Ground Hum Noise in 5150ii with ProRackG Stereo Mod

[GuitarGod87]

So I got ride of my Randall RM100 for this 5150ii. I love the tone but when I engage my gate I get this hum sound out of my amp. I've tried lifting the ground on the head and on the gate and there's a difference but the hum still isn't eliminated. I know it's the gate since when the amp is on the clean channel and I disengage the gate the hum stops.

Anyone have the same issue. I'm kinda upset since this is a pretty high end gate too. Suggestions?

 

[GuitarGod87]

So I got ride of my Randall RM100 for this 5150ii. I love the tone but when I engage my gate I get this hum sound out of my amp. I've tried lifting the ground on the head and on the gate and there's a difference but the hum still isn't eliminated. I know it's the gate since when the amp is on the clean channel and I disengage the gate the hum stops.

Anyone have the same issue. I'm kinda upset since this is a pretty high end gate too. Suggestions?

Could it be your power supply?

Not sure but I'll switch them out. I don't have another adapter so I'll have to get a new one.

 

[TrueTone500]

Not a good idea to lift the primary ground.

 

[GuitarGod87]

Even the tech at ISP suggested to lift the ground in attempt to eliminate the hum.

 

[steve_k]

Common problem with these ISP's. Grab you an MXR noise gate and run it in front of the amp. Problem solved. Money in your pocket.

 

[glpg80]

Put the amp on a seperate breaker/outlet from the ISP and see what happens. Very well could be your house wiring is 180 out causing hum. Very common in older houses. Also try the ISP with another amplifier if possible.

I ran one through the loop and front end of my 5150 II without a problem. I know the power supplies that originally come with ISP's are proprietary and bulky but needed. It could be that you're not using the correct power supply for the unit, or the power supply that you have could be at fault. I used the ISP power supply into a power conditioner without a single problem.

If ISP recommended lifting the ground of your amplifier they are breaking IEEE ground reference laws which are required for your own safety. The ground is tied to the chassis and neutral/hot is wired through the power transformer. Ground references on the secondary depend on how it is rectified, but still tie to earth. If you lift that ground reference of the amplifier the ground is essentially floating. If it rises to any potential, and you complete a current path through neutral ground of another appliance, you become a conductor between two different potentials. It is deadly and painful.

An example for musicians would be getting shocked by mic's on the lips either by poor grounding connections of the gear, defective gear, faulty ground references, or false neutral/ground references which are build code violations.

It is important for you to know that you can change which phase the neutral is referenced to ground without a problem - but lifting the hardwired ground reference all together is putting your life in danger when the B+ in these amplifiers is 500VDC+.

 

[GuitarGod87]

Now can I continue to play with this hum. It really isn't that bad but if it is a the ground causing the hum is there any damage being done?

 

[Anonymous]

do you have a light switch on on a dimmer, or some kind of outside lights on that switch on?

these cause major hum when i have my gear on. the light in our dining room is on a dimmer, so i cant jam when the kids are doing homework.

when i run my 5150 and my tourmaster together, i lift the ground off my tourmaster with a 3 prong adapter. you still keep everything connected and safely grounded via the cables connecting the amps and guitars.

i know this advice will draw the ire of the engineerically minded and the technically paranoid, but, fact is, it works, and you're safe.

 

[GuitarGod87]

All of my gear is in my room and there are no lights that dim in the room.

 

[1meanplexi]

I had the exact issue....bought a Furman voltage regulator and poof, solved.

 

[baron55]

do you have a light switch on on a dimmer, or some kind of outside lights on that switch on?

these cause major hum when i have my gear on. the light in our dining room is on a dimmer, so i cant jam when the kids are doing homework.

when i run my 5150 and my tourmaster together, i lift the ground off my tourmaster with a 3 prong adapter. you still keep everything connected and safely grounded via the cables connecting the amps and guitars.

i know this advice will draw the ire of the engineerically minded and the technically paranoid, but, fact is, it works, and you're safe.

Yes this will work and the amp with the ground lift theoretically is grounded through the shield of the cables from the other amp . But this is not safe. Why, because the shield of the cables are not designed to handle any significant current. So if you had a short to ground in the ground lifted amp the shielded wire in the cables will probably overheat, melt and then leave you with an ungrounded amp.

A much safer approach, is to make 2 cables ( audio ) but do not connect the ground on one of the connectors on each cable. This way you can safely plug both amps to a grounded outlet providing the safe ground reference. The reason to lift the ground on one side of the signal cables, is that this will prevent the devices (ground loop) from "sharing" the ground source ,but since one side of the cable is grounded, this provides the shielding required to reject interference. Of course this applies to guitar cables, patch cables, etc. But does not apply to speaker cables. This method is used all the time by professional audio techs and most amps that use shielded cable inside the amp also do this. Now you can't do this with a guitar cable that you use for a guitar, because the guitar gets its ground reference from the amp. But when you are plugging items in the FX loop, etc. This works great.

 

[JerryP]

The input jacks and loop jacks on the 5150 can't be tied together or you'll get hum.
Jerry

 

[GuitarGod87]

The input jacks and loop jacks on the 5150 can't be tied together or you'll get hum.
Jerry

Thanks Jerry. That makes since to me. So the way the Decimator Rack works is causing the hum?

 

[JerryP]

The input jacks and loop jacks on the 5150 can't be tied together or you'll get hum.
Jerry

Thanks Jerry. That makes since to me. So the way the Decimator Rack works is causing the hum?

I don't know for sure, I thought they took care of that but maybe not. I know years ago guys used them in the loop with the input in one gate and the loop in another and they would hum. I thought ISP changed it so the grounds were isolated, but I don't know for sure. I do know the ground potential is different for the loop and input jacks so if they are, tied together you will get hum.
Are your pedals powered with a power supply that is isolated? If you have pedals in the loop and pedal in front of the amp powered off one cheap power supply you can ground loops there too.
Jerry

 

[GuitarGod87]

I went through the process of trial and error and took out all my pedals leaving only the gate connected to the head along with my guitar. I had a Randall RM 100 that had high gain as well but I didn't encounter this issue at all.

 

[Anonymous]

do you have a light switch on on a dimmer, or some kind of outside lights on that switch on?

these cause major hum when i have my gear on. the light in our dining room is on a dimmer, so i cant jam when the kids are doing homework.

when i run my 5150 and my tourmaster together, i lift the ground off my tourmaster with a 3 prong adapter. you still keep everything connected and safely grounded via the cables connecting the amps and guitars.

i know this advice will draw the ire of the engineerically minded and the technically paranoid, but, fact is, it works, and you're safe.

Yes this will work and the amp with the ground lift theoretically is grounded through the shield of the cables from the other amp . But this is not safe. Why, because the shield of the cables are not designed to handle any significant current. So if you had a short to ground in the ground lifted amp the shielded wire in the cables will probably overheat, melt and then leave you with an ungrounded amp.

A much safer approach, is to make 2 cables ( audio ) but do not connect the ground on one of the connectors on each cable. This way you can safely plug both amps to a grounded outlet providing the safe ground reference. The reason to lift the ground on one side of the signal cables, is that this will prevent the devices (ground loop) from "sharing" the ground source ,but since one side of the cable is grounded, this provides the shielding required to reject interference. Of course this applies to guitar cables, patch cables, etc. But does not apply to speaker cables. This method is used all the time by professional audio techs and most amps that use shielded cable inside the amp also do this. Now you can't do this with a guitar cable that you use for a guitar, because the guitar gets its ground reference from the amp. But when you are plugging items in the FX loop, etc. This works great.

thats an awesome remedy...one i dont think i've read before...or if i did, i didnt get it.
i'll be doing it this weekend and dumping that 2 pronger!

thanks for this!!!!!!!!

 

[the4thlast1]

I used my ISP Gstring pedal through the front and the loop simultaneously in my 6505+ with no hum problems, dead silent. I have a pro rack G in my live setup that I normally use with my EVH 5150 III . I will try that setup with the peavey and get back to you. Does your ProRack G have the ground lift buttons on the back ?

 

[roodboy]

Does this one have the three ground lift buttons on the back?
If it is I would try different combinations of the three buttons to see if it will stop.
The versions I have owned with the buttons are quieter, but I never owned a stereo one.

 

[GuitarGod87]

I do own the stereo mod with the 3 ground lifts on the back and i tried every possible combination and there's a slight difference but the hum is still there.