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Dirty-South Blues Harp forum: wail on! >
Astatic JT 30 problems.
Astatic JT 30 problems.
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bluzlvr
390 posts
Jul 18, 2010
1:49 PM
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I have a JT30 that I've owned since 1986 that suddenly stopped working.
I think it might be the element. Is that what happens when an element goes bad? After all the mic IS 24 years old.
I would like to get it fixed and sounding as bitchin' as it always has.
I have another JT30 that I bought around 1991 that came with a volume control and doesn't quite have the "balls" as the first mic does.
Would both of these mics have the same type of element or could it be that the volume control had something to do with the ballsyness of mic #2?
I've never really worked on microphones before so I'm not familiar with the ins and outs.
Do they just pop in and out?
Maybe I'll just send them both to Greg or something...
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myspace
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rharley5652
209 posts
Jul 18, 2010
2:14 PM
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Bluz ,. If your mic has a crystal element inside ,.
The easiest way to tell if the element is dead is to shake it close to ya ear,.if it makes noise or sounds like a babies rattle it's dead.
The JT30 that you bought around 1991 that came with a volume control could have the wrong Ohm VC for the element inside,.Hard to tell with out looking at it ,.it may also have a cheap Japan made element inside ,..where as your other may have had an Astatic crystal inside er.
I can't help ya with a replacement crystal but I can help ya with a Vintage Shure CM ,.E-Me thou myspace,. if your interested,..
As for a replacement Crystal I guess I could help ya ,.
You can get a Genuine Astatic Crystal Element from:
www.jt30.com/jt30page/eacstore.html
but at $160 bucks ,.thats steep!!
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Simply Unique Kustom Mic's By Rharley
Last Edited by on Jul 18, 2010 2:44 PM
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harpwrench
318 posts
Jul 18, 2010
2:46 PM
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I have an incredibly strong vintage Astatic crystal I'd sell for $125. It has lots-O-bass output. It sounds best with smaller amps like my Kalamazoo, feeds back too easily with my Super Sonny.
Last Edited by on Jul 22, 2010 7:50 AM
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HarveyHarp
79 posts
Jul 18, 2010
9:35 PM
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Thats interesting. I have an extremely strong JT30 from the 70s, and I find it too bright with my Kalamazoo, but it sounds great, with lots of bottom end with my Super Sonny. Is got a MC151 in it. Go Figure. I'm running a 12AY7 in V1 and a 5751 in V3.
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barbequebob
1026 posts
Jul 19, 2010
10:53 AM
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@harpwrench -- If you have an older MC-151 that's ridiculously hot, especially at the bottom end (I've played a few made in the 50's that were like that), the thing I learned to do is to turn the bass setting in the amp MUCH lower than you'd usually set it. Most people crank the bass way up on the amp and when you do that with a crystal like that, it's often too loud to even turn the amp on, but I later learned that it becomes manageable when you lower the bass setting by several notches.
I own a real '59 Bassman and when I played a few 50's crystals like that, I couldn't even turn the amp on without it feeding back, but later I learned that instead of having the bass at 8 or higher, it worked out better by turning the bass down to about 6 or 7 and I never had problems with that again. Most guys almost automatically turn the bass way up and for some mics, it can be the wrong thing to do and make things worse.
@HarveyHarp ---- The JT 30's had 4 differenct cartridges, MC-151 crystal, MC-101 crystal, MC-127 ceramic and MC-126 ceramic. The MC-151 and MC-127 have the midrange presence rise and the other two do not have that at all and the ones without that presence rise would work better on the Kalamazoo.
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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
669 posts
Jul 19, 2010
12:05 PM
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Yep, yep, yep. The best way to figure if a crystal is deal is to hook it with clip leads to the amp - bypass any volume control or your normal cable to eliminate those as culprits. With respect to RHarley, an element doesn't have to have reached the "rattle" stage to be dead. Moreover, crystals can get very weak on their way to the grave. A good crystal has as much or more output as a good CM or CR.
I do have lots of good crystals and can repair for you if you like.
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/Greg
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MP
730 posts
Jul 19, 2010
12:39 PM
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i've had crystals that go dead and then come back to life, and then die again.
once a crystal starts acting funny, or stops working and magically starts up again, it can't be trusted.
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MP
hibachi cook for the yakuza
doctor of semiotics
superhero emeritus
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barbequebob
1028 posts
Jul 19, 2010
12:39 PM
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Another thing in the equation are bad/worn cables and also the possibility of the wiring worn out or accidently disconnected on the inside.
The grille on the pre-1984 JT30's were better than the ones made after that because sinc e'84, they have a flimsy piece of paper behind the grille that often lets in far too much heat and moisture and they can kill a crystal quickly. The pre-84 versions had a totally different "mesh" material (for a lack of a better description) that prevented a lot of moisture and heat from going thru the element and it did a far better job. In fact, on the Rod Piazza JT30 I got back in 1995, I swapped the grille from that (which was made from then newer stock stuff) to one that I had on one of several pre-1984 JT30's I had and never had those problems again.
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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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