[Harp-L] RE: JT 30 Question



Hi,
Just an fyi, first thing I’ve seen  guys do when checking out an old  JT 30 is give it a little shake (not too hard!)  to listen for any rattle. Rattle typically  means  a dead crystal and they are not  usually salvageable although some people I  have tried. I’m sure someone will chime in if they know of a crystal repair method.  I have used very small flat bladed screwdrivers to pry the grille off when they stick, just be careful not to force it.  But odds are you won’t be happy with what you find inside. 
Good luck on finding an Astatic   crystal.  Astatic/CAD (who also make or used to make the Blues Blaster that is a JT 30 with their label)  changed to a smaller design from a different maker after the old supplier stopped making them and it is not as popular with players (lots of reviews on the web).  NOS ones can easily go for $100 or more with no guarantee they are not on the way out.    I had a couple still in the box I bought from Farrell’s back in the 80s and when I went to try them out a while back they had died (these are heat sensitive, as well as breakable by dropping). This is why a lot of guys these days (check Ebay) replace them with controlled reluctance or controlled  magnetic cartridges from Shure, which are close to indestructible and also have a good sound. So, now those have gotten pretty pricey too!  
Sorry I can’t be more helpful.  I got absurdly lucky with a $5  JT30 swap meet find years ago with a strong element, and when it went south I put an Astatic ceramic in it (don’t know if you can find those) which sounds pretty good too.  But now I mostly use an old Shure 545 so I’ve left the crystal stuff behind. 



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