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Gibson GA 15 RV


rami939

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Howdy,

Does anybody knows if there's a way to change the output transformer taps without taking the amp to a technician ?

The amp does have internal taps,but it seems like there's a little transistor or something that looks like it,that have to be move from tap to tap ,desoldering first and then soldering again .

There's an speaker output jack that is marked 16 ohms.

Would using a 8 ohms external cab damage any thing in there ?

Thanks in advance.

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  • 5 months later...

Howdy,

Does anybody knows if there's a way to change the output transformer taps without taking the amp to a technician ?

The amp does have internal taps,but it seems like there's a little transistor or something that looks like it,that have to be move from tap to tap ,desoldering first and then soldering again .

 

If you're handy with a soldering iron, then you can do it yourself.

If I remember correctly, that "transistor" is a zero ohm resistor. It's effectively a jumper wire.

I've switched it myself when I wanted to use an 8-ohm speaker.

 

The dangerous part about working in an amp is the electric charge that may still be present in the large capacitors of the power section.

So before working on the amp, you should learn how to check if there is a charge in those caps and how to discharge them.

If I remember correctly, I think this amp is designed to automatically discharge the caps when you turn the power off but I don't know how long it takes to discharge them to a safe level.

 

 

Would using a 8 ohms external cab damage any thing in there ?

 

I try not to do it, but I have done it in the past without any damage.

My Fender Twin reverb has a 4-ohm load, but they have an extension speaker jack so you can run an external cab in parallel with the speakers in the amp. By doing that, you lower the resistance to something below 4 ohms. If it really is that bad to run it with a lower resistance, why would Fender risk potential damage by adding an extra speaker jack?

 

What I've read is that it is always bad to go to a higher resistance (e.g. something more than 16 ohms in this case). That is why they always say you should have a speaker or "load" connected to your tube amp before turning it on. When you have no speaker connected, you have infinite resistance.

 

I don't have one, but a handy tool to have would be a Weber Z-matcher. It's a box that allows you to do stuff like match a 16 ohm output of your amp to an 8 ohm speaker.

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