Author Topic: Logarithmic or linear potentiometers for volume and a 3 band EQ  (Read 933 times)

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Offline Pexy13Topic starter

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Greetings!

I am in a proces of going trough my junk pile to find all the components I need for a Bass guitar preamp.

Looking at the schematic and the text that was posted about the project I can't find if I should use logarithmic or linear potentiometers.
There should be one for each (volume, treble, bass and mid).

The Scehematic is attached below.
 

Offline TimFox

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Re: Logarithmic or linear potentiometers for volume and a 3 band EQ
« Reply #1 on: April 06, 2020, 01:44:18 pm »
Usually for amplifier controls, the tone controls (treble, bass, and mid) are linear (sometimes center tapped) and the gain control (volume) is logarithmic.  You can make a quasi-log pot from a linear pot with an appropriate load resistor between the wiper and CCW.
 

Offline Pexy13Topic starter

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Re: Logarithmic or linear potentiometers for volume and a 3 band EQ
« Reply #2 on: April 06, 2020, 01:57:18 pm »
Usually for amplifier controls, the tone controls (treble, bass, and mid) are linear (sometimes center tapped) and the gain control (volume) is logarithmic.  You can make a quasi-log pot from a linear pot with an appropriate load resistor between the wiper and CCW.

Thanks I'll try it out.
 

Offline basinstreetdesign

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Re: Logarithmic or linear potentiometers for volume and a 3 band EQ
« Reply #3 on: April 07, 2020, 12:52:34 am »
The way that volume pot is configured, a linear pot is good since the relation of gain using the two halves of the pot is non-linear, actually hyperbolic.  Just how well it emulates a log pot is a function of the 47K value against the 10K pot value.  You may have to play with the 47K value to optimize this.
I'm sure this is what the designer was going for, to begin with.
« Last Edit: April 07, 2020, 12:54:45 am by basinstreetdesign »
STAND BACK!  I'm going to try SCIENCE!
 
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Offline obiwanjacobi

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Re: Logarithmic or linear potentiometers for volume and a 3 band EQ
« Reply #4 on: April 07, 2020, 06:54:41 am »
FYI: the -15V on opamp B is on pin 4 not on pin 1 as shown in the schematic (pin 1 is output for opamp A).
[2c]
Arduino Template Library | Zalt Z80 Computer
Wrong code should not compile!
 
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