microphonic tubes

Hey guys,

I have a Boogie DC-3 and about a month ago the clean channel preamp tube (the original 12AX7) became microphonic. I replaced it with an EI 12AX7 and now it is also microphonic. So, I am wondering if some problem with the amp can cause tubes to become microphnic, or if it was just plain bad luck... Any input would be greatly appreciated. (Sorry if this is a dumb question...)

Thanks and my best to all,

Luis

[VaughnC]

Modern tubes are somewhat hit or miss but every EH preamp tube I've tried was horribly microphonic. For modern preamp tubes, I've had very good results with the Sovtek 12AX7LPS. Generally speaking though, NOS tubes are much better but are more expensive.

Your amp will not cause tubes to go microphonic per se but speaker vibration can contribute to it over time, especially with cheaply made modern tubes. If you have a combo there's not much you can do but, with a seperate head & cab, padding between the two can help your tubes to last a little longer.

Just bad luck really but you can reduce the chances of a tube going microphonic by selecting one that has a thicker glass envelope.
Shaun.

Thanks Shaun and VaughnC for the replies!

I think I'll try a JJ this time... Let's see.

Thanks again,

Luis

I havea DC-5 and I was thinking of using EH's. Let me know how you like the JJ's. I was told they would darken the amp and that is the last thing I want with this amp. Good luck!

[John Phillips]

Welcome, PDL - that's a cool set-up you have BTW... what color is your Std 22?

Me... trans. purple Std 22 & DC5 combo.

I improved the sound of my DC5 enormously by fitting old Sylvania power tubes instead of the rattly Chinese ones that came with it - it made it deeper, richer and less fuzzy-sounding.

I haven't changed the preamp tubes yet, but I wouldn't use EHs - as Vaughn says they're usually microphonic. When I do, I'll probably use NOS types of some kind, or simply old tubes. The only new-production ones I like at all are JJs (and I'd quite like to make my amp even darker!).

Hey Unquiet,my standard 22 is a little strange. Because of the options, it's basically a custom 22 w/o a 10 top. It's black w/ white binding(when I bought in '96 that color came w/ a maple top, now an option) 22 fret wide-fat w/birds and Dragon pu's. what kind of music do you play? I'm thinking of putting in some 6L6GE's (new manufacture made in USA by GT) What settings do you use?