[2386] Booster Gain

Date: April 4th, 2018 | Comments : [2] | Categories: DIY.

I see posts occasionally asking which booster pedal has the most gain.

The available gain of a booster by itself tells you very little. Two additional deciding factors are: How large is the input signal, and what is the max voltage swing of the booster output?

Each circuit has a maximum voltage swing and when that is exceeded, distortion will result. In a standard circuit powered with 9v, the max output voltage swing is probably 7v or so (+/- 3.5v). Therefore, if your pedal has 20dB (10x) of boost, then the maximum input before distortion is 0.7v peak-peak (7v/10). Any more gain will distort. Any signal larger than 0.7v pk-pk will distort. Most guitar pickups exceed 1.0v pk-pk on the initial string pluck.

If you pedal has 35dB of boost, that is a voltage gain of 56x. So the maximum input signal before distortion is 7v/56 or 0.125v pk-pk. Not much headroom.

You don’t need more gain if you want a boosted clean signal. You need (want) more headroom, and the easiest way to do that with a booster pedal is to power it with a higher voltage, such as 18v or 24v, to give a larger output voltage swing before distortion.

More reading: Boosters, Gain and Distortion

 

2 Responses to “Booster Gain”

[785290] Kerry Maxwell Says: 4:32 pm, April 15th, 2018

An unfortunate effect of the widespread conflating of “gain” with distortion.


[785587] Junk McNuggets Says: 3:54 pm, July 3rd, 2018

This little bit of info is immeasurably helpful.

Thanks a shit ton.


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