Good evening, I am a user of a marshall sv20c, yesterday arrived my tone king attenuator from music store, i connected it to my amplifier and everything was fine... today as I opened my combo with attenuator a noise appeared (apart from the natural noise it makes as always due to volume...) so this noise appeared with a sound like "zzzzz" for less than 5 seconds and then stopped... after 5 minutes it reappeared... this happened for about 3-4 times if i am not mistaken, for the next 2 hours the amplifier did not do it again... while this unwanted noise was present for a few seconds the amplifier sounding without any problem on the guitar strings. The amplifier has been purchased new since June 2020, i also had about 1.5 - 2 months to put it into operation, another strange thing I noticed the moment that made these noises the weather outside was blowing very strong wind and just the wind stopped just the noise did not reappear ...accidentally? Anyway, the power strip im using for amplifier, attenuator and pedals its from APC with indicator surge protection, grounding and circuit breaker and all indicators were open I am waiting for your answers to my problem, guess any tube started to wear out? Thanks!
That can be anything from marginal parts starting to show failure signs to your cell phone too close to tubes or sockets with issues. If you are totally unfamiliar with electronic circuits, I'd highly suggest finding a local competent tech to repair it (and to keep you safe!). Extreme intermittents can happen with other electronic devices being too close to the amp or guitar. Rule out the simple things first. Brad
Microphonic tubes picking up cell phone or other sources of RF maybe. My amp makes noise if I touch my computer with my guitar in my hands.
Weird ground loops can pick up cell phone signals on oldskool devices Back in the early 2000's, I had a jury-rigged "home theater" built out of a big screen plasma and an old Akai component system jacked into a laptop... if I put my phone nearby, every time just before I got a text message, the screen would briefly show "running waves" across the image, and the stereo would make an odd warbling sound
Reading your answers guys looks like you must be right, because inside my room I have laptop and my cell phone at a very short distance from the amplifier 1m..(and when the amp made this unwanted noise my cell phone was drinking!! although this unwanted noise was made before the call and after repeated a little more it stopped!) but next or my room is the home phone (2m or less..) Today after end up with my work i will test it again ... Thanks all...
sometimes it doesn't even have to be close to an amp. i can hear my phone in my pocket in our ampless setup at church
Unwanted noise every two minutes......I thought this was going to be about having kids. Am I right??? hahahaha Sorry for the dad joke.
Hello guys again, today when I came back from work I put my equipment into operation just like I did yesterday (there is a video for the whole signal from start to finish) I left them open for about 45 minutes and the annoying noise did not appeared ... Therefore, out of my curiosity, I placed my mobile phone at a shorter distance than 1m from the amplifier, had someone call me and the unwanted sound did not appear .. (this zzzzz noise for about 5 seconds) I would like to add that my parents told me that the house we live in has quite old electrical installations ... (maybe 80s) they also informed me that in the next room where the tenants live there is a router just behind my wall, so still 2 telephone devices ... Also the weather today was relatively good without strong winds. Informatively the attenuator is so close to the amplifier because I have not got an even bigger speaker cable! and this time I use the speakers mini cable I am waiting for your answers ... You say it was random and not to be repeated again ?? hmm https://streamable.com/0dv61m Thanks
Cell phone would be my guess. I had a similar sound in my old jam room in the studio equipment. Turned out to be cell phone. It didn't have to ring just being on was enough. I wish I asked these guys about it because I never realized what the problem was till much later.
How did your cell phone turn out? Hmm...like mine ?? Which is something like ZZzzzz for 2-3 seconds then stop....and after (maybe) 1 minute again the same... xD (exaclty today and yesterday this unwanted noise did not reapear What do you mean you have no problems with this? are you using the same attenuator and amp? Thanks guys again!
I have a rat box slo 50 . Most noice in a audio system is ground related try to relocate the plugs you might have a ground loop
