Dealing with dirty power/grould loop issues

I swear by the Monster Power Pro 2500/3500. That's my recommendation. And I bought my 3500 from a site that offers payment plans.

 

You probably don't have "dirty power" issues, and no power "conditioner" is likely to help, even one with a substantial price tag.

The issue in a so-called "ground loop" usually boils down to what are actually "pin 1 problems" as well as questionable gain structure.

So in addition to the Kustom powered PA loudspeakers, you also have an amp and a PC. Feedback when you bring your bass close to the amp is understandable, but it's really unusual to get feedback through a PC. Can you elaborate on what exactly is feeding back in that situation?

In the situation where you heard the juke box music coming out of your loudspeakers, can you describe what else was in the system and how it was all hooked up? That could help us figure out what was picking up the interference and where.

 

Are you sure you were getting jukebox music through the PA loudspeakers when they were powered off? That seems unlikely.

Was the hum when your bass was close to the PC in addition to the feedback? Did you perhaps have the bass feeding into the computer and the computer loudspeakers turned up when it fed back?

Does the other PA loudspeaker also buzz when you you plug it into the same outlet strip as the PC or Mac, or only one of them? What sort of AC/mains plug do your PC and Mac have?

 

Bob, do you always use the same loudspeaker for left and the same one for right?

A feedback issue would indicate that something's turned up way too loud. If your bass is feeding back, then sound from the loudspeaker is somehow strong enough to either get picked up directly by the bass pickups or to excite a string and keep it vibrating indefinitely (think Jimi Hendrix).

 

Before you go dropping big money (especially over priced Monster anything) on a fancy power conditioner try this.
http://www.ebtechaudio.com/humxdes.html If the problems went away when you lifted the ground this will fix it without lifting the ground. For what it is it's over priced, but it's not hundreds of dollars either.

 

Bob, in what way is the power sketchy? Have you measured the voltage or anything?

I really doubt that the jukebox audio comes in through the power line. Your powered loudspeakers's power cord inlet is not an audio input. At first you said everything was powered off and you heard sound, and later you said it was all on and then turned off.

When you say "mostly hum," are you referring to when you were also getting feedback? Or is that a different issue a different time, or something?

Can you perhaps start all over with your descriptions? You've added information that either contradicts what you said before or is a different situation than what you'd described. Tell us what you have in your system(s) and how they're hooked up. Try to be as accurate and complete as possible, OK?

Do you know what kind of AC/mains plug(s) your PC and Mac use?

 

So two active speakers switched off still made noise. I don't think that could possibly happen.

 

I agree. I am assuming that what was powered down was the board and the speakers were still powered up.

 

There is the aforementioned Monster unit. And Voodoo Labs makes several great power conditioners.
http://www.voodoolab.com/pedalpower_mondo.htm

 

"Voodoo" is an apt name for a power "conditioner" manufacturer.

When you play live, plug the two powered loudspeakers into the same outlet or outlet strip.

In your home setup, do you get buzzing if the PC and Mac are not hooked into it and not turned on?

 

Wow Bob, you really hate power conditioners, lol

 

How are the cables routed? Are they laid parallel to or draped over speaker wires for the juke box? If that uses 70V speaker output, it can contribute to picking up the sound.

Staticy, buzzy sound is usually from a computer's screen or power supply. Try moving the computer farther from any sensitive devices, like mics, guitar pickups, etc.

You want all of your equipment to be on the same circuit. If any external items are plugged into your PA, make sure they're on the same circuit. This can be a problem in an older home or a bar, because these kinds of places don't necessarily have dedicated circuits for anything- they often share one with freezers, coolers, neon lights, cash registers and others. Once you plug a PA in, the circuit can be overloaded, causing additional problems- voltage often drops before breakers pop. If you have ground loops, Jensen Transformers are about the best for isolation. They're expensive, but they work. EbTech's HumX work, too. I have even used Radio Shack (I prefer not to) and PAC ground loop isolators when RCA connections are used. The PAC are designed so they provide a 1 or 1.25dB increase in level, which is good if hiss is present, along with the hum. Proper level setting is still necessary, though.

If the lights dim or flicker when the wind blows, the fridge kicks on or maybe the furnace/AC starts, the wiring should be checked- it may be as simple as the connections to the cable from the pole, outside. I have seen these go bad and cause this kind of problem, at my parents' house. Once they were replaced, everything was fine.

However, a 100 year old house probably has what's called 'knob and tube' wiring and if you decide to have an electrician change or connect to the same circuit, you need to know that the electric code calls for this kind of wiring to be disconnected and abandoned, including removing as much as possible to keep it from being used in the future.

 

Possibly sympathetic vibration/resonance of the cones/enclosure?