Jcm800 sc20h hiss

william vogel

Well-Known Member
Joined
Dec 18, 2016
Messages
973
Reaction score
1,166
Thanks for the suggestion, just feels a bit odd to already tinker with a brand new amp.. I would expect it to just do it's work :)
It’s actually doing exactly what it was designed to do. It’s amplifying a low voltage signal from the guitar to a high voltage signal. The guitar signal is amplified enough in the early stages to surpass the level of the voltage rail and becomes clipped/compressed and it’s amplitude no longer rises but the noise voltage is low enough compared to the root guitar signal that it’s able to be amplified and it’s amplitude continues to rise and get more audible amongst the restrained amplitude of the guitar signal. A noise gate simply clips away this low level noise voltage and removes the initial low level signal. It mutes away the very small portion of the signal around the 0 volt line of the input voltage and unfortunately it’s not transparent but will make the amplifier noise floor much lower.
 

Chris-in-LA

Well-Known Member
Joined
Jul 19, 2018
Messages
3,308
Reaction score
3,417
Location
Los Angeles
There seems to be a slight hiss on the video but when you turned everything on, the 60 cycle hum drowned it out. That pop/boom noise seems to be coming from your pedal board. The only problem I really heard was that screaming at the beginning of the video. 😂
 

daanromein

New Member
Joined
Jun 24, 2022
Messages
14
Reaction score
3
I
There seems to be a slight hiss on the video but when you turned everything on, the 60 cycle hum drowned it out. That pop/boom noise seems to be coming from your pedal board. The only problem I really heard was that screaming at the beginning of the vi

There seems to be a slight hiss on the video but when you turned everything on, the 60 cycle hum drowned it out. That pop/boom noise seems to be coming from your pedal board. The only problem I really heard was that screaming at the beginning of the video. 😂
Indeed, the scream is another issue in itself! With 4cm there is way less hiss, but that boom sound is odd. Someone mentioned I should just leave the loop in my multi effect on so the amp doesn't make that sound
 

Chris-in-LA

Well-Known Member
Joined
Jul 19, 2018
Messages
3,308
Reaction score
3,417
Location
Los Angeles
Indeed, the scream is another issue in itself! With 4cm there is way less hiss, but that boom sound is odd. Someone mentioned I should just leave the loop in my multi effect on so the amp doesn't make that sound
Maybe, I don’t mess with loops or boards that much. But, your hiss seemed pretty normal. I just turn my guitar down between songs at rehearsal if the hiss or hum is bothersome.
 

daanromein

New Member
Joined
Jun 24, 2022
Messages
14
Reaction score
3
Maybe, I don’t mess with loops or boards that much. But, your hiss seemed pretty normal. I just turn my guitar down between songs at rehearsal if the hiss or hum is bothersome.
I'll post a video of the hiss later on, when I plug the guitar directly in the amp, way more loud
 

ACHIEVEIT

Member
Joined
Aug 29, 2009
Messages
145
Reaction score
4
Location
Athens, Greece
Mine hisses quite a bit more than my SV20H, but so does my 2203X compared to my 1959SLP so I dismissed it as normal (albeit annoying). Already tried exchanging the whole tube set between SC20H and SV20H - no difference so I attributed it to the circuit. Curious to read the experience of other users.
 

marshallmellowed

Well-Known Member
Joined
Jun 26, 2009
Messages
5,375
Reaction score
8,910
The level of "hiss", or noise as I call it, in that video is normal. This is one reason I have to have a loop in all my amps, as the loop is the "optimal" location for a noise gate. Put a decent noise gate (Decimator...) in the loop and forget about it. That said, that pop when switching would annoy the hell out of me, which sounds like a time based effect location issue. Reverb, delay... FX should also be in the loop, after the noise gate..
 
Last edited:

Latest posts



Top