Got home early and the JVM was waiting for me...

mctallica1

mctallica1

Well-known member
I like this amp a lot. Cleans are very good (for a Marshall....definitely good enough for my purposes), crunch is pretty damn good as well (I am no authority on crunch tones though :p )

OD1 and OD2 are where I spend most of my time. I really like the orange and red modes on these channels...BUT, there is a hum on the red channel of both that I can not get rid of. I am running the gain around noon on both OD channels and when playing it is right where I want to be, but as soon as I stop, the hum bothers the hell out of me.

I have switched out all the Marshall preamp tubes for tung sols (seem to be the reccomendations from the folks at the JVM board) and the tone is awsome, but it didn't help with the hum.

I was able to eliminate the hum by putting a Mesa relable 12at7 in v1, but then I didn't like the tone of the amp at all.


There was hum when I played these amps in the stores, but I was straight in every time. At home, I am using a decimater in front and I thought that would eliminate most of it, but it does nothing for the hum. Works perfectly for eliminating any unwanted guitar noise though (as always)

Have already tried all new cables, different power sources (I also use a power conditioner), ground switches on my Voodoo Labs Amp selector and even using a HumX adaptor (which has worked well in the past with other amps I couldn't get rid of noise on).



Any suggestions to eliminate the hum on the red channels?


FWIW, if I were not trying to get this thing into high gain territory, there would be no hum...meaning as long as I stay off the red channels on OD1 and OD2. Maybe it is inherent in the amount of gain available, which is HUGE.

I really like the tones, but if I can't get rid of the hum...... :thumbsdown:
 
Oh yeah...one thing I found interesting and don't know what to make of it:

I am using a Voodoo Labd Amp Selector to switch between amps and if I hit the button on the selector to cut off signal to the JVM, the hum goes away. However, if I run Guitar/decimater/amp, I still have hum.


Weird.
 
That is crazy. I don't know what to tell you. I can sit right in front of my JVM on the red modes in OD1 and 2 and have no hum just hiss which is acceptable with that amount of gain. You probably have done all this but have you tried a different guitar, or does the hum go away as you get further away from the amp? :confused:
 
Have you tried using the decimater in the loop of the JVM ? If that doesn't cure it.....take the voodoo amp selector out and go straight into the JVM with the decimater still in the series loop. What level have you set the loop at ? Is the dec a line level device or the pedal ? Try both amps into a different power socket. Try to have all the pedals and amps run from one well grounded source ( 20 amps would be great ). Make sure amp heads are well away from sources of RF and EMI emissions. Try rotating amp heads (if you do have comp and tv monitors close by) on a an angle away from those sources.
Make sure you are not on the same phase leg as fridge,freezer,or any other heavy appliance. You can determine this by looking at the breaker box. Each leg(side of breakers) 120 v ac with all the receptacles marked. Make sure the outlet your using is not directly opposite a major appliance (trying to remember this shit when I put in my own isolated circuits for the audio/amps and HT).

Just a couple of things to try. Good luck !
 
I had the same problem until I checked the guitar which made the most noise and realized the ground wire had come loose. Once I fixed that the noise went down substantially.

Noon is a LOT of gain in the red modes for OD1/OD2. Just curious if you happen to have the amp near a computer, TV, radio, etc?
 
:|::QBB:
SgtThump":b69d5 said:
I can't even imagine running the gain at noon on the red modes of OD1/OD2! That is an INSANE amount of uncontrollable distortion (in my opinion!!!!!!!!)

I can barely control my guitar when I'm using the orange modes of OD1/OD2 with the preamp gain around 10:00 o'clock!
Click to expand...

The gain at noon on red mode OD1 or 2 is insanity. I have a hard time using the red modes because I prefer the distortion sound of the orange. It seems way more clear to me. I just have OD2 set up as rhythm with the orange mode gain at 10:30 and OD1 set up as lead on the orange mode with gain at 11:00. However, both of those channels sound great to me doing either and I am having a hard time deciding which one to use as my final sound for lead or rhythm. I guess that is a good problem! :D
 
:|::QBB:
SgtThump":76e54 said:
I can't even imagine running the gain at noon on the red modes of OD1/OD2! That is an INSANE amount of uncontrollable distortion (in my opinion!!!!!!!!)

I can barely control my guitar when I'm using the orange modes of OD1/OD2 with the preamp gain around 10:00 o'clock!
Click to expand...


Keep in mind 2 things:

I am playing at conversation volume...at home. Certainly at gig volume I would have the gain lower.

I play modern metal (well, thrash up through modern metal), not a hell of a lot of rock type stuff. To get the tones I am looking for, noon or slightly below is about as low as I am gonna go.





As point of comparison, I run the gain on my VHT CL red and green channels around 1 oclock. To get theat level of gain (hairier on teh Marshall of course), the gain needs to be in the area I have it set.
 
I never really spent much time in od2/red, but when I did I had the gain around noon. It was slightly noisier than od2/orange with the gain on 7. The crappy noise gate in my g-major (in the loop) took care of it.
 
Take everything our of the signal path. plug the amp straight into the a/c wall outlet and the guitar straight into the amp and see if there is a hum.
Dont use wnything in the loop or anything before the guitar. Just straight amp and guitar nothing else no power conditionors. Then unplug the guitar and turn the amps volume up to see if there is a hum.
If there is still a hum then there is something going on. You can try another outlet in another room as well.

I was able to use your settings with zero hum so knowing that I was able to do it should tell you that there is either something going on in the signal chain, wall outlet or the amp itself.
 
:|::QBB:
PoPSkuLL":979cc said:
Have you tried using the decimater in the loop of the JVM ? If that doesn't cure it.....take the voodoo amp selector out and go straight into the JVM with the decimater still in the series loop. What level have you set the loop at ? Is the dec a line level device or the pedal ? Try both amps into a different power socket. Try to have all the pedals and amps run from one well grounded source ( 20 amps would be great ). Make sure amp heads are well away from sources of RF and EMI emissions. Try rotating amp heads (if you do have comp and tv monitors close by) on a an angle away from those sources.
Make sure you are not on the same phase leg as fridge,freezer,or any other heavy appliance. You can determine this by looking at the breaker box. Each leg(side of breakers) 120 v ac with all the receptacles marked. Make sure the outlet your using is not directly opposite a major appliance (trying to remember this shit when I put in my own isolated circuits for the audio/amps and HT).

Just a couple of things to try. Good luck !
Click to expand...


I have tried the decimater in teh loop. It does nothing.

Decimater is a pedal.

My amps are in mybasement with NO other electrical equipment nearby...no flourescent lightint either.



Don't have a clue what a phase leg is :LOL:


I can tell you, I am using the exact same setup I have used with literally 50 plus amps and have never had an issue like this.
 
:|::QBB:
RO223":1df9f said:
I had the same problem until I checked the guitar which made the most noise and realized the ground wire had come loose. Once I fixed that the noise went down substantially.

Noon is a LOT of gain in the red modes for OD1/OD2. Just curious if you happen to have the amp near a computer, TV, radio, etc?
Click to expand...

I haven't checked my guitar, but I doubt it is the problem. I am using it with a VHT CL right beside the JVM and there is NO noise.
 
:|::QBB:
Gainfreak":0bd8d said:
Take everything our of the signal path. plug the amp straight into the a/c wall outlet and the guitar straight into the amp and see if there is a hum.
Dont use wnything in the loop or anything before the guitar. Just straight amp and guitar nothing else no power conditionors. Then unplug the guitar and turn the amps volume up to see if there is a hum.
If there is still a hum then there is something going on. You can try another outlet in another room as well.

I was able to use your settings with zero hum so knowing that I was able to do it should tell you that there is either something going on in the signal chain, wall outlet or the amp itself.
Click to expand...

Haven't tried that. Will try guitar/amp/outlet and see what happens.
 
sounds like a ground loop to me due to using more than one amp( or the amp selector).

You can eliminate the ground loop with the amp selector itsel. This is taken from their manual:

Ground Problems
You should always start with all of the Amp Selector’s Grounds
Lift switches in the ON position. This means the output is grounded.
If the amp is humming, the first place to look is if there is a two or
three position ground switch on the amplifier itself. Try each position
of the amp’s ground switch to find the least hum. If the amp
continues to hum, then try switching the Amp Selector Ground Lift
to the OFF position. This now isolates that output. Then try each
position on the amp’s ground switch again to find the least hum.
If you are still having problems, make sure that all amplifiers are
powered from the same power source. Outlets in different parts of
a room can have significantly different ground potentials making it
more difficult to find settings that are hum free.
Since ground connections in a multi-amp setup can get complicated,
you may need to experiment a bit with different combinations of
settings to find one which keeps all the amps from humming.

It should help but make sure that the amp doesn't hum when connecting the guitar straight into it with the guitar volume at zero.

S.
 
:|::QBB:
Santiall":e4365 said:
sounds like a ground loop to me due to using more than one amp( or the amp selector).

You can eliminate the ground loop with the amp selector itsel. This is taken from their manual:

Ground Problems
You should always start with all of the Amp Selector’s Grounds
Lift switches in the ON position. This means the output is grounded.
If the amp is humming, the first place to look is if there is a two or
three position ground switch on the amplifier itself. Try each position
of the amp’s ground switch to find the least hum. If the amp
continues to hum, then try switching the Amp Selector Ground Lift
to the OFF position. This now isolates that output. Then try each
position on the amp’s ground switch again to find the least hum.
If you are still having problems, make sure that all amplifiers are
powered from the same power source. Outlets in different parts of
a room can have significantly different ground potentials making it
more difficult to find settings that are hum free.
Since ground connections in a multi-amp setup can get complicated,
you may need to experiment a bit with different combinations of
settings to find one which keeps all the amps from humming.

It should help but make sure that the amp doesn't hum when connecting the guitar straight into it with the guitar volume at zero.

S.
Click to expand...


I should have mentioned that I have played with the ground switches on the Selector as well.


I am gonna try Ralph and your suggestion and see what happens.


I am really hoping it is something in my signal chain because I really like the amp ;)
 
FWIW, I can't use Tung Sol pres in my Wizard amps they hum for some reason. In my VHT they didn't hum though. I'd try a different brand and see if that helps.
 
:|::QBB:
Santiall":cae4c said:
sounds like a ground loop to me due to using more than one amp( or the amp selector).

You can eliminate the ground loop with the amp selector itsel. This is taken from their manual:

Ground Problems
You should always start with all of the Amp Selector’s Grounds
Lift switches in the ON position. This means the output is grounded.
If the amp is humming, the first place to look is if there is a two or
three position ground switch on the amplifier itself. Try each position
of the amp’s ground switch to find the least hum. If the amp
continues to hum, then try switching the Amp Selector Ground Lift
to the OFF position. This now isolates that output. Then try each
position on the amp’s ground switch again to find the least hum.
If you are still having problems, make sure that all amplifiers are
powered from the same power source. Outlets in different parts of
a room can have significantly different ground potentials making it
more difficult to find settings that are hum free.
Since ground connections in a multi-amp setup can get complicated,
you may need to experiment a bit with different combinations of
settings to find one which keeps all the amps from humming.

It should help but make sure that the amp doesn't hum when connecting the guitar straight into it with the guitar volume at zero.

S.
Click to expand...

Howdy Stranger!!! :D


Hope all is well in amp building land!! :D

~R~
 
:|::QBB:
Gainfreak":f4473 said:
:|::QBB:

Howdy Stranger!!! :D


Hope all is well in amp building land!! :D

~R~
Click to expand...

hey there, yeah everything alright so far, thanks for asking and hope you and the rest of people over here are also doing well :thumbsup:

back to the topic, yes, if you have a pedalboard or something else it is very probable that you got a ground loop or noise from the power supplies bleeding in somewhere. Start with the basic setup and then add devices till you find the culprit.

S.
 
Well I'll be go to hell :D ( My grandma says that all the time...have no real idea why, but I think it is funny)

I tried the guitar/amp/outlet routine.

NO hum...just a little bit of high gain hiss as you woudl expect with no supressor.

Started adding things in the chain to see what was causing the problem and it is the thing that I was always using in every attempt at troubleshooting....


The JVM makes a shitload of noise as soon as I connect the Decimator! :confused: :confused:

Have never had that as a problem before.


I really like a gate in front of amps because I do a lot of start/stop heavy rythms.

I guess I will buy an NS2 and try it. Any other suggestions for a gate? Maybe a MXR?

Who woulda thunk :D
 
You must log in or register to reply here.
Back
Top