Audio Asylum Thread Printer
Get a view of an entire thread on one page
|For Sale Ads|
My three channel crossover is developing crackling sounds that seem to be tube related. I ruled out bad resistors. The reason I ask is the crossover is at the top of a forced air thermal thermal chimney in a rack with three KT88PP and three 6V6PP amps under it. To spite that heat the crossover tunes directly under two biscuit blower fans are abnormally cool - no heat to the touch.
Can tubes start to fail from being too cool?
P.S. The tubes are EH 12AX7's four per channel. The bottom of the chimney has a small furnace blower feeding it. There is plenty of airflow, perhaps too much>
Edits: 10/09/08Follow Ups:
That looks like the rack out of an old AM Collins transmitter I had that I used on 160 meters.Anyway I agree with twystd and you should clean the tube sockets and use Deoxit.Are you sure its in the crossover?
If the power supply waveform isn't pretty,neither is the sound in most cases.
I had crackling sounds from my amps, and traced it back to bad contact in my tube sockets. I cleaned and re-tensioned the contacts and the problem went away. Sometimes all you have to do is take the tube out and put it back in.
Wow. That is a nice stack.
From a purely convection cooling standpoint it would be preferable to have the sources low, the line stage in the middle and the amps up top.
I have had issues with EH tubes. High failures and poor sonics after break in.
So many items come into play with a complex system.
Why not spin some different tubes if you are happy that the heat from the amps is not an issue.
Tubes will not wear out prematurely if they are played in lower temperature environments, but they sound differently.
Many using complex tube dampening / cooling devices report better overall sound.
I am not sure how you this plays out in your system. I can tell you that I have had far too many issues with EH tubes than I care to disclose on a public bullitin board.
I don't have a single EH in play in my current system and I could not be happier with the sonics.
Hmm - not encouraging.
I haven't had any problems with EH 6V6s, EL34s or gold grid 300Bs (so far). Theu have a few 100 hours on them.
I have very little trouble with EH stuff. VERY little. I've replaced a few KT-88s, 12AX7s, and EL34s, but I can't recall replacing any other numbers at all. I'm not sure they are always the best tube sonically, but some are clearly VERY good sounding (the 6CA7, 7591A, and the 6072/12AY7 come to mind right away).
Their Philips big bottle variant and it sounds excellent and is perfectly robust at 475 volts.
Thanks Jim for recommending the EH that work best! I need to be careful not to paint such a broad stroke on an otherwise fine manufacturer.
Post a Message!
This post is made possible by the generous support of people like you and our sponsors: