jhiter24

I just hooked up my Sony SAWM40 sub to my Pioneer 509 through the preout. There seems to be a nagging hum when the volume is up and there are those silent spots during a movie. IT is fine when all the music is going but when there is just speach, the noise gets to me. I was wondering if it could just be a bad cable that hooks them up. I am only using the cable that came with the sub. SHould I get a better one. And if so, which cable should I get. Thanks for the help.

Chris

audrey

it could be the cable, but the hum could result from other sources as well. some things to try:

-disconnect the cable from the receiver and sub; turn up the sub's volume. does it still hum? if so the problem isn't in the cable. if the hum goes away, try a different cable.

-try reversing the polarity of the electrical plug to the sub (you may need to get a cheater plug to do this)

-try a different electrical outlet for the sub

if none of the above help, you might have defective sub.

sfunk

Also try an attenuator if the above does not help. It will reduce the line voltage from the receiver to the sub. Sometimes receivers put out just a bit too much line voltage. You may also notice that your sub will not turn off automatically when you power down your receiver due to this.

I got one from MCM electronics (on-line). If you need one let me know & I'll see if I can help!

Scott

Use a shielded cable to the sub.

Kojack

I would bet that the hum is still there when the music is on, but you just can't hear it since the dB level of the music is loud enough to mask it. I had this same problem with my sub (which I actually sold, but not because of the hum) and it was a ground loop, fixed with a cheater plug. My first guess is that you're experiencing the same problem.

Here's a link for more info on ground loops:
http://www.smr-home-theatre.org/Ground-Loops/index.html

Hope that helps - good luck!

jhiter24

I just noticed that even my other speakers give off a very faint hum. What is a cheater plug, where can I get one, and how much are they? I tried doing a few things that that link said to do and some of it helped. But I can't stop concentrating on this hum.

Kojack

A cheater plug is a couple dollars at Home Depot and converts a 3 prong outlet to a 2 prong outlet. Worth a try for a couple bucks.
Good luck!!!

Rainman15

jhiter24,

I have the same receiver and sub hooked through the receiver's subwoofer preout, with the provided cable. When I do the test sounds on the remote I get NOTHING out of the sub. Is the preout cable the only connection you have between the receiver and the sub? I checked the receiver to make sure I have the sub ON. Do I need to adjust something? I have the crossover set at 100.

jhiter24

Rainman

I have a feeling you have the sub hooked up to the wrong preout. This receiver has a 5.1 channel sub out and then there is another REAL SUB PREOUT. Look on the back of your receiver and find the other sub out and switch them. THis confused me at first but it should fix your problem

Rainman15

jhiter24

Thanks for your response, I'll check it out tonight. I was using the Sony sub with a Pro-Logic receiver and was pleased with it's performance.

jhiter24

Ok, a question on the cheater plug. I have a bunch of things plugged into a power strip in the back. Now would I use the cheater plug on that or just plug in the sub on its own? Thanks for the help.

audrey

my advice would be to buy several cheater plugs and experiment. since you are getting hum through your speakers as well as the sub, the receiver might be the source. i'd start there.

you might also look to see what else is plugged into the same circuit. florescent lights or anything with a transformer can introduce hum into the line. try unplugging some items to see if one of them is the culprit.

BTW: depending on the kind of outlets you have, you may need to file down the "fat" prong on the cheater in order to reverse the polarity (i.e. change the orientation of plug in the outlet). try just the cheater plug first; if that doesn't help, flip it in the outlet.

jhiter24

OK, the cheater plugs didn't work and I tried different circuits. So I am going to look at the attenuator. Now, I have no clue what this is or what it does. SOmeone please help. I live in an old house so I really think it might be some the old wiring that is causing it.

sfunk

Send me an e-mail and I'll help you out!