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jlh

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About jlh

  • Birthday 10/14/1950

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  • occupation
    Software Engineer
  • Location
    Colorado Springs,CO,United States
  1. Myles, I've finally decided to repair/upgrade my old Gibson GA35RVT Lancer amp. I think I know enough to do it without breaking it or frying myself, but could sure use some advice. It appears that the push/pull phase inverter is a transformer so no issue there, but it is full of unusual tubes and some advice on replacing or substituting would be handy. I always loved the tremelo and reverb sounds that it has and it breaks up nicely at reasonable volumes, but the tone has always been kind of "honky". That is way too much midrange with no boom or shimmer. I've been told that it is just a crappy design and I'm stuck with that, but I'm hoping you can offer some advice. There is a schematic posted here: Gibson Amp Schematics The output tubes are 7591s. I know they can be had, but are they really the best choice? I noticed that THD has a yellow jacket to use EL84s in place of the 7591s. Is this a good choice or would it be a better idea to get some real 7591s from Torres or someone? Also the preamp front ends are 6EU7s hard to get too. Same story anything better? Finally should I look at changing some of the R/C values in the coupling and filter stages to let more bass and treble through if the tube changes don't do the job? This would no doubt be a LOT more effort and maybe more study than I want to do. Sorry this is so long, but the topic has been percolating in my brain ever since the old filter caps went out and I shelved the amp. Thanks for being such a great and generous source of information Myles(stroke stroke). Sincerely, Jamie
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