microphonic tubes

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by finotti, Mar 23, 2002.


  1. Mar 23, 2002 #1
    finotti

    finotti Guest

    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
     
    finotti, Mar 23, 2002
    finotti, Mar 23, 2002
    #1
  2. Mar 24, 2002 #2
    VaughnC

    VaughnC Supporting Member

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    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.
     
    VaughnC, Mar 24, 2002
    VaughnC, Mar 24, 2002
    #2
  3. Mar 25, 2002 #3
    Shauno65

    Shauno65 Guest

    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.
     
    Shauno65, Mar 25, 2002
    Shauno65, Mar 25, 2002
    #3
  4. Mar 26, 2002 #4
    finotti

    finotti Guest

    Thanks Shaun and VaughnC for the replies!

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

    Thanks again,

    Luis
     
    finotti, Mar 26, 2002
    finotti, Mar 26, 2002
    #4
  5. Mar 25, 2003 #5
    PDL

    PDL Guest

    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!
     
    PDL, Mar 25, 2003
    PDL, Mar 25, 2003
    #5
  6. Mar 26, 2003 #6
    John Phillips

    John Phillips Member

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    Scotland
    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!).
     
    John Phillips, Mar 26, 2003
    John Phillips, Mar 26, 2003
    #6
  7. Mar 26, 2003 #7
    PDL

    PDL Guest

    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?
     
    PDL, Mar 26, 2003
    PDL, Mar 26, 2003
    #7

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