bias cuestion on a JCM900?

[Ostia Man]

If the bias of a JCM900 is set to high does it makes ground noise?
I leave mine in a tech's shop and he told me it may be the bias.

 

[Outlaws]

If the bias of a JCM900 is set to high does it makes ground noise?
I leave mine in a tech's shop and he told me it may be the bias.

Are you just making sure you are getting good info or is that what he said after looking at it? He should know, otherwise I would take it to another shop.

 

[Ostia Man]

really?
so it dos'nt.
shit!

 

[Outlaws]

really?
so it dos'nt.
shit!

I ain't saying that. I edited my post to make my point more clear, since it wasn't after proof reading.

Grounding issues is like a hum or buzz sound. I haven't messed with the bias on an amp, but for guitar effects, if the bias is too high they will squeel.

 

[Ostia Man]

well, when i turn on my amp even on standby you can hear the hum.(Its like a B or Bb I can remember) and I think is in power section because when i use the fx loop send it dos'nt make noise. the tec said it may be bias.
I just wanted to know if that makes any sence...

 

[dementedchord]

jeeeezis julius.... aint no way in hell that that's a bias problem.... hums on stand by??? dont see how... stand by removes the B+ voltage from the outputs.... and bias for a pedal??? bias is ONLY any issue for tube output stages... not preamp/linelevel devices.... you guy's NEED to find better techs... seriously...

 

[Outlaws]

and bias for a pedal??? bias is ONLY any issue for tube output stages... not preamp/linelevel devices.... you guy's NEED to find better techs... seriously...

Right......because you can't adjust the voltage to a pedals circuit. And by the way, a pedal isn't a preamp/linelevel device.....

 

[Ostia Man]

when the amp is on stanby you can hear the hum but not from the cab, from the head... it rumbles...

 

[dementedchord]

Right......because you can't adjust the voltage to a pedals circuit. And by the way, a pedal isn't a preamp/linelevel device.....

are you trying to agree or is it sarcasm....really?? i was kinda giving the pedals the benifit of the doubt by including them in with line levels.... and there is no bias adjust on a pedal.... not sure what kind of voltage adjustment your alluding to... guess it's just my bad for trying to help... i was just a pro tech for @18 yrs... warranty certified for boogie/marshall/fender/crown/qsc/soundcraft/allen and heath/roland/korg/kurz/yamama/hammond/and others.... so what could i know right???