Question for computer/electronic/musician techs.......

[luckydog]

My keyboards (piano/synths) are plugged into a big ole 120 watt Behringer 4 channel amp.
Yesterday, when I turned it on there was a noticable high pitched, staticky buzz that faded in and out.
I switch channels, change cables, etc but to no avail.
Definite interference from somewhere.
Thinking it might have something to do with this solar storm we're going thru (affecting radio & TV), I get on the computer to do some research and notice that when I scrolled with my wireless mouse, I can affect the static coming out of the amp. Hmmmm......
I unplug the mouse.......no change.
I unplug a USB cable that runs from one of the keyboards to the computer ( keyboards are OFF)
and the staticky buzz disappears ???!!!???

Is this a computer or USB cable problem ??

Thanks for your help....

LD

[TomSteber]

Is the USB line running parallel with any power cords or any other cords for that matter?
I know that can cause issues sometimes even if their not touching.
Just a stab in the wind.

[alain95]

His there any special works around your home with electric generator and High voltage cables ?
You should also check the ground cables from your power connectors to the Pc and music devices.
I had an issue many years ago with a customer who experience troubles with his PC keyboards,
we change the keyboards many times but it didn't fix the problem, in fact his PC was just few inches from a High Voltage city cable... The definitve solution was to take the Pc away from that cable...
I also hardly suppose that there's a electricity leak in your amp... or it's to close to your PC...

Good luck LuckyD
:engel016:

[cliff527]

My keyboards (piano/synths) are plugged into a big ole 120 watt Behringer 4 channel amp.
Yesterday, when I turned it on there was a noticable high pitched, staticky buzz that faded in and out.
I switch channels, change cables, etc but to no avail.
Definite interference from somewhere.
Thinking it might have something to do with this solar storm we're going thru (affecting radio & TV), I get on the computer to do some research and notice that when I scrolled with my wireless mouse, I can affect the static coming out of the amp. Hmmmm......
I unplug the mouse.......no change.
I unplug a USB cable that runs from one of the keyboards to the computer ( keyboards are OFF)
and the staticky buzz disappears ???!!!???

Is this a computer or USB cable problem ??

Thanks for your help....

LD


Something to try: Radio Shack sells "ferrite cores", the kind that snap on, around a cable. These are basically filters; USB cameras usually have 1-2 in their USB cable; monitors often have one at one or both ends of their cable. The difference is the kind you buy at RS are split, length-wise, and in a plastic 'shell', - allowing you to open it up and "clamp" it around a cable. (It does not puncture or otherwise affect the cable in any way...just being around the cable is all it takes for this type filter to work).

http://www.radioshack.com/product/index.jsp?productId=3012599 I think there are 2 in teh package for US$2.99. (Even if it doesn't work, you're out very little time and money).

We had problems where I work - horrible problems with some USB data acquisition units...and these cores put a *screeching* halt to it. Often, USB cable shielding isn't what it should be, and this can cause problems with noise from induced "EMF" interference.

Hope it helps.

[luckydog]

Thanks for the input everybody........

Time to do some shopping for "shielding" or shielded USB cable, me thinks.....

LD

[gigabyte]

I will back cliff527, ferrite cores have solved more interference for me that any other trick or tactic I have ever used. I use them on every cable in my server rooms, especially the server power cables. They are not costly and worth every penny.

[Tako_Kichi]

As Gig says ferrite cores are a 'standard' weapon against EMI (electro-magnetic interference) and are certainly worth trying in your situation.

I have been a fully qualified ham radio operator for many years and most hams keep a few around in case a neighbour happens to complain about the ham 'breaking through' their hi-fi/TV/surround sound systems. The culprit is usually not the ham operator but the 'complainer's' equipment being built to poor/low specifications without interference rejection circuits to reduce costs. Usually putting a ferrite core on each of the speaker leads as close as possible to the amp cures the problem.

As to computers, they are well known for spraying EMI around (especially in the radio frequency spectrum). You mentioned you had a wireless mouse and that is a possible cause too (as are any portable phones, cell phones and wireless internet/networking devices) as they all operate in the radio frequency spectrum and their signals can be picked up and re-transmitted through amp/speaker systems.

How long are your speaker cables from the amp you use with your keyboards? If they are more than 6 ft long they could easily be acting as 'antennas' picking up any spurious 'noise' and feeding it back into the amp where it gets amplified and sent out to the speakers. Putting ferrite cores on the speaker leads could help you out.

[luckydog]

As Gig says ferrite cores are a 'standard' weapon against EMI (electro-magnetic interference) and are certainly worth trying in your situation.

I have been a fully qualified ham radio operator for many years and most hams keep a few around in case a neighbour happens to complain about the ham 'breaking through' their hi-fi/TV/surround sound systems. The culprit is usually not the ham operator but the 'complainer's' equipment being built to poor/low specifications without interference rejection circuits to reduce costs. Usually putting a ferrite core on each of the speaker leads as close as possible to the amp cures the problem.

As to computers, they are well known for spraying EMI around (especially in the radio frequency spectrum). You mentioned you had a wireless mouse and that is a possible cause too (as are any portable phones, cell phones and wireless internet/networking devices) as they all operate in the radio frequency spectrum and their signals can be picked up and re-transmitted through amp/speaker systems.

How long are your speaker cables from the amp you use with your keyboards? If they are more than 6 ft long they could easily be acting as 'antennas' picking up any spurious 'noise' and feeding it back into the amp where it gets amplified and sent out to the speakers. Putting ferrite cores on the speaker leads could help you out.

Cables running from the keyboards to the amp are 6' "shielded"...........several ferrite cores should arrive in a day or two.

[Tako_Kichi]

Cables running from the keyboards to the amp are 6' "shielded"...........several ferrite cores should arrive in a day or two.
I was more interested in the cables going from the amp to your speakers. Speaker cables are usually two-core unshielded and can act as antennas drawing in unwanted signals.

[luckydog]

I was more interested in the cables going from the amp to your speakers. Speaker cables are usually two-core unshielded and can act as antennas drawing in unwanted signals.

Thanks fo the interest Tako,

4 channel amp and speakers are one unit (big cabinet, 15" woofer, 5" horn and a tweeter).
The interference only occurs when I plug the USB cable from the keyboard into the computer to record my playing.......

[Tako_Kichi]

Thanks fo the interest Tako,

4 channel amp and speakers are one unit (big cabinet, 15" woofer, 5" horn and a tweeter).
The interference only occurs when I plug the USB cable from the keyboard into the computer to record my playing.......
Ahh now I see! You are using an instrument amplifier rather than feeding the keyboards into a stereo system of some type or into a mixer/power amp setup. I am very familiar with instrument amps being a former recording studio engineer and a bass player/guitarist. I have a Fender 15" bass combo here and a Roland Cube 20x for my guitar.

Sounds very much like an unshielded USB cable could well be the culprit here.

[cliff527]

Just as point(s) of clarification:

The length of a speaker cable being over (or under) 6 feet wouldn't necessarily have anything to do with how likely it is to cause (or suffer) RF interference. Signals are propagated in a certain frequency range ("band"); wavelength is a function of frequency. Antennas physical attributes (number/type elements and their arrangement/dimensions) are what makes them good (or bad) at transmitting/receiving a given frequency. For example, I seem to recall that FM radio antennas are 1/4 FM wavelength @ 33 inches long (I didn't check, I could be wrong...haven't been in school for about 27 years now *lol*). Anyway, the point is that any wire, of almost any length, can act as an 'antenna'...it will be most sensitive to frequencies having wavelengths at or in multiples/fractions of it's length.

These days, with most everything operating at higer and higher frequencies, even short pieces of cable/wires can pick up interference. Also, some devices (like some cordless phones) actually *rely* on their base unit's telephone cord as an antenna for the cordless units. If you were to put a ferrite core on this cable, it would likely cause problems with these phones.

So, while ferrite cores can solve lots of problems with interference, they should be used carefully, not just snapped on every cable in sight :)

Also, unless I'm mistaken, there is technically no such thing as an "unshielded USB cable". I do realize that unshielded USB cables are not uncommon in reality, of course - what I'm saying is that (I believe) shielded cables are part of the actual USB specs. If a cable is made to spec, it will be shielded. You can buy cheap junk just about anywhere, and unfortunately there's no 'law' that says they cannot make/sell unshielded cables. But, proper USB cables are always shielded.

USB is one of the most widely abused specs ever to exist. If I had a dime for every USB device I've seen that somehow *didn't* meet the specs, I'd be wealthy. Some things I seem to recall:

- Technically, there's no such thing as a "USB extension cable" (Yes, I know you can buy them everywhere; but I do believe they were expressly forbidden in the USB 1.1 spec).

- Anything (read: "external hard disk USB connectors") that relies on a "Y" or 'splitter' type USB cable to get sufficient current from a USB port (even USB 2.0) is technically not compliant with the specs. Not only do these 'splitters' contradict the specs, but also the specs say (IIRC) that any single USB device is not supposed to draw over 500mA of current - and *all* USB 2.0 connectors are supposed to be capable of providing 500mA to a connected load.

This means that, if a device requires one of these 'splitters' to work properly, then either your USB ports or your external drive (or both) is not compliant with the USB spec (I believe).

- *NEVER* use a USB device to control an inductive load. Relays, solenoids, mechanical counters...any type of electromagnetic device generally constitues an inductive load.

These are only some of my "list of most misunderstood USB things"; there are lots of others. Basically, it all boils down to "Just because you can buy something that plugs into a USB port does NOT mean it is a properly designed, spec-compliant USB device".

Hope this is helpful.