Hey guys,
I recently acquired a Definitive Technology Prosub 1000, but after hooking it up to my receiver, and turning on the power, it produced a low hum that changes from time to time in volume. When music or a movie is playing it intermittently thumps really hard (as though its working well) and then quite's off again. The low pass filter on the back and the volume on the side work fine, its just not performing consistently. The bass is still coming but goes up and down, and I think it even works better when the movie/song calls for heavy bass.
Is this a Capacitor problem?
The sound, that generated when no music is playing and when its plugged in is a low hum, that will get loud and then go back to quite and occasionally go right out for a few moments (seconds).
Any help would be greatly appreciated!
Cheers
Matt
I recently acquired a Definitive Technology Prosub 1000, but after hooking it up to my receiver, and turning on the power, it produced a low hum that changes from time to time in volume. When music or a movie is playing it intermittently thumps really hard (as though its working well) and then quite's off again. The low pass filter on the back and the volume on the side work fine, its just not performing consistently. The bass is still coming but goes up and down, and I think it even works better when the movie/song calls for heavy bass.
Is this a Capacitor problem?
The sound, that generated when no music is playing and when its plugged in is a low hum, that will get loud and then go back to quite and occasionally go right out for a few moments (seconds).
Any help would be greatly appreciated!
Cheers
Matt
Hi Matt'
The advice that Inductor gives is good. Posting a link to the sub/amp's data sheet will be helpful, along with photos' of the "control panel". How old is this unit, and in what condition? I have a "Pro-sound" bass amplifier that I use on stage from time to time. What I love the most about it is that I got to select each "modular component" e.g., Two very high-end 18's, eight 10's, 2 eighteen inch "W-bins", "Millenia-stt1" pre-amp, 2 Crown power amps etc...
Opps'... that has nothing to do with this; just a bit of my "OCD" kickin' in again
But what happened to me was, I had just gotten the brand new power amp and was setting it up for the very first time. When I turned it on to do a test run, it did just as you've described; the volume level was in and out, up and down, and the air coming from the cooling tunnel was really heated, I mean like "get it shutdown REAL... quick" hot!I checked it out, giving particular attention to the new "Neutrik Speakon" wiring cables because I had just built them, like the night before; using a 75' spool of "12ga, 4 conductor", stranded copper. I guess I wasn't careful enough during the splicing & terminating process. When I took the "inter-locking" male connectors apart, I saw that I had allowed just 1 or 2 strands, to stray across the insulation barrier, causing the amplifier's "protect mode" to trip. The amp was designed NOT to shut-down under these circumstances but rather, to limit the amount of power (current) released from it's output devices when it see's a "low operating impedance" condition.
The only thing that's not like what I experienced, is the hum. But you may just be picking up an EMF (electro magnetic field) through your line level input cables. I don't know how long your runs are (between the preamp, and the power amp), or if those cables are near any equipment that may be emitting a level of magnetic field, like a lighting ballast (a step up transformer). You can run "unbalanced" cables for short distances. These are the ones that use only two conductors; the neg (-) serves as ground and shielding. "Balanced" cables provide a separate (braided) conductor which is designated to shield both, the pos and neg conductors.
Because my rig is a bass amp, all of my line level cables are usually rolled up inside of the rack, and so are pretty much protected from any magnetic field source. So I only need to run "unbal" cables. Well, good luck, and I'm sure you'll find a solution to both these issues, be sure to let us know!
rigtec, cheers!
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