Marshall Amp Forum - View Single Post - Preamp Tubes?

MartyStrat54 · 03-24-2009, 07:29 PM

Well that sucks!

Try the 12BZ7 in V4. You did use the slip on cover for the 12BZ7...correct? It should have a shield on it in the V1 position.

Try the GE in V1 and the JJ gold pin in V2 and see how that sounds. If that's cool, then try the 12BZ7 in V4. If it creates noise then either it is not compatible with your amp, or it may have become microphonic (why I use the special rubber bands around my tubes).

For a short term experiment, you can take a medium rubber band and wrap it around the tube until snug. Try the tube for a while to see if it works, or if it still has the same problem. If it does, the tube might have gotten damaged in shipping (which would suck

).

Keep me posted.

Marty

03-24-2009, 07:29 PM	#34 (permalink)
MartyStrat54 Senior Member Join Date: Feb 2009 Location: Formerly Phoenix, now north of KC Posts: 2,583	Re: Preamp Tubes? - Who, What, When, Where, Why, and How? Well that sucks! Try the 12BZ7 in V4. You did use the slip on cover for the 12BZ7...correct? It should have a shield on it in the V1 position. Try the GE in V1 and the JJ gold pin in V2 and see how that sounds. If that's cool, then try the 12BZ7 in V4. If it creates noise then either it is not compatible with your amp, or it may have become microphonic (why I use the special rubber bands around my tubes). For a short term experiment, you can take a medium rubber band and wrap it around the tube until snug. Try the tube for a while to see if it works, or if it still has the same problem. If it does, the tube might have gotten damaged in shipping (which would suck). Keep me posted. Marty