Volume pedals may not be as simple as they seem. In this article we cover some of the common questions and answers about using volume pedals with guitars and other instruments.
Q: What is the difference between active and passive volume pedals?
The difference between these two can cause confusion due a difference in whether we really mean active or passive volume pedals or are in fact referring to volume pedals for active or passive pickups. These are not the same thing, so let’s see if we can clear it up starting with active or passive volume pedals.
Passive volume pedals are basically a potentiometer mechanically turned by a pedal, and work much the same way as the volume knob on a regular magnetic pickup guitar. A quick way to identify a passive volume pedal is it doesn’t normally need power. These are simple to use and convenient since they don’t need power, but are often sensitive to the types of instruments they are used with, and where they are placed in the signal chain. Passive volume pedals with tuner outputs can be especially problematic as they have to split the signal into two causing loading on the pickups which can result in a loss of high frequency, AKA ‘tone suck’.
An active volume pedal contains and amplifier circuit that is normally used as a buffer, and sometimes for other features such as boost, tuner isolation, and so on. Active volume pedals require power from an internal battery or an external power supply. The buffer isolates the input side from the output ensuring that whatever you have after the volume pedal, including effects pedals and long cables, does not cause additional loading and the resulting signal loss.
Passive pickups are the regular single coil or humbuckers in your typical Strat or Les Paul. They don’t need a power supply of their own, and work happily using only the power generated from the vibrating strings in the magnetic field of the pickup poles. If your electric guitar does not need power or batteries, it has passive pickups.
Active pickups have an amplifier. This is normally built into the guitar body or the pickup assembly. Active pickups require power from a battery or external power supply. See the next question for information about choosing a volume pedal for active or passive pickups.
Q: Does it matter what resistance value potentiometer is in my volume pedal?
For passive volume pedals, yes. It’s important to match the input impedance of the volume pedal as closely as possible to what the pickup expects in order to avoid tone loss as a result of an impedance mismatch. If you have passive pickups, a passive volume pedal in the 250K – 500K range will normally be fine. If you have active pickups you’ll need a passive volume pedal in the 25K – 50K range. If you mix these up, you’ll likely suffer some tone loss from the impedance mismatch.
If you are using an active volume pedal you don’t need to worry about the value of the potentiometer. In this case it is just acting as a controller for the output of the internal amplifier. Both active and passive pickups should work with a well designed active volume pedal.
Q: What taper should a volume pedal have?
Volume controls should be logarithmic, sometimes also called ‘audio’ taper, or at least something approximating it. A log control increases the volume more slowly at the beginning of the rotation and more steeply at the end. This is because human loudness perception is also logarithmic. If you were to use a linear control for a volume pedal it would seem like all the volume increase happens when you first move the pedal, and then very little at the end. A logarithmic volume control gives the perception of a smooth, proportional increase in volume. Check out RG Keens secret life of pots for more great taper details.
Q: Can I use a volume pedal in an effects loop?
Effects loops generally expect low impedance devices, and often have buffers in them of their own. A passive volume pedal with 25-50K Ohm range should work fine. It is not generally recommended to use high impedance passive volume pedals in an effects loop. You may find that the taper feels abrupt, more like an on/off switch than and smooth sweep.
Q: Can I use a volume pedal with other instruments?
Active volume pedals, can generally be used with many other instruments such as electric bass, keyboards, harmonica mikes etc. Specialty PZ compatible pedals designed to work with passive Piezo electric pickups should be used on acoustic instruments such as guitars, violins, cellos, stand-up bass etc.
Q: Can I use a volume pedal as an expression pedal?
You can sometimes use a passive, low impedance volume pedal as an expression pedal by using a TRS stereo insert cable to connect the input and output from the pedal to the expression controlled device. The volume pedal will likely have a log pot and expression devices normally expect a linear input so you may find the response not to be very smooth, unless the device is designed to accommodate a log pot. Some digital devices can be programmed to compensate for a log pot if you use a volume pedal as an expression pedal.
Q: Will connecting a tuner cause tone suck?
If you have a passive volume pedal that splits the signal between the instrument and tuner out, you can potentially experience some signal loss. The additional loading of the low impedance tuner device, and that fact that the signal is being split between two different paths can create effectively a low pass filter that removes some of the high frequency component of the signal making it sound less bright. This can be avoided by using a volume pedal with an isolated tuner out, or using a tuner with a hardwire bypass that can be disconnected from the signal chain when not in use.
Q: My fuzz pedal sounds strange when I use a buffered volume pedal in front of it. What’s wrong?
Transistor based Fuzz pedals behave strangely after buffers because they depend on the impedance (Z) of a pickup to limit gain, and since the buffer has a low output Z, the fuzz can sound unusually loud and be non responsive to the volume control. Another effect is that the low input impedance of the fuzz will limit high frequency response when driven by the pickup, but the low Z of the buffer lets more highs through and that can make the fuzz sound harsh. The Mission VM-Pro has a fuzz friendly impedance switch that lets you use it in front of a fuzz. The buffer is always active, and the impedance switch adds a fixed resistance in series with the output to restore the proper fuzz sound and performance.
Find your perfect volume pedal at Mission volume pedals.
Most players will setup their pedal as the first piece (or the first piece after a buffer). This is especially important for swells and overdrives.
However, some people also like having a pedal or volume control after all of the effects and right before it feeds into the amp. That way if you are finishing a piece with a lot of sustain, you can quickly truncate the sound and move into the next piece.
However, for this second volume control, a lot of artists opt for a simple knob instead of a foot pedal. But you can even set up a pedal on the front and the back (and the middle, if you want). It’s all up to you
I’m gonna order a new pedalboard and I’m thinking of running two signal chains: raw and wet. My acoustic guitar output (9v battery) will go through an Aura Spectrum and then a chorus pedal which will also split the signal (it has two outputs). The first output of the unit will go directly to amp.
I will put a volume pedal in the beginning of the second output before a leslie simulator, delay and reverb to control the overal volume of the signal route and also create ambient swells.
Should I go for an active or a passive volume pedal?
You should only use a passive volume pedal if you are connecting it first in line with passive electric guitar pickups connected directly to the input. For An acoustic guitar with active pickups, you should use an active volume pedal.
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I have a dunlop dvp4 250k passive volume pedal. What is the output of this pedal? Input is 250k? as is mye vol.knob in my guitar so this should be fine, but what is output ohm?
My fuzz doesent sound good unless guitar is plugged directly into it. So having a 250k volume pedal in front will do?
Also i have a tc BonaFide Buffer that states on website: 1M ohm input and 100 ohm output. So in theory this ohm is to low for having in front of either vol.pedal and my germanium analogman peppermint fuzz?
Also are there any overdrive that is output 250k? If i want to use it after overdrive/dist?
A lot of questions. Thanks.
Fuzz pedals typically do not work well with buffers in front of them. You can connect the guitar directly to the fuzz, and then put any buffers and volume controls after them. Alternatively you could use a Mission VM-PRO which is a buffered volume pedal that has a fuzz compatibility switch that allows it to be used in front of most fuzz pedals.
I just received your VM1-Aero and will be running it near the front of a chain. However the guitar will first go through a Moen GEC selector which I like to use and will start with a buffer that is built into this selector because of the amount of pedals and length of cable used. Am I OK running your pedal first after the buffer circuit or do you see any issues with this alternate set up : buffer, Fulltone MDV-3, Xotic XW1 wah, and then the VM1-Aero before going through the rest of the front in pedals?
The VM-1 pedals are designed to be connected directly to passive pickups. If you place it after the buffer there will likely be an impedance mismatch that causes the taper of the volume pedal to react differently. You can put the VM-1 first and then the buffer right after and that will be fine. As long as you only have a short cable running between the output from the VM-1 and the input of the buffer, the buffer performance will be unaffected. Guitar -> VM-1-> buffer -> other pedals. If you want to use a volume pedal in the middle of a signal chain after buffers and other pedals, the VM-PRO will be better suited.
How can one tell if the tuner output on a volume pedal is isolated or not?
What about putting a tuner with true bypass in front of a high impedance passive pedal using a guitar with passive pickups?
I just started using pedals and don’t know a lot about them. Here is my line up. Guitar passive pick ups, volume pedal also passive, true bypass tuner, true bypass over drive, true bypass tremelo, true bypass chorus then my amp. For some reason my telecaster losses volume and sounds muddy and not as bright as normal. How can I change this? Do I need to rearrange my pedal board or add another pedal like a boost?
Most likely The problem is that multiple true bypass pedals plus the cables between them are adding up to create a low pass filter, removing the higher frequencies from your guitar signal by the time it reaches the amp. You can resolve this by adding a buffer first in line in the signal chain. You could replace the passive volume pedal with a buffered volume pedal such as the Mission VM-PRO which is specifically designed to resolve this exact issue. Or you could add a standalone buffer, or buffered effects pedal right after the volume pedal.
You should also check the impedance of the passive volume pedal that you are using. If you are connecting it directly to a passive pickup, you should have a volume pedal with a potentiometer value of at least 250K Ohm. 400 – 500K Ohm is even better in most cases.
I have a 25K Ohm Ernie Ball passive volume pedal.
I am wanting to run this directly after my passive pick up electric guitars.
From some reading, it appears that 25K Ohm is quite low and I should have gone with something different. (next time ill go with an active pedal). But in the mean time:
Could anyone explain to me why that is? What effects using the lower impedance will have?
The two guitars im wanting to use have
1. two Gretsch mini humbuckers and then
2. the Strat with one single coil and two humbuckers if that is telling of anything either.
Your thoughts and knowledge are so appreciated
Passive guitar pickups are low output impedance devices. They need a high input impedance on the other side (the volume pedal in this case) to work efficiently. Generally the lower the input impedance of the volume pedal, the greater the amount of voltage drop, and therefore signal loss. A typical value for the output impedance of a passive electric guitar pickup is 10K Ohm (They differ but this is a reasonable average). A rule of thumb suggests the input impedance of the following device should be 100X the output impedance of the pickup. This is why the input impedance of a tube amp input is normally around 1M Ohm (100 * 10,000).
If you use a low impedance volume pedal, the voltage drop will at least make the signal quieter and possibly change the frequency response too depending on the exact nature of the volume pedal and what else comes after it. AKA tone suck. Most passive volume pedals when connected first in line to a pickup should normally be at least 250K Ohm, or you’ll get tone suck.
The reasons for why you need a high impedance input following a low impedance output are actually quite complex. By far the most enlightening explanation I have seen is this one from Applied Science on Youtube https://youtu.be/vcSc16tnVqk. Ben has a two part video series on impedance on the channel that goes into more detail on electrical impedance but it was the one linked that was the light bulb moment for me. There’s also a good article here http://whirlwindusa.com/support/tech-articles/high-and-low-impedance-signals/
To get around it you can replace the pedal with a high impedance one, replace it with an active volume pedal, or you can use your low impedance volume pedal and put it after another pedal.
I play a Taylor T5z, and two Godin Multiacs, one steel string, one nylon, ( both with 13 pin pickup that I don’t use much). Which of your volume pedals should I use? I am also interested in the curved heel feature as I play sitting down mostly.
Thanks for your help.
The most appropriate volume pedal would be the Mission VM-PRO since these guitars use active pickups. Unfortunately we do not have an Aero version of the VM-PRO. You can still use the standard one sitting down and it will work fine, it just doesn’t have the curved top piece so it’s not quite as comfortable, but the VM-PRO will give you the best audio performance.
I greatly enjoyed your article because it addressed exactly the question that puzzled me this week when I found out that my pedal was a low impedance (Ernie Ball VP 25 K) suited for active signals.
I do not have effects loop in my amp.
I understand that if the Volume Pedal is placed in the end (after Guitar, wah, drives and distortion, chorus, delay, reverb and boost) right in front of the amp, it should be exactly the one I own? Or would a change to a 250 K present any advantage?
If you place the volume pedal AFTER these pedals, you should use a low impedance volume pedal around 50K. If you are going to place the volume pedal FIRST and connect passive guitar pickups directly to the input, you should use a high impedance pedal. 250K is OK, but somewhere around 400 to 500K is usually better.
Good Lord! All this ridiculous “tone chaser” minutia. Shut up, plug your crap in and play for Heavens sake. Does anyone think that Clapton, Hendrix, Page, Beck, Blackmore, Vaughn, West, Trower, Frampton, Buckingham, Baxter, Ford, and the other 900 guitarist not mentioned here checked to see if their volume pedal potentiometer matched the Ohm value of their guitar volume pot? Sheesh! As Clapton once mused about all these new guitar players with “All there little boxes all over the floor, (with a wry smile…) it’s all (wiggling his left hand fingers in the air) in the fingers isn’t it!”
Many A list guitar players don’t worry about it because they have guitar and amp techs to take care of it for them. I work with many guitar techs, and they absolutely do care because they need to keep the boss happy. Volume control impedance is not about tone chasing, it’s about physics. If you get a significant mismatch, it won’t work. In Claptons case, I believe Fender significantly modified the volume control adding a boost circuit in his signature Strat to give him the exact sound he was looking for.
very clear and good article easy to understand. Thank you
Did you try putting the volume pedal first, before the wah pedal or any other effects?
I found this a helpful explanation. I have a BOSS volume pedal FV-500H just after my Wah pedal, it goes into a Tube Screamer. A delay and flanger and looper are in the effects loop. With or without other pedals the volume pedal sends a distinct noise when its pushed on. I sent the first pedal in as I though it was a fault and received a new one but it does the same thing. The amp is a mesa boogie mk5:35. The wooshing noise it makes is quite annoying as I like to use a lot of volume swells. Any thoughts as to what might be going on?