RE: [Harp-L] Fender Vibrosonic

[David Harris <snakehead_1@xxxxxxxxx>]

Jim,
  Great job on your project.
   
  Your 12AT7 idea in the pre-amp Normal channel makes sense.  
   
  You didn't say if the tech replaced the phase inverter tube.  If he lowered that tube to a 12AU7, you would defintely get more breakup.
   
  You initially mentioned that you had a 12AT7 in the phase inverter.  Just switch the pre-amp normal and phase inverter tubes.  You would then have a 12AU7 in the phase inverter and a 12AT7 in the pre-amp Normal channel.  That would be a free way to beef up you amp.  :-)
   
  These changes should make the amp growl a little.  Heh heh.  Of course the right mic would be the finishing touch.  A nice crysal mic would sound badass on your amp.
   
  All in all, you are very close to harp amp nirvana.
   
  The best part is you can do the tube swaps yourself now that the amp has been given a clean bill of health.
   
  Please let me know how the tube changes go.
   
  Dave
   
  
"Priest, Jim" <Jim.Priest@xxxxxx> wrote:
      I took my Vibrosonic to local amp guru Steve Rowse...
  http://www.stevesamps.co.uk/index.html
  who did a great job on it. He cured the hum (blown plate resistors or somesuch tech-speak) and gave it a thorough once-over - apart from the hum it didn't need much else fixing, just a bit of a spring-clean. He then modded the Normal channel to be more harp-friendly, and left the Reverb channel alone so it's still set up for guitar. On the Normal channel he brought the gain down by swapping the 12AX7 pre-amp valve for a 12AU7 and altered the eq on the tone controls. Now I have a great dual-purpose amp which can be used for both harp and/or guitar as needed.
   
  I tried it out in public for the first time last weekend... and it's awesome! Wonderful tone... really thick and creamy and resonant... LOADS of volume (guitar players watch out!), but not a trace of feedback (at least not at the relatively restrained volume I was using - haven't tried really cranking it up yet). OK, it doesn't break up much, so for a really dirty tone it's probably not ideal ... but there is break-up there if you push it hard. I was using a (non-vintage) GB and haven't had a chance to try it with other mics yet... something with a tad more bite might well get it to distort that bit more. But I just love the way it sounds.
   
  I reckon I've still got a lot to learn about this amp and how to get the best out of it. I'm still experimenting with the control settings and I'd like to try it with maybe a 12AT7 in the preamp rather than the 12AU7. I'd also like to hear it through different speakers... a 2x10 or 4x10-inch cab rather than the 15-inch beast that's in it now. I suspect this is going to turn into a lifetime's project!
   
  But right now I'm so happy with it I could have its babies!! Of course its one and major drawback is the weight... it is HEAVY! I like fjm's description of it being a "boat anchor" - you could anchor the QE2 with this monster! Right now I'll put up with that... in time it may prove to get too much of a effort just to lug the thing around.
   
  Given the ludicrously low prices these amps seem to go for (compared to the more fashionable models) I certainly think they should be higher on the harp amp shopping list. Provided you have strong back muscles!
   
  Jim

    
---------------------------------
  From: David Harris [mailto:snakehead_1@xxxxxxxxx] 
Sent: 29 April 2008 18:24
To: Priest, Jim; harp-l@xxxxxxxxxx
Subject: RE: [Harp-L] Fender Vibrosonic


  
  Jim,
  I hear that amp hum may be caused by bad filter caps.  What did your tech say?
   
  Dave



       
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