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Tube Diagnosis

I am a bit limited in my experience with Tube quirks so looking for a bit of insight.

With no music playing I noticed a small amount of noise coming from the left channel of my system a couple weeks ago.

I isolated it to my preamp (Aesthetix Calypso - 12AX7 gain and a 6922 output in each channel) and then further to the left channel output tube. I did this by swapping the left and right output tubes and the noise moved with the tube.

I am running used tubes with a reasonably low but unknown amount of hours, all was silent until a couple weeks ago. Telefunken ECC803S for Gain and amperex PQ white 6922's for Output.

The 'noise' is a low level crackle that seems random. i.e. crackle crackle---silence for a random amount of seconds--crackle and so on. It is independent of volume and does not change if the tube is lightly tapped! The noise is low as I mentioned but can be heard during silent sections of music and is distracting enough for me to buy new tubes to get rid of it. The only other thing I have noticed is that the noise is a bit more pronounced when I first turn on the system, after it warms up things mellow but the noise does not go away.

I have experience with tube rush and what I would call microphonic noise - tube noise that increases with volume and responds to tapping of the tube. This is something different.

So, is this the sound of a Tube that is dying or just a tube that went noisy and will now stay that way?

Thanks
nikturner920
nikturner920 OP
144 posts
 
Tried cleaning the pins last night, no dice. Looks like I am going to try and get a NOS pair. Real bummer as it is just enough noise to annoy me but the tube still sounds great otherwise.

I was able to dig up another pair of 6922's to swap in for the time being. Noise free, but a bit of the magic gone that I had with the amperex PQs.

Looks like I will be calling Andy at VTS.
atmasphere's avatar
atmasphere
11,778 posts
 
Cleaning the pins will not do a thing- that was obvious when the problem moved with the tube!

The tube will be like this forever. If you don't mind tapping it occasionally, you might be able to use for quite a while longer, but you will find that when you get a quiet tube in there that it will be a real relief.

Vintage Tube Services was/is an excellent recommendation. Andy takes the time to delve into the circuitry of his customer's equipment; IOW he already knows what sort of tube you will need for your preamp.
nikturner920 OP
144 posts
 
Bit the bullet and called Andy. He is great. NOS set of amperex super low noise a-frames on the way to try and decided to test out a pair of Mullard cv-4004s for in the 12AX7 slots.

Tube rolling is fun, but damn I wish they were $10 like the old days.
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