CTS Pot issues

[p2pAmps]

Hey Gang,

So I do not post often but I thought this was a good topic for discussion.

I am very fortunate to be building quite a few amps these days.  That being said I buy a whole lot of parts and have lately notice something rather disturbing.  CTS pots have been failing me pretty regularly for some reason.  Now I've been using CTS for a good long time and always been fairly happy but lately not so much.  Things like bad tapers, or just plain low volume situations etc etc etc.  Just had 3 -1M in one day that were garbage.

Ok, so am I alone on this?  Tell me folks, is there a better choice out there?  I have used Alphas but they always seem kinda cheap to me and are stiff.  What about Bourne?  Looking for an alternative I can count on if that exist.

Cheers Ya'll

Mike

[tdvt]

I don't know about alternatives, but I spent the better part of 2 evenings chasing a buzz in a Hoffman AB763 build, that was eventually eliminated by replacing a brand new 1MA CTS pot in the volume position.

It had a sloppy feel, but was brand new so.....took a while to get there.

I did replace it with an Alpha, which seems fine, feels more substantial.

[DummyLoad]

I migrated to Bourns a few years back, mainly because the bushing length. I use .08-.09" Al chassis and when you add a faceplate, the threads on a .375 bushing are on the scarce side. I have had issues with CTS 1M but just the 1M Audio. The 500K A have not given me problems yet, but then again, I haven't ordered any in over a year. I may move to PEC exclusively, but 7-10bux a piece is a bitter pill to swallow. 


--Pete

[shooter]

I tried the Bourns,  guessing a bad lot, I bought 5, all 5 had issues, went back to alphas.  That said, haven't bought parts in about a year, judging from the "stuff" I have bought over the past year, quality took another step DOWN.

[66Strat]

It would be interesting to see the dissection of a failed pot to determine the cause of failure.

[DummyLoad]

You're likely doing this already? Maybe going forward you'd want to screen any pot before installing? If you're building enough amps, then perhaps you could create an arduino project that drives a small stepper to cycle the part some number of turns and re-test to weed out infant failure... If you don't install the part and you are procuring from a reputable supplier, that they would replace the failed part(s)?

--Pete

[p2pAmps]

You're likely doing this already? Maybe going forward you'd want to screen any pot before installing? If you're building enough amps, then perhaps you could create an arduino project that drives a small stepper to cycle the part some number of turns and re-test to weed out infant failure... If you don't install the part and you are procuring from a reputable supplier, that they would replace the failed part(s)?

--Pete

I hear ya but the goal is not to take even more time building as time is money when is business.  Yes I could test every part before installing but labor time would increase but labor costs would remain the same.  If I were building for myself time wouldn't matter too much.

I do want to add that it seems the CTS 1MA has been the majority of the failures so far.  I built over 100 amps in 2022 so thats a lot of pots haha...  Thanks Pete

Mike

[p2pAmps]

It would be interesting to see the dissection of a failed pot to determine the cause of failure.

Indeed it would be good to know/see the failure.  Problem is they do work just don't work well.  I do have some in my stock and the next failure I will pull one apart and peek inside. 

Cheers

[66Strat]

I built over 100 amps in 2022 so thats a lot of pots haha...  Thanks Pete

Mike

Congratulations on your success. It is certainly well deserved, as evidenced by the quality of your builds displayed on this forum.

[EL34]

Alpha pots are fine.
I never liked the plastic shafts on CTS pots

Just spray some cleaner with lubricant in the bushings if you want them to turn easier
Turning a bit harder is not a bad thing IMO

All the amps I built in the 90's had Alpha pots are are still going strong

https://hoffmanamps.com/MyStore/catalog/PotsKnobs.htm

[p2pAmps]

Alpha pots are fine.
I never liked the plastic shafts on CTS pots

Just spray some cleaner with lubricant in the bushings if you want them to turn easier
Turning a bit harder is not a bad thing IMO

All the amps I built in the 90's had Alpha pots are are still going strong

https://hoffmanamps.com/MyStore/catalog/PotsKnobs.htm

Yes Doug, I will certainly be headed in that direction.  Thanks for the input fellas

[EL34]

The only issues with the Alpha pots is that they are not available in the odd values like 50KRA and 3MRA
Other than that I stock all the common values found on amps.

[p2pAmps]

The only issues with the Alpha pots is that they are not available in the odd values like 50KRA and 3MRAOther than that I stock all the common values found on amps.

Thanks Doug.  Seems like the 1MA in the CTS is giving me the most headache.  It eats up too much time honestly.

Mike

[uki]

In 2018 i bough 2 CTS 1M and both were faulty.

There something about it in this thread.

So it isn't a new thing...