Peavey 6505+ Hum Problem! ARGHHH!

[mick thompson]

hey,

so i had my array of boss pedals which were all running of 9 volt batteries and when i ran it through the fx loop of my peavey i got this horriffic hum sound, i understand that the boss pedals make a bit of buzz but this is just annoying. im running a boss ns-2 noise gate in the loop and well its not really doing much to fix the noise.

so i decided to pick up a power brick - i hoped this would somehow fix my problem. i plugged it in today and euck, ive still got hum.

what i noticed: the hum is at a constant volume and only present when the fx loop button on the foot switch is pressed. its certainly not my guitars because they're all earth grounded etc and i dont get noise through other amps.

its not the fx return because i ran an mp3 player into it and used the peavey as a power amp to test and i didnt get a single annoying bit of noise.

from what i've noticed its almost as if when i use the fx loop the preamp signal doubles (and the peavey is already a prety noisy amp) so it tends to double the noise.

what the fuck can i do to shut the fucking thing up? its really pissing me off.

so noise gates dont work? would a power conditioner to the job? is there a small device i can just clip onto the end of my plug to like...earth it better? i dont want to go out spending lots of money on different things to try and fix the problem. if anyone has the same problem as me and learned how to fix it then please let me know.

on that note im in ireland so our voltage is between 220 and 240 and on the amp there is a switch to swap between 220 and 240. i tried both and to no success.

im running everything at the correct ohms and voltage and my cab is a brand new marshall 1960 lead A using a marshall speaker cable.

HELP!!! i really want to use my fx loop as this christmas im investing in shit loads of pedals and a voodoo labs ground control etc and it will all be a big waste if i cant even get a clean sound from the amp.

is it possible that the fx loop is damaged because the return has no hum but the send seems to create a humming sound. it almost sounds like a guitar cable plugged into an amp but not into a guitar and when you touch the head you get a buzz - its pretty close to that. but all my cables are fine because i tested them going into the guitar input on the amp and they are pretty much noiseless

10 browny points for the chap or chapess that comes up with the fucking solution!

 

[Jahbulon]

Hey man thanks for your suggestions on those effects... I've only used the preamp out ( to use with impulses) and haven't hooked any effects up yet so I'm sorry, but if i come across anything in my search I'll let you know.

 

[Genius Gone Insane]

Didn't read your whole post but you may want to try a different power outlet if you haven't already. That can definitely make a difference.

 

[mick thompson]

hmm - nice idea actually, i've only used the amp in 1 room as its fairly new and i have not got a chance to gig it around, its 1.44 am though here in ireland so i'm going to give it a go in the morning. i'll post back my results

 

[TravisW]

Here's where I'd go with troubleshooting, for what it's worth.

1. Plug one cable into both the send and return of your effects loop. Click the loop on and off.

2. If it still hums, try a different cable.

3. If it still hums, you probably have a problem (dirt or other) with one of the jacks.

4. If it doesn't hum for one cable or another, you have a bad cable.

5. If it doesn't hum with either cable, add one pedal into the loop. Keep adding pedals one at a time (on battery power) until the hum returns.

6. If you have all of your pedals in the loop, and no hum, it's apparently fixed. But, at that point I would try switching over to the wall power to see if that is adding the hum to your signal.

 

[wishtheend]

I would check the cables running out of the amp for the FX loop, and also your coupler cables. Since the noise is only there with the FX loop enabled - there is probably just either one bad pedal, or one bad cable.

I just recabled my whole rig with mogami - and it's silent as can be.

 

[Morgorroth]

Try a ISP Noise Decimator, it's way better than the boss (which produces a little bit of noise too, when I plug it in the FX loop of my bugera)

 

[Wolfeman]

Sounds like a ground loop. Buy an isolator and throw it in your loop.

 

[mick thompson]

ok so i decided to try out TravisW's ideas and i started testing all my cables.

i started off with 2 patch cables and both produced a hum at around the same volume (they are both gold plated) then i started plugging in my guitar cables and i noticed that some cables produced a much larger hum then others. i then thought that "no all my cables cant be fucked" and when i was plugging out the final cable i cracked it!

it turns out that the position of the cables seems to be producing the noise. if i force a patch cable to stretch as far as it can towards the ground away from the amp the hum completely stops, if i raise it to the top of the amp it gets really loud and if i place them near random parts of the back of the amp (eg the plastic grips for taking off the grill the hum gets less noisy.

i then decided to plug in my boss noise gate through the fx loop, i used my 9v dc brick and my 2 patch leads, same shit - if the pedal is on top its noisy, if its down low its not too bad, it its on the floor in my chain its noisy because of whatever way the cables are positioned going through the fx loop of my amp.

so clearly gold plated cables dont work to eleminate the hum but they do make it less audible. so what can i do to shut it up? i was thinking of mounting my boss noise gate onto the back of my cab and having the cables running downwards to shut the hum up but when it comes to gigs what if i cant bring my cab, then im fucked.

perhaps my house is an electrical nightmare because i get the hum in all rooms of the house (and their on different circuts - its a 5 bedroom house) i cant hook it up to a multiple phase supply because my house only has the 1 supply.

so its the cables running in and out of the fx loops position that make the hum - what to do chaps? any ideas?

 

[mick thompson]

HAPPY DAYS - I'VE FIGURED IT OUT - I THINK IT IS A MIXTURE BETWEEN A GROUND LOOP ERROR AND CABLE INDUCTANCE.

I DONE A GOOGLE SEARCH ON "AMP GROUND LOOP HUM" AND I CAME ACROSS A HARMONY CENTRAL REVIEW ON THE "EBTECH BY MORLEY HUM ELIMINATOR 2"

I HAD MY DOUBTS THAT THIS DEVICE WOULD DO THE TRICK UNTIL I CAME ACROSS ONE REVIEW WHERE A GUY WAS SAYING THAT HE WAS HAVING PROBLEMS WITH CABLE INDUCTANCE. I SORT OF KNEW WHAT THAT MENT SO JUST TO CHECK I ASKED ON YAHOO ANSWERS - I GOT A ANSWER WHICH BASICALLY TOLD ME THAT IT IS INTERFERENCE PICKED UP BY CABLES DUE TO BAD INSULATION, BEING COILED UP, AND MAGNETIC FIELDS INTERFERING.

SO I FIGURED IT WAS A MAGNETIC FIELD INTERFERENCE PROBLEM WITH THE ELECTRICAL COMPONENTS IN THE AMP CREATING A FIELD EFFECTING THE FX LOOP.
I THEN CONTINUED TO READ THE REVIEW AND THE CHAP SAID IT WORKED PERFECT / 1000% / NOT A HUM IN SIGHT AND HE RAN IT THROUGH HIS FX LOOP.

SO I NOW HAVE TO GO FORK OUT 70 EURO'S ON ONE OF THESE BUT ITS MONEY GOING TO BE WELL SPENT. IM JUST HOPING THAT WHEN I HAVE IT AT THE END OF MY LOOP THAT EACH PEDAL WONT START CREATING ITS OWN HUM, IF IT DOES IM GOING TO HAVE TO FORK OUT ON THE 8 CHANNEL RACK UNIT. FINGERS CROSSED.

THANKS ALOT GUYS FOR ALL THE COMMENTS POSTED, REALLY HELPED ME GET TO THE BOTTOM OF THIS, ITS BEEN PISSING ME OFF SINCE JULY.

BROWNY POINTS FOR ALL!

ps: sorry for the long ass posts!

 

[TravisW]

When you are moving the cables around, is it pulling on the jacks at all? It could be the ground contact on your effects loop jack as well.

 

[mick thompson]

nope - its not putting any pressure on the jacks what so ever - i plugged in a 6 foot guitar cable and held the cable in the centre to create a hoop and moved the centre part of the cable around the amp (as if i were probing for radiation or using a metal detector). i moved it around the amp at different parts, the top caused more hum, the bottom was silent, the middle was slightly humming.

when i was doing this there was plenty of slack on the rest of the cable so there was no pressure on the jack causing them to short out.

 

[TravisW]

Cool, sounds like you're on the right track.

 

[mick thompson]

cheers for all your help TravisW, and thanks to all the other posts lads - i wouldn't have figured it out without your help

 

[Mr. Brokenamp]

The simplest way to block the interferrence:
Try a steel plate.

 

[mick thompson]

im not going to house my peavey head in a steel box because

1: I dont want to get electrocuted if something shorts out
2: It would just add more weight to an already heavy as fuck head
3: It wouldn't stop the cables picking up shit from other amps further down the cable.
4: It would look horrendous
5: It would be quite expensive to get a steel encasing around my amp especially if i want it to look well

Dont get me wrong, its a nice idea and i would do it if my amp was in a specific environment 24/7 but im a gigging musician always on the move and its just not practical enough for me.

Thanks again for the idea though!

 

[Mr. Brokenamp]

OK what does the amp do if you just run a plug from the send to the return?

 

[mick thompson]

it hums! even if i just use a small patch cable. and if i move the cable downwards towards the floor the hum goes away, if i move it upwards closer to the tubes height it gets louder. and its a preamp / fxloop problem for sure because the power amp doesn't amplify the sound. i can drown out the hum but i'll have to krank her to about 5 or 6 and it will still be present when im not playing, a gate does not remove it.

amazingly out of all the guitar shops in dublin city i went into only 1 chap knew what i was talking about when i said cable inductance and ground loop but he didnt have any ideas on what to do, im just going to try the morley product and see if it helps.

 

[Mr. Brokenamp]

IT sounds to me like the effects loop is putting out way more gain than it should. If you can find a schematic maybe I can be of more help.

 

[Wolfeman]

Don't waste the money on that Morely, buy one of these and never look back.... http://www.adamhall.com/de/AH_K--Palmer-line-box__p--project_27__b--PLI01__parid--12