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Scott 299A Static/Snow Sound Diagnosis

A

AnimaMvndi

New Member
Hi All,

First post on this forum and would greatly appreciate the help. I have a Scott 299A Tube Amp that was restored about 5 or 6 years ago. It runs fine most of the time, but occasionally after listening somewhere around 45 minutes to a few hours, the amp will begin to produce a static like sound. It isn't a "buzz", but closer to the snow you used to hear on TVs when turned to the wrong channel.

Once the snow sound appear, I can turn the volume knob and it was come in and out as I turn the knob, but it doesn't go away unless I power down the amp and turn it back on. After that, it's usually fine.

Is this a faulty tube? Any ideas?
 
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Both channels. Edit: Just to add, I can still hear the music playing. There's just this snow/static sound that is heard over the music.
 
Hi @AnimaMvndi and welcome.

I am just a novice and there are some great and knowledgeable tube guys that can help you better. A few questions though.
When you say restored; what was done?
Does it happen at all volume levels?
Do you have other speakers to try?
Does it happen with all input sources (i.e. phono, tape, radio)?
My point is try to isolate if it is the amp and not something else.
You may want to check connections and cables.
I have found that it helps to provide as much elimination and information as possible so that someone can help.

Hope that helps

Cheers
Rick
 
Last edited:
Good questions! I received the amplifier restored, so I don't know what was done to it. There's just a date of the restoration.

Yes, it does happen at all volume levels. I haven't tried different inputs, I can try that. Although, I have to check whether the 299A has different inputs I can use. It has a phono and radio, but I think that's it. It was made in the late 1950s.

I am confident it's not in any of the connections leading to the amplifier. Whether there are any connections in the amplifier that are faulty is above my knowledge level.
 
Try reseating the tubes (with the amp off of course) It sounds like a socket is not making great contact after it warms up thoroughly.
 
Probably a tube issue but could also be a switch or a knob.

Did you try all of the knobs and switches while it was making the noise or just the volume?
 
agreed on re-seating the tubes and giving all of the controls some exercise if you haven't yet. No point in getting too deep in the weeds with diagnostics yet. Since its in both channels that significantly limits what its likely to be, but random noises like this often tend to be bum contacts somewhere.
 
AnimaMvndi said:
So, I reseated the tubes and gave it a listen for several hours with no problem. Seems to have fixed it. Thanks for all the help!
Click to expand...
Good to hear. On 9-pin tubes, what I have found with HH Scott amplifiers, the tube sockets, whilst good manufacture, often have some form of corrosion after all of these years. I absolutely do NOT use anything abrasive in the socket. I use the orange Dentek dental brush with DeOxIt D5 and brush each opening of each socked slowly. You can actually feel the resistance to the brush decreasing after several strokes.

For the tubes, remember tube pins are raw metal (except gold pin Radio Shack Realistic). I often use a very thin X-Acto knife and literally scrape each pin. It only takes a few strokes and they are shiny. They are not plated and this, in conjunction with the cleaning of the sockets has solved all but one tube socket problem. (I did have to replace one socket).

Hope that helps.
 
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