PEC Pots

[Blackburn]

Is it just me, or do these pots get dirty far too easily in a sealed container? I'm wondering if they just come from the manufacturer a bit dirty. I have more than a few that have never been opened in a few amps built a while back and they are scratching pretty bad now. I'm sure the caps are good, they're relatively new Sozos. I'm wondering if you guys think it would be a good idea just to open them all up and spray them when getting them in as new, since it's a PITA for me to remove them after installation. Anyone else had this happen with PECs? I don't think I've heated them excessively with the iron and I don't know what else could put the fault on me. Any ideas?

David

[M Fowler]

I only have PEC pots in a few amps and quit using them after having problems of cutting out and noise. I haven't had that problem with CTS or Alpha and they are less expensive.

Mark

[ToneMerc]

Scroll down to the pot question, see UPDATE

http://www.aikenamps.com/TI_Aiken_Q&A.html

TM

[Blackburn]

Good to know, Mark. It seems I'm not the only one.

And here's the link TM mentioned from the Aiken site, which also substantiates my findings. Thanks, TM.

Q: What kind of potentiometers do you recommend?
A: I prefer to use sealed RV4 mil-style 2W potentiometers. They are available in both hot-molded carbon and conductive plastic elements. I originally used the conductive plastic Clarostat units, but their inconsistent torque and feel caused me to switch to the hot-molded carbon types from PEC, which I now use exclusively. They are extremely well-built units, even better looking than the Clarostat, but more expensive. These RV4 type pots are more expensive than other types, but their sealed construction, reliability, and precision feel makes them worth the extra cost. UPDATE: I have to admit I was wrong on this issue. After having quite a few amps in the field for going on 12 years now, I am starting to see a few complaints of noisy pots from people who own my amps. Normally, I would just tell them to open the amp up and spray some contact cleaner in the pots. Unfortunately, you can't do this with a sealed pot, so you have no choice but to replace the pot. No pots are going to last forever, so you may as well use a cheaper pot like the Alpha, that can be cleaned or replaced for a fraction of the cost of one PEC pot. The Alphas have a nice smooth torque feel to them.

[dartanion]

I stopped using them after getting a bulk order where over 50% were rejects. Every single 1M audio that I order was a dud, the 250k and 500k were about half duds, and the 5k just under half. Sent them all back. I was a bit pissed off, but nice to know that the Alphas at less than a 1/4 of the cost work better.

By dud, I mean no continuity!! Totally dead.

[Blackburn]

I've been using Alphas lately and I guess I'll be switching to those permanently. For cost and reliability, sometimes cheaper is better. Anyone prefer CTS to Alpha?

[Andy Le Blanc]

those mil. rv4 have a carbon contact that wears down, it literally gets "dusty", that contact noise, its pencil dust ...
better off going with a pot thats cheaper than the time spent trying to clean one.

Sometime I think the CTS feel better than the Alphas, but I've used both and ain't too picky

real pisser getting bulk thats half bad right out of the box

[Blackburn]

real pisser getting bulk thats half bad right out of the box

Yeah. Far too many reports of funkiness with PECs to justify the cost. The amps in which I've had issues with them have only been alive for a little under a couple years. I've never had any problem with an Alpha and I do happen to like the feel of the rotation. And of course, easy to clean. Take up less area too.

[Firestorm]

I've been using Alphas lately and I guess I'll be switching to those permanently. For cost and reliability, sometimes cheaper is better. Anyone prefer CTS to Alpha?

I find I do a lot of pot disassembling/reassembling (to replace resistance tracks in vintage pots or to change them in dual-gangs, concentrics, etc. ) For that, CTS is the only way to go. But for just sticking a pot in and wiring it up, I do like the Alphas.

Anyone have experience with the equivalent Bourns pots?

[M Fowler]

The Bourns pots are like the Alpha and CTS but rotation is stiffer so I haven't used them much anymore. I didn't have any problems with them though.

Apexjr has a good choice of Bourns 3/8" shaft pots they match the Mojo CTS/Alpha pots in size and shaft thread length.

[Leo_Gnardo]

those mil. rv4 have a carbon contact that wears down, it literally gets "dusty", that contact noise, its pencil dust ...

I have, on rare occasion, been able to revive some of these Ohmite or similar sealed pots by prying off the cover, carefully cleaning the track and wiper contact with super fine sandpaper (1200-2000 grit), then a short shot of Caig F-5 (previously Cramolin) and reassemble. Sometimes even a well worn wah pot has responded well to this treatment. OTOH in the time I've spent fiddling around with it, could just as soon replace with a new one. I suppose it may be worth a try for sealed pots with rare values.

[Firestorm]

those mil. rv4 have a carbon contact that wears down, it literally gets "dusty", that contact noise, its pencil dust ...

I have, on rare occasion, been able to revive some of these Ohmite or similar sealed pots by prying off the cover, carefully cleaning the track and wiper contact with super fine sandpaper (1200-2000 grit), then a short shot of Caig F-5 (previously Cramolin) and reassemble. Sometimes even a well worn wah pot has responded well to this treatment. OTOH in the time I've spent fiddling around with it, could just as soon replace with a new one. I suppose it may be worth a try for sealed pots with rare values.

PITA isn't it? I really only go that far if I'm trying to preserve an original pot in, say, a '54 something. Good idea on the wah pots, tho, as you can't always get new ones that sound that same.

[Cantplay]

In the audiophile world there are many builders whi are convinced that the PEC sound better.

John

[pablogt]

I have used PEC in most of my amps with no problems. All my amps are less that three years old so that does not tell you much. What I do notice a lot is that PECs approximate much closer a logarithmic scale that Alphas. PEC gives you about 10% resistance at noon, while Alphas give you about 35%, Since I tend to use my amps with all controls except gain at noon, and adjust voicing in that setting, changing pots can have a big impact on the amps sound. Particularly if you are building a clone!.

P.

[martin manning]

PEC gives you about 10% resistance at noon, while Alphas give you about 35%.

Hmm... this has not been my experience. I find audio taper pots from both manufacturers to be ~10% of the max resistance at mid-rotation.