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previous: Gil Ayan What a great little discussion. So... -- 5/16/2000 11:18 PM

Re: Thanks Guys....

5/17/2000 12:28 AM
MBSetzer	Re: Thanks Guys.... Hi Gil & All: One of the original 6V6GT in one of my SF Champs was actually a Sylvania that had been relabeled by Fender, it was the same type as the JAN Philips we see now. I also have a few more old Sylvania, and other company (including RCA) relabels of the same tube type. They all do the red seam especially in a champ where stock dissipation is almost 50 ma, 20Watts at 400 to 420VDC. To me it seems intentional, logically the plate would best be able to handle the focused beam where there is more material. Of course these amps stock had no screen resistor but Leo actually didn't expect us to maximize the volume either, I like 1K 2W Carbon. Of course these are class A amps and only glow when you are not playing through them. As soon as you even jam at moderate volume, the excess current making the plate glow is then transferred to the OPT instead. This tends to explain why there are less problems running 50ma bias current at idle compared to push-pull class AB. It might be worthwhile to see if the Deluxe also cools off the plates a little as you play at moderate volume, it could happen We know the screens would like to heat up. I wouldn't do this on a Fender amp, but on my bench model champ, I adjust the B+ downward for the old Sovtek tubes, not because the plates glow at idle, but I set the variac while jamming maximally with a hot guitar and watch the screen glow as bright as I can stand it for the peak signal events. My findings agree well with JStokes here, I wish the Sovtek were better tubes, the screen is the weak point for them, but I also do not disregard what O'Connor the recognized tonemeister says, I find they sound actually excellent when operated at the maximum conditions determined this way for each tube. I just wouldn't take the chance in an expensive amp with the old Sovtek. I think the darkened room evaluation is too sensitive for the JAN, I don't worry until it seems too noticable in a well lit environment, or the ambient temperature is above 85 degrees F or so. Then I place a fan behind the amp. For your amp I would consider using a variac and return it to operating at original design voltage to keep it stock without any B+ dropping resistor. Might even go as far as reducing mains until the heaters are 6.0VAC on the true RMS meter, might be worth checking in case that is all it takes to make the plates cool to a comfortable temperature, all the tubes would likely last a lot longer too. Hope this helps, Mike

5/17/2000 12:28 AM

MBSetzer

Re: Thanks Guys....

Hi Gil & All:

One of the original 6V6GT in one of my SF Champs was actually a Sylvania that had been relabeled by Fender, it was the same type as the JAN Philips we see now.

I also have a few more old Sylvania, and other company (including RCA) relabels of the same tube type.

They all do the red seam especially in a champ where stock dissipation is almost 50 ma, 20Watts at 400 to 420VDC. To me it *seems* intentional, logically the plate would best be able to handle the focused beam where there is more material. Of course these amps stock had no screen resistor but Leo actually didn't expect us to maximize the volume either, I like 1K 2W Carbon.

Of course these are class A amps and only glow when you are not playing through them. As soon as you even jam at moderate volume, the excess current making the plate glow is then transferred to the OPT instead. This tends to explain why there are less problems running 50ma bias current at idle compared to push-pull class AB.

It might be worthwhile to see if the Deluxe also cools off the plates a little as you play at moderate volume, it could happen ;-)

We know the screens would like to heat up.

I wouldn't do this on a Fender amp, but on my bench model champ, I adjust the B+ downward for the old Sovtek tubes, not because the plates glow at idle, but I set the variac while jamming maximally with a hot guitar and watch the screen glow as bright as I can stand it for the peak signal events. My findings agree well with JStokes here, I wish the Sovtek were better tubes, the screen is the weak point for them, but I also do not disregard what O'Connor the recognized tonemeister says, I find they sound actually excellent when operated at the maximum conditions determined this way for each tube. I just wouldn't take the chance in an expensive amp with the old Sovtek.

I think the darkened room evaluation is too sensitive for the JAN, I don't worry until it seems too noticable in a well lit environment, or the ambient temperature is above 85 degrees F or so. Then I place a fan behind the amp.

For your amp I would consider using a variac and return it to operating at original design voltage to keep it stock without any B+ dropping resistor. Might even go as far as reducing mains until the heaters are 6.0VAC on the true RMS meter, might be worth checking in case that is all it takes to make the plates cool to a comfortable temperature, all the tubes would likely last a lot longer too.

Hope this helps,
Mike