geordiebluesman
623 posts
Oct 02, 2012
2:34 PM
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Hi guys,I recently bought all of Kingleys gig gear and got a lovely JT30 Crystal mic.
The mic has no volume control but i have found a guy in the States selling some at a great price, I just wanted to check what spec of volume pot I need to get in order to leave the tone and power of the mic as is.
Any help would be great.
Cheers Geordie.
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1847
253 posts
Oct 02, 2012
3:16 PM
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use a mouser 5 meg pot
put it in front where it belongs
you be glad you did
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1847
254 posts
Oct 02, 2012
3:19 PM
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by the way
william clarke never used a jt30
that had a volume control.
it seems pretty useful to me
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Joe_L
2083 posts
Oct 02, 2012
7:48 PM
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I would not add a volume control to that mic. Buy a volume control from Greg instead. It's cheap and will any collector value that Mic may have.
Kingley had some good stuff. He sounded great playing it. Why don't you just pay the shit out of it?
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The Blues Photo Gallery
Last Edited by on Oct 02, 2012 7:54 PM
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NiteCrawler .
204 posts
Oct 03, 2012
4:15 AM
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I second what JL says.Buy a screw on as to not mess with the original.I have a 50,s JT that I didn,t want to mess with,keeping it original.I use the screw on for other mics that come along the way,Ev,s,spherodines,etc.Its a great tool to have.
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AirMojo
312 posts
Oct 03, 2012
4:29 AM
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I also recommend getting a V/C from Greg... I have one on my JT30 with MC-151 crystal element... it screws on and has the female 1/4" plug built into it... works great !
Last Edited by on Oct 03, 2012 4:29 AM
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barbequebob
2041 posts
Oct 03, 2012
8:02 AM
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Until they stopped making them in 1978, many players used a JT30 with a long discontinued Swtitchcraft 329 volume control adapter and I often saw Big Walter using one. The originals never came with one. If you put the 5meg pot in it (it's the correct pot if you're using a crystal or ceramic cartridge, but for anything else, that would be the wrong pot to use), do the rest of the Rod Piazza mod, which also included a low value capacitor so that when you roll down the volume control on the mic, you don't lose the mids and lower highs. When the pot is turned all the way up, the capacitor doesn't do anything as what it would be doing isn;t necessary.
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Sincerely,
Barbeque Bob Maglinte
Boston, MA
http://www.barbequebob.com
CD available at http://www.cdbaby.com/cd/bbmaglinte
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Greg Heumann
1798 posts
Oct 03, 2012
8:41 AM
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@geordiebluesman - yes, I make an "extra hi-Z" variety of my "vintage volume control" for crystal mics. Contact me by email to order.
@BBQBob - a clarification. You're almost right, but technically - a capacitor in a passive circuit cannot add - it can only subtract. The way that circuit works is to cut some highs at full volume. This effect is reduced (i.e. less subtraction - sort of like addition) as you reduce the volume. The goal is maintaining an even freq. response across the range, but the drawback is that it actually removes some highs to begin with. The circuit is frequently used on guitar volume controls and was certainly NOT invented by Rod P! Personally, I don't mind the idea of a little high freq roll as I reduce the volume - reducing the volume usually means I'm comping instead of soloing. But I've actually wired up this circuit with a switch to cut the cap in and out, and I can't hear it at all anyway - I just don't bother with it. Nice in theory, useless in practice - for harp players anyway.
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/Greg
Last Edited by on Oct 03, 2012 8:42 AM
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bloozefish
52 posts
Oct 03, 2012
10:37 AM
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I've built mics (JT 30s and 520s) with VCs added, but sold all of them. I now only use Gregs in-line VCs. I have two; one for my crystal/ceramic mics and one for my CR/CMs. Can't recommend them enough....great tools.
james
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geordiebluesman
624 posts
Oct 03, 2012
11:46 AM
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Thanks for all the advice chaps, I just found a e-mail from Kingley in my inbox he saw my post and gave me the following info on the mic.
The JT30 has a Shure 99A86 controlled magnetic ellement installed in it.
I expect that will have an effect on the advice already given.
I am playing the hell out of it by the way and I really like it,it's much lighter and more cupable than my Green Bullet but if I'm gonna use it on stage I would like the extra control of a volume pot.
I think Gregg will most likely be my salvation it's just a matter of the cost.
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geordiebluesman
625 posts
Oct 03, 2012
11:52 AM
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Greg just thought I would add a complication my other favourite mic is an EV RE10 which as you know has a different lead conection,would it be possible to get an adapter of some kind so that one volume control could be fitted to either mic?
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harmonicanick
1743 posts
Oct 03, 2012
12:05 PM
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Hey Geordie, has your mrs done that indexing of Kingley's cd's that the boss asked for? lol
and remember the UK harp fest is end of month:)
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Rick Davis
771 posts
Oct 03, 2012
12:05 PM
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I can strongly recommend the vintage style volume control from Greg Heumann.
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-Rick Davis
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