oldwailer
1367 posts
Oct 01, 2010
6:58 PM
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I'm rewiring an old broken up SM57 and I'd like to add a volume pot. Inside the mic, there is this lump of stuff with two wires coming out of each end. Do I put the pot on the mic side or on the connector side?
It probably doesn't matter, but I don't really know what is inside that lump. . .
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Joe_L
674 posts
Oct 01, 2010
8:04 PM
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That is likely the transformer. Considering, that if you were going to buy a Blows Me Away volume control, it would go on the connector side, I would say that it should go after the volume control.
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oldwailer
1368 posts
Oct 01, 2010
8:44 PM
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That sounds logical, Joe_L--thanks!
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Greg Heumann
802 posts
Oct 02, 2010
2:11 AM
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It could be on either side, but I recommend the connector side. Do you know how to get the transformer out? Do you know whether there's room for your pot? Do you know how you will wire the pot into that circuit? There are many, many, many choices and combinations but if you're willing to experiment you'll find something that works for you.
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/Greg
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rharley5652
240 posts
Oct 02, 2010
2:21 PM
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@ oldwailer,..
put the VC on the connector side & find the smallest Diameter,. 100K-250K VC ,..check out Mouser,.
there is room for the pot but ya need the small diameter pot w/short shaft to save ya alotta headache<>
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Simply Unique Kustom Mic's By Rharley
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oldwailer
1372 posts
Oct 02, 2010
9:04 PM
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Thanks for the help guys--I bought two SM57's on ebay for less than 5 bucks for both--the catch is that they both had shattered barrels--that made removing the transformers really easy--they were just kind of laying there. How such a popular mic could be made with pot metal like that is beyond me--anyway--the barrels on both will be rebuilt with PVC parts--so I get to choose how much room there will be.
I finished one of them (without the pot) last night and it works great.
I was planning to get a 1 meg pot like I put on my bullet a couple of years ago--it seemed to work better than the 100K I put in at first--is that the wrong choice?
I was an electrician for over 35 years--but most of this electronic shit is a mystery to me--but at least I know how to solder and follow a wiring diagram. . .
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Last Edited by on Oct 02, 2010 9:09 PM
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Greg Heumann
803 posts
Oct 02, 2010
10:51 PM
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OldWailer
I have more SM57 barrels than I know what to do with. They've had the XLR connector and transformer extracted out of them - they're totally empty. You're welcome to as many as you want - just pay the shipping. Contact me if you are interested.
PVC. Hmmm. How will you attach it to the head? You cannot buy a tap for the thread of the SM57 head - it is 32TPI but it is a non-standard diameter. You'll need a lathe to thread it. You could glue it on but then you'll have a hard time ever getting it apart.
Promo: Or you could Ultimatize it and get a slim, light, good looking barrel with the volume control already built in... $139. (Sounds like you like doing this sort of thing - if you're doing it for the fun that's great - do it!)
Wiring the pot is not the same as for your high impedance mics. SM57's are wired balanced. There is no ground in the signal path.
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/Greg
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rharley5652
241 posts
Oct 02, 2010
11:19 PM
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@ oldwailer,..
1 meg pot is good for Crystal or ceramic ,..go with the 100K-250K VC
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Simply Unique Kustom Mic's By Rharley
Last Edited by on Oct 02, 2010 11:19 PM
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Greg Heumann
804 posts
Oct 03, 2010
9:11 AM
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Sorry but this is a low impedance mic. 250K is way too high. Depending on how you wire it, you'll want between 5K and 50K.
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/Greg
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oldwailer
1373 posts
Oct 03, 2010
10:36 AM
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@Greg--thank you so much for helping me out on this project--I really appreciate it. I tried to contact you through your site, but the image is invisible to computer. (BTW, Thanks for the free download on mic info--I'll read it and try to learn something).
I would be very interested in getting two of those barrels shipped to me--if you could just tell me what the shipping would cost, I can go to your site and post it to your paypal account. My email is available by clicking my user name here on the forum.
I don't know if this kind of project could be called "fun" for me--if I could afford it, I'd just pay you to fix them up right. I think I'd rather be building myself a new harp--which is a lot more fun for me.
FWIW: I found that the head will thread itself into a 3/4" PVC coupling if you ream it out just a little--then I screwed it in, using very firm pressure and keeping it very straight. Then I could attach any length of pipe I wanted. It seems sturdy enough--but very fat and uncool looking--on the upside, it won't shatter easily. . .
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Last Edited by on Oct 03, 2010 10:37 AM
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barbequebob
1276 posts
Oct 03, 2010
11:37 AM
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On dynamic mics, putting in a pot any higher than 250K is going to be nothing but an over glorified on/off switch and won't do anything to control the actual volume, and with that mic, I'd stay closer to 100K.
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Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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rharley5652
242 posts
Oct 03, 2010
12:11 PM
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OK,.Ok ,.. I'm thinking Hi Z when I said 100K -250K,.I forgot the 57's a low z mic,..2K is what it should be <>
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Simply Unique Kustom Mic's By Rharley
Last Edited by on Oct 03, 2010 12:24 PM
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