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What causes a volume boost in a pedal?

blackie59

Member
Messages
1,120
I have a chorus pedal that definitely boosts the volume when I use it and I wondered if anyone can tell me why it would do it and if there's anything than can be done to tame it? I running it in the effects loop of my amp if that's any help.
 

Bobby Wasabi

Member
Messages
2,101
I have a similar problem, same amp (head version), although it has nothing to do with the amp.

I have an MXR micro chorus that has a slight volume boost. I run it out front because it sounds better there (to me) and it was noisy in the loop.

I googled this issue in regards to the MXR a while back and found where people had contacted MXR about it. MXR had a response that it was due to other pedals in the chain or lack of a buffer (or something like that). I've hooked up guitar-->chorus-->amp and it still has a volume boost so I don't buy that explanation.

My guess is it's something in the design of the circuit, where they did not match effect-on output volume with bypass volume (unity gain).
 

Derksen

Member
Messages
34
Probably a buffer in the pedal or a buffer before pedal that jacks the output.

Either that or you have a pedal that is 'voiced' in such a way that increases the output.

Which pedal is it?
 

blackie59

Member
Messages
1,120
Yes it's the mini-chorus. It's a great sounding pedal but the volume boost alone is really irritating. Enough that I'm considering posting it on the emporium.
 
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AXXA

Silver Supporting Member
Messages
7,112
You have to consider that chorus pedals are doubling your signal, like many time based effects do. I know that doesn't help you fix your problem, but perhaps that puts some perspective on the issue. A chorus with a volume or effect level knob may be helpful to solve this. FWIW, the Small Clone I had did the same thing.
 

NHBluesMan

Member
Messages
6,117
it may just be a percieved boost and not an actual boost... sometimes changes in frequencies make this sound louder/softer- i.e. Tremolo pedals are usually accused of dropping the volume level (a percieved drop, not an actual drop), so some companies incorporate a boost in the circuit to accomodate for this, maybe that's the case with your chorus?
 

Blues Lyne

Member
Messages
3,463
Have you contacted Analogman? I'm sure Mike would have a pretty good idea why it did that and if there is a way to change it.
 

blackie59

Member
Messages
1,120
Yeah, I emailed Mike but he was only concerned if it dropped volume. He also suggested upping the voltage from 9 to as high as 18. I did this and the pedal sounds better but I still have a boost in volume. And it's not a slight increase it is as much as my Timmy at unity gain and the gain set at noon.
 

Blues Lyne

Member
Messages
3,463
Yeah, I emailed Mike but he was only concerned if it dropped volume. He also suggested upping the voltage from 9 to as high as 18. I did this and the pedal sounds better but I still have a boost in volume. And it's not a slight increase it is as much as my Timmy at unity gain and the gain set at noon.
Either I'm missing something, or you meant something different than what you wrote. If the Timmy is at unity gain it is neither boosting or cutting the signal.
 

Philippe_CGC

Member
Messages
339
It shouldn't be that difficult to add an attenuator/volume control just to the output when the effect is on, it's a pretty simple mod. I would recommend asking Mike if he might do that for you.
 

jdel77

Member
Messages
10,224
Just what I was about to write, Phillipe. Any true bypass pedal can be easily modded for this. Take the pcb output wire and disconnect it where it hits the stomp switch. Connect it to lug 3 of a 100k trim pot. Lug 2 goes to the stomp now and lug 1 to ground. Boom. Instant volume control.

Non TB pedals are trickier, as the bypass and effect signal can be altered at once. Not good.
 

Bobby Wasabi

Member
Messages
2,101
Just what I was about to write, Phillipe. Any true bypass pedal can be easily modded for this. Take the pcb output wire and disconnect it where it hits the stomp switch. Connect it to lug 3 of a 100k trim pot. Lug 2 goes to the stomp now and lug 1 to ground. Boom. Instant volume control.

Non TB pedals are trickier, as the bypass and effect signal can be altered at once. Not good.
I'd love to try this on my MXR micro chorus. Is the trim pot something that stays hidden in the enclosure (set it once and forget it) or do you drill a hole in the pedal enclosure and mount it for external control?
 

jdel77

Member
Messages
10,224
If it's doable then you can drill a hole in the side ala the earlier Skreddy pedals or just solder it direct to the stomp or on a little daughter board. Then it would be a set and forget inside the pedal with no external drill hole.. Though I'm not sure the mxr is truebypass from memory. Then you need to convert it to tb and do the mod.
 

Blues Lyne

Member
Messages
3,463
Sorry, volume at unity gain.
Right, that's what is confusing because if the volume is at unity gain you have no boost. In reading your post again, I'm wondering if you mean you set the volume to unity and then change the gain knob on the Timmy. If that's the case then the volume is most likely no longer at unity gain. Where the volume knob achieves unity gain is usually very dependent on where the dirt/gain control is set. And, from my experience with the Tim, if you set the volume to unity and then turn the gain up it will get louder and the volume will no longer be at unity. This is because the gain knob is usually a volume control (or boost control) prior to the clipping element of the pedal. In other words, there isn't a specific setting on a pedal's volume pot that is always unity gain, there are only settings that are unity gain for a given gain, treble and bass pot setting.

As others have said, it shouldn't be too hard to add a volume pot.

I'm surprised Mike didn't have any input on your specific problem. I did some digging and found a thread on another forum where Mike was helping a guy with the same problem. Mike said that about 10% of people hear a reduction in volume and 10% a boost, so he figures the pedal must be right around unity. He also said that he hasn't experienced a boost with his. In that thread it turned out that the pedal was interacting with one of the pedals around it. This was my first thought when I was reading through this this morning. That guy ended up going guitar>chorus>amp and then adding in the other pedals one at a time to see what one was interacting with the mini-chorus. He found that if he moved his buffer so that it was between the chorus and his volume pedal and things worked fine.

Are there any other pedals in the effects loop? I'm assuming the Carbon Copy is also in the loop. Have you tried taking the carbon copy out of the loop just to see if you still get the volume boost from the chorus? It looks like the effects loop is buffered in your amp. I wouldn't expect there to be an issue with the loop itself unless it was unbuffered.
 
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blackie59

Member
Messages
1,120
Yes I swapped the order of the pedals and tried them by themselves and still get a pretty solid boost from the chorus.
 

oxtone

Member
Messages
5,024
For years I used a L6 Echo Park that had a slight volume boost when I'd engage it. But, I liked that about it, since I'm a delay freak.

Now I use an iB Modified Nova Delay, which sounds great.
 

StompBoxBlues

Member
Messages
20,148
If it's doable then you can drill a hole in the side ala the earlier Skreddy pedals or just solder it direct to the stomp or on a little daughter board. Then it would be a set and forget inside the pedal with no external drill hole.. Though I'm not sure the mxr is truebypass from memory. Then you need to convert it to tb and do the mod.
It's a cool idea, and from what you say, it seems to work okay. The only possible problem is, it ought to be a buffer then instead of pure resistance, because you are adding a fixed resistance to "impede" (like impedance but one that is equal over all frequencies in theory...in reality it may not be that equal but is not as varied as real impedance) the signal, in addition (when the pedal is on, as in this case) you have the actual, pre-mod, input and output impedance of the pedal, you've just added MORE impedance to that, and that may affect the pedals upstream and downstream?

I'm trying to figure out how it would affect. Input impedance? If it does it would raise it, which is usually good, more signal IN to the pedal, but for output it might be less good, where you want low impedance OUT.
 






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