Gibson sg systems amps

[Guitar_master]

hey, im Dean. this is my first post, and i really like what i see when i read replies from experienced members, you guys are really helpful.

Anyway, i was wondering, do you guys know anything about sg systems amplifiers? i've got one, and it's like 30 years old or so, but i can't find any info on the net anywhere about it, so maybe some one here has one, or has had one, or can just tell me andy sort of review or useful information.

thanks

[Brian]

Hi Dean, welcome to the forum

Might want to try here and read a little review here.

[Guitar_master]

very useful, thanks Brian, i've been looking for a while to find anything on the amp

[Brian]

Put Gibson in the search window at this Auction Store in Ebay and you can find a manuel for it as well i think.

[Brian]

If you can't find it there try here

[ytsejam777]

[quote name='Guitar_master' post='16576' date='Aug 7 2003, 01:57 AM']hey, im Dean. this is my first post, and i really like what i see when i read replies from experienced members, you guys are really helpful.

Anyway, i was wondering, do you guys know anything about sg systems amplifiers? i've got one, and it's like 30 years old or so, but i can't find any info on the net anywhere about it, so maybe some one here has one, or has had one, or can just tell me andy sort of review or useful information.

thanks[/quote]


I have a Gibson SG System Amplifier Myself.
I bought it back in 1980 from a friend who had bought it brand new.
Its model # is the SG 100G, the 100 Meaning 100 Watts RMS, and the "G" meaning the Guitar version of the Amp. They had both a Guitar and a Bass version of the same amp. This is actually a"true" 2 channel amp. In the sense that there 2 are 2 completely different circuits for each channel. You can actually plug 2 guitars into it at the same time. The amp comes in a 2X12 Combo arrangement. Now on the Left side there is the "Clean" channel input. Which only has a few control pots for treble and bass contol. And the Right side has the Controls for the "Dirty" channel. Which has alot more option in it, such as a Built in Phase Shifter, a true spring reverb and some other settings that basically let you get more "distortion from the amp. Now when I first got the amp, it had a nasty 60 cycle hum, that is would pick up from just about any electrical outlet you plugged it into. But after I went and got a degree in electronics, I decided to restore the Amp, and hopefully get rid of the noise.

Now at that time, it was around 1990 or so, and I had no manuals or specs at all. I couldnt even find replacement Tubes for the things, other than the 12ax7 preamp tube. So I called up Gibson, and told them I was looking for some Specs, Manuals and Schematics for the Amp. They put one of their "older" engineers on the phone. Apparently he had been working there since they were making the amp. So he knew just about everything about it. After talking with him for a while, he said he was going to send me copies of any of the Schematics and manuals he could fin, "Free Of Charge" No Less!!!!! Well he was true to his word. A few weeks later I recieved a rather large envelope, with the schematics, the voltage check points and the basic setup manual, as well as a cool Gibson Bumper Sticker! So now I had everything I needed to restore the amp, and hopefully make it "better than it was before, better, stronger, faster!"

The only problem I had was finding a set of "Matched" RCA 8417 Power Tubes. After some diligent research on the web, I found a pair for $90 US. Well, the amp also had other issue, the power transformer had a bad wire in it, and it was impossible to find another replacement transformer. So I very carefully took it apart and soldered a 12 gauge, solid core wire, in place of the damaged wire. Mind you, it was a little messy looking, but it would handle allot more current now. Now My amp was made in 1973, a time when they really didn't have PC board tracing technology developed too far. So rather than rely on the ancient traces, I replaced all the traces with standard 12 gauge wire. And also, all of the components, like the Capacitors, Diodes and resistors were of older technology. So I replaced them all with higher tolerance and higher wattage ones. The list that I ended up making, to order all the electronic components had somewhere around 70 some odd items. Thanks God for that Newark Catalog!! hehe


After finally rewiring about 80% of the amp, I put it all back together. And then carefully reassembled the entire amp. Then I began the tedious process of checking all the Various Voltage points, to make sure they were within range, and were correct. Some of the voltage were seriously dangerous, up to 500 volts in some places. When I fianlly thought I had everything right. It was time to see if I knew what the hell I was doing.


Let me tell you, plugging it in the first time had me seriously scared. I was expecting an explosion or some serious noise. But I got neither. Actually after plugging it in and turning it on, I didn't hear anything. No hum, no static, no noise. Nothing at all. I thought I had totally ruined it.

So I checked all my connections and made sure my guitar cable was good. I then realized the "Standby switch was on. After I flicked it off. The amp came to life. I had my 1978 Gibson Les Paul plugged into the Dirty Channel, I heard no hum or static or any other kind of noise.. But when I played a chord, WOW!!!!! I was blown away. I couldn't believe the difference. The noisy, static filled hum of an old amp was gone. the only thing was pure guitar Tone. And when you weren't playing something, there was not a sound. I only was able to turn the Master Volume knob up to 2, otherwise it was so loud, You couldn't be in the same room with it. All my hard work had paid off. I played that amp for several years after the restoration. Mostly using the Signal Line in, from my rack system and just using the Power Section. Because there was plenty of power.
Even though both the clean and dirty sounds were awesome, at the time, "the 80's" I need a Rack System.

But I still have the amp, and it is still as loud as ever. I am thinking of selling it. But I cant even begin to think of how much I should ask for it. Especially since it has been customized. Because I "tricked out" the pre-amp section. By adding a little extra top the gain circuit, just to get a little more dirty sound.

But all in all. It was worth it. I spent about 80$ in parts and came away with a true Tube Amp that has more power than any other amp I have ever owned. so now truly. "Mine goes to 11".