I just bought a GFA 555 and gtp-400 preamp, paid 300 for both about ten years old both still work perfect, this amp has never been opened is there any kind of maintenance i should do? What size wires should i use to speakers? this amp sounds awesome, thanks in advance.
Joe
Joe
It's a nice amp, but it is older than you think. As such, it is wise to replace the electrolytic caps (even the big ones on the Power Supply).
If it is a mk 2 version there are probably smaller bypass caps on the PS caps, otherwise you can add these (it will tighten up the bass). Other than that, check the bias adjustment (use the factory recommendation).
With any old amp, check if there is DC on the output. If it is in the range of 10's of millivolts (and comparable in each channel), then don't worry. If it is in the the range of 100s of milivolts do not use it.
If it is a mk 2 version there are probably smaller bypass caps on the PS caps, otherwise you can add these (it will tighten up the bass). Other than that, check the bias adjustment (use the factory recommendation).
With any old amp, check if there is DC on the output. If it is in the range of 10's of millivolts (and comparable in each channel), then don't worry. If it is in the the range of 100s of milivolts do not use it.
when you talk about the millvolt test could you explain, I am new to all this I just bought a fluke multi meter would you do the test in ohms?
I have made some incorrect assumptions about your skill-set. In all honesty, this is not a project for you.
Well, to check the DC offset in your amp, you have to measure the outputs just leave the meter in DC and then measure the outputs(speakers terminals). make sure there is not source in the inputs. leave the unit "warm up" for at least 1/2 hr then measure it. DO NOT SHORT THE OUTPUTS
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