfectly replicate the input signal though they may come so close our ears can't tell the difference.

The thing is the nature of analog signal amplification is fundamentally different than digital so a great many things affect signal quality. Like guys here have said before, buffers are appropriate in certain circumstances but you really have to know when to use them to get the best results.

I'm sure I've missed a few talking points but long and short of it is a good buffer is excellent. And also while I'm thinking of it the bypass system in boss pedals goes a bit beyond a buffer - it's designed as part of their relay switching system so it's different in kind when compared with something like the klon buffer which is a better example of just a straight up buffer without any extra bells and whistles.

[Liko]

Re: Difference between BUFFERED and True Bypass......

The other explanations are good but I'll try to simplify it a little while being technically accurate. In short, the statement you made that "true bypass has no tone coloration" is actually not true, because of the way that real-world conducting materials work.

Quite simply, your guitar's signal path, from the pickups to the tone-shaping controls through the cable into your pedal board and from there to the amp, is not all built from room-temperature superconducting materials. Sorry about that. The electrical path to your amp is primarily copper, with a healthy dose of zinc, chrome, iron, tin, silver, aluminum, and a few other conducting metals. All of these are not perfect conductors; they have a range of properties that "impede" the flow of electrons and thus reduce the energy transmitted through them by "wasting" some of it as heat or electromagnetic interactions. The amount by which they do this is called "impedance", and is measured in ohms.

The first property, and the most familiar to people who paid attention in elementary school science class, is resistance. This is basically "friction" in an electrical circuit, and is a property of the conductor that resists any transfer of electrons through it, reducing the flow of current at a particular voltage potential.

If these terms confuse you, think of the circuit as a water hose. Voltage is analogous to the pressure at one end of the hose. Current is the amount of water flowing through the hose, and resistance is basically the combinations of things inherent in the system that reduce the flow of water, such as a narrow-diameter hose, a rough interior surface, blockage or kinks in the hose, etc that require more pressure to produce the same flow of water as a hose (conductor) with less resistance.

Two additional components of impedance only matter to alternating current, where the direction of the flow of electrons within the conductor changes at some arbitrary rate. First is capacitive reactance. Back to our hose analogy, conductors have a property called capacitance that is like the water hose being made of an elastic material. As the pressure increases, the hose will swell, holding a larger volume of water within it than the amount flowing through it at any given time. Back in the electrical world, capacitance is a conductor's ability to store a charge of electrons given a voltage difference between the ends of the conductor. Now, if the conductor stores these electrons, they aren't flowing through to the other side, at least not as long as the voltage remains constant. If the voltage changes, however, those electrons can "drain" from the conductor and maintain a higher flow of current for a little while. When you apply this to a system where the direction of flow is constantly changing, and so the voltage across the wire is constantly changing including an instant where it's zero, then the charge being stored in the conductor is constantly being built and discharged. This has two main effects; first, the charge that is soaked up as voltage builds and then released as voltage drops causes the change in the flow of current to "lag" behind the change in voltage. Second, the slower the change in current direction (the lower the frequency), the more charge can build up, so the energy loss through the conductor is higher at lower frequencies.

Inductive reactance is caused by a related property, inductance, which is the ability of a conductor to store energy in its electromagnetic field. This is a little harder to bring into the water hose analogy, but consider that in the middle of this hose is a piston with zero mechanical friction. Water flowing through this piston's cylinder will raise up the piston against the force of gravity; the higher the pressure, the more the piston is lifted. Now, we put this into a system where the current changes direction. We find that as the pressure builds on one side, the piston rises, but then as the pressure declines on that side and increases on the other, water flows back out of the piston shaft in the new direction of current faster than the inlet pressure would normally create. So, the flow of water from the outlet of this hose "leads" the change in pressure input into it. Similarly, in an inductor, the energy of the moving electrons is harnessed to produce an electromagnetic force, and as the current changes direction, this electromagnetic field strengthens and weakens, producing its own "electromotive force" (voltage) on the electrons in the conductor, which causes current to "lead" the change in voltage from the actual voltage source. This also produces a similar "impedance" to alternating current as capacitive reactance, but this "inductive reactance" has a greater effect as frequency increases; the amount of current flow lost to this building and discharge of electromagnetic field increases the faster the direction of current changes.

All of these contributors to "total impedance" of an AC circuit are non-zero in any real-world conductor, and so they have an additive effect as the total amount of conducting material in the circuit increases (which is primarily due to the total length of the circuit). So, as your signal chain from guitar to amplifier increases in length by adding more pedals and longer cables, total impedance of the circuit increases. This has three effects: overall signal voltage decreases, requiring more gain at the amp; capacitance increases, reducing the presence of low frequencies; and inductance increases, reducing the presence of high frequencies. So, the longer your signal chain continues as a single circuit, the weaker your guitar's signal will be and the more middy (nasally) the tone will be. This is the infamous "tone suck".

To prevent this, some pedals have an "impedance buffer". Essentially, they divide the signal chain in half, creating two different circuits, and present an impedance "load" on each side that is consistent with what the other equipment on that side of the circuit was designed to work with; so, a buffer "looks" like the front end of an amplifier to your guitar (about 1-10 Mohms of impedance), but more like a guitar to your amp (about 100kohms impedance). This is accomplished in most examples using an "op-amp" similar to the one behind your amp's pre-gain control, in a specific configuration called a "unity amp" where the input signal isn't noticeably amplified, but the use of the amplifier's power source to generate the output signal creates the two differing circuits with the varying impedances. This buffer also means that in theory it doesn't matter how many pedals exist in your chain; because each one is buffered and therefore its input circuit originates at the previous pedal, the impedance through the chain is nromalized whether you have one pedal or ten.

However, there's a tradeoff. This "impedance buffer", like any conductor, has nonzero impedance (in fact it has quite a bit of it on either side, as I mentioned). That means it has its own capacitance and inductance affecting your tone. So, the overall quality of your signal chain and resulting tone is now dependent on the design and implementation of this buffer stage. Early impedance buffers were very colored and noisy, leading many to prefer true bypass pedals. Buffers in more modern pedal designs are of much better quality, transmitting the signal much more transparently, but they still aren't 100% perfect. Second, the output impedance of most buffers is based on the op-amp used, which by happy coincidence is "close enough" to a guitar's natural load. Depending on the pickups and the settings of your volume and tone controls, it can actually be much lower, and so a single buffered pedal can have a noticeable effect on tone simply by changing the downstream circuit impedance to something very different from your guitar and one or two true bypass pedals.

[TimmyPage]

Re: Difference between BUFFERED and True Bypass......

Some of the guys here have had some great posts that go really in depth on the topic, so I'm going to go with the opposite and put it as concisely as I can:

It's not a TrueBypass Vs Buffered situation. You know how if you have a reaaaally long guitar cable, the tone starts to get darker and muddier by the other side? Having enough true bypass pedals on your board will cause a similar effect. A buffer helps give your signal a little push so that your pure signal is strong enough to be pushed to the end. Having too many buffered pedals (especially with low quality buffers like older Boss pedals..) could potentially make your sound too tinny.

Secondly, when you turn a pedal ON it is buffering your signal, albeit not in quite the same way as a buffered bypass. It is no longer true bypass, it is affecting and pushing your signal.

[PFDarkside]

Re: Difference between BUFFERED and True Bypass......

Niels will come in here and crap on "Shmru Shmypass" soon enough, but here's the way I see it:

Originally there were guitar effects, they required a little switch or a dial to turn them on. At some point, someone realized a panel push button could also function as a "stomp" switch, so that guitarists could engage them during a performance.

These switches only had two poles (switches inside) so in order to have an LED indicator, only one side of the circuit can be switched in and out of the path. These components, still connected to the circuit path, load down the signal, usually resulting in a loss of lows and highs, and/or a ghost effect overlaid with the bypass signal. Additionally, these switched were not the most robust, as they were designed for panels not stomping.

Ibanez and Boss style pedals started employing buffered bypass to more efficiently and more reliably switch the effect in and out of the circuit. These buffered pedals use FETs to redirect your signal in and out of the "effect" but always provide a low impedance output signal. (This is more electronically "correct", as they were electronics companies). These large companies are more worried about reliability and low cost than tone, so component changes over the years began to degrade the quality of the effect circuit. (Up for debate, but that continues into the next step below)

The next wave of effect makers (the "boutiques") realized two things:
-By using more consistent complements and by more specifically selecting components, they could recreate the absolute best of those vintage effects from the first two categories.
-The most complicated part of the Boss/Ibanez overdrive pedals are the FET switching circuits, and they were modifying the effect portion.
By this point (90's) manufacturers were making 3PDT stomp switches, allowing a "true" (total) bypass of the effect, and avoiding the need to design a buffer.


The benefit of true bypass is that it avoids the tone suck of the first style of bypass. The tradeoff is that it can result in tone suck from the additive capacitance from cables as others have noted above.

The commonly accepted strategy now is to go:
-Guitar
-Vintage wah/fuzz that rely on "seeing" the guitar's high impedance
-Good buffered pedal
-Other pedals (in true bypass loopers if they use a poor style of bypass)
-amp


***All that said, as the joke goes, "Everyone tried to enjoy themselves at Woodstock, despite Jimi's pedals being non-true bypass". That is, this is the last 10% of tone, getting everything else first is more important, IMO****

[Vasshu the humanoid typhoon]

Re: Difference between BUFFERED and True Bypass......

As it is I really do not care......
Does it help anyone play more music??

[Darg1911]

Re: Difference between BUFFERED and True Bypass......

As it is I really do not care......
Does it help anyone play more music??

No, but a tone altering buffer still bugs the **** out of me. I'm funny that way

[Vasshu the humanoid typhoon]

Re: Difference between BUFFERED and True Bypass......

So??
It is a detail of no real consequence!
Loads of stuff alters the "tone"....
Your mood, the room, the current....in other words loads of stuff.....why get obsessed with something as minor?
You can still play...
If not, then I guess details really matters, and life is very complicated....

[Myaccount876]

Re: Difference between BUFFERED and True Bypass......

The optimal buffer just lowers the impedance of the output signal, which will reduce it's susceptibility to signal degradation over longer cable runs, which tend to have a higher resistance and capacitance. True bypass leaves the impedance alone (keeping it high). If you don't have even 20 feet of cable, you don't need a buffer - some effects like treble boosters do not like certain buffers before the input; these effects should be the very first in the chain, and when the effect is on, the signal is low impedance. If you have more than 20 feet of cable, you can benefit from a buffer, unless you have an effect that is always on at the very start of your signal chain, like a boost or something. In that case, the impedance is already low and not too susceptible to long cable runs (unless we're talking stupid-long cable runs as you're playing arenas, in which case, why are you asking the forum? Hire an electrical engineer to help design your stage rig).

[blueman335]

Re: Difference between BUFFERED and True Bypass......

20 feet of cable

20 feet of cable includes all the jumpers between pedals, and the cable from the last pedal to your amp. It's not hard to have 20 feet of cable.

[Myaccount876]

Re: Difference between BUFFERED and True Bypass......

20 feet of cable includes all the jumpers between pedals, and the cable from the last pedal to your amp. It's not hard to have 20 feet of cable.

Except if you have enough jumper cables between enough pedals to get over 20 feet of cable, I'd assume at least one of those pedals are on at any given time (or one of those pedals have a built in buffer, like all Boss pedals), lowering the impedance. If you have over 20 feet of cable before you even get to the first pedal in your chain, the signal degredation can be noticeable.

[Hank-]

Re: Difference between BUFFERED and True Bypass......

One way to get around an effect that sounds great when ON but sucks the spice out of the signal when OFF would be to use a true bypass looper. Simple enough to diy with those.

If all pedals 'have' to be true bypass then getting low capacitance cables everywhere & avoiding gold plated plugs can help the signal from losing too much high end.

Then again, some of those true bypass switches themselves are tone suckers, while some buffers are poorly implemented giving rise to issues, so its not a very perfect world unless you start modifying deeply, including the amp which might be creating impedance mismatches in its loop.

Long story short, dozens of pedals out there, hard to audition all options but most will have atleast one legit review somewhere online, so narrowing down a few to check out helps to decide what works in your signal chain.

[Chickenwings]

Re: Difference between BUFFERED and True Bypass......

A chain of true bypass pedals sucks tone too.
There is no best solution for any of this stuff.
You just have to try things until you can find the best solution for your gigging needs.