KT120's with cj amps

[tonytsui]

Originally Posted by microstrip

conrad-johnson connect the filaments of the tubes to a resistive voltage divider fed by the HV to control leakage current of cathode to filament. Perhaps you should contact the factory about this problem - maybe changing one of these resistors can solve the problem.

Thanks for the suggestion. Will contact CJ.

[Bill Stevenson]

I live in South Florida and our local power company, FP&L, increases the line voltage during high demand periods. All my bias LEDs light up like a Christmas tree. This happens daily during peak demand times in the summer. We also have frequent lightning strikes. For example, during a typical summer afternoon thunder storm we register over 5000 lightning strikes in Palm Beach County alone. The Tampa area actually has even more lightning strikes. This can and does cause voltage spikes in the distribution network that can cause damage to electrical/electronic equipment. Your experience suggests to me the possibility that there could be something like this going on where you live and that it may be the cause of your tube failure rate.

[Coppy]

Hey Bill,

I'm running all 120s in a pair of LP140 mono blocks with no particular problems here in Sarasota. We do share FPL. I have noticed the bias lights however and will now pay some attention during warm afternoons. Don't guess you re-bias at those times. Thanks for your comments.

Bob

[tonytsui]

Originally Posted by Bill Stevenson

I live in South Florida and our local power company, FP&L, increases the line voltage during high demand periods. All my bias LEDs light up like a Christmas tree. This happens daily during peak demand times in the summer. We also have frequent lightning strikes. For example, during a typical summer afternoon thunder storm we register over 5000 lightning strikes in Palm Beach County alone. The Tampa area actually has even more lightning strikes. This can and does cause voltage spikes in the distribution network that can cause damage to electrical/electronic equipment. Your experience suggests to me the possibility that there could be something like this going on where you live and that it may be the cause of your tube failure rate.

Thanks Bill for the info. Here in Hong Kong there aren't many lightning strikes, and tube failures happen both in summer and winter, or quite evenly spread in the year. And there are not many occasions when I listen while lightning strikes. Furthermore, I am told my Audience conditioner has surge protection. And yes, the LEDs glow from time to time and I adjust them on the spot. Am waiting CJ's response.

[Bill Stevenson]

Jeff at cj says not to obsess over the bias and to ignore the lights if they come on due to the utility company raising voltage. This is a common practice apparently and according to Jeff it is not a cause for concern. But it seems to me that if the voltage is set too high or for too long that it is going to increase leakage between the heater and the cathode. Lightning strikes even moreso, but if you don't have them that idea is a non-starter. Nevertheless, your experience suggests that something in your environment could be the root cause.

[Bill Stevenson]

Originally Posted by Coppy

Hey Bill,

I'm running all 120s in a pair of LP140 mono blocks with no particular problems here in Sarasota. We do share FPL. I have noticed the bias lights however and will now pay some attention during warm afternoons. Don't guess you re-bias at those times. Thanks for your comments.

Bob

No I do not re-bias, see my note to Tony for the reason not to over worry.

[Coppy]

Thanks Bill... Jeff is the man at c-j. Not obsessing and no worries here.
Seems to me in this hobby some of us fuss a bit too much over things that really don't matter. Figuring out what makes a hearable difference and what are just silly obsessions is an interesting challenge we face. It's about the music.

[Bill Stevenson]

You guys all have nice systems. I should figure out how to list my system as part of my signature like you have. But I completely agree that it is about the music. The stuff we use to get there is interesting of course, but it is a means to an end.

Bill

[Coppy]

Originally Posted by Bill Stevenson

You guys all have nice systems. I should figure out how to list my system as part of my signature like you have. But I completely agree that it is about the music. The stuff we use to get there is interesting of course, but it is a means to an end.

Bill

You may need to subscribe to get access to the signature area. And you get the pretty red thingy by your name. Not a bad idea anyway as you'll be able to buy at a discount as well. It has paid me and most others to join.

Bob

[Joe Appierto]

Originally Posted by Coppy

You may need to subscribe to get access to the signature area. And you get the pretty red thingy by your name. Not a bad idea anyway as you'll be able to buy at a discount as well. It has paid me and most others to join.

Bob

Exactly right. Plus I like the thingy.