Paleo-Electronics Blog

Regular readers (hahaha…. I kill me) will remember that I bought two Gibson Skylarks.  One of which I fixed immediately and the other sat waiting.    This is a story about the other.

This is a Gibson Skylark in the “Crestline” series.  It is one of the many amps released with the GA-5T model number.   This was made sometime in the early 60′s as the later model “Whiteface” amps would be released in ’65.   This is not as popular as the true Class A SE Skylarks from the 50′s so it cost me $202.50 with shipping a couple of years back.  It’s not working right now and I’ve decided to refurb it.

When it worked (which it actually did at some point) it had the best tremolo I had ever heard.   It is so weird that Gibson tremolo is the shame of high end amp world these days.  They used to do it brilliantly.   However, I don’t like trem, so it’s going out..  in it’s place is a Master Volume.   I’ve read all the gasbags saying “It’s not the same!  You won’t get .. “  but the truth is I don’t care.  It makes a good sound.   If I get a different sound from 11 on both dials, great!  That’s just more versatility to me.

Here is the plan in general :

• Use the original  Iron, Speaker, Cabinet and Chassis as much as possible
• Mod back to original GA-5 specs, removing tremolo circuit.   except as noted below.
• Replace all discretes using original bone stock values
• Add Standby switch (hopefully I can do this with a rotary switch like they have now)
• Use multiple parallel caps for filtering ( a la TUT5)
• Add Master Volume before the Phase Splitter
• Add Pentode/Triode/Other switch
  • Pentode – Standard operation except provide 1k flameproof resistor for each screen
  • Triode – Put the screen in the plate loop (keeping the 1k resistors)
  • Other – Lower the voltage supplied to the screen (should be something between the other two in terms of breakup)
• “Galaxy” grounding, again, a la TUT5
• Careful layout and use of shielded wire on the signal path.

Should really be doable in a weekend if I have the parts, but I really want to nail this build, so I’ll take my time.