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I did an unintentional mod on my V4 - I replaced the four output tube anode plate resistors (R39, R40, R45, R46) and used 10 Ohms instead of the 3.6 ohms that were in the amp. The values weren't labeled on the Ampeg schematic, and I used Joe Piazza's schematic which showed 10 ohms when I ordered the parts. The 3.6 ohm resistors are listed on the Ampeg replacement parts list, and my old resistors do measure 3.6 ohms. Anyone care to comment on the effect of this resistor change? Is it insignificant or should I order up some 3.6 ohm power resistors and put it back to stock.
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It might increase sag a little, slightly softer attack when the amp is drawing more current. If you turn up your V4 loud enough to notice your going to need earplugs anyway."Take two placebos, works twice as well." Enzo
"Now get off my lawn with your silicooties and boom-chucka speakers and computers masquerading as amplifiers" Justin Thomas
"If you're not interested in opinions and the experience of others, why even start a thread?
You can't just expect consent." Helmholtz -
Those extra 6 ohms or so ought to drop the B+ to the tube by about a half a volt at 100ma. That doesn't seem like enough "sag" to hear.Education is what you're left with after you have forgotten what you have learned.Comment
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Enzo, right - and some of the V-4s came with the 10 ohm resistor - have serviced a few and could not tell any difference. But it's hard as hell to get a V-4 to sag anyway - lotsa reserve in the power supply.
RobComment
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Thanks gentlemen for the great info and saving me the trouble of replacing those resistors....
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