What makes a good pot?

Everyone seems to talk badly about alpha pots, but never seems to give any reasons other than saying they're "cheap". I've used alpha pots in just about every DIY project I've built, and I think they're great. They feel better than any Bourns conductive pastic pot (which many people consider to be "good" pots) and have better tolerances too. The tolerances for Bourns Conductive Plastic = 20%, Alpha Carbon = 10%. So tolerances can't be it. Carbon drifts you say? Well it would still have to drift 10% more to be as bad/good as the Bourns.

So what's the reasoning? I love the alpha pots. They have a nice feel and they don't show any signs of crapping out any time soon. Anyone?
Please tell me it's not just because they're "cheap".

I use alphas in stomp boxes. I dont like the feel of them at all, but thats a totally personal thing. I compared them a long time ago to PEC carbon pots (which are what, 8 times the price, just like the bourns) and thought they sounded better in the pre I had them in.

lately Ive been using the clarostat 308 series plastic pots with 1/8 shafts. Digikey has them for around $10 but for some reason they are only in the $4 range from allied, which is awesome, I think they sound really good and they feel really really nice.

dave

talk to CJ... he was just telling me about his *special* cookies

Yeah man. You should pick up an issue of High Times to find that out.

Dang it Steve!
Can you spell FBI?
How about CIA?
:twisted:

:razz: :razz: :razz: :razz:

How many did you want? :grin:

Ethan, fork out for some Alps plastic.

No, don't do that. You will end up pot poor. Just like me!

You won't have a pot to piss in! :razz:

What makes a good pot(entiometer)?

Two words: mil-spec

Although trying to find mil-spec log in some values can be rather challenging. :sad:

The difference between low- and high-grade potentiometers is mainly a matter of how long it will last under what kind of conditions.

I have found that the Taiwan-Alpha carbon pots has very good life expectancy for audio circuits - that is IF you don't expose them to DC current. This means that if you have a leaky electrolytics (or stray opamp bias currents) in your circuit, they will get scratchy long before a high-quality conductive-plastic pot. But use them wisely, and they behave well for a long time.

Oh, and yes, the feel of these is much better than just about any high quality type. Let's not underestimate that factor.

Jakob E.

interesting thread
I have all the pots (rev log etc...) for the Calrec EQ in both conductive plastic AND carbon

Both are OMEG - but I much prefer the feel of the metal spindled Carbon pots than the Platic ones
The metal ones have more mechanical resitance - a sort of "he man" turn to them....
Still can;t decide which way to go

I like the "feel" of the Alps pots - doesn't matter if they are cheap or expensive.

The expensive ones are good, and last for a long time. I don't know how well the cheap ones hold up.

Best regards,

Mikkel C. Simonsen

I think the "feel" of the pot is due more to the thick grease they put on the shaft and bushing during assembly. This can quickly be destroyed as mentioned in another thread by careless use of contact cleaner sprays.

fluffiness, light green color with no seeds. thats what i like.

One thing I learned the hard way was how seriously to take Alps' specs on maximum power dissipation.

In a tube design that was mostly d.c. coupled I had a big Alps part for level adjustment. There was a d.c. servo around that circuit section so there would be essentially no wiper current (this level adjustment was mostly to be a set-it and forget-it one anyway). I had relays clamping various points in the circuit but there was a momentary surge through the pot on turn-on that eventually burned it up. I was blithely assuming that the physical size of the thing translated into at least a few-watt kind of rating, but the actual datasheet revealed anything but.

At least it was just a prototype!

Ethan, you won't hear me dissing the Alphas--at least not the full-sized chassis-mount models, which I use quite often. There's a number of Alphas I've used in guitar amps and other projects which are still going strong over ten years later. I like 'em and the price is right.

Yeah, I should add the qualifier that I've never used the Alphas in an application where there was a significant DC offset across the pot. They've worked well for me in AC-coupled circuits.

this is stuff that I have been thinking about for some time. Years ago I was talking to some people that worked on there own guitars. Pots came up it the weird thing is a "bad" pot can make a guitar or bass sound like crap. The allparts, dimarizo and CTS stuff seems to be some of the best for guitars and basses

You can measure the resistance and taper and the "bad" ones measure close to the "good" ones. The best I can fingure is it might be the terminal to wiper and carbon trace crimp connection.

I have been wondering if it is a diode effect at the interface or somekind of interface problem. I also wonder if it is linked to the number of wipers on the wiper some of the better pots have five contact points for the wiper to carbon.

Has anyone else noted this?

Gus does it sound like odd-order distortion? It would be plausible that one could have a high voltage coefficient in the vicinity of the wiper interface.

You could get diode-like effects if the beryllium-copper wiper started to get oxidized, as copper oxide is a semiconductor---used in power rectifiers that even predate selenium I believe.

It is hard to explain. The best I remember it sounded like hearing less detail of the guitars strings and body. Not a distortion sound. I think I saved some of the pots I changed in some guitars, I will look for them.