Hi Guys,
Hopefully this is in the right section, if not then could the mods move the post where required.
I have a Sherwood AV amplifier that is circa 20 years old. It's no longer used for surround sound (long story) - so its connected to the PC so we can listen to streamed music. It's been fine up until the other day when I noticed a very low buzzing sound from the speakers (Floor standing Gale units) whilst I was waiting for the PC to boot. The PC's line out is connected to the analogue input (CD) and isn't noticeable when the music is played, unless there is a really quiet section. The digits on the display for the volume run from 0 to 70, and the buzzing only starts to get louder after 40. At full volume with nothing being played there is a constant underlying hum with the buzzing.
I first thought that it may be the output from the PC, so installed a dedicated sound card, but the buzzing is still present. If I disconnect the two phono plugs at the rear of the amp, the buzzing is still there too, which would suggest the problem is with the amp rather than the PC or any ground loop issue
I've also tried connecting via the coax digital output from the new card and when nothing is playing there is no buzzing even at full volume. However as soon as the PC outputs audio the buzzing starts, and then stop when the audio stops. I'm assuming that with digital output, the signals will go through some digital to analogue conversion before being fed into the pre-amp section of the amplifier?
I've attached an image from the scope of the output from the headphone socket (max volume) just in case it helps someone advise me what may be the cause. My thoughts are either power supply, or possibly needing a re-cap of the pre-amp ??
Thanks in advance
Malcolm
Hopefully this is in the right section, if not then could the mods move the post where required.
I have a Sherwood AV amplifier that is circa 20 years old. It's no longer used for surround sound (long story) - so its connected to the PC so we can listen to streamed music. It's been fine up until the other day when I noticed a very low buzzing sound from the speakers (Floor standing Gale units) whilst I was waiting for the PC to boot. The PC's line out is connected to the analogue input (CD) and isn't noticeable when the music is played, unless there is a really quiet section. The digits on the display for the volume run from 0 to 70, and the buzzing only starts to get louder after 40. At full volume with nothing being played there is a constant underlying hum with the buzzing.
I first thought that it may be the output from the PC, so installed a dedicated sound card, but the buzzing is still present. If I disconnect the two phono plugs at the rear of the amp, the buzzing is still there too, which would suggest the problem is with the amp rather than the PC or any ground loop issue
I've also tried connecting via the coax digital output from the new card and when nothing is playing there is no buzzing even at full volume. However as soon as the PC outputs audio the buzzing starts, and then stop when the audio stops. I'm assuming that with digital output, the signals will go through some digital to analogue conversion before being fed into the pre-amp section of the amplifier?
I've attached an image from the scope of the output from the headphone socket (max volume) just in case it helps someone advise me what may be the cause. My thoughts are either power supply, or possibly needing a re-cap of the pre-amp ??
Thanks in advance
Malcolm