# Electrovibe Chorus volume



## doublej (Sep 8, 2021)

so this may not really be trouble shooting, I have never had a uni-vibe and maybe this is how they work but on vibrato volume is full just with the effected signal.  on Chorus I also get the effect but at a pretty decent volume drop.  I have messed with the trims inside and have the volume maxed out.  should I have a decent volume loss on chorus, not really perceived but obvious.  I will get a pic as soon as I can


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## Big Monk (Sep 8, 2021)

doublej said:


> so this may not really be trouble shooting, I have never had a uni-vibe and maybe this is how they work but on vibrato volume is full just with the effected signal.  on Chorus I also get the effect but at a pretty decent volume drop.  I have messed with the trims inside and have the volume maxed out.  should I have a decent volume loss on chorus, not really perceived but obvious.  I will get a pic as soon as I can



This is an inherent part of the circuit.

I would tweak R4 until you get unity gain in chorus mode.


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## Bricksnbeatles (Sep 8, 2021)

I’m not familiar with authentic univibe circuits either, but I’ve seen the volume drop mentioned by a few people on the forum


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## NickC (Sep 8, 2021)

I can confirm, the volume drop is normal for this circuit.


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## Big Monk (Sep 8, 2021)

R4 is the place, for those interested, to start tweaking for unity gain. I'll be tweaking this in my build so I'll be the guinea pig here.


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## Bricksnbeatles (Sep 8, 2021)

Big Monk said:


> R4 is the place, for those interested, to start tweaking for unity gain. I'll be tweaking this in my build so I'll be the guinea pig here.


Probably worth just using a trimmer


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## doublej (Sep 8, 2021)

Big Monk said:


> R4 is the place, for those interested, to start tweaking for unity gain. I'll be tweaking this in my build so I'll be the guinea pig here.


so I may sound like an idiot here but which one is R4, I couldn't find a doc with the locations.  I just know its 47k


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## Big Monk (Sep 8, 2021)

thewintersoldier said:


> The answers you seek on how to implement the volume mod are in the schematic in these build docs. https://madbeanpedals.com/projects/_folders/FilterMod/pdf/HarbingerOneFive.pdf



This is probably a better reference:

https://docs.pedalpcb.com/project/ElectroVibe-Schematic.pdf


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## Big Monk (Sep 8, 2021)

doublej said:


> so I may sound like an idiot here but which one is R4, I couldn't find a doc with the locations.  I just know its 47k


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## Big Monk (Sep 8, 2021)

thewintersoldier said:


> I'm sorry if I was being confusing. I was referring to where in the circuit to put the volume control. The harbinger is adapted from the deja vibe. I assumed people would use both schematics and decide a plan, probably wrong on my part. I guess my wife is right about me yet again...lol



I see.

The Volume control is in the same place on both circuits. I see the Harbinger adds an additional option for an input buffer, but it seems much easier and less invasive on the Electrovibe to simply increase R4 until you hit unity gain at a suitable place on the dial.


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## doublej (Sep 8, 2021)

Big Monk said:


> View attachment 15804


thank you!!


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## Jonnytexas (Sep 13, 2021)

Quick question fellas.  I gigged mine this weekend and the tone was glorious, but I did notice the small volume drop.  Would R4 need to go up or down to increase volume?


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## Big Monk (Sep 13, 2021)

Jonnytexas said:


> Quick question fellas.  I gigged mine this weekend and the tone was glorious, but I did notice the small volume drop.  Would R4 need to go up or down to increase volume?



Up.

The R1/R4 divider can be tweaked to allow more signal to pass into the circuit. Stock, it lets 68% of the signal get through. So if you find that you are having volume issues, you can tweak R4 up. For example, 100k goes to 82%, 250k to 92%, 2M to 99%, etc.

I'd maybe tack in a 100k pot and see what gets you to unity, or a volume in general that works for you, then replace with the closest fixed resistor.


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## Jonnytexas (Sep 13, 2021)

Big Monk said:


> Up.
> 
> The R1/R4 divider can be tweaked to allow more signal to pass into the circuit. Stock, it lets 68% of the signal get through. So if you find that you are having volume issues, you can tweak R4 up. For example, 100k goes to 82%, 250k to 92%, 2M to 99%, etc.
> 
> I'd maybe tack in a 100k pot and see what gets you to unity, or a volume in general that works for you, then replace with the closest fixed resistor



Ok, thanks, will report back.


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## Jonnytexas (Sep 13, 2021)

One more question before I fire up the iron....should I go 2M? Then I have the volume pot to dial it back if it's too much.  Also, if I was to use a pot to dial it in, I would use lugs 2 and 3?  Sorry for the newb questions,  Still learning


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## Big Monk (Sep 13, 2021)

Jonnytexas said:


> One more question before I fire up the iron....should I go 2M? Then I have the volume pot to dial it back if it's too much.  Also, if I was to use a pot to dial it in, I would use lugs 2 and 3?  Sorry for the newb questions,  Still learning



You could go 2M. Going higher is just going to move unity down the dial.

Yes on the pot. Since you need a variable resistor, use either 1 and 2 or 2 and 3.


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## doublej (Sep 17, 2021)

Big Monk said:


> Up.
> 
> The R1/R4 divider can be tweaked to allow more signal to pass into the circuit. Stock, it lets 68% of the signal get through. So if you find that you are having volume issues, you can tweak R4 up. For example, 100k goes to 82%, 250k to 92%, 2M to 99%, etc.
> 
> I'd maybe tack in a 100k pot and see what gets you to unity, or a volume in general that works for you, then replace with the closest fixed resistor.


I know you didn't design the circuit but why would stock only let 68% through, I mean why would someone want a vol drop?  is that how the original worked?


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## Big Monk (Sep 17, 2021)

doublej said:


> I know you didn't design the circuit but why would stock only let 68% through, I mean why would someone want a vol drop?  is that how the original worked?



Voltage dividers are common in circuits to drop the signal down to manageable levels. For instance, the original Epiphone Valve Junior dumped something like 50% of the input signal with a 68k/68k voltage divider.

I doubt they designed it to not have unity gain. At the time, many artists were playing through very loud rigs and frankly would have compensated in other places on the fly, i.e. volume knob manipulations.


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