Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tone Junkie on October 04, 2011, 02:00:05 pm
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Sorry to put this here but in the past someone had posted a good link to some good quality pots i cant find it. Its in my last computer that crashed a while back, damn machine
Thanks Bill b b :BangHead:
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Webber speakers has them. 25K/50K locking pots. Small size, low cost. Bought some, have'nt used one yet , but they look/feel pretty good.
Brad :icon_biggrin:
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I've used the Weber locking pots with success, but if you'd like some other options, here's a digikey part number for a PEC 25K locking pot:
RV4L253C-ND
Probably better quality than the weber offering.
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I too have used those small Weber pots with success. But I always felt they were cheap somehow, not that they ever failed me yet.
In the past I had modified full sized CTS and Alpha pots by marking the shaft with a scribe and disassembling them so I could cut the shaft just below the scribe mark. I would dremmel a slot in the shafts end and reassemble them.
I then felt that somehow my monkeying might compromise the pots, until I read a recent post by Doug stating the same technique.
Those tiny locking pots need a tiny screwdriver and are easy to slip out of. The modified CTS pots have a lip created by the pot barrel and a larger screwdriver is prevented from slipping around.
Besides that, between Alpha and CTS you have a pretty big variety of values to choose from too.
Just offering another avenue to pursue.
OH!
After the Bias is set, a dab of nail polish on the shaft adds a bit of hold to prevent accidental adjustment and gives a nice tell tale if someone does try adjusting the bias.
Ray
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Thanks guys i like the Weber 2watt conductive plastic . But I hate how long it takes to get things from them.
Ray thanks for the nail polish trick never thought of that
Bill
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PEC - digikey..
25K part.
http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=RV4LAYSA253A (http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=RV4LAYSA253A)
50K part.
http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=RV4LAYSA503A (http://search.digikey.com/scripts/DkSearch/dksus.dll?vendor=0&keywords=RV4LAYSA503A)
--DL
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I have some of the ones DummyLoad linked to. I have them in 4 of my amps and they are great and look and feel practically indestructible. That was until Doug told me about cutting them. I will never pay $9 plus shipping again since Doug told me this. I couldn't believe I never thought of it. I used a ziz wheel or wizz wheel, whatever you want to call it. Cut the shaft about 1/16 below the edge of the hole on the pot. I cut 4 slots down through the threads. Mounted it and then squeezed another nut just a little making the opening squeeze on the shaft to get resistance so it will not turn unless I loosen it a bit. Opened up a whole new world of options for pot values for bias. The coolest thing is I did not have to wait for anything or weed through mouser or digikey's website. I would have to say it is one of the best suggestions I have been given in a while. :worthy1: :worthy1: :worthy1: :worthy1:
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I always use mutiturn cernet potenetiometer. Their 10 turn won't change by itself and they are low cost
http://www.futurlec.com/PotRect.shtml (http://www.futurlec.com/PotRect.shtml)
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I like the reguler style potentiometers with the locking nut because then I can put them through the bottom side not to far from the tubes so I can change the bias without pulling it totally from the head or amp Im lazy. :l2: