Re: Channel noise in Scott 200c amp

in article 1130531236.821125.279290@xxxxxxxxxxxxxxxxxxxxxxxxxxxx,
kaczmar2@xxxxxxxxx at kaczmar2@xxxxxxxxx wrote on 10/28/05 4:27 PM:

> I have a Scott 299c amp that has been working great for the past few
> years. Recently, I have been hearing noise in one of the channels
> (right.) The noise is an intermittent hissing/crackling sound (not
> too loud - low volume will drown it out.) This white noise does not
> change if the volume is adjusted up or down.
>
> I am not very well versed in tube electronics (or electronics in
> general) for that matter, so I really don't know what the culprit could
> be or how to test for it. I suspect it could be the output tubes but I
> really have no idea.
>
> On a related subject, is there a good book(s) out there that give a
> nice practical overview of consumer tube/solid state electronics.
>
> Thanks,
>
> Christian


Could be any number of things, such as a noisy plate resistor. First, clean
the tube sockets and check the tubes by substitution to eliminate them as
possibilities.

Good primers are by Morgan Jones (e.g. Valve Amplifiers) or Bruce Rosenblitz
(sp?). However, these authors cover more about design and operation than
troubleshooting.

There were many books written years ago dealing with troubleshooting tube
circuits. Check your local library.

Jon

.

Relevant Pages

  • Re: Relationshp of Vk to Rk and noise?
    ... a shield over the tube all helped, but there is room for significant ... I'm assuming that the hiss you are referring to is ... Resistor and tube noise is White Noise, at equal energy throughout the bandwidth. ... Likewise, as it is with the single vacuum tube, the single jfet can not present anything clearly ...
    (alt.guitar.amps)
  • Re: basic understanding of how electric guitar gear works
    ... Fender Frontman 15R Amp ... amp I can't get them last that long (say, I'd like the sound to last as ... amplifying initial small noise as well). ... I'm older, have been playing for a while, and have accumulated some tube amps. ...
    (alt.guitar.beginner)
  • Re: Relationshp of Vk to Rk and noise?
    ... a shield over the tube all helped, but there is room for significant ... I'm assuming that the hiss you are referring to is ... Resistor and tube noise is White Noise, at equal energy throughout the bandwidth. ... Even at the same gm FETs have a 6dB advantage from the get go due to ...
    (alt.guitar.amps)
  • Re: MC PHONO PREAMP
    ... gives a calculated effective input noise resistance of 1250 ohms which ... Draw a vertical line through a wanted Ea for the tube and plot where Eg1 ... Its input noise ... that's why I am suggesting a 40dB amp before it. ...
    (rec.audio.tubes)
  • Re: MC PHONO PREAMP
    ... equivalent input noise resistance for a tube. ... The EINR isn't the only source of tube noise. ... In my case the following amp has gain of 1,500, so this becomes 180mV, ...
    (rec.audio.tubes)