Gorilla Amp

[Strat68okc]

Back when I was first learning to play, I had a friend named Jimi I used to jam with. He had a Hondo Strat and a Gorilla amp. I loved the sound of its overdrive with those cheap single coils. "TubeStack Technology" it was called. So I google-fued up a schematic.  Problem is, I'm too much of a noob to read that. Its fairly complex to me. I can sort of read it, but I'm having trouble figureing out where the pre amp stops and the power amp starts.... plus a couple of symbols I got no idea wth they are. Any of y'all super gurus possibly help out? I'm trying to get educated here. Plus be a nuisance.

http://db.tt/NRYcScJB

I wanna steal the pre-amp and make an OD out of it.

[Earthscum]

You would take the output from R18.

Basically, instead of going into Pin 1 of the TDA2030, you would go to a jack. I would recommend a buffer, possibly, so the tonestack will work properly, but I'm not really sure about that.

[Strat68okc]

Okay... Sweet. I wasn't wayyy off then. What are the two triangular symbols? I'm assuming transistors of some sort?

[artifus]

two halves of a dual op amp. google image search schematic symbols.

*edit* http://en.wikipedia.org/wiki/Electronic_symbol http://www.talkingelectronics.com/CctSymbols/Circuit_Symbols.html

[PRR]

Dual opamp. +/-10V power (two 9V batts would work).

Opamp type not shown, and it could affect sound.

Low-power output stage. It could be that the overdrive goodness you remember was power stage and speaker overload.

But is a fine/funky preamp, and not overly complex.

[Strat68okc]

Thanks for the links and the info. I'm going to try to hunt up some gut shots... unlikely, but hey, might get lucky. Its likely the OD goodness I remember sounds better in my minds ear, but never know til I try. Funny thing is, I used to see these amps everywhere. Now, they seem to be gone.

I do know that we were living room rock stars, and weren't really allowed to turn up very loud.

I got so much stuff on my build list now.... I just HAD to add more.

[Strat68okc]

I found another schematic, and a dude saying that the dual op-amp was likely a 4558 of some kind. A TS? Wild.

http://db.tt/xy4ud8Ke

This one is a 120 watt amp. I had no idea they even made amps that big.

[Seljer]

Just because it has a 4558 opamp doesn't mean its a tubescreamer. They've made millions of those little chips and used them all over the place (you'll probably find them in any tv or hifi equipment from japan from the 80s).

The schematic you've found for the 120watt amp is just the power amp section. You don't need that if you want ot build an overdrive box.

[Davelectro]

This thing looks like a copy of the Marshall Lead 12. Different power amp, though.

As far as i recall, the op amp should be a 4558.

[Mark Hammer]

First, thanks for the schematic.  I'm looking at my Gorilla GG25 at the moment, which is also a TDA2030-based practice amp.  The two won't be identical, but they won't be that dissimilar either.   In my case, however, it would appear that the lonely little 4558 has a number of clipping diodes to assist in producing the sought after distortion, while the TC35 does not.  That is not to say the TC35 won't produce pleasing clipping from pushing the 4558 past its capabilities, but it may not be the amp you recall.

[Strat68okc]

Glad to be of assistance. I have no idea which one it was. I know he had one of the larger wattage amps of the bunch of us... we were all jealous

Could have been a 20 or 25 watt.

[Mark Hammer]

Well if it uses a TDA2030, it certainly isn't going to be able to put out more than maybe a dozen watts of power, no matter what the label suggests.

[Paul Marossy]

Just because it has a 4558 opamp doesn't mean its a tubescreamer. They've made millions of those little chips and used them all over the place (you'll probably find them in any tv or hifi equipment from japan from the 80s).

The JRC4558 opamp can be found in just about anything. It's really just a cheap general purpose BJT dual opamp. Somehow it has obtained magical properties through the course of time.