Metropoulos Forum

I've built three Metros so far, each one utilizing a different brand of potentiometers. I'm gearing up for some more builds, and would love to hear which brands you guys prefer, and why? I want the one which is closest to vintage Marshall specs as far as composition and taper...which one is it, in your opinion?

I have some viewpoints on each of these brands, but I'll save it for a little later...I haven't tried to swap brands in the same amp though, so it's not really a fair comparison. I'd love to hear from those of you who have tried different brands in the same amp.

Other than PCB mounted, I've never tried Alpha's in amps, but have used several in guitars. My opinion is they they don't feel very nice, or last all that long compared to the CTS and PEC's. They've ended up scratchy in only a few years in both guitars, and in my horizontal input 4104 (in fact three of the pots in there now are CTS chassis mounts that I've bent the lugs on and soldered solid core wire through to the board) Function is more important to me than historical accuracy.
The PEC's are very sexy, but the grounding issue might be a large one for some people. They certainly don't look the part, but I'm not worried about looks.
CTS look good, feel good and seem to last really well in my experience, but if I'm going for all out quality, I'll continue to use the PEC's. I can't hear a difference, and I can't prove they're actually any better, but big pots without the buss bar sure look cool to me! How sad is that!

The CTS pots have seemed to get stiffer the last couple years.
As in hard to turn, in a guitar I prefer an easy turning pot.
There also seems to be several different kinds of CTS.
Like nylon shaft and brass.
There seems to be two different type of cans on them as well.

I have used the Alphas in several amps and haven't had any problems so far.

The PEC's that I have used are nice, they are sealed so they last a long time.
They have stainless steel cans so you can't solder to them but you can get a ground lug that goes on the bushing and run your buss through that or just hang it off the terminals at top.

A local store I go to has them usually for $10 each but only seem to carry the linear ones.

The grounding thing is not an issue for me, as I no longer build amps with a ground buss. I prefer individual star grounds for each stage of the amp (i.e. "Larry"-style grounding).

Has anyone actually tried different brands in the same amp and found a difference, sound-wise? If they are made using different composites (compare carbon comp vs carbon film vs metal film resistors), then presumably they would also sound slightly different. Then there's the taper... IIRC, George said a couple of years back that he was hoping to have "metro-speced" pots made specifically from tear-downs of original pots used in Plexi Marshalls, to clone both the composition and taper. Whatever came of that?

I like the feel of the Alphas, but some report having issues. CTS are fine. The PEC feel a little too loose for me but their quality is super! I've also used CGE pots and found them to feel and work just fine.

Personally, I would use PEC if cost is not an issue. Otherwise the CGE have worked well for me.

Ive done 4 amps with alpha's, the first in
Jan 05 and still no probs at all.

Jimmy

Alphas seem pretty reliable to me.

My preferences are for the Clarostat or PEC 2W types though.

I'm using Alphas in all my amps and Marshall rebuilds since 1995 - and these were many, but not only one prob yet!
I've used CTS in most of my Fender rebuilds, but some people claimed after a while, that the pots are turning too strong and seem to stick in its position, if it wasn't used over a longer time.
And I've built only one DINO with PEC's as an exception by customer's advice, but couldn't get the same warmth out of this amps as opposed to DINO's supplied with Alpha's...
... and the reason is quite simple! The Alpha's do have a taper of CC, the PEC's of conductive plastic.

Moreover I didn't like the turning feel of the PEC's, what was nearly like there's a grinding paper inside between the wiper and the taper - far not as smooth as the Alpha's. And I don't like the positions of the solder lugs on the PEC's, don't like the too long bushing and the too long shaft.

Larry

I tried using CTS pots. I prefer Alpha they are cheaper and to me feel better.

Someone told me and I can't remember if it was here or elsewhere, that CTS makes a large number of custom pots for various vendors. In other words they are built to specs.
They can vary the tolerance between the bushing and shaft as well as the grease inside, so that sometimes you might buy some from one dealer and they feel stiff and buy some from another dealer and have those feel almost loose by comparison.

I know the last two CTS pots I bought for my Telecaster project were from Allparts and they almost turn themselves they are so loose feeling.
So I guess it isn't fair to say, all CTS pots are this way or that way.

I have a small electronics store in my town and they have a rack of PEC pots but they are all linear taper.
But the few I have bought there seemed very high quality and they are in fact a sealed potentiometer. So most likely you wouldn't be able to squirt any contact cleaner in them to fix a scratchy pot, which for the most part is usually a band-aid approach to a worn pot.

The amp I built used all Alpha pots and they seem fine. Plus you can solder on the cases.

Thanks for all the responses!

Larry, your observations are most interesting. I built my JTM45/100 with PECs, and while the amp is very, very quiet and the pots are no doubt high quality, I can't get exactly the same sweetness out of it as my JTM45 with Alphas. Different amps, for sure, but all the other preamp parts are the same. Even with the PEC's reputation for high quality, I have some intermittent trouble with one of the volume pots. I'll swap them all to Alphas and see what that does with the tone.

Does anyone know what original Plexis had for pots? Were they carbon comp tapers or different? And what are the CTS ones?

I was just checking out PEC's website, the RV4 have a carbon element
http://www.precisionelectronics.com/Mil ... 0Specs.htm

The Clarostat RV4 are the ones with the conductive plastic, like the ones you can get from West Lab. http://westlabs.com/Frames.HTML BTW these are the same pots that are used in the Soldano SLO100 and Komet 60 amp.

The PEC RV4 in carbon are available with the correct shaft lenght from CE Distribution http://www.cedist.com and Antique Electronics http://www.tubesandmore.com/

shakti wrote: Even with the PEC's reputation for high quality, I have some intermittent trouble with one of the volume pots.

If you cut off the shaft then that is the problem. I use to do that as well and I was having multiple pots getting scratchy and cutting in/out. I decided to call PEC directly about this. Basically once you cut the SS shaft you've damaged the pot. You can get them in the correct shaft length from Antique Supply http://www.tubesandmore.com/ or order them directly from PEC in 100 piece quantities

2308to wrote:

shakti wrote: Even with the PEC's reputation for high quality, I have some intermittent trouble with one of the volume pots.

If you cut off the shaft then that is the problem. I use to do that as well and I was having multiple pots getting scratchy and cutting in/out. I decided to call PEC directly about this. Basically once you cut the SS shaft you've damaged the pot.

Yikes I must be lucky, few year ago I cut down the shafts of some PEC's with no problems...yet.

Wonder how they get damaged, did they say?

Structo wrote: The amp I built used all Alpha pots and they seem fine. Plus you can solder on the cases.

Try as I might I've never had an Alpha that took solder well on the case. Are you sanding them?