To me the hiss (as long as it's not TOO loud) is just part of the whole experience of playing a real (tube) amp, and I wouldn't want to fully do away with it, just how some people really like the noises between tracks on the old vinyl LPs. Same for the cycle hum with SC pups. Some amps make more noise than others - my Mesa has way more hiss than my Marshall (which is my quietest amp), but it's all good.
Just joined the forum to give my experience... I bought a brand new SV20 head and have only ever used it at home in conjunction with my UAD Ox loadbox (local practise space has been closed since Covid kicked in and I can't get away with using a cab in the flat for obvious reasons). First time setting it up I was getting a horrible squealing sound whenever my hands weren't touching the strings and/or the controls on my amp. This only applies to the high treble pot whenever it's set above 2/3 whereas the normal gain pot is totally fine with no issues. The squealing was present regardless of whether I had the channels jumped or not, and similarly present with my pedalboard in the chain or just plugging directly into the amp. I contacted the store I bought it from and they arranged for it to be returned to Marshall for their engineer to look at it. The feedback was it was an issue with the screening plate and the amp wasn't close enough. It was then returned to me and everything appeared to be okay for approximately 4 weeks before the squealing started again with the high treble pot. It's getting collected next week for the engineers to look at it again, so we'll see what happens. I don't have this problem with any of my other tube amps when used with the Ox in my home studio setup, so I don't believe it's an issue with the electrics in my home. I'm glad I didn't spend the cash on a set of replacement valves as judging by other's experiences on here it didn't appear to resolve the issue. It looks like it is indeed a problem with the overall design, which is a real shame as the amp sounds amazing when it's functioning properly. I'm hoping the engineers can sort this out for me as I'd hate to think I've wasted £££ on a dodgy amp, so I guess time will tell...
Just a follow up... Marshall returned the SV20H with brand new tubes installed and hey presto, the noise has thankfully gone! I'm assuming both preamp tubes were faulty as I did swap them around to determine whether that was causing the issue before sending it back. Regardless, the new set has rectified the problem and now I'm very happy
Good news!! I got my SV20 and was worried about this noise. I saw some people complaining about it on YouTube as well... But I had no problem with noise. I recorded a fast sample using the High Treble input on max, and got a acceptable noise
Nice playing and tone. To hear the problem, you need to record another without playing. Just mic the cab, turn the mic gain up, and go slowly from 0 to max gain on the high treble channel. Listen for the static. You'll decide for yourself whether that noise is OTT or acceptable. For my purposes it was too much.
A new SV20C owner, I have the same hiss when running through the speaker, but when I use an attenuator the hiss is barely noticeable. May be I'll try the preamp tubes next week. When I had my bassbreaker I had the same issue, but after a few weeks the his just went away.
Had our first gig of the year last night. Small place, per usual. Power cables, audio snakes, DMX cables, patch cables all over the place (controlled chaos). And I had a high level of white noise with my SV20H. It seemed to fluctuate some and switching to a different patch cable from the amp to my board seemed to help a bit. When the entire band was playing, it wasn't an issue. There's one song where I use a fuzz and I had to be on it at the end of the song to turn it off immediately or the hiss really sounded bad. My other guitarist swears by Fuhrman power conditioners... I'll be giving that a go, along with a noise gate in the loop.
i have same issue and just received about two weeks ago. doesn't bother me though. my 2204 does same thing..
Furmans make a world of difference. I purchased mine after a very problematic gig with my DSL (channel switching relays not working, amp eventually shutting down) and never had a single issue ever again. And the whole rig is quieter when powered by the Furman. The one I use is the AC210 A E (designed for EU/220V-50Hz power)and I seriously can't recommend it enough. Best 180€ I ever spent on my gear, I wouldn't consider gigging without it ever again. Also, I do my own wiring, and take extra care to solder my connectors properly and only use properly shielded cable (I use Sommer Tricone Mk2 for pretty much all my runs, with Neutrik and HiCon connectors) and quality power supplies (a pair of Voodoo Labs PPs on my big board, a Truetone CS7 on the small one). Even turned up (ie the point where instantly to feedback if I open the volume and release the strings -that's gig volume competing with a loud drummer), with all pedals kicked off and guitar volume off, the rig is dead silent, produces less hiss than the PA does. And if anything, my rig with the SV20H is even quieter than it was with the DSL100. All of this without using a noise gate, of course. So yeah it can be done, you just have to stack the odds in your favour. And again, the Furmn makes a HUGE difference in cleaning up noise in your rig.
