Gibson GA- Clones?

kmckenna45

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Anyone know of combo amp makers that clone the Gibson GA-? (Not the GA-5)... I know you can get a GA-5 pretty reasonably, fully built or kit. But I'm talking about the Gibson tube amp with 10" or 12" speaker combo's.

I'm presuming they must be very expensive to build - because they're not easily found.

Thx.
 

Lowerleftcoast

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There are posts about Gibson amps. They don't appear to be anything too difficult to build. Idk if any company is offering a clone type kit. Here is a recent build of a GA-20.

https://www.tdpri.com/threads/gibson-ga-20t-build-some-progress.1083798/

Imo, it is expensive to build an amp. An individual can not get the economies of scale a large producer of amps can. I would think a GA-20 parts alone would be between $500 and $1000.
 

muscmp

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victoria makes a few of the gibson amps.

tons of gibson amps are for sale but since you can build one, you'll save some $$. grab a ga20, 20t, 40, 18 or 19 schematic and go for it.
play music!
 

kmckenna45

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There are posts about Gibson amps. They don't appear to be anything too difficult to build. Idk if any company is offering a clone type kit. Here is a recent build of a GA-20.

https://www.tdpri.com/threads/gibson-ga-20t-build-some-progress.1083798/

Imo, it is expensive to build an amp. An individual can not get the economies of scale a large producer of amps can. I would think a GA-20 parts alone would be between $500 and $1000.
Thank you for this. I am tempted to build one - I’m pretty good with a soldering iron - but little experience with an ohm meter. My concern is that I’d get done building and have hum or noise or no sound. And I’d be trapped in troubleshooting hell. I used to try and build stuff from the old “Electronics Projects for Musicians” and wind up being frustrated. Is there a common way to test speaker build projects along the ways, to verify operational quality while building? I am beginning to think anything beyond a GA-5 is going to be a custom build. Thanks again.
 

Smokin OP

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Check out the podcast, Truth About Vintage Amps. Skip Simmons discusses Gibson/Epiphone amps quite often.
 

Lowerleftcoast

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There are a few things that can be checked as you build. The power section can be installed first which makes it easier to check for shorts/opens/power before the rest of the circuit is connected. Other parts of the circuit can be metered before they are installed. The grounded wires can be metered to make sure they are connected properly.
It is helpful to color code the wiring as a reminder of what is hot, grounded, plate, cathode, etc.

Of course the most important thing is safety. Knowing how to use all the high voltage safety precautions is the first thing to learn.

The troubleshooting hell is where the most learning happens. Most of the troubleshooting on a new build is finding misplaced or poor connections.
 

Wally

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Thank you for this. I am tempted to build one - I’m pretty good with a soldering iron - but little experience with an ohm meter. My concern is that I’d get done building and have hum or noise or no sound. And I’d be trapped in troubleshooting hell. I used to try and build stuff from the old “Electronics Projects for Musicians” and wind up being frustrated. Is there a common way to test speaker build projects along the ways, to verify operational quality while building? I am beginning to think anything beyond a GA-5 is going to be a custom build. Thanks again.

search> Vaccum tube history….this is of interest for anyone who wants to start dealing with tube amp circuits, imho.

Tube Data Sheet Locator…..to study tube pinouts and specs for tubes.

Schematic Heaven…..I suggest studying Fender schematics since the schematic is accompanied by a layout for almost all of the circuits. One can start to understand how to read a schematic IF one knows the tube pinouts, and the one can relate that schematic to the layout….the layout being a drawing of the physical circuit. One can then compare the Fender Champ and Vibrochamp circuits to the schematic for the various GA5 circuits.

Aiken Amps…..Tech Info….White Pages….
Buy some books,too.
 

kossovian

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There are posts about Gibson amps. They don't appear to be anything too difficult to build. Idk if any company is offering a clone type kit. Here is a recent build of a GA-20.

https://www.tdpri.com/threads/gibson-ga-20t-build-some-progress.1083798/

Imo, it is expensive to build an amp. An individual can not get the economies of scale a large producer of amps can. I would think a GA-20 parts alone would be between $500 and $1000.

Thanks Lowerleftcoast for the shout out (and all the help) - I have been building the GA-20T in that thread. I guess the truth is it's always borderline building these things yourself if all you care about is acquiring a great amp. I did it for this reason AND to learn. You probably shouldn't expect to save too much money when you add it up (certainly if you value your time at all). So do it if you're prepared to fight hard for new expertise.

With a subject as niche as tube amp building, the only way to really acquire the knowledge is to try. The current state of the project is that I got as far as I could on my own with great help from this forum. I would say it's 99% of the way there, but it is now making a brief detour to the amp doctor to get a squealing issue fixed. Once that's done I will find out what the issue was, what the fix was, and I will have a great amp and a load of new insights.
 

RadioFM74

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Check out the podcast, Truth About Vintage Amps. Skip Simmons discusses Gibson/Epiphone amps quite often.

sorry for the ot but as a vintage amp junkie I wanted to thank you for mentioning the podcast. Sounds interesting!

Funny thing: one of the first subjects I've seen debated was "Getting more headroom out of a Silverface Fender Twin". Reaction: "WHAAT?? A-WHAAAAAAAT???":eek:

:D
 

Wally

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sorry for the ot but as a vintage amp junkie I wanted to thank you for mentioning the podcast. Sounds interesting!

Funny thing: one of the first subjects I've seen debated was "Getting more headroom out of a Silverface Fender Twin". Reaction: "WHAAT?? A-WHAAAAAAAT???":eek:

:D

indeed there are times where one might want more headroom from a Twin Reverb….for steel guitar or keyboards, for instance. The first thing to do is what Fender did in 1977…..use 2 x 220mfds in series for the first stages of filtering as opposed to 2 x 70Mfds in series. The original 2 x 70s yield a cap that is 35mfds. The 2 x 220s give a 110mfd cap…almost three times the filtering. fwiw, take a look at all of the amps that command high dollar on the market….Soldano, Dumble, Trainwreck, Big Mesas, etc….they all have a large capacitance in that first stage. It helps hold things together…especially on the low end and makes the amps more articulate….even when dealing with high gain in the preamp.
 




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