#1
Alright, I'm getting frustrated here. I'll try to be short and sweet as I have already performed a number of tests. My 6505+ gets extra hum when the effects loop is on, but only if a pedal is connected (even if the pedal is off or not even plugged into power).


So far I have run these tests:

Effects loop off - No hum

Tested with a good patch cable going from send to return w/ the loop on - No hum

Tested with various pedals connected into the loop with 2 good cables - Hums when the pedals are on, off, not plugged into a power supply, and run off a battery

Tested the pedals in front of the amp - No hum


Another thing I have noticed is that if I put my Decimator out front and max the threshold, I can't get signal to pass through. However, in the loop with the threshold maxed, a little bit of signal still passes through, almost as if it were a parallel effects loop with the dry mix set low. However this is a series effects loop.

I have tried plugging into various outlets in different rooms, and even have used a power conditioner to no avail. It's done this since I have had it, and new tubes didn't change it. The hum is just loud enough to be annoying, especially since it isn't there with the effects loop off.

Any help is greatly appreciated.

Jackson RR3 Rhoads and DK2M Dinky
Peavey 6505+ w/ Avatar 212 cab
Ibanez TS9, ISP Decimator, MXR 10 Band EQ
-Digitech RP1000
#2
Have you tried switching your ground switch?

Also- if you jumper the loop you have no hum? The second you have a pedal the hum starts?
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#3
does it have a line level /instrument level selector switch, if so flip that and it may do the trick
#4
The FX loop on that amp is tube driven, try a new 12ax7 in it
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#5
Remove everything and start adding it back one piece at a time until you find the culprit. It's also possible that the extra cable length is picking up noise.
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#6
I was curious were he was setting his pedals. Might have an impact ? If the case is grounding on something it might cause a ground loop hum.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#7
Quote by mmolteratx
Remove everything and start adding it back one piece at a time until you find the culprit. It's also possible that the extra cable length is picking up noise.

I disconnected everything and found out that plugging a cable into the effects return results in the hum I was talking about. Plugging the other end of the same cable into the effects send gets rid of the hum. When two cables are placed in the loop (one in the send and one in the return) but not connected in any way, there is hum. When they are connected with a pedal, the hum does not go away.

The hum only occurs when the effects loop is on.

Quote by higgycr
does it have a line level /instrument level selector switch, if so flip that and it may do the trick


The effects loop on this amp is instrument level and is not switchable. Just a plain old series effects loop.

Quote by R45VT
Have you tried switching your ground switch?

Also- if you jumper the loop you have no hum? The second you have a pedal the hum starts?


I have tried all 3 positions of the ground switch to no success. And yes, as weird as it seems, jumping the loop with a patch cable yields no noise, but putting a single pedal in the loop causes hum. I have tried several different pedals and verified that they aren't the source of the hum by running them in front to compare (with batteries too).


I just did a bit more goofing around and have figured out that plugging a cable into only the effects send does not cause hum, but plugging only one end into the effects return causes the same hum I described. I don't know if that is useful to anyone.


Quote by R45VT
I was curious were he was setting his pedals. Might have an impact ? If the case is grounding on something it might cause a ground loop hum.

I've had them on the floor on my wooden pedalboard as well as on top of the amp and it hums both places. Tomorrow I might haul it downstairs and spread everything out as far as possible.


Quote by Robbgnarly
The FX loop on that amp is tube driven, try a new 12ax7 in it


For now I'm going to swap some spare tubes in the fx loop slot and try that, but I am not expecting it to help as I changed all the preamp tubes and the problem did not go away.


I am really baffled here

Jackson RR3 Rhoads and DK2M Dinky
Peavey 6505+ w/ Avatar 212 cab
Ibanez TS9, ISP Decimator, MXR 10 Band EQ
-Digitech RP1000
Last edited by Tremolo Bum at May 14, 2013,
#8
How much hum are you talking?

Is it something you can go effect loop send>pedals>ISP>return and have the noise go away?

I know on my old 6505 there was a slight change with the FX loop active.
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#9
It's not a lot of hum, it probably would not be noticeable live. It's just weird that even with my decimator maxed, it does not stop it.

And if I play with the decimator in the loop with the threshold all the way up, some of the guitar sound can still be heard in the speakers, but if the decimator is maxed in front of the amp nothing can be heard except for a bit of preamp hiss.

It might be normal for all I know, but it's weird that it will go away with a cable jumped, but not with a known working pedal. Hopefully I'm not making a mountain out of a molehill.

Jackson RR3 Rhoads and DK2M Dinky
Peavey 6505+ w/ Avatar 212 cab
Ibanez TS9, ISP Decimator, MXR 10 Band EQ
-Digitech RP1000
#10
Have you tried Deoxit/electronics cleaner in the FX return jack?
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#11
I cleaned the jacks around december because I was having trouble with the loop. I will clean them again in the morning and see if it fixes it, but I'm not holding my breath.


I am trying to figure this out because I might buy a second noise gate so I can run one in the loop and one out front, but with my decimator out front, most of the noise is gone. What's left is mostly just this slight hum that I can't kill with a gate, so I don't know how useful a second noise gate will be.

Jackson RR3 Rhoads and DK2M Dinky
Peavey 6505+ w/ Avatar 212 cab
Ibanez TS9, ISP Decimator, MXR 10 Band EQ
-Digitech RP1000
#12
so if you loop only a noise reduction pedal in the loop the hum is still present?

Yeah unlikely it will do anything if that is true.

Can you try another one at GC and see if it hums as well?
Quote by DeathByDestroyr
See, it's important that people clarify when they say "metal", because I pretty much always assume they are a Cannibal Corpse fanboi.
#13
nobody has asked yet, but what volume are you playing with and how much gain and to a lesser concern what is the room like?

6505+s are loud amps. i had one for a while and i got through it fine, but i sold it. not a bad amp but i funded one of my splawns.
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#14
Quote by Tremolo Bum
I disconnected everything and found out that plugging a cable into the effects return results in the hum I was talking about. Plugging the other end of the same cable into the effects send gets rid of the hum. When two cables are placed in the loop (one in the send and one in the return) but not connected in any way, there is hum. When they are connected with a pedal, the hum does not go away.

The hum only occurs when the effects loop is on.


I'm 90% certain you've got a ground issue and a ton of EMF interference as a result.
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#15
My money's on a faulty jack in the amp's loop.
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#16
Quote by mmolteratx
I'm 90% certain you've got a ground issue and a ton of EMF interference as a result.


this may come out stupid, but i know you know your shit matt and have wondered...

is the EMF something that could be tested by inducing it. for example sit it by your microwave and put the amp close or buy a fluorescent light or microwave?
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Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
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Resentments and Rambling from a Guitar Junkie
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#17
Quote by R45VT
so if you loop only a noise reduction pedal in the loop the hum is still present?

Yeah unlikely it will do anything if that is true.

Can you try another one at GC and see if it hums as well?

Yeah, the noise gate won't kill it. In fact, the hum only occurs when a pedal is actually in the loop. Like I said before, with a patch cable going into the send and return, there is no hum.

I didn't think of trying one at GC. That's a good idea. The store by me actually has one so I will probably try that tomorrow because I'm going there anyway.


Quote by trashedlostfdup
nobody has asked yet, but what volume are you playing with and how much gain and to a lesser concern what is the room like?


Normally I play with the pre gain at about 3 (on the amp, not 3 oclock) boosted with my TS9. I'm usually playing at practice volumes around 1 on post gain but some times I crank it up. It does this in my basement and right now I have it set up in my bedroom.

The hum does not increase as post or pre gain is increased though. It's most notable at low volumes. That's why I'm wondering if this is normal or if it's a problem. However, if it were normal I would have expected the hum to be present with just a patch cable in the loop too.

Quote by Cathbard
My money's on a faulty jack in the amp's loop.

As in the send or return jacks?

Jackson RR3 Rhoads and DK2M Dinky
Peavey 6505+ w/ Avatar 212 cab
Ibanez TS9, ISP Decimator, MXR 10 Band EQ
-Digitech RP1000
Last edited by Tremolo Bum at May 15, 2013,
#18
Quote by Tremolo Bum

Normally I play with the pre gain at about 3 (on the amp, not 3 oclock) boosted with my TS9. I'm usually playing at practice volumes around 1 on post gain but some times I crank it up. It does this in my basement and right now I have it set up in my bedroom.

The hum does not increase as post or pre gain is increased though. It's most notable at low volumes. That's why I'm wondering if this is normal or if it's a problem. However, if it were normal I would have expected the hum to be present with just a patch cable in the loop too.


As in the send or return jacks?


i have seen you for a while on here and i know your shit, but i remember in one peavey 6505+ having bad hum thread before. i assumed he was playing reasonably and the thread went on for a while, and somebody finally asked him what the settings were, and he was boosting it with the gain on the amp dimed . could have saved a lot of effort if it was asked. earlier. i didn't think that you would be another case, but i had to check
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Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#19
My gut tells me it's the return but it could be either really. When you plug a cable into the return you are opening up the power amp and giving it a little antenna so it's not necessarily the source of the hum you are chasing.
'Twer it me, I'd just buy replacements for both and just do both while I had it open.


You have cleaned the tube socket haven't you?
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Last edited by Cathbard at May 15, 2013,
#20
Quote by Cathbard
My money's on a faulty jack in the amp's loop.


Yea, I think that's what's causing an intermittent grounding issue that's cutting off the shield and letting in interference.

Quote by trashedlostfdup
this may come out stupid, but i know you know your shit matt and have wondered...

is the EMF something that could be tested by inducing it. for example sit it by your microwave and put the amp close or buy a fluorescent light or microwave?


Yup. Most people test it by putting their gear near stage lighting, which is notoriously noisy.
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#21
Exactly. Could even just be a dry joint where the socket meets the (I presume) PCB. I'd check that first. Just hit it with an iron and see how it flew. But my money is still on the socket itself.
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Last edited by Cathbard at May 15, 2013,
#22
Have you tried switching the preamp valve for the loop yet? Could be the cause of the issue. The inside of a 6505 does not contain that much solder that you can play around with, its PCB with a lot of computer motherboard style connectors and thick prongs with things plugged onto them.



Top left black cylinder shape things on a seperate PCB connected with a computer style connector is the effects loop, if I'm not mistaken. Only been inside a 5150 mk 1 personally, they look a bit different.
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Last edited by Bigbazz at May 15, 2013,
#23
I tried cleaning the jacks to no avail. I did not get to GC to test out their 6505 to see if it did the same thing. Switching preamp tubes also didn't help.

I want to try and figure out if I just have unreal expectations for killing noise because the hum is not that loud and does not increase in volume. Do all tube amps have a little bit of noise that's impossible to kill with a gate in the loop?

Hopefully testing another amp will help me figure this out before I buy new jacks. I don't know if I would have to order those from peavey or if the local electronics shop will carry them.

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Peavey 6505+ w/ Avatar 212 cab
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-Digitech RP1000
#24
Quote by Tremolo Bum
I tried cleaning the jacks to no avail. I did not get to GC to test out their 6505 to see if it did the same thing. Switching preamp tubes also didn't help.

I want to try and figure out if I just have unreal expectations for killing noise because the hum is not that loud and does not increase in volume. Do all tube amps have a little bit of noise that's impossible to kill with a gate in the loop?

Hopefully testing another amp will help me figure this out before I buy new jacks. I don't know if I would have to order those from peavey or if the local electronics shop will carry them.


some amps make a little noise just being on, but i have a feeling its probably louder than it should be.

i can't really think anything easier to test it, but best i got is if you have a smart phone download a decibel reader app and see what it does.

they aren't the most accurate. maybe then you could get somebody else to do the same thing. and compare??? i don't know. last ditch effort.

have you considered contacting peavey? i don't expect them to do much, but maybe something to test. or a common failure they have gotten.
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Quote by andersondb7
alright "king of the guitar forum"


Quote by trashedlostfdup
nope i am "GOD of the guitar forum" i think that fits me better.


Quote by andersondb7
youre just being a jerk man.



****** NEW NEW NEW!
2017-07-07 2017-07-07 Update and a Chat On Noise Constraints *** NEW FRIDAY 7/7
2017-04-13 RUN AWAY from COMPUTERS!!! TCE? RANT ALERT!!!
2017-03-02 - Guitar Philosophy 1001- Be Prepared For the Situation (Thursday 2017-03-02)
2017-02-21 How to Hot-Rod the Hell of your Stratocaster for $50! (Tuesday 2017-2-21)
Resentments and Rambling from a Guitar Junkie
---> http://trashedengineering.blogspot.com/
#25
If it's like that pic ^^^ it would be piss easy. Looks like it's all held in place by the jacks themselves. Pull it out and check the solder joints (by reflowing the solder). If you can solder, replacing the jacks would be super simple. A dyslexic frog could do it.
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Marshall 18W clone
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Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#26
Apologies for necrobumping this thread- I'm having the exact same issue with my 5150 III 100w head. I was really hoping to see how/if the issue was resolved?
#27
Quote by Kinjin
Apologies for necrobumping this thread- I'm having the exact same issue with my 5150 III 100w head. I was really hoping to see how/if the issue was resolved?

New tube
2002 PRS CE22
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Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
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