Please help identify an odd noise issue... power supply?

[Mr Wolf]

Hi all,

It has been a while since I last posted here! I hope some of you may be able to assist. There are two problems that I encountered during recent gigs and rehearsals. I would be very grateful your collective knowledge and experience on these issues because I am no electronics expert! Main problems were...

1) Pops/noise caused whenever the mains extension lead (which my pedal board is connected to) or the pedalboard itself was physically knocked. This has only happened in some locations. Most recently during last week's rehearsal, when I turned pedals on and off it led to a pop depending on how firmly I stepped on the switches.

2) On one occasion at a gig I had the embarrassing issue of my volume fading in and out. On removing my pedal board and running Guitar>OD>Amp the gig went on without technical issues and the band got paid. I assume it was a current issue from the mains supply.

So far I am of the impression that it is a mains power/pedal power supply issue. I am no expert on these things and how they happen, but I imagine the answer is to upgrade my pedal power supply. That said, they are costly - which in itself I don't mind as long as it would definitely sort these sorts of issues.

These problems have only come to light in the last few gigs and rehearsals and I never had these issues before - but I guess luck runs out! Anyhow many thanks in advance for any input on these.

Cheers,


FYI my rig is...
Gibson ES-137 (with p90's)

Pedalboard with usually 5 pedals, usually Boss or MXR, powered by a fairly inexpensive 9V splitter box.

Into Laney GH50L with 2x12" cab.

 

[Gearjoneser]

Re: Please help identify an odd noise issue... power supply?

powered by a fairly inexpensive 9V splitter box.

There's no isolation between pedals run off a cheap power supply, and any grounding issues usually stem from that. You may also be plugging that into a cheap power strip that just adds the potential for problems.

Spend the money and buy a Voodoo Lab Pedal Power II +. Also flex all your cables while you're playing to see if any pops and crackles are coming from them. If so, resolder them or throw them away.....or cut them down to 1 ft patch cables.

 

[Mr Wolf]

Re: Please help identify an odd noise issue... power supply?

There's no isolation between pedals run off a cheap power supply, and any grounding issues usually stem from that. You may also be plugging that into a cheap power strip that just adds the potential for problems.

Spend the money and buy a Voodoo Lab Pedal Power II +. Also flex all your cables while you're playing to see if any pops and crackles are coming from them. If so, resolder them or throw them away.....or cut them down to 1 ft patch cables.

At the time I swapped cables about which led to the same problems. I have heard about the Voodoo Lab unit, it definitely seems to be a well liked one. Is a fair amount of money but if it does the job then that is what needs to be done.

Would you think the problems I described as being caused (or at least made more likely) by lack of isolation in my power supply?

I tried 2 different power strips. Trouble is both were pretty cheap so I don't think that side of things is ruled out either!

 

[Dr. Vegetable]

Re: Please help identify an odd noise issue... power supply?

If the main power is questionable where you are gigging, you might want to invest in some Furman power conditioners for your gear. This will at least tell you if you have bad power or a brownout condition onstage, and may be able to regulate the power better so your gear doesn't malfunction.

If the pops and volume problems have just started happening, and if they happen in more than one venue/location, then I would check for a bad cable or pedal. From what you've described, this is a new ghost haunting your rig. Maybe something broke? Try taking one pedal at a time out of your effects chain to see if the problem goes away.

Good luck!

 

[Mr Wolf]

Re: Please help identify an odd noise issue... power supply?

Thanks! The pops I describe are strange. It is not like the odd random crackles you get from poor leads wiggling about. If you kicked a mains extension a little, or stepped on a pedal firmly it would make a noise sounding more or less like an amplified version of the physical "clatter" that you would normally hear.

I took out some pedals (not all though) at the last rehearsal and messed about with leads (some were new) to no avail. I am no electronics expert so I'll resort to a bit of trial and error if it comes about again.

That said, you mention Furman's... I have had it recommended to use a power conditioning mains extension lead (HiFi/TV type ones). I imagine that would somewhat do what the Furman units do? Judging by costs maybe to a lesser degree, but anyhow my thoughts are on doing that, and upgrading the pedalboard power supply should hopefully take care of these mysterious rig ghosts!

Many thanks again to you both for your input.

 

[d1dsj]

Re: Please help identify an odd noise issue... power supply?

Are all your pedals into the front of the amp or are some into the loop? If you are running some in front and some in the loop and using the same power supply you may have created a ground loop, so always use a different power supply for pedals in the front and pedals in the loop. As already suggested a Voodoo Lab PPII(+) or similar with individually isolated outputs is the way to go.

 

[Mr Wolf]

Re: Please help identify an odd noise issue... power supply?

Cheers for that info. In this instance though all effects are in front. As far as power supplies go I have had the Diago Powerstation recommended which come in at around a third of the price of a PP2+ so I am tempted to go down that route, along with a power conditioner of some sort.

 

[glassman]

Re: Please help identify an odd noise issue... power supply?

Thanks! The pops I describe are strange. It is not like the odd random crackles you get from poor leads wiggling about. If you kicked a mains extension a little, or stepped on a pedal firmly it would make a noise sounding more or less like an amplified version of the physical "clatter" that you would normally hear.

If I'm understanding this correctly, you are saying that you are hearing mechanical sounds amplified through your rig; as in the click or crunch the actual switch makes when you engage a pedal. If you tap on the 1/4 cables between the stomp boxes, can you hear the tapping sound through your amp? If so, it's a ground issue...most likely a cable but a bad connection in an effect or the amp is also a possibility. What's most likely happening is that a ground is open somewhere in the chain and instead of the effect's buffer referencing ground through itself at the jack where it's supposed to, it's referencing it through the pedal power supply and using another buffer in another effect. This makes everything in the chain very sensitive to mechanical noise.

Keep you current power supply (for now) and check each of those cables. Clean all connections with DeOxit.

 

[ErikH]

Please help identify an odd noise issue... power supply?

Any time I hear a pop when engaging a pedal it's because that pedal is true bypass. This happens because a charge builds up in the output cap in the pedal when it is bypassed. Once it is engaged, that charge is now released through the switch and creates the pop. Quick fix is a 1M resistor from hot to ground at the input and output jack.

Volume drop could be bad cable, could be dirty power. I'd run a continuous signal through the board (radio would work) and wiggle each cable, replacing any bad ones. Also make sure the power is a regulated supply.

 

[Mr Wolf]

Re: Please help identify an odd noise issue... power supply?

If I'm understanding this correctly, you are saying that you are hearing mechanical sounds amplified through your rig; as in the click or crunch the actual switch makes when you engage a pedal. If you tap on the 1/4 cables between the stomp boxes, can you hear the tapping sound through your amp? If so, it's a ground issue...most likely a cable but a bad connection in an effect or the amp is also a possibility. What's most likely happening is that a ground is open somewhere in the chain and instead of the effect's buffer referencing ground through itself at the jack where it's supposed to, it's referencing it through the pedal power supply and using another buffer in another effect. This makes everything in the chain very sensitive to mechanical noise.

Keep you current power supply (for now) and check each of those cables. Clean all connections with DeOxit.

Thanks very much for the insight. Going to do a thorough check of each part of the board to see if I can determine the cause. Fingers crossed it is something simple. I assume DeOxit is some kind of electrical contact cleaner? Haven't heard of it over these shores. Anyway I'll go through each thing in turn to see if I can figure it out. Many thanks

 

[Mr Wolf]

Re: Please help identify an odd noise issue... power supply?

Any time I hear a pop when engaging a pedal it's because that pedal is true bypass. This happens because a charge builds up in the output cap in the pedal when it is bypassed. Once it is engaged, that charge is now released through the switch and creates the pop. Quick fix is a 1M resistor from hot to ground at the input and output jack.

Volume drop could be bad cable, could be dirty power. I'd run a continuous signal through the board (radio would work) and wiggle each cable, replacing any bad ones. Also make sure the power is a regulated supply.

At the gig where I was having those issues I did cable checks to no avail (all rather embarrassing!). Given how I lost signal so smoothly (almost like a fade) I think it must have been a dodgy mains supply. Given that most of the gigs are paid I shall most probably upgrade my power supply to make things more reliable. That said, from Glassman's comments I am concerned there may be more than one electrical demon floating about my rig!

Thank you all for your collective inputs. I now know more than I did previously!