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- Euntaek

Buffers

Buffers

Euntaek
Gear/Tech-talk
 
A Morningstar Engineering buffer on my board

A Morningstar Engineering buffer on my board

 

If you’re a guitar-straight-into-an-amp kinda person, this topic is likely something that you won’t need to worry about so much (unless, of course, you use insanely long cables to connect your guitar to the amp). This article is primarily intended for those who use/intend to use effects pedals, aiming to show how understanding the concept of the buffer can help minimise tone loss and help with pedalboard design.

It’s easy for this topic to get technical with the various terms thrown about, but I’ll try to make it as simple as possible. If you’d like to know more about the technical aspects of buffers, there are plenty of references online (complete with circuit diagrams!) that I would be happy to direct you to.

Contents:

  • 1. Background
    • a) The problem
    • b) What is a buffer?
    • c) Buffered bypass and engaged pedals
  • 2. Do I need a buffer?
  • 3. Usage
    • a) Current setup
    • b) Placement
    • c) Exceptions and other considerations
  • 4. Other things to note
    • a) Not all buffers are created equal
    • b) There is such a thing as "too many buffers"
  • 5. Summary
  • Annex A: Typical pedal bypass methods

1. Background

 

a) The problem

Before getting into what buffers do and how they can help you, I want to talk about the very issue that buffers are supposed to rectify - tone loss.

You plug your guitar straight into your amp, and everything is intact - everything rings true from the top to the bottom of the frequency range. Plug into your pedalboard, and suddenly your sound becomes muddy, and it seems like all the high-end just disappeared.

Most guitarists who use a fair number of pedals have the potential of running into this issue at some point, especially more so these days where many boutique, high-end pedal manufacturers offer pedals that are true bypass, where the electrical circuit is completely removed from the signal chain when the pedal is off.

So where is this signal loss occurring? Primarily, the signal loss occurs in the cables. Cables have a characteristic known as capacitance, which interferes with the electrical signal being transmitted and causes signal loss, especially in the high-frequency region (It should be noted that all cables have capacitance, even the expensive, high-quality ones - generally, higher quality cable manufacturers offer cables with lower capacitance, as a means to reduce signal loss). Now that you know where the signal loss is coming from, you can see why it could be a potential problem when you string a bunch of pedals together:

Let’s say you have 8 true bypass pedals, and they are connected to each other by 15cm long patch cables. You also have a 3m long cable going into the first pedal, and another 3m long cable coming out from the last pedal into your amp. Each pedal will also provide its own effective “cable” when it is off (as the signal is passing through the true bypass circuitry), so let’s set that as 15cm as well.

Total cable length = (guitar to pedal 1) + (7 x patch cables) + (8 x pedal circuit “cable”) + (pedal 8 to amp) = 3 + (7 x 0.15) + (8 x 0.15) + 3 = 8.25m

Compared to a case where you plug straight into an amp from your guitar with that 3m cable, you have almost 3x as much cable length in the way of your signal. Now, 8.25m of a high quality cable may not be enough to degrade your signal enough that you’d notice a change in sound, but if you scale it up and consider some realistic possibilities such as longer patch cables, lower quality cables, more pedals, greater distance from where you’re standing on stage to the amp (requiring longer cables) etc, it’s not difficult to see that you may run into some audible tone loss at some point.

What makes this issue even more problematic is when you hear an audible tone loss and try to use the amplifier’s EQ to offset the treble that’s disappeared. Everything seems to have gotten under control, but once you engage one of the pedals, all the high end in your signal comes back (I explain why this is the case in section 1c) and now you’ve got a shrill, trebly sound.

With these issues in mind, we can now move on to what buffers do and how they can help mitigate these potential problems.

 

b) What is a buffer?

A buffer is a unity gain amplifier designed to transform the electrical impedance of a signal. In the context of guitars, it is a circuit that will change a high-impedance signal coming out of a guitar into a low-impedance signal, without changing the volume (gain) of the signal.

Impedance is a measure of the total resistance to current flow in a circuit. A typical, passive guitar outputs a high-impedance signal, and since high-impedance signals are more susceptible to being affected by the cable capacitance, the negative effects of a longer cable (or a lower quality cable) is more adverse than for an instrument that outputs a low-impedance signal such as a digital keyboard.

When a buffer is introduced into the signal chain, it converts the high-impedance guitar output signal into a low-impedance signal, allowing it to pass through cables with drastically less signal loss, preserving the original signal’s frequency response and level.

 

c) Buffered bypass and engaged pedals

In section 1a above, I mentioned true bypass pedals. These pedals, when off, disconnect the effect circuitry completely form the signal chain and pass the input signal into the output directly. On the other hand, there are pedals that have buffered bypass - this means that when the pedal is off, it is still buffering your input signal.

When pedals of either bypass types are engaged, the output signal is effectively buffered as the input signal is modified by the effects circuitry. This is why some people can experience their tone getting brighter as soon as they engage a pedal - the engaged pedal effectively buffers the signal, bringing back the high-end that was previously loaded down.

For more information on typical bypass types, check out Annex A.

2. Do I need a buffer?

 

This question is heavily dependent on what you, as a guitarist, want from your tone. In my case, I like my clean sound to be exactly the same whether I’m running the guitar straight to my amp or going through my pedalboard, so I can shape it however I want after that. On the other hand, Jimi Hendrix used coiled cables (which increased the total length of the cable greatly), which removed a considerable amount of high end bite from his original guitar sound, but that didn’t stop him from being awesome, with great tone that many to this day try to emulate.

My point is, don’t just get a buffer because everyone else is getting one, or someone tells you you need one. Consider what you want from your sound and if you are new to buffers, use the information I’ve provided in this article to figure out how a buffer would affect your existing tone when introduced into your setup. Now that you know exactly what a buffer does to your signal, you can make an informed decision as to whether or not you want it in your chain.

I’ll be laying out some information on pedalboard considerations for a buffer in the next section.

3) Usage

 

a) Current Setup

Now that you know what buffers do, you need to evaluate what it can do for you, and whether you actually need any buffering in your signal chain. Most guitarists typically have a mix of buffered and true bypass pedals in their pedal chain, and depending on how they are placed, you may not need a dedicated buffer.

 

b) Placement

You can choose to place your buffer anywhere in the chain, but here are some typical places I see people place buffers:

- First: Since the buffer is the first thing your guitar signal hits, it will keep as much of the original signal intact as possible as compared to the other cases. Of course, since the guitar is connected to the buffer using a cable, there is some tone loss that occurs, though unless the cable is of low-quality (i.e. high-capacitance) or extremely long, the signal degradation is likely a minor one.

- Last: This buffer primarily minimizes signal loss that occurs between the pedalboard and the amp (it is typically more likely that this is the longest cable run that happens in a guitarist's signal chain). For a short signal chain with only a few pedals, this method may work but if your signal chain is long, it is possible that enough degradation has occurred already before the signal actually hits the buffer.

- Middle: This is when the buffer is placed somewhere in the middle of the chain. Some find that having a buffer before drive/distortion pedals affects how the guitar interacts with them, so they only place the buffer after the drive section before the modulation/time-based effects.

- First and Last: This is typically referred to as a dual-buffered system, where the signal is buffered once at the beginning of the signal chain and once at the end. This is especially useful for larger pedalboards with a large number of pedals, where the signal chain is long enough that a single buffer first-in-line may not be enough to drive the signal through the whole signal chain and the cable into the amp.

 

c) Exceptions and other considerations

Buffered pedals & Always-on pedals: As mentioned in section 3a, you may or may not need a dedicated buffer pedal depending on whether you already have some buffered pedals in your chain (e.g. Boss pedals, most Ibanez pedals). If you do already have buffered pedals placed where you want them and you're happy with your tone, there is hardly any need to add a dedicated buffer pedal. The same logic applies if you leave some pedals on all the time, since these always-on pedals will have your signal buffered at their respective points. In some cases, however, some buffered pedals or always-on pedals may not have a low enough output impedance to drive the signal all the way through, and this is when a dedicated buffer could still be useful.

Fuzz faces: When a buffer is placed before a fuzz face type pedal, it typically makes the fuzz effect sound shrill and thin. This is because fuzz faces are designed to interact with a high impedance guitar input signal - that is why they clean up amazingly when you roll back the volume knob on your guitar. Avoid putting a buffer or a buffered pedal in front of a fuzz face to avoid disappointment.

Active pickups: Active pickups like EMGs already have an active circuit within the guitar the buffers the signal, so as soon as the signal comes out of the guitar it is buffered before it even hits the first cable. If you are a user of active pickups, you will likely not require any front-end buffers, though depending on the length of your signal chain you might want to consider getting a buffer at the end.

4. Other things to note

 

a) Not all buffers are created equal

Older buffered pedals such as vintage Boss pedals have differently designed buffers with higher output impedance than the modern equivalents, which would mean that there would be a larger potential tone alteration that could happen if they are part of your pedal chain. Vintage Wah-wah pedals are also known to have badly designed buffers that would cause a considerable amount of tone loss. Some of these pedals can be modified to true-bypass, but since not all of these pedals lend itself to that kind of modification, it is a consideration one has to make when deciding to include these pedals in the signal chain.

 

b) There is such a thing as "too many buffers"

Having a signal chain of purely true-bypass pedals can be an issue as discussed above, but so can having too many buffered pedals. Tone aside, some find that this negatively affects the way the guitar interacts with the pedals/amplifier, in areas such as the sensitivity or dynamic range available. This has a lot to do with personal preference, and would likely be more obvious to some than others, meaning a lot of trial and error is necessary in order to figure out whether or not this is an issue for you.

5. Summary

 

In this article I've talked about what buffers are and what they could potentially do for you. Hopefully I've provided enough information for you to be able to decide whether or not you need one in your chain. Every individual has a different setup and a different preference in tone, so there really is no right or wrong when it comes to this. As long as it works for whatever musical situation you are in, I'd say you're okay. After all, there's no need to fix what ain't broken. If you've got any questions or concerns, please feel free to leave them in the comments section or contact me directly and I'll be happy to answer them to the best of my abilities. Thanks for reading!

Annex A: Typical pedal bypass methods

True bypass: When the pedal is off, the input is physically disconnected from the effects circuitry through a mechanical switch or a relay, and passes through to the output. You will likely get some pops when you engage/disengage the effects pedal due to the mechanical nature of the footswitch.

Buffered bypass: There is a buffer circuit that is active at all times in both the input and output section of the pedal, and the signal passes through this circuit even when the pedal is disengaged (it just removes the effects circuitry from the signal path). A pedal that uses this kind of bypass won’t pass any signal when it has no power. Due to the fact that the switching is done electronically, the switching is silent.

Hardwire bypass: Less common these days, but you may run into these at some point. This is somewhat of a half-assed bypass, where even when the pedal is off, the signal still flows through the pedal’s circuitry. Because this kind of bypass does not physically remove the pedal circuitry from the signal chain when the pedal is disengaged, it adds an extra layer of signal degradation from the pedal circuitry when the pedal is disengaged.

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