Biasing

I went to bias a tube but I couldn't. I couldn't get it to stabilize then the next day it wouldn't come off 0. I tested it and it tested good. But I also have been getting weird noises from that channel. Any ideas?

What kind of noises? Sometimes tests aren't everything in valves or in other electric components. Don't you have another valve to test if it's a valve problem or not?

I swapped them around the problem followed it. The sound was a squeel. I removed it out of my system. I still don't have all of the store moved. So you think I should replace it?

What gets me is I don't even have 50 hrs on this Chinese tube. To replace is going to cost anywhere from 150.00 to 300.00 for a matched quad set.

Sounds like you're on the path to learning why chinese tubes are not allowed in my home.

It's bad enough that we spend good money on them only to discover that many don't even come close to their minimum ratings. Chinese rectifiers are the worst.

Paying for quality tubes up front is much cheaper than trying to replace an unobtainable power or output transformer.

Sure there are some chinese tubes that are fairly satisfactory, but i have neither the disposable income, or disposable gear to determine which are satisfactory and which are junk.

Just my .02 y'all understand...........................

I do.

Did the noise come from the valve you'd try to biasing? If it so, maybe you doing that in some way affected it....I know that many sources for biasing information just specify plate (or cathode) current settings; telling you to bias your 6L6s (for example) at "35 milliamps" is nonsense. Unless you take the plate voltage into consideration, a current specification is meaningless.

Sounds like you're on the path to learning why chinese tubes are not allowed in my home.

It's bad enough that we spend good money on them only to discover that many don't even come close to their minimum ratings. Chinese rectifiers are the worst.

Paying for quality tubes up front is much cheaper than trying to replace an unobtainable power or output transformer.

Sure there are some chinese tubes that are fairly satisfactory, but i have neither the disposable income, or disposable gear to determine which are satisfactory and which are junk.

Just my .02 y'all understand...........................

We represent both Shuguang and TJ FullMusic in North America. Their 'Export' quality tubes are second to none of the current crop of manufacturers both with over 50 years of continued manufacturing experience. TJ Fullmusic is widely recognized as making some of the best sounding and performing tubes in the industry, so to dismiss all Chinese tubes means you are listening to less than the best, your call of course.

If you buy the cheap 'not for export' tubes from unauthorized sources you are likely getting the 'dissapointing tubes'

Speakerman, is that the amp you dropped? A bad tube with 50 hours on it is why there are the common 90 day warranty on tubes, if they are going to fail prematurely, they do usually within the warranty period.

With a manual bias amp, especially with tubes that have low hours, you do not need a matched quad, simply swap out a single tube and you will be fine. For high hour tubes, a matched quad is recommended.

Cheers,
Ian

no i didn't drop it nor am i in a good mood when i have to spend money on a low time tube.

How long have you owned the tube for? If only 50 hours on it it should have shown up within your tube warranty period.

Not being able to bias a tube can also be caused by a failed resistor or connection in the bias circuit, which is why I asked you if it was the one that dropped. Of course having an amp drop isn't going to do much for tube life either.

i have a bad tube. i'll take care of it. if it's more than a tube i'll use it as a boat anchor.

The tubes are coming home Sun. I replaced the tube in the 1 hear and hooked up the cdp. Stevie Ray sounds great.
Will do pics Sun. evening of both systems.

Nice.

This post has been edited by speakerman1 on January 14, 2009 03:00 pm

The beginning of the end.