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Post by plinker on Mar 11, 2023 17:59:35 GMT -6
How do potentiometers get dirty? I've always assumed that dust migrates into them, but is that really the way it works? If so, whey aren't they sealed better?
My place is old and dusty. Should I be covering my gear?
Thanks!
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Post by keymod on Mar 12, 2023 12:55:03 GMT -6
Svart.....
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Post by plinker on Mar 12, 2023 19:37:32 GMT -6
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Post by the other mark williams on Mar 13, 2023 10:52:57 GMT -6
You’ll probably need to tag svart to make sure he sees the thread… |
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Post by svart on Mar 13, 2023 13:54:05 GMT -6
How do potentiometers get dirty? I've always assumed that dust migrates into them, but is that really the way it works? If so, whey aren't they sealed better?
My place is old and dusty. Should I be covering my gear?
Thanks!
Well, I guess a few different ways. One is the grossest imaginable.. A lot of that "dust" might be skin cells that migrate down into the pot.. Some of that dust is worn track material that gets stuck in the lube. Some of it is dust that's gotten into the pot through holes and poor junctions. Unfortunately, the grease that lubes also holds the dust. Some pots are indeed sealed. Most are not. Not really sure anymore if manufacturers intend for you to do any maintenance on them, but in the past there was some expectation that folks would clean/lube them occasionally. Sealed pots can't be re-lubed very easily, so they're one-time usage. My guess is that manufacturers have a life expectancy (time, not rotations) on their pots and by the time they're dirty they might be at the end of their life expectancies anyway. One theory that I've never bothered to look into is that electronic fields might induce enough static to attract more dust than areas around them. I've seen the insides of electronics that seem to have 4x more dust than the surrounding areas, almost as if it had attracted it. Seems to possibly be why bugs like roaches like the insides of electronics too. There are pot sealing covers that can slip over the backs of the pots that might help. www.tubesandmore.com/products/dust-cover-plastic-covering-16mm-potentiometers-clearHowever, a lot of "dirty pot" problems are not actually dirty pots. They're damaged tracks from excessive DC through the tracks which cause a scratchy sound when turned. Usually a sign of a leaky series capacitor or drifting DC offset somewhere. |
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Post by EmRR on Mar 13, 2023 16:23:22 GMT -6
There's definitely a mechanical quality factor that's hard to quantify. I've seen a lot of 70-80 year old pots on filthy barn equipment that were fine. Seems so unlikely, but sometimes you crack one open to see how it's made, and it's total old school overkill on the mechanicals. You might get an idea reading between the lines on rotational life...or not.
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ericn
Temp
Balance Engineer
Posts: 16,107 
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Post by ericn on Mar 13, 2023 16:35:45 GMT -6
There's definitely a mechanical quality factor that's hard to quantify. I've seen a lot of 70-80 year old pots on filthy barn equipment that were fine. Seems so unlikely, but sometimes you crack one open to see how it's made, and it's total old school overkill on the mechanicals. You might get an idea reading between the lines on rotational life...or not. Yeah I think the modern dust issue is as much about how we build things today and the modern materials used as anything. I mean think about it, in the grand old days every studio smelled like an ashtray, yet the pots on an old Altec are probably going to be less noisy than a new Behringer! |
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Deleted
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Post by Deleted on Mar 13, 2023 17:00:47 GMT -6
There's definitely a mechanical quality factor that's hard to quantify. I've seen a lot of 70-80 year old pots on filthy barn equipment that were fine. Seems so unlikely, but sometimes you crack one open to see how it's made, and it's total old school overkill on the mechanicals. You might get an idea reading between the lines on rotational life...or not. Those Alps parts aren't sturdy at all. Bournes are sturdier ime but don't stereo track as well. Switches and binned resistor ladders are better but way more money. Digital encoders might be the future but good luck with self repair. You better had hope the manufacturer of your digitally controlled analog gear is Empirical Labs, FMR, or maybe Better Maker! I like the Apogee and RME digital knobs better soundwise with an additional dither than any hifi pre or monitor controller but they won't be repairable in 50 years! |
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Post by plinker on Mar 13, 2023 17:05:45 GMT -6
How do potentiometers get dirty? I've always assumed that dust migrates into them, but is that really the way it works? If so, whey aren't they sealed better?
My place is old and dusty. Should I be covering my gear?
Thanks!
Well, I guess a few different ways. One is the grossest imaginable.. A lot of that "dust" might be skin cells that migrate down into the pot.. Some of that dust is worn track material that gets stuck in the lube. Some of it is dust that's gotten into the pot through holes and poor junctions. Unfortunately, the grease that lubes also holds the dust. Some pots are indeed sealed. Most are not. Not really sure anymore if manufacturers intend for you to do any maintenance on them, but in the past there was some expectation that folks would clean/lube them occasionally. Sealed pots can't be re-lubed very easily, so they're one-time usage. My guess is that manufacturers have a life expectancy (time, not rotations) on their pots and by the time they're dirty they might be at the end of their life expectancies anyway. One theory that I've never bothered to look into is that electronic fields might induce enough static to attract more dust than areas around them. I've seen the insides of electronics that seem to have 4x more dust than the surrounding areas, almost as if it had attracted it. Seems to possibly be why bugs like roaches like the insides of electronics too. There are pot sealing covers that can slip over the backs of the pots that might help. www.tubesandmore.com/products/dust-cover-plastic-covering-16mm-potentiometers-clearHowever, a lot of "dirty pot" problems are not actually dirty pots. They're damaged tracks from excessive DC through the tracks which cause a scratchy sound when turned. Usually a sign of a leaky series capacitor or drifting DC offset somewhere. Great info! Thanks!!
Interesting concept about the electronic fields. I've seen this on my own outlets that have wall-warts in them for years -- usually behind a piece of furniture. There's usually discoloration on the faceplate from all the dust/dirt that's settled around the wart.
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ericn
Temp
Balance Engineer
Posts: 16,107
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Post by ericn on Mar 13, 2023 17:32:58 GMT -6
There's definitely a mechanical quality factor that's hard to quantify. I've seen a lot of 70-80 year old pots on filthy barn equipment that were fine. Seems so unlikely, but sometimes you crack one open to see how it's made, and it's total old school overkill on the mechanicals. You might get an idea reading between the lines on rotational life...or not. Those Alps parts aren't sturdy at all. Bournes are sturdier ime but don't stereo track as well. Switches and binned resistor ladders are better but way more money. Digital encoders might be the future but good luck with self repair. You better had hope the manufacturer of your digitally controlled analog gear is Empirical Labs, FMR, or maybe Better Maker! I like the Apogee and RME digital knobs better soundwise with an additional dither than any hifi pre or monitor controller but they won't be repairable in 50 years! I don’t completely disagree but, as we pointed out when discussing digital faders making broad statements about ALPS is dangerous because they do have a much deeper catalogue than anyone else. Funny enough the one pot I have had the most issues with noise is one of their very highend sealed rotary’s in a Conrad Johnson Stereo preamp. Replaced it with the equivalent P&G years ago no problems, except in the crazy world of High End Consumer HIFI my expensive “mod” devalued it, they think Alps is better than P&G! Oh yeah did you know P&G makes the control boards for a bunch of mid priced powered wheelchairs? I’m thinking of getting a custom decal for a friends chair that says his other chair is a NEVE! |
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Post by keymod on Mar 14, 2023 4:30:46 GMT -6
I read somewhere that it ( may ) be possible to restore a sealed pot by carefully drilling a tiny hole to then be able to inject Deoxit, or similar. Anyone ever try that ?
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Post by svart on Mar 14, 2023 7:55:36 GMT -6
I read somewhere that it ( may ) be possible to restore a sealed pot by carefully drilling a tiny hole to then be able to inject Deoxit, or similar. Anyone ever try that ? That would be risky. At least some of the drill shavings would be on the inside of the hole and impossible to get out. |
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Post by christopher on Mar 14, 2023 19:03:05 GMT -6
I just got some keyboard slime. I tried it on one thing and will see if it doesn’t damage it. It worked really well getting the dust between the knobs and switches. I’ll need a lot more though. If I don’t report back, assume it did no damage. My kids used to make slime I’ll just have them follow the recipe.
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