#@$%*^+@ Rack Buzz

[ryan]

As usual, I can't make up my mind about what amp I wanna use.

I reassembled my rack over the weekend. *Upon hooking it up with a newly acquired Rocktron Hush IIC, I was greeted with the most disgusting hum and buzz I had ever heard.

If I disengaged the effects loop, the noise went away. *I started plugging/unplugging all of the stuff to figure out what was the culprit.

A lot of noise went away when I removed the Hush from the rack (this still strikes me as the best part...) as it seems to have been grounding against the rack rails. *However, it was still humming.

After about an hour or so, I determined that most of the buzz was from my head sitting on top of the rack right above the power conditioner.

Putting the rack on top of the head eliminated the loudest buzz.

However, something still remained.

My effects loop send goes to the input on a Rolls RFX Patchwork. *The effects loop return comes from the out of the Patchwork.

With no other effects plugged into the Patchwork, I was still getting hum. *Not very loud, but annoying none the less.

I finally tracked it down to the MIDI cable...

I use a 5-pin MIDI cable from the Patchwork to a DMC Ground Control pedal. *The Patchwork comes wired to provide Phantom power via 5-pin cable.

If I plug the MIDI cable into the Ground Control, it hums. *It I unplug it, it's clean and quiet as can be.

This is a 25' Hosa MIDI cable. *it's black plastic all the way around... *Plug it in and it buzzes.

Now... I have a 6' MIDI cable with full-metal connectors. *If I connect this one, I don't get any buzz.

My concern now is *-- If I buy a 25' MIDI cable with metal connectors, is it going to buzz or not? *Is the LENGTH of the cable the problem, or is it the connectors? *I have two 25' Hosa cables, both of which buzz...

Anybody have any clues? *

Could the MIDI cable be a symptom of something else not being grounded properly or from something touching the rack rails?

I've never had to deal with this ****
before, cuz any other time I've screwed it in, hooked it up and played. *No problems...

Thanks in advance for any advice.

Ryan

[Vaibanez]

Replace the cable. Chances are it is fuchie-manooly.
If the new one still buzzes, take it back until you get one that doesn't.

It's the cable...no doubt about it. You kinda' answered your own question. =o)

J>

[ryan]

Well... my question regarding the length or the connectors still stands.

I have two 25' cables with plastic ends. *Both buzz.

Is it the connectors or the length?

[Project Guitar]

Ryan when you remove the platic plugs off of the cables can you tell if the cable itself has a wound sheilding through the length of it or not?

Sounds like (an I am not really sure about this) By default the cables are picking up all the RFI in the area because they are not properly sheilded.

If you do see a sheild on both those and the metal tip ends one check to see if the sheild on the metal plugs is attached to the plug itself thus grounding the RFI signals by default.

You may want to ask Bob Oakman about this since I am only guessing here or you could e-mail Rob Super he has extensive knoledge and does this kinda thing for a living....

[ryan]

I've found a work-around for the MIDI problem, but I'm still having other buzz crop up here and there.

I got a 25' Monter DigiLink MIDI cable, which promised on the package to be "fully shielded blah blah blah" so... I take it home, plug it in and "....." *no power to my Ground Control.

I take the connector apart and find that only the middle three pins are actually wired... *whatta crock.

Anyhow, I need a power supply on-stage for my wireless receiver (sitting next to my wah so I don't have to run a long cable...) so I'll just use another wall-wart to power the MIDI pedal, too. *Doing this results in no hum, so it'll be fine by me.

Now I need to get rack isolator things cuz I can't figure out why the other buzz comes and goes.