Electronic components question

[-=Rudy=-]

Maybe someone who's good with a soldering iron and a schematic can help me here. ;) It is only 21 years since my last electronics class.

I'm repairing a dbx model 1DS single-band compressor/expander. It was literally a steal on eBay--it has two bad potentiometers, but was dirt cheap. The two bad potentiometers are for impact restoration level, and ambiance level. Someone had already tried to replace one of them, but used a wrong value (by an order of magnitude).

I'm confused over linear taper vs. audio (logarithmic) taper. Not knowing which one to use in this circuit is frustrating--they're not strictly "volume" controls, so I would almost think that a linear taper might be better (especially if it's controlling a voltage that, in turn, controls gain on a circuit).

On the potentiometers, as well as in the schematic, the values are suffixed with a "B". So one says 5kB, and the other is 10kB. I'm wondering if this is some kind of callout for either linear or audio taper, or maybe some other kind of taper.

On one website, I saw a parts catalog that listed a taper as "B Linear", and on another, "BZ Linear".

Gut instinct says they are linear taper.

Anyone know for sure?

[VU Master]

You can find out by checking the good pot with an ohm meter.
First, disconnect the pot, and measure resistance between the two outer terminals. The reading you get will be the total resistance of the pot.

Then, set the pot's shaft to it's midway (12 o'clock) position and measure the resistance between the middle and left terminals (as viewed from the front of the pot, with the terminals pointing down).

If the second resistance is 50% of the total resistance of the pot, it's linear taper. If it's 10%, the pot is audio (aka logrithmic) taper.

If it's 90%, the pot is reverse audio (aka anti-logrithmic) taper, a type of pot sometimes used in gain control and EQ circuits.

[-=Rudy=-]

I think I can do that on the 5k...I'd have to unsolder it first. The other one no longer has a shaft in it. :D (Someone turned it too far and snapped it off...probably because they'd replaced the original 10k with a 100k.)

I don't know what is wrong with the 5k, just that the person I bought it from said it was bad. (It may just be noisy/dirty--if that's the case, I have an industrial contact cleaner that will take care of it.) I could unsolder one of the good ones if I had to. The schematic shows all four to be the same "B" type, just different values.

You'd just think there would be some kind of common nomenclature on these pots.

Thanks!