You are here

Log in or register to post comments
Reptiles00
Reptiles00's picture
Offline
Last seen: Never ago
Joined: Mar 16 2006 - 6:28pm
New Tubes, New Noise

Hi All,
I just received new JJ EL34 tubes for my amplifier and now when I turn it on I receive a FIZZING type noise through my left channel. The Volume does not effect the sound and I only have about 14 hours into breakin.
The sound comes about 10 seconds after I power up and goes away completely after about 20 seconds later.

Thoughts?

Thanks,
Don L

ampnut
ampnut's picture
Offline
Last seen: Never ago
Joined: Sep 4 2005 - 5:26am
Re: New Tubes, New Noise

Swap the tubes between the left & right channels.... just to make sure its tube hiss...

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

Do the swap, but you are probably hearing some excess gasses or oxidations burning off inside the tube envelope. With the lights off and with the room darkened, observe the tubes when you first power up the amplifier. You want to see all the tubes come up to the same temperature evenly and together. If the tubes warm up evenly and all have a similar "glow" when at operating temperature, there's likely nothing to worry about and the noise will disappear over the next few days. If not, and the noise travels with the tubes, that's the time to call your tube dealer.

Reptiles00
Reptiles00's picture
Offline
Last seen: Never ago
Joined: Mar 16 2006 - 6:28pm
Re: New Tubes, New Noise

Thanks,
The noise did travel with the tube swap and when I power up one tube seems to take a little longer to light up to the same brightness as the others.

I'll just have to keep and eye on it and if it doesn't go away I'll get it swapped out.

Thanks :-)

Don L

imispgh
imispgh's picture
Offline
Last seen: 3 years 2 months ago
Joined: May 23 2006 - 10:37am
Re: New Tubes, New Noise

If it is the tube settling in- the getter burning in - you want to change tube vendors next time and find one that checks the tubes and does this for you. Most likely they are not matching pairs.

CECE
CECE's picture
Offline
Last seen: Never ago
Joined: Sep 17 2005 - 8:16am
Re: New Tubes, New Noise

When you don't order matched pairs, you don't get matched pairs. They also sell matched quads. Checkout www.partsexpress.com They have JJ, Harmonix, some NOS, lotsa new I got a whole bunch of different types for spares EL34, 12AX7WP 12AU7 etc etc. Even got some NOS Philips Holland, amperex Holland/USA, all kinds of NOS, good prices and stock The one Russian factory is making most of the brands. Tung-Sol, JJ, Harmonix, Svetlana, and a couple of CZ brands, how many factories are there really making tubes, not many, a few Chinese ones?

Reptiles00
Reptiles00's picture
Offline
Last seen: Never ago
Joined: Mar 16 2006 - 6:28pm
Re: New Tubes, New Noise

Thanks again :-)
They came in as a matched quad and the test numbers on each box shows 32 - 50.

Tonight when I got home I had the fizz and a small pop then the noise went instantly away.
hmmmmmmmm

Don L

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

Ahhhh, the magic of tubes!

ampnut
ampnut's picture
Offline
Last seen: Never ago
Joined: Sep 4 2005 - 5:26am
Re: New Tubes, New Noise

One tip I was given for NOS tubes ( Which I have Not tried ! ) was to bake them in a (food) oven at about 150 deg C, for 3 hours, then shut down the oven, and keep it closed, cooling down overnight.

Next Morning the tubes are good to use.

Any feedback on this ?

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

I believe you are referring to instructions for resetting the potting material in transformers, not for NOS tubes. A tube runs at several hundred degress, so it is unlikely a 150 degree oven is likely to affect anything in a tube's structure.

ampnut
ampnut's picture
Offline
Last seen: Never ago
Joined: Sep 4 2005 - 5:26am
Re: New Tubes, New Noise

Maybe I got the temperature wrong.... but the procedure WAS given to for Tubes, not Transformers.

I also wonder if the Outside of tubes, including the glass envelope would reach several hundred degerees C during regular operation...

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

Do you also wonder what happens should you apply your tongue to the outside of a frozen flagpole? Look at a tube in operation. Actually, go ahead and touch it. There is a burning, glowing filament a few millimeters away from the glass envelope. And, the glass envelope is the only heat sink that filament has. It is no coincidence it resembles both a light bulb and a space heater. Have you touched one of those while in operation? Now, do you really still wonder about how hot a tube gets?

Just what is your "method" supposed to do to a tube and when would you apply it? There is nothing you can do to a tube at 150 degrees. Even the solder connections require more heat than 150 degrees. What are the symptoms of a tube that would make you use this technique? You certainly can't be trying to restore the vacuum. Once the tube is worn out, it's worn out. What do you expect after completion? And, why only NOS tubes? Who told you this bit of information? What else did they tell you? That you would go blind?

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

Of course, I meant you would go blind if you sat too close to the television. Of course.

CECE
CECE's picture
Offline
Last seen: Never ago
Joined: Sep 17 2005 - 8:16am
Re: New Tubes, New Noise

150 C? What kind of oven is that in a house?

ampnut
ampnut's picture
Offline
Last seen: Never ago
Joined: Sep 4 2005 - 5:26am
Re: New Tubes, New Noise

I thought this would be as good a time as any to research the net on the operating temp of the glass shell of a audio vacuum tube.

There was a ref ( http://www.harpamps.com/micKtubes/RTV-Tube-Damping.html ) on Tube dampers, which says

" By the way, vacuum tubes are specified for dissipating their rated power at a glass envelope temperature of about 200-250C, according to the data books. What does 3M
O-ring material do at over 200C? Does it decompose, melt, or just quit damping? "

Just out of interest to readers ..... the site recommends
"A workable and highly effective alternative that I've used for quite some
time is the high temperature RTV gasket material sold in auto parts stores.
This gook goes for about $4.00 a tube (of gook, not vacuum...) and one tube will treat MANY vacuum tubes. It cures to a dense silicon rubber..."

So the glass temp does not get near the several hundred degree C mark.

DUP, looks like I'm lucky ?? The oven at my home has a thermostat, that runs from 125 deg C to 275 deg C. !

Anyway, its all besides the point now, that Don L's Tube noise has vanished....

CECE
CECE's picture
Offline
Last seen: Never ago
Joined: Sep 17 2005 - 8:16am
Re: New Tubes, New Noise

So you can only use metric recipes? Must be one of them thare furon ovens. We should only be cooking with "F" heat, not "C" heat. It will affect the food flaor. similar to how wire heated and cooled affects teh sound.

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

Ampnut - You must work for the government and have failed to read further into the article from which you draw your "facts".

"Of course, it's preamp tubes that really need vibration damping, and they
usually aren't run that high, but I'd be careful about putting the rings
on high temperature output tubes until I knew it would not melt down into
the tube socket, glueing the tube in, or decompose in place."

A variance in C and F temps seems to be at the heart of our discussion and, as stated above, there should only be F's allowed in any discussion of "tubes". To discuss C's we should instead be discussing thermionic "valves". The usage difference is quite unacceptable under the new Congressional Guidelines of Official Languages. You are excused this time; but, be forewarned, in the future deportation of all non-Official languages and their users will be carried out posthaste.

ampnut
ampnut's picture
Offline
Last seen: Never ago
Joined: Sep 4 2005 - 5:26am
Re: New Tubes, New Noise


Quote:

there should only be F's allowed in any discussion of "tubes".

That is SUCH A NARROW View of the world..... !

Infact most of the world now works in deg C .... but then, "World" itself must have a Very Local perspective for you....

Jan Vigne
Jan Vigne's picture
Offline
Last seen: Never ago
Joined: Mar 18 2006 - 12:57pm
Re: New Tubes, New Noise

Yep, you get it.

  • X
    Enter your Stereophile.com username.
    Enter the password that accompanies your username.
    Loading