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Old 23rd July 2012, 03:11 PM   #1
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Default St. George Amplifier

Got this Massie degined amp, model 24-10
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(2) 50C5's and (2) 12AX7's

I 've replaced the caps and it sounds excellent, EXCEPT, I can't get tremolo to work. Anyone a) have any ideas, b) know of a source for a schematic?
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Old 23rd July 2012, 04:22 PM   #2
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Well - One approach would be to draw the schematic from the actual amp. Baring that, one could draw just the tremolo circut and post it here. A tremelo consists of a low frequency osicalator that controls a variable gain stage. Take a look at other schematics and try to identify the parts. I asume that the tremulo uses of one of the 12AX7's so start by figuring out which tube is the tremulo tube. Check for supplly voltages on that tube. Check for signal input to the tube. It may help to follow the wires from the tremulo control to the tremulo tube. Do you know about safety around tube circuts?
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Old 23rd July 2012, 04:49 PM   #3
kevinkr is offline kevinkr  United States
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Given the tube complement I would check to make sure this thing has a power transformer in it, if it does not add an isolation transformer to minimize the danger of electrocution in use. There may be room inside for a small transformer, and a proper line cord with grounding conductor is a must.
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Old 23rd July 2012, 05:35 PM   #4
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Thanks for the responses. I'm well familiar with tube equipment, but mostly radios and HiFi Stereos, guitar amps are a new thing for me. I will run with an isolation transformer because this thing doesn't have a transformer on board.

There is a circuit board of sorts where all the components are mounted. I'll see what I can do tracing one of the 12AX7's back to the speed and intensity controls.

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