Pots and other crockery

Buzz Fretboard · #1 03-13-2002, 06:40 PM

Live from the UK, it's Buzz Fretboard with yet another fascinating question which only the good folks at TalkBass.com can answer!

Got a bass that I'm refurbishing. The electronics are, in a word, missing. So I'm thinking to myself "Self...why is it I can get a 500k pot for cheap at the corner electronics shop, but from some guitar supply shops they're 5 times as much?"

Then it occurred to me: if there's a difference in price, is there a difference in construction, or tolerance, etc in what I can get at Radio Shack vs what I can get from, say, Warmoth?

You have no idea how much I look forward to hearing from you all.

rllefebv · #2 03-13-2002, 10:27 PM

I know that there can be intended differences in the 'taper' of a pot for apparently different applications... The amount the volume changes when you turn it for instance... I've seen 'audio' taper, (where 5 is 'perceived' to be half as loud as 10), and 'linear' taper, (where the resistance at 5 is half of the total, with 0 being full resistance and 10 being almost zero)... I am sure that someone will be along shortly to correct any misconceptions with what I laid out above. This is just my limited, and probably faulty, understanding of the issue...

That being said, I can never find 500 or 250 pots at Radio Shack anymore... just 50, 100, 5K and 10K. I always buy 'em from Stewart MacDonald ! That way, I know I'm getting the right stuff

-robert

#3 03-13-2002, 11:44 PM

rllefebv: You are correct in your tapers. Audio taper is also known as a "logrithmic" taper. Unfortunately the pots Radio Shack carries are all "linear" taper now and therefore unsuitable for any audio volume controlling work. A good replacement is to go to any TV repair shop and find one from a parted out tube radio that's in decent condition. A squirt of WD-40 and away you go.

No, that's not as good as a new one, but given the option of 40 cents or 40 dollars, it is a practical way to go until a better fix is warranted.

Buzz: That drives me nuts too. The price that is. In front of me right now are two 1 Meg audio taper pots, both have been extremely reliable and quiet in my systems. One cost me $1.39 new at a HAM fest and the other is a scavenged military TRW part listed at $229, EACH! Both are the same size. The only difference is the TRW is guaranteed quiet and reliable for 1,000,000+ turns. I think my bass will be long dead or in my great, great, great grandkids care before it will wear out.

Price ain't everythin'

merlin · #4 03-14-2002, 03:34 AM

Some manufactuers, like Washburn (

don't get me started been through 5 different pots and its still the wrong one they send), they have their pots especially made. Aka the thread may be longer on this bass pot or such and such maybe a different resistance.

The different resistance is ok, try to get close to it or slightly lower maybe.

If you can find it at Radio Shack, then buy it. Pots are only resistors. Nothing too special about them in the long run.

Merls

pkr2 · #5 03-14-2002, 08:37 AM

Quote:

Originally posted by merlin
Some manufactuers, like Washburn ( don't get me started been through 5 different pots and its still the wrong one they send), they have their pots especially made. Aka the thread may be longer on this bass pot or such and such maybe a different resistance.

The different resistance is ok, try to get close to it or slightly lower maybe.

If you can find it at Radio Shack, then buy it. Pots are only resistors. Nothing too special about them in the long run.

Merls

A couple or three points that you may want to rethink in your response, Merl.

You are correct, they are only resistors, however the specs can make a noticeable difference either in longevity or performance between different pots.

A tone control is an R/C circuit. If the capacitor or the resistor is changed in value there will be a corresponding difference in the tone of the instrument.

A volume control is wired in as a potentiometer circuit. A change in value of the pot is seen as a change in maximum output from the pup. Lower value means lower output at the jack. Higher value and the circuit could be more prone to noise because of the higher impedence to ground. Much as a high impedence mike is more noise prone than its low impedence counterpart. More likely to be a problem if you go very high in resistance.

Unless one is experimenting, it's probably better to stick with the stock values.

The quality of pots can vary widely.

As C.R. mentioned, If you are lucky enough to locate military surplus pots, you have hit the jackpot. In fact any electronic part that is stamped "mil spec" is likely to be of higher quality than its garden variety equivelant.

As you said, a resistor is a resistor. Maufacturing and material specs can make a big difference though. There are many variables such as the thickness and stability of the substrate that the carbon is deposited upon, the tension, material and degree of polishing of the wiper arm, the thickness of the carbon film and the abrasiveness of the carbon material.

A pot is easily disassembled and reassembled for part replacement. I suggest that you simply put the resistive element and wiper arm from the pot that Washburn sends you into the original pot shell. Just be careful that you don't break off the little foldover ears that hold the assembly together.

Sorry if all of this is more than anyone wants to know about pots.

Pkr2

Hambone · #6 03-14-2002, 10:30 AM

Buying from Radio Shack stores is a total loosing proposition but if you look at the Radio Shack website, you can find a LOT more components that won't ever see the inside of the store. A word of warning however - Be very sure of what you are looking for. Even though the site has photos of the products, you MUST be able to read the specs to compare.