Oh no - funny noises coming from my mic
Mon, 03/07/2011 - 12:10
Hello Fritz. I have a mid 90's Blues Blaster with the MC 151 element. I hadn't used it for a few years, so I dusted it off and plugged it in. It sounded good for a bit, but it makes a crackling/staticy sound when pushed hard. It is not constant, but every so often when pushed hard there it is. I tried a few different cords, but no luck. Have I experienced for the first time what a crystal element sounds like when going bad? Any thoughts? I really enjoyed your videos on this site! No person should know that much about microphone!
Hello Johnny,
The good news is that trouble shooting the ASTATIC JT-30 products (A BLUES BLASTER in this case) isn't too difficult or complicated. The bad news is that your deepest fears may be realized...
You've got a BLUES BLASTER with the full-sized element and likely a 500K potentiometer if it's original. One of the symptoms exhibited by electronics that have gone unused and unattended for long periods is a degree of corrosion or decay of their contact points. Connectors and potentiometers are easy prey to creeping decrepitude. What you've described could be attributed to an intermittent or inconsistent electronic connection. You've tried different cables to no avail. At least you've eliminated one of the principal culprits. Make certain the mic's contact points (male XLR pins, right?) are clean and functional. No luck? Time to go inside... The next step is to clean & lube the V/C potentiometer with an electronics-approved solvent. This is intended to improve the continuity of the contact points within the pot. No substantial improvement? It's time to disconnect the MC-151 from the mic's wiring and test it separately. This is the moment of truth for the crystal element. If you find that the element continues to respond erratically on its own then you DO have a crystal with a piezoelectric defect (such as a fracture) and replacement of the element will be required to make it fully operational. There are several replacement options...
TIP: If you find the culprit is indeed the pot, now's your chance to swap it out for a replacement that's at least twice the original's rating (1 MEG as opposed to 500K) in order to realize more of the crystal's output & bass response.