Vintage R12R Ampeg - guitar amplifier - lack of audio output gain - need help
I have a vintage amplifier Ampeg R12R reverberocket '62s. There are 2
X 6SL6, 2 X 6SN7, 2X 6V6 and 1X 5Y3GT. I would like to know what is the power output of this amplifier? Not the reissue ... I mean the vintage ... I know that the R12R reissue is a 50 W RMS and use others vacuum tubes ( 6L6 instead of 6V6 and 3 X 12AX7). Here is my problem. There is a lack of audio power at the output . The volume position between 1 to 5 is very week (weak audio output) . From 5To 10 (the maximun) the output is strong (guitar control at max) and clean.I think that I have a lack of audio gain at the output of my amp. I checked the bias resistor of cathodes 6V6 (275 ohms on my meter) and I replaced the cathode bias capacitor by a 50 uf 50 V located to the cathode of the 2x 6V6 output tubes.The problem is always similar. I'm quite sure that I have a lack of audio power at the output. I checked all voltages ... it seems all OK. I tested the 2 audio output tubes with a Hickok 600A and I read 4000 mho for the 2 X 6V6 ... OK. The 6SL7 read normal. The 2 X 6SN7 read about 1700 mho the normal value is 2600 mho). I checked all the solders joint and I resolder each eyelets. Many coupling capacitors have been replaced in the section V1, V2, and V3 with very good caps.I checked all power supply caps = OK. The 2 x 6V6 run a bit hot. There is no Hum or strange noise. My problem is ... I have the feeling that ... my output have lack of power. Is it normal with the vintage R12R? If not, what is the problem? Help me a bit. Thanks a lot! Mike |
Vintage R12R Ampeg - guitar amplifier - lack of audio output gain - n
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