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[Harley Hexxe]

    I think that just means it's likely to fry the wall wart in the event of a power surge. With no earth ground, it's out of the loop in that respect, but it can be a source of noise if there is any kind of short in it.
    Since wall warts are cheap, and easily replaced, they didn't include an earth ground on most of them. I would try just adding one piece of equipment at a time to your guitar rig until the noise appears. That would at least get you close to the source if there are no ground-lift adapters available.

    Harley

[rabidgerry]

maybe not.

If you take out the GT-5 and plug the guitar straight into the preamp and plug the preamp into the power amp do you still have this noise?

Shit I shall have to try this wont I,  ok that's one test I need to do.  Should I also make an equally high gain patch using the GT5 by itself running into the amp

    I think that just means it's likely to fry the wall wart in the event of a power surge. With no earth ground, it's out of the loop in that respect, but it can be a source of noise if there is any kind of short in it.
    Since wall warts are cheap, and easily replaced, they didn't include an earth ground on most of them. I would try just adding one piece of equipment at a time to your guitar rig until the noise appears. That would at least get you close to the source if there are no ground-lift adapters available.

    Harley

?

seems the only thing for it.  I'm just confused as the noise is not always present, it certainly is not a noise I get at home, and I didn't get that noise at home using the exact same preamp (I tested it at home when I first bought it you see before I moved it to rehearsal room)

[MarshallJMP]

I don't think that the GT5 uses a wall wart, from the pics I saw there is cable coming out of the GT5 that plugs straight into a wall plug correct?

BTW RG is the noise also present when you turn down the guitar volume to zero?

From what I can tell you use some cable length, a few meter from the guitar to the GT5,then a few from the GT5 send to the preamp, then you need to come back to the GT5 return and then back to the power amp, am I correct?

[rabidgerry]

Yes correct GT5 has it's power supply built in unlike any of the other GT units.  Handy!

Yeah no the noise goes away when I turn down the guitar.  I think it does anyway    Actually I can't remember now.  What does that determine?  I think it goes away.

Yeah I use long cables,  and now I think about it, one I'm using is not the higher quality stuff I make my cables from.  It's just a generic Stagg cable I bought years ago so isn't shielded as well as the other cables I make.  I had no lead on hand when I first started putting the a preamp in the FX loop so I just grabbed that older cable as it was lying about.  In my experience, the noise I am getting is not that kind of noise though so shit cable or not in the chain I do not think it's the cable.

And my guitar is shielded well also.  Before that it buzzed a lot, shielding stopped a lot of that or reduced it significantly.  It also is quiet as a mouse in my home setup.  But in rehearsal room its got this shit hum in the backgroud and sometimes is not there but most of the time it is.

[MarshallJMP]

Could you check if it goes away when the guitar vol is zero?

[rabidgerry]

Ok I think it does, last week I wanted to see if the noise would go away if I connected the GT5 to the PC in case that was the issue.  So I dragged the pedal over closer so that the plug of the GT5 could connect into one of the vacant supplies on the PC.
When I then turned everything back on and tested I specifically remember I had to roll the volume of the guitar back up again, and the noise came back.  What does this mean?

I might try and see if I can test the rig this evening again.

[MarshallJMP]

Well this could mean you have some sort of electro magnetic pollution that is picked up by the PU's of your guitar.
Do you have fluorescent lights in that room?

[rabidgerry]

There are flourescent light in the room, but they were'nt on.

Sometimes flourescent lights from the floor below cause noise, more for the bass guitar, and we have had to go down stairs and turn them off before in order to get rid of the noise.

Another thing, a taxi depot is across the road, say 100meters, I have heard their radio shit can cause issues.  However I have never heard anything like people talking through my stuff.  I will record this noise and let everyone hear it, and also perform some tests and hopefully begin process off elimination.

[Harley Hexxe]

Hey RG,

   Okay, I thought your GT5 had a wall wart adapter, my mistake.
   So what you're telling us is that you only get the noise at certain places you plug in at. You don't get it at home, but you do get it most of the time at your rehearsal spot. There could be other things plugged into the circuit that you happen to be plugged into. (Neon lights, appliances, video equipment, or maybe even something like a heat exchanger of some sort).
   What sort of establishment is your rehearsal room in?

    Harley

[rabidgerry]

Hey RG,

   Okay, I thought your GT5 had a wall wart adapter, my mistake.
   So what you're telling us is that you only get the noise at certain places you plug in at. You don't get it at home, but you do get it most of the time at your rehearsal spot. There could be other things plugged into the circuit that you happen to be plugged into. (Neon lights, appliances, video equipment, or maybe even something like a heat exchanger of some sort).
   What sort of establishment is your rehearsal room in?

    Harley

Well I'll give you an example, at home, I use a GT5 also with either a Peavey Rockmaster or an MP1 in the GT5 loop and I do not get that noise at home using same guitar.  The noise I get is regular hiss that I dial out using noise reduction, but it's not a lot of noise anyways so I don't need much.

In my live rig, the only real difference is I plug into an amp as opposed to a multitrack.  At home I monitor via the multitrack.

Um well (and I shall take photos), say there are two wall sockets, then I run an extension chord from one socket to my gear, then plug the PC into it.  However in the other wall socket, I might have a mixer and PA plugged in.

I figured perhaps it might be something like this, so I ran the extension chord from sockets on the other side of the room and plugged my PC in to that instead, and I still get noise.

The establishment is a big mill, like it used to be a linen mill.  It has since been converted into rooms, and many things go on in the rooms.  Some clubs are there, weights etc some business are on ground floor, like for cars tyres, and some random artists, and also a few moire rehearsal rooms for othe bands.

[rabidgerry]

The noise see attached clip

this is everything normal, a patch on GT5 including the preamp in loop, I bang the floor to vibrate guitar to show how the noise gets worse.

[rabidgerry]

guitar plugged into just the peavey and nothing else, then into the amp.

[rabidgerry]

the noise from a patch made using a pre in the loop of GT5 then switching to a patch made solely on the GT5 with full on board hi gain amp model and od in front (so no preamp in the loop) then back to a patch with the preamp in the loop

noise disappears when I switch to a GT5 only patch, I get hiss instead but that's way more acceptable.

[rabidgerry]

Ok then the BIG F U C K ING revelation!

I decided in an experiment, detach the earth on the peavey rockmasters plug and leave it disconnected from the third centre pin.

The clip below starts off with guitar plugged in, the noise has really reduced.  Then I unplug the guitar and there is virtually no noise.  Then I plug it in and some noise but a lot less that the first clip I posted called "noise 2"

Noise 2 has my normal patch, with preamp in the loop and guitar attached.  At one point I take the guitar out of the GT5 altogether and there is still noise.

Note also that when I have the guitar plugged in everything is the exact same from when I recorded the crazy hum noise, so the volume on the amp you name it, yet detaching the earth from the peavey plug dropped the noise a shed load and taking the guitar out made it zero noise altogether where as before taking the guitar out and having the peavey still in the loop there was noise.

Now the big question, how can I have this earth wire detached safely?  Do I need it?

[MarshallJMP]

Just did a FFT analysis on the noise2-wav and I see mostly harmonics of 50 Hz,the biggest spikes are the 2nd up to the 8th harmonic.
50Hz   -81dB
100Hz -47dB
150Hz -36dB
200Hz -26dB
250Hz -32dB
300Hz -32dB
350Hz -23dB
400Hz -34dB
450Hz -32dB

So this seems to me it has got something to do with the power grid and ground loops, or a bad or no earth connection. From what you say the guitar does pick up stuff but also there's a nasty ground loop. Another possibility is a bad cable.

For safety reasons you should never detach the earth connection.