OP, I’m having the exact same issue with mine. I’m used to slight buzz and 60 cycle hum, but my SV20 combo has way more idle noise on the Treble channel than any of my other tube amps. I do constantly have both channels jumped and haven’t un-jumpered it since the first few minutes I tried it, so maybe that’s the issue. I’m glad I’m not the only one though, lol.
Yeah, it's definitely an issue. I've recorded with mine though and just pretend I'm doing it old school. Back in the day guitars and amps were noisy as sh*t. I'm pretty sure the only fix is something Marshall can do- if you want it under warranty. Otherwise, put a gate in the FX loop and that solves the problem at idle. Not close to a deal breaker for me man! The tone is to die for!
Yeah, I’ll probably go the noise gate route then. I agree with you, as soon as you start playing, the tone is the best I’ve heard. I’m just afraid in between songs when I’m talking to the crowd that the thing is going to be buzzing like no other and driving the sound guy nuts, lol. I may contact my dealer and see if Marshall acknowledges that this is an actual problem or if that’s just how plexis are, lol. I have a feeling it’s the latter.
Let us know the response. I never found any way to speak a human being at Marshall USA. Is there one?
My sv20 was fine.. now bright channel has a ssh. Sound... seems others having same issue..changed preamp tubes....anyone sort out fix?
If you don’t want that hissing noice get off that high gain stuff . When tubes get so much gain they become unstable and pick solar activity .
If you run these non master amps with the presence and /or treble controls high, you're going to get hiss. If you don't like it, you can try changing the bright cap, but it's the nature of the beast. Any plexi circuit (1959, 1987x...) will do the same.
I have the sv 20 combo and there is quite a bit of hiss when turning up the treble chamnel. Very frustrating!
The cure is a noise gate in the loop. I run a simple ISP Decimator in the loop, dead quiet when not playing.
I'm not noticing it- for some reason. I mostly run the amp on 7 jumping both channels. Yes, there is noise but it's pretty typical for turning an amp way up. But the gate in the fx loop definitely works to eliminate it.
Hi guys, I have the SV20H, running it on a 4x12, and I noticed the same noise in the high treble channel. But its not only whitenoise, its a rustling noise as well, sometimes like leaves in the wind, its not very loud, but loud enough that you notice it. Symptoms: its only in the high treble channel, and it starts as soon as you turn up the high treble channel up starting from 0. The bass channel has zero noise, very interesting. I hear the highbtreble channel noise in 5W mode as well as in the 20W mode. It doesnt matter how much I turn up the high treble volume, that noise stays more or less the same (besides volume at 0 of course). It doesnt matter if channels are jumped or if a guitar is plugged in, the noise is always there. The noise disappears only in case I install a 4cable method noise gate in the effects loop. Then its gone, so itmust be the preamp right? Downside of the noise gate: itsomehow damages the guitar sound on peak signals, it sounds sometimes „damaged“. My question to you: do you hear that rustling noise as well? Should I be concerned? Can a failing preamp tube damage my amp? Thank you guys! Stay well and safe! Chris
It doesn't seem to be as bad when running into my Two Notes Captore instead of the internal speaker. Could it have something to do with the internal speaker, wire, or placement? Update: So I tried it with an external speaker cab and it's the same. I tried a couple other SV20Cs at the store... same thing so, I believe Robus might be right... is it a design flaw? I will say, however, that when playing the guitar it's not really noticeable and the amp sounds awesome. So, if there is a simple fix It would be great to know. And, if there are any SV20H (head only) owners, it would be great to hear if you have the issue.
i joined the forum just to add my $0.02 I picked up a brand new SV20C after reading nothing but stellar reviews. I thought i liked the sound... but daaaamn, i dont know about some of you saying it's not really noticeable. I had my first paid recording sessions in months just this weekend and this amp completely ruined the recording session. The engineer wasn't sure if the SV20C so accurately faithfully recreated the 59 plexi circuity that it comes with all the vintage kinks and idiosyncrasies and what not but he also thought it was so bad, so noisey, so unusable for recording dynamic guitar music that it might as well be malfunctional or defective. He was disapointed with it especially considering its actually made in 2019. The i jumper the 2 channels but that treble hiss... once you turn that knob to 2 just to incorporate it into the blend it ruins everything. With my wah and fuzz pedals in the mix it was just death by white noise and hiss and radio signals in a foreign language. Wayyyy less impressive than his $800 made in china vox EDIT: i forgot to mention that playing at home with more mellow "jazzier" tones didn't make this noticeable. It's specifically a mix of that high treble channel, high volume, dynamic music, and pedals that made it sound absolutely UNUSABLE
Fought the high channel hiss a lot myself. My SV20H is my favorite of my amps. I understand, a certain amount comes with high gain. My SV20H is really quiet, but... I have a new house. I have a voltage regulator plugged into the wall. An isolation transformer is plugged into the voltage regulator. A Furman noise suppressor is plugged into the isolation transformer, and the SV20H is plugged in the Furman. Additionally, I specifically chose to replace the tubes with quiet tubes. I used this resource, the link below, bought a few, and rolled some. Only old high gain pedals or unpotted noisy pickups bring the annoying hiss back. https://www.tubesandmore.com/tech-corner/12ax7-comparison-current-made-tubes I am no EE, and I am likely to be flamed for what I've just typed, but I studied the best I could and came up with this setup.
