Hi all,

I'm having some trouble -

I use a PP2+ and PP Digital, and have noticed a lot of magnetic field induced hum depending on the position of the power supplies. I have found that with the PP2+ facing towards my feet, and the Digital facing away from them has solved the problem, but I live in fear that cables are going to move during transit, and hum is going to creep in.

Does anyone have any suggestions for avoiding this type of hum, without positioning things in stupid ways?

Many Thanks

I would assume that the main problem you have is that something on the board is particularly sensitive to the small magnetic field around the transformers. If you really want to solve this, first find which pedal is the main culprit.

The cables will not cause any of this as they are carrying DC power... you can lay them any way you want and they will not couple noise into your signal path.

Good Luck!

Thanks for the reply John.

It seems that the problem isn't with a pedal being over sensitive, but my cables - 'low noise' van damme cables.

Here are some photos to help you (and anyone else who wants to chip in) understand the situation.

Board 1: The main hum problem on this board comes from the cable going from wah to moog, and another going from moog down to the boss bypass loop return. Moving these cables even very slightly can range from silence to extreme hum (I have tried using different cables)

http://imageshack.us/photo/my-images/38/p1010001ck.jpg

Board 2:

The main hum problem on this board is the two blue leads going from the Line 6 DL4, up to the Cathedral reverb. I've had to tape and velcro them in this position as any other hums like no other!

http://imageshack.us/photo/my-images/13/p1010004ea.jpg

On Board one, one PP2+ is located here, under the moog:

http://imageshack.us/photo/my-images/51/p1010002wk.jpg

and the other here, under the Line 6:

http://imageshack.us/photo/my-images/109/p1010003lk.jpg

I found optimum positions for the PP2+s by literally moving them around until I found a place with no hum, and these were the ONLY places!

On Board two, the PP2+ & Digital are placed here:

http://imageshack.us/photo/my-images/441/p1010007kv.jpg

& these are the problem cables:

http://imageshack.us/photo/my-images/192/p1010005fb.jpg

http://imageshack.us/photo/my-images/580/p1010006cb.jpg

Any idea why they could be so sensitive? I really don't think my cables are abnormally close to the supplies - I can't stop worrying that it is to do with the metal edging on the tier?

NOTE this hum is with every pedal bypassed.

Oh... you were talking about the audio cables. I've not seen this before that I recall. If this isn't unique to the physical cables you are using at the moment (i.e. if another cable in the same position does the same thing), then routing them securely in whatever manner is quiet is likely the best choice.
Generally, on a pedalboard or rack setup, you want to secure as much of the cable as possible anyway. Today's flexed cables are tomorrow's failed cables... or something like that

Do you know whether having the power supplies underneath the tier could make things worse than average? I can't help thinking that the magnetic field of noise is being trapped under there, or somehow reacting with the aluminium edging on my board?

My main issue is, i've spend the best part of £600 ($920) on these 4 power supplies - and feel I am entitled to be confident I won't get any hum, even if my cables move couple of cm!


EDIT:

I have now uploaded a video to youtube to demonstrate the problem

http://www.youtube.com/watch?v=QXc0Nh_XMQg

The aluminum should have no bearing on this as it is a non-magnetic material.

Just so I'm clear, have you tried a different brand of cable in these positions?

While what I see and hear in your video does seem extreme, it is not unreasonable that you would secure the cables once finding the routing that produces no noise.

I have tried other cables, but the only ones I have that are long enough are about 6 foot, it still hummed, I had most of the cable coiled up and held in the air... completely away from the power supply!

Are there any brands of cable you'd recommend that will have sufficient shielding?

Thanks for your time.

I don't have a brand recommendation, it was really as a test to see if there was anything going on with the cables you are currently using.