K60/Asteroid...VVR? Which power tubes?

[dayn]

Dana, will VVR work on a 60 watter? (website says under 50 watts, but others say they have used it on the K60)

Which power tubescan/should I use? Mine came used with JJ E34Ls. Can I use 6L6, KT-77, 5881?

Thanks!

[UR12]

Dana, will VVR work on a 60 watter? (website says under 50 watts, but others say they have used it on the K60)

Which power tubescan/should I use? Mine came used with JJ E34Ls. Can I use 6L6, KT-77, 5881?

Thanks!

I spec'd the VVR out at 50 watts because after that you get ino all kinds of nightmares like fans,etc trying to cool the mosfet. The Komet amps have a thicker than usual chassis and makes a great heat sink. I have known a few people who have added the VVR and it worked but one amp in particular kept blowing mosfets. I found out later that this amp was being used in a studio and left on over 8 hours a day with the VVR at 1/2 to 3/4 power and the standby switch in the Operate position. There was also no external heatsink installed on that amp. So yea you could probably make it work but I don't support installing the VVR in any amp over 50 watts.

[Roe]

the k60 is a 40+watt amp, not a real 60 watter imo

[UR12]

the k60 is a 40+watt amp, not a real 60 watter imo

I don't remember off the top of my head which model it was installed in other than it was a Komet.

[M Fowler]

The K60 has 480v to 500v on the plates running a 5k8 primary OT with a pair of EL34's that should be 60 watts as far as I know.

Mark

[dayn]

Thanks for the VVR info!

What about power tubes; stick with the JJ E34Ls or can I go with JJ KT-77's? How should I bias either?

[Gaz]

I've had many screen grid failures with the JJ KT77s in Plexis (even with 1k and high screen resistors), which run them hard like a Komet, The tone between the KT77 and a 6L6 is marginal to me, and I would say stick with E34Ls, Winged C EL34s, or some nice 6L6s, which are more robust and draw less screen current than a Kt77. Just my very humble opinion, of course.

[Roe]

The K60 has 480v to 500v on the plates running a 5k8 primary OT with a pair of EL34's that should be 60 watts as far as I know.

Mark

mine measures 452v with kt88s and 484v with el34s.

the wattage readings are not exact. for instance, the k50 is rated as a 50w amp althought voltages are higher and the primary is lower

[M Fowler]

The K50 uses a 4k8 primary OT but has SS rectifier so increased voltage; however, with the lower primary OT reduces the wattage.

[Roe]

The K50 uses a 4k8 primary OT but has SS rectifier so increased voltage; however, with the lower primary OT reduces the wattage.

I thought that the lower z (4k8 vs 5k8) increases the wattage if the voltage is the same.

[dayn]

I think I will stick with JJ E34Ls.

WHat number should I bias them to?

[Roe]

what sounds good but watch for redplating and do no exceed 70% by much

[Zippy]

The K50 uses a 4k8 primary OT but has SS rectifier so increased voltage; however, with the lower primary OT reduces the wattage.

I thought that the lower z (4k8 vs 5k8) increases the wattage if the voltage is the same.

Hmmm, free power... Too good to be true?

[Roe]

no free power. I don't even think what I'm saying is controversial