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Topic: Looking for pot(entiometers) |
Don Downes
From:
New Hampshire, USA
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Posted 2 Nov 2021 5:27 pm |
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I'm looking for two 125K pots. A .047uF mylar or polystyrene cap would be a bonus. (if you have a ceramic 047, that's ok, too)
Please email me if you have these lying around your shop. I'm not looking for freebies. I need these to get my MSA Vol/Tone controls working.
Thanks.
_________________
"The secret to a long life is to keep breathing." |
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Jack Stoner
From:
Kansas City, MO
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Posted 3 Nov 2021 2:21 am
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| Are you sure about the 125K pots? Most volume/tone control circuits use either 250K or 500K pots. Most that I find use a 500K with the .047 cap. |
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Don Downes
From:
New Hampshire, USA
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Posted 3 Nov 2021 7:27 am
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I know it sounds odd. But, I measured them and they are 125K. I heard from Mitch at MSA, and he says they haven't been available for years. I'm not as concerned about the resistance as the size. They're very small. I can work with a different pot if I can find a small one.
_________________
"The secret to a long life is to keep breathing." |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Don Downes
From:
New Hampshire, USA
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Posted 3 Nov 2021 8:13 am
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Thanks, Bill. I saw that last night. What I'm beginning to think is that the original pickup was replaced with a Wallace TT-10. The output of the p/u was wired directly to the output jack bypassing the V/T controls. Either the person who installed the Wallace didn't like the tone with the controls, or didn't know how to wire it in. Judging by everything else I see, it's likely the latter based on the soldering job. I think I'll do a little more research on V/T controls for a Wallace, and use that as a reference.
_________________
"The secret to a long life is to keep breathing." |
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Carl Gallagher
From:
New York, USA
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Posted 3 Nov 2021 8:29 am
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| Did you try wiring up the pots that are in there? |
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Don Downes
From:
New Hampshire, USA
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Posted 3 Nov 2021 9:06 am
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Some of the tabs on the pots are broken off. I've tried using solder wick to try and save them, but to no avail. I think I'm just going to get a 250K pot since the Wallace is a single coil. I'll recycle the cap. It's a good mylar.
But, size matters. 
It's all good.
_________________
"The secret to a long life is to keep breathing." |
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Bill A. Moore
From:
Silver City, New Mexico, USA
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Posted 3 Nov 2021 2:46 pm
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| Don, I suppose you could try the 250K, and if the sweep is wrong, drop a 250K resistor across the pot, and see if you like it better. |
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Don Downes
From:
New Hampshire, USA
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Posted 3 Nov 2021 3:12 pm
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That is a very clever idea that I never even considered. Well played Mr. Moore.
I am considering other options, such as increasing the pot to 250K (sans a parallel R). That will gave me a little bit more flexibility, especially with regard to the impedance of the circuit. Also I'm considering adding a balanced XLR/TRS out for recording.
If I'm going to drill holes to accommodate pots, I may as well get real. (Plus a balanced I/O mitigates noise.)
Thanks!
_________________
"The secret to a long life is to keep breathing." |
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Don Downes
From:
New Hampshire, USA
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Posted 3 Nov 2021 3:30 pm
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On the other hand, I just might screw the whole thing. I'll take the output, plug it into an EQ, compress it, and put it into my amp.
That's a lot less heartburn, boatloads of math I don't have to do, and gives me more options.
Yep. I vote for that. 
_________________
"The secret to a long life is to keep breathing." |
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Donny Hinson
From:
Glen Burnie, Md. U.S.A.
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Posted 3 Nov 2021 3:41 pm
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Volume pot on an MSA? No, you do not want a 125k pot!
Plenty of RV6 250k or 500k pots available on EBay. (These are the tiny, dime-sized pots). You probably won't find an audio taper, but a linear taper will do. Also, if it's an early metal frame Classic MSA, you probably won't find a long-bushing pot.
As you mentioned, it may be best to relocate the pot anyway. I don't think the XLR/TRS option be effective (noise free) if you're using a single-coil pickup. |
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