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VTL driver tube question
VTL driver tube question
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Old 29th August 2012, 02:51 AM   #1
speakerfritz is offline speakerfritz  United States
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Join Date: Jul 2008
Default VTL driver tube question

I do have a manual and schematic on order...not sure how long it will take to get here. Maybe someone knows the answer to this question. On the amp I am asking about there are 2 6350 tubes and 1 12at7 tube. After hitting the mute switch, one of the 12at7's blew and one of the 6350's was really hot. checked fuses nothing blew. replaced both tubes and amp powers up and works. But now I'm wondering, if one side of the driver tube circut is damaged...I would still hear sound. So I shut off both amps...the one that blew the tube and the one that did not. I pull out the left 6350 driver tube on both amps and powered the amps up. As expected....I heard music. shut the amp off. put the left 6350 tube back in both amps and pulled the right 6350 tube. powered up both amps. On both amps...no music. So one of the 6350's bust be a phase inverter which does not work if the partner driver tube is removed....but the partner driver tube is able to drive some power tubes with the phase inverter removed. A schematic will certainly help....may wind up making a tube test socket for the 6350 that will let me measure output on both 6350's. I looked at a few VTL schematics and it does look like their inverter runs of the driver tube instead of the input tube. My test would work great if both 6350's were fed by the 12at7 directly.
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Old 29th August 2012, 10:50 AM   #2
palmas is offline palmas  Portugal
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Join Date: Jun 2007
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File Type: pdf VTL750 bal input circ.pdf (31.1 KB, 199 views)
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Old 4th September 2012, 08:39 PM   #3
speakerfritz is offline speakerfritz  United States
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Join Date: Jul 2008
ok, that explains it...thanks for posting
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