Sovtek 7199

[Dynacophil]

Hi

I use one of my st-70 for the rear-speakers of my system. I installed the 7199 a while ago, new, and didn't listen in 5channel-mode a while...

Yesterday i did, and wondered about the light rustling noise coming out of the speakers behind me. really made me nervous. checked the connections, alright. after a while i switched the 7199 to a set of RCA and the amp was dead quiet, as I knew it.

I bought those 7199 Sovteks some time ago and just stored them to have reserve... does anywone know this effect? I am not really sure about the description. Rustle shall be a sound paper makes - very lightly (our translator mrs. Gale told me...).
A Crackle would be way too much. "Knistern" would be the german word, or maybe a light "rascheln" - dictionary.com didn't really help me.

Are Sovtek 7199 known for this? I guess they are the only New Production 7199...

Helge

 

[GordonW]

I know the sound you are talking about. Not many 7199s make that noise, but 6DJ8s do it fairly frequently. It's like a semi-random rumble (like thunder), but several octaves higher and at very low volume.

Unfortunately, when a tube does that, IME, there's no saving it. Must just be replaced.

Regards,
Gordon.

 

[bricktop]

Give the pins and socket a little cleaning to ensure the connections are solid, if they are and it still makes the noise, then you can give up on it

 

[Dynacophil]

mmmh, it seems that I can't blame the Sovtek. in another ST-70 they are quiet, and the noise appeared again. I gotta check the sockets and maybe the solderjoints of pcboard. it rises or finishes when moving the 7199.

Sorry for the Sovtek prejudication...

 

[marty59]

I've got some Sovtek 7199's on my Dynaco also and I can't complain about 'em.

 

[GordonW]

If it's not the tube (as it appears), the sockets are indeed the next culprits to check.

If it's not the sockets or other bad connections, chances are it's a noisy resistor somewhere... resistors can make that sound, when growing old past their prime.

Regards,
Gordon.

 

[Dynacophil]

Hi
but - if Resistor, it wouldnt't change intensity ore go moving the Tube in the socket... doesn't it?
I guess I have a problem with the old plastic-sockets. Does it make sense to replace them or just clean chemically? (deoxit?)

 

[Dynacophil]

Hi

found the necessary half hour today

result:
a bad solderjoint on the old brown but upgraded PC-Board in the left half did this noise sometimes... I found the possible area light knocking with a tool on the board and resoldered all connections around this area.
Was not even one of the socket (what I thought because of the reaction on moving the tube) - it was an inch away... now it's quite quiet