NVAD coming up!

The kids and wife will be out of the house tonight. I see guitar playing in the very near future for me. Might shoot some soundclips with my iPhone. I don't have any better microphones, since my son will be bringing his Røde USB mic to a friend's house for some LAN action... Still can't wait, though.
 
Ok, so I won't be able to make any proper soundclips today, because my 80+ year old neighbor's family is throwing a party for her. I don't think I would have disturbed them much, even if I played fairly loudly, but I don't want to do anything to annoy them today. I'll see what I can do tomorrow around noon (I have the day off).

Anyway, I did snap a couple of shots of the guts. Seems like some caps are new and some fairly old, but according to the shop it is all ok. No idea on the age of the tubes. The tubes seem to be (from right to left) 12AX7 (preamp normal channel) , 5879 (preamp tremolo channel), 6SQ7 (tremolo), 12AX7 (inverter), 6V6 (power amp), 6V6(power amp) and 5Y3 (rectifier). This may or may not be the types it came with originally, as Gibson was notorious for swapping things around. The Gibson Amplifier book claims that the GA-20T came with a 12AY7 preamp tube in the normal channel, and a 7025 inverter. I have seen schematics where the normal channel had a 12AY7 preamp tube, a 6SQ7 for the tremolo and a 12AX7 inverter. The GA-20 (non-tremolo version) came with a 12AX7 preamp, 12AX7 inverter, 2 x 6V6 power and a 5Y3 rectifier tube according to the book, so I don't find it unlikely that some of the GA-20T models might have had two 12AX7 tubes. Whatever the correct tubes might be, it sounds great. It starts breaking up as soon as you turn it up to 1.5(!), so I don't have to extremely loud to get a creamy overdrive. If more headroom is needed, could swapping the preamp 12AX7 for an 12AY7 be an option? Then again, the magic really happens when playing through the tremolo channel. The 5879 seems to be the key to the great sound, so the 12AX7 in the normal channel doesn't really matter, since I won't be using that one much anyway.

The speaker is obviously not original. The correct one would be a Jensen P12R, i think.

Lighting is pretty bad, but all right, here we go:
jUL5WXP.jpg


bYy2fub.jpg


vkt1hDq.jpg
 
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Gahr said:
Ok, so I won't be able to make any proper soundclips today, because my 80+ year old neighbor's family is throwing a party for her. I don't think I would have disturbed them much, even if I played fairly loudly, but I don't want to do anything to annoy them today. I'll see what I can do tomorrow around noon (I have the day off).

Anyway, I did snap a couple of shots of the guts. Seems like some caps are new and some fairly old, but according to the shop it is all ok. No idea on the age of the tubes. The tubes seem to be (from right to left) 12AX7 (preamp normal channel) , 5879 (preamp tremolo channel), 6SQ7 (tremolo), 12AX7 (inverter), 6V6 (power amp), 6V6(power amp) and 5Y3 (rectifier). This may or may not be the types it came with originally, as Gibson was notorious for swapping things around. The Gibson Amplifier book claims that the GA-20T came with a 12AY7 preamp tube in the normal channel, and a 7025 inverter. I have seen schematics where the normal channel had a 12AY7 preamp tube, a 6SQ7 for the tremolo and a 12AX7 inverter. The GA-20 (non-tremolo version) came with a 12AX7 preamp, 12AX7 inverter, 2 x 6V6 power and a 5Y3 rectifier tube according to the book, so I don't find it unlikely that some of the GA-20T models might have had two 12AX7 tubes. Whatever the correct tubes might be, it sounds great. It starts breaking up as soon as you turn it up to 1.5(!), so I don't have to extremely loud to get a creamy overdrive. If more headroom is needed, could swapping the preamp 12AX7 for an 12AY7 be an option? Then again, the magic really happens when playing through the tremolo channel. The 5879 seems to be the key to the great sound, so the 12AX7 in the normal channel doesn't really matter, since I won't be using that one much anyway.

The speaker is obviously not original. The correct one would be a Jensen P12R, i think.

Lighting is pretty bad, but all right, here we go:
jUL5WXP.jpg


bYy2fub.jpg


vkt1hDq.jpg
Click to expand...
Each and every point to point connection is shexshier than the next!
 
Nice pics... :yesway:

Gahr said:
Seems like some caps are new and some fairly old, but according to the shop it is all ok.
Click to expand...
Did any conversation happen regarding that old electrolytic cap, with the 200 ohm piggyback resistor?

The zigzag pattern of some of those resistor leads on the circuit board looks pretty cool. I wonder if that was just a personal artistic embellishment provided by whomever populated the circuit board... :hmmm:
 
syscokid said:
Nice pics... :yesway:


Did any conversation happen regarding that old electrolytic cap, with the 200 ohm piggyback resistor?

The zigzag pattern of some of those resistor leads on the circuit board looks pretty cool. I wonder if that was just a personal artistic embellishment provided by whomever populated the circuit board... :hmmm:
Click to expand...
Nothing was said on that cap in particular, but everything has been tested and found in order. I'll probably have someone look at it regardless.
 
syscokid said:
Nice pics... :yesway:


Did any conversation happen regarding that old electrolytic cap, with the 200 ohm piggyback resistor?. :hmmm:
Click to expand...

That (20uf) electrolytic with the 200 ohm resistor piggybacking it is the cathode bias arrangement for the two 6V6's, so there's a good chance the cap is ok. I see new filters so imagine it was checked to be serviceable when the filters were done. Those zig zag resistors do look cool. Sweet amp, congrats & enjoy. Cheers
 
I sprained my ankle on Saturday and have torn some ligaments. Seems like there will be no work for me this week. So when I'm stuck at home anyway, I figured I could make the best of it and mess around with a some sound clips of the Gibson GA-20T amp. Here's the first one.

Very quickly recorded with a Røde USB microphone, placed about 1' away from the speaker, directed towards where the dust cover meets the cone. Amp is turned to about 2 (the tremolo channel). I play my Les Paul goldtop. I mess around a bit with pickups and pickup volumes, and you can probably hear pretty well when I change pups. I also play a little in the middle position; the "Peter Green" sound is pretty easy to pick up.

I recorded it using Garage Band. No EQ-ing was done after recording, but I added some compression and limiting. The reverb is also from Garage Band.

I didn't plan what to play, but started doing a rather sloppy impromptu version of "How Great Thou Art", because I think it fits the raunchy clean sound of the amp. I start playing on the neck pup.

i hope it gives you an idea of what this amp can do at a fairly low volume.

Gibson GA-20 test
 
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syscokid said:
OUCH!!!! Did you get really excited and tried to jump off your vintage Gibby amp?
Click to expand...
Haha, if it were only that glamorous! I found the only patch of ice on the ground in the whole of my suburb and fell on it, on what was the very first fay of sub-zero (°C) temps this fall. My twisted left foot caught the whole weight of my 240 lbs petite frame. Ligaments torn on both the inside and outside of the ankle. The doctors first thought it was broken, but after four x-rays they luckily concluded it wasn't. The B. B. King tune "How Blue Can You Get?" describes the looks of my foot at the moment. It looks like i stepped in a can of paint...:D
 
Gahr said:
Haha, if it were only that glamorous! I found the only patch of ice on the ground in the whole of my suburb and fell on it, on what was the very first fay of sub-zero (°C) temps this fall. My twisted left foot caught the whole weight of my 240 lbs petite frame. Ligaments torn on both the inside and outside of the ankle. The doctors first thought it was broken, but after four x-rays they luckily concluded it wasn't. The B. B. King tune "How Blue Can You Get?" describes the looks of my foot at the moment. It looks like i stepped in a can of paint...:D
Click to expand...

Ouch and re-ouch, man.
 
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