Gibson Skylark Guitar Amp

[CJ]

probably 1965, sounds awesome so we blog it out,

 

[CJ]

6AQ5's in push pull, nice sounding 6V6 type in a smaller envelope,

schematic is different, as always, from those you find online as things change.

nice sounding Tremolo!

 

[CJ]

Output>

 

[CJ]

unique square wave from the output transformer,

top is 1 KC, then 10 KC and 100 KC on bottom,

and also note weird response from OPT print above, starts rising at 5K ! never seen that,

then keeps rising to 100 K with a few surprise dips and peaks after that.

 

[CJ]

it is very rare but it happens, factory wiring error,

thought we had a wiring error, but pin 1 and pin 7 are both G1.

 

[CJ]

very quiet amp, 6EU7 preamp tubes, 6X4 rectifier, had a cap job already with the old carcass intact>

 

[Tubetec]

A good pal of mine got a JCM800 combo as a gift from a music store that was closing down .
The amp had sat there for 30 years ,returned by the original customer as the boost channel was intermittant, worked the very odd time .
Was a mystery to all untill I got to have a look at it , turned out pins 4 and 5 of a preamp 12ax7 werent soldered together , only one heater section of the dual triode fired up.  A quick touch of the iron and he was back in business .

Gibson amps are rare as hens teeth here this side of the pond , I dont think I ever laid eyes on one in the flesh ,
They did seem to know a thing or two about crunch and tone though, 6AQ5 or 6BQ5 in duets or quads throws out piles of volume cranked , worlds apart from Fenders offerings of the late 60's many of which were loud n clean and dont distort very gracefully .

Thanks again for the interesting post .

 

[Gus]

Do you think they did not care about the transformer response because guitar does not go that high in frequency?