JCM 800 2205 Noise issue !!

[softmc]

Hey guys

Still loving my JCM 800 2205 from 88 HOWEVER ti my ears it sounds best with the Gain dimed but here is the problem , with gain set at about 3.oclock its pretty quiet soom as you move from 3 to 5oclock (full gain) it is reall noisy interfereance static whatever, now one guy who builds dumble clones on another forum reckons the led circuit causes the unwanted noise and if you provide a different power source for it it helps ?? I can find my way around ok and can do simple mods The other thing is to change the filter caps which is on my to do list , done it on my Jubilee but jubes are not as noisey any suggestions for a quiet JCM800 dimed

 

[RickyLee]

Where are you setting the Boost channel Volume? I can't run my '88 2205 Gain at max 10 unless I back the channel Volume down a bit. I usually set that channel Volume from 8 to 10. Plus, I do have a hot humbucker bridge pickup as well. But to add, I do not remember having static and noise issues either.

I will have to experiment with that myself.

 

[ampmadscientist]

Hey guys

Still loving my JCM 800 2205 from 88 HOWEVER ti my ears it sounds best with the Gain dimed but here is the problem , with gain set at about 3.oclock its pretty quiet soom as you move from 3 to 5oclock (full gain) it is reall noisy interfereance static whatever, now one guy who builds dumble clones on another forum reckons the led circuit causes the unwanted noise and if you provide a different power source for it it helps ?? I can find my way around ok and can do simple mods The other thing is to change the filter caps which is on my to do list , done it on my Jubilee but jubes are not as noisey any suggestions for a quiet JCM800 dimed

It's high frequency oscillation. It does that a "little.."
This is a minor problem in a lot of high gain Marshalls.

The factory started installing a 7 pf 1000V disk cap between the plate and grid of the first preamp tube stage.
This cap is soldered directly to the preamp tube socket.
Fender Factory used the same method...

Second Marshall Factory Method
(this is probably the most effective method)
Shielded wire, the shield is connected to the plate of V1A (only).
The shield is NOT grounded. The shield is energized.
The center wire is connected to the grid of V1A.
The wire is rated 600 volts or higher.
This forms a capacitor between plate and grid of V1A.

Another way to deal with it is using a lower gain lower noise tube for V1.

Another way is to use a very long guitar cable. Like 30 foot.
This increases input capacitance and kills some of the very higher frequencies. (Guitarist Glen Kuykendall from Nashville, TN Uses this method)

Basically, to snub some of the highest frequencies from the first preamp stage, stops the HISSING oscillations.

 

[softmc]

Hi

cheers for the replys , boost channel volume is set at 3 oclock using master to control volume boost gain set at 3 0clock is usable above that noise city , and it seems to come and go , I really notice it when I use my LEHLE Dual to switch between Jubilee and Jcm800 (by the way its the 2x12 version combo not 2205)
the noise generated is terrible from the JCM , I have ordered filter caps, the tubes are all original marshall tubes ,(I know) but they sound damn good I can live with setting the gain at 3.oclock but would like to squeeze every bit of gain from it cos this thing sings .

 

[softmc]

It's high frequency oscillation. It does that a "little.."
This is a minor problem in a lot of high gain Marshalls.

The factory started installing a 7 pf 1000V disk cap between the plate and grid of the first preamp tube stage.
This cap is soldered directly to the preamp tube socket.
Fender Factory used the same method...

Second Marshall Factory Method
(this is probably the most effective method)
Shielded wire, the shield is connected to the plate of V1A (only).
The shield is NOT grounded. The shield is energized.
The center wire is connected to the grid of V1A.
The wire is rated 600 volts or higher.
This forms a capacitor between plate and grid of V1A.

Another way to deal with it is using a lower gain lower noise tube for V1.

Another way is to use a very long guitar cable. Like 30 foot.
This increases input capacitance and kills some of the very higher frequencies. (Guitarist Glen Kuykendall from Nashville, TN Uses this method)

Basically, to snub some of the highest frequencies from the first preamp stage, stops the HISSING oscillations.

THANKS I will look into these suggestions as I go along

cheers Derek

 

[RickyLee]

Are you using some sort of ABY switcher with this device you mentioned? Is that what that is? Did you check for any Ground loops?

Also, I am certain I might have ran my 2205 and Jubilee together, but I am not remembering if they were in phase with each other. Are you running them at the same time at all, or just switching back and forth?

 

[softmc]

Hi

yes the lehle dual is a aby box but just switching between the amps prefer a strat for my jubilee and les paul for the JCM , Tried the ground loop thing was my first thought but didint help .

 

[RickyLee]

So just running the 2205 by itself guitar straight in, you have the same issue with noise?

 

[softmc]

mmm

I need to double check this

cheers D

 

[softmc]

DAMN

How did I miss that ,yes it appears the ABY box is is causing the noise must be some fault in it , worked fine for 7years thats why I never considered it

cheers Ricky thats why these forums work good having someone looking outside the box so to speak will report back my findings

ordered new filter caps wont go wrong as its 27 years old

cheers Derek

 

[mickeydg5]

Always check cables and jacks at least once in a while. Clean them with an electronic contact cleaner as needed.

 

[ampmadscientist]

Hi

cheers for the replys , boost channel volume is set at 3 oclock using master to control volume boost gain set at 3 0clock is usable above that noise city , and it seems to come and go , I really notice it when I use my LEHLE Dual to switch between Jubilee and Jcm800 (by the way its the 2x12 version combo not 2205)
the noise generated is terrible from the JCM , I have ordered filter caps, the tubes are all original marshall tubes ,(I know) but they sound damn good I can live with setting the gain at 3.oclock but would like to squeeze every bit of gain from it cos this thing sings .

If the noise comes and goes:
The 2 input jacks should be changed or cleaned.
The jacks have internal switches. The switches must be working 100%.
A bad switch is oxidized or corroded. This causes intermittent problems.

If you don't ever use the LOW input jack:
The switch contacts still need to be 100%.
The audio path goes "thru" that switch contact.
If the contacts are oxidized, it will cause major problems.

The best cleaner will be Deoxit D-100 or G-100. Make sure the cleaner gets in between the switch contacts on the jack.
Or, just install new jacks.
Despite the jacks being new, I still treat the switch contacts with Deoxit.

Clean all the volume, bass, mid, treble pots with deoxit D-100 also.

CHECK the soldering connections for the input jacks and controls.
These should be re-soldered, the connections tend to crack over time.

 

[buzz]

Hi

cheers for the replys , boost channel volume is set at 3 oclock using master to control volume boost gain set at 3 0clock is usable above that noise city , and it seems to come and go , I really notice it when I use my LEHLE Dual to switch between Jubilee and Jcm800 (by the way its the 2x12 version combo not 2205)

I have the 4211 combo and previously ran as you describe at the 3 o'clock settings.....after a little experimentation (from suggestions on here ) I now have the channel volume turned up to almost max and the master knocked down a touch.....it really puts the amp in another dimension....absolutely untouchable for punch, gain and tone.........

 

[softmc]

Think I may have solved issue , I had contacted lehle who were very helpful considering the pedal is 12 years old the asked me to send it back to check it over, now thats service ! I ahavent done this yet as im still not convinced

Today I decided i would run both amps into a single speaker instead of using 2 speakers for each amp so I had to change the ohms selector back to 8 after doing this there was no noise !!! think the issue may have been the impedance selector has dirty contacts on the 4 ohm setting but the noise has gone for now ??