Old MIXER

[rosa]

I am repairing an old mixer and it uses 5meg pot for the volume control of each channel. Would a 2 meg pot work instead? Also, how can I be certain that these are logarithmic pots and not linear?


thanks

 

[Rleo6965]

Try using 2meg pot. If not satisfied with sound result. Series 3meg resistor to 2 meg pot.
You can try these combination 3m then the pot or 1.5m - pot- 1.5m or pot - 3 m. depends of volume you of preamp you need.

Also, how can I be certain that these are logarithmic pots and not linear?

Buy 2 meg pot with same for letter written on original pot body. ( A or B)

 

[davenn]

Try using 2meg pot. If not satisfied with sound result. Series 3meg resistor to 2 meg pot.
You can try these combination 3m then the pot or 1.5m - pot- 1.5m or pot - 3 m. depends of volume you of preamp you need.

Buy 2 meg pot with same for letter written on original pot body. ( A or B)

and failing that mesure it with a multimeter in resistance mode.
a log pot will change in reading quickly as you turn the shaft, a linear one will change in value "evenly" as you trun the shaft

Dave

 

[rosa]

cool, thanks

 

[rosa]

If a pot in the half way position gives half the resistance value of its total 50k resistance, can I assume it is linear?

 

[Rleo6965]

Probably. But it's much better if you take the advice of Davenn . Connect your multimeter probe to terminals of potentiometer and observe multimeter reading corresponding to the shaft movement. This more accurate to determine correct type of pot.

 

[(*steve*)]

If a pot in the half way position gives half the resistance value of its total 50k resistance, can I assume it is linear?

Almost certainly.

In fact that was what I was going to suggest earlier, but I noticed you already had plenty of suggestions and I didn't think it was worth adding to any possible confusion.

edit: there are some really weird tapers that may exhibit this, but be non-linear either side of it, however the chance of finding one of these is pretty unlikely. davenn's suggestion is a generalisation that will work, but you do have to know what you're looking for. Confirming it's linear or not is the easiest option though.

 

[Rleo6965]

I think most Linear pot was use for volume control and balance control for audio equipment. Non-linear is for Tone control? or the other way around?

 

[(*steve*)]

Log pots are typically used for volume controls.

 

[Raven Luni]

Log pots are typically used for volume controls.

I discovered that when I put linear pots in my bass guitar - now I have a tiny useful zone

 

[rosa]

two more questions

It seems that they are linear.

how are audio or logarithmic potentiometers built to achieve their function? physically, what is the difference with the linear pot.

also, I have disassembled the pots, cleaned and reassembled. they are well built so it was easy to do. Is it OK to apply a dab of mineral oil. Can anyone recommend something to lubricate them? I have read answers to this in other forums, but there seems to be a confusion between cleaning and lubing.

thanks

 

[shiekh]

I have been know to use silicone oil, but I would avoid mineral.