Sony SAWM20 Subwoofer - Please help

Discussion in 'Archived Threads 2001-2004' started by Cecee Green, Jan 27, 2003.

  1. Cecee Green

    Cecee Green Auditioning

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    I recently added a sony SAWM20 (Cheap, CAD130) subwoofer to my sound system. When I use my TV, it picks up a lot of noice. I kept the sub at least 15feet from the TV. Even during normal conversation (CNN news), the subwoofer is creating buzzing, booming sound. With all the rumbling sound from the woofer, it looks as if my system is better off without the subwoofer.

    The woofer is connected to my Pioneer-VSX811s Receiver. When I adjust the cut-off frequency, do I have the make the changes in the receiver setup as well on the speaker (using the freaquency knob)? Any suggestions about the cut-off levels? My seapker setup is 5.1 and the speakers are set to 'Small' as told in the receiver manuall.

    Of course I can turn it off. Just wondering if anyone has any suggestions or any comments about this particular subwoofer model & setup. Any help is appreciated (I'm sick & tired of the experiments)

    Thanks

    Cecee ([email protected])
     
  2. Tom Wyatt

    Tom Wyatt Extra

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    ah-ha! I have that same setup (receiver and sub anyway). I hopefully can shed some light on the situation.

    1. The noise situation: what are you using to wire your sub to your amp? If you're using a single "rca" type wire, then check to see what it is running near. The cheap cable that comes with this sub tends to pick up a lot of interference from power and/or speaker cables if they're nearby. check to see that it is not running close to either of those other wires. Same thing goes for all other interconnects (keep them all away from both power and speaker wires). If this doesn't fix it, then it may be electrical noise that is in your electrical wiring in the house. This too can be fixed, I believe by a line "conditioner". (Someone else jump in here if I'm wrong, make sure I'm not misleading him on this latter point.)

    Note that you don't want this sub too close to your tv anyway - I have had problems with distortions in my 55" widescreen tv when the sub hits hard from within about 12" of the TV. I currently run my sub about 5-6 feet from the TV.

    2. The cutoff settings. This Pioneer receiver has multiple cutoff frequencies (100, 150, & 200 I believe). Depending on where you want your sub/speaker crossover to happen (depends on how low frequency you want your other speakers to run), you can adjust this in the "setup" or "quick setup" menu (I forget which - it is inside the front door of the receiver). Run through this setup if you haven't already - instructions are in the booklet that came with the receiver. Generally, if you have your receiver sending all frequencies below, say, 100Hz to the sub, then you can really set the sub to anything above that, it will only play what it gets from the receiver.

    I personally have large front speakers, so I have those set to "large" in the setup menu, and then I have the surrounds and surround backs set to "small". I have the crossover set at 100Hz. If you truly have small speakers, set the cutoff to 150 or so. Go between 100 and 150, see which one sounds better to you. I went with 100 because (1) I have large front speakers, and (2) this sub seems to hit harder when it is only concentrating on the lower frequencies in my experience.

    Good luck and let me know if I can be of further assistance.
     
  3. GregLee

    GregLee Stunt Coordinator

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    I have that sub and a receiver similar to yours (not quite as good). I don't have any of the problems you describe. From your description of how voices sound, I'd guess you have the sub's volume set too high. I have mine at 9:00. But as Tom says, interference of some sort is possible. In principle, the sub's crossover should be at the maximum position, since you're using your receiver's crossover.
     
  4. Cecee Green

    Cecee Green Auditioning

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    Tom / Greg,

    Thanks very much for your suggestions. I'm a newcomer to home theater, hence please bear with me.


    1. I didn't use the cable that came with the subwoofer. I bought a somewhat decent (AR $20) subwoofer cable. The speaker is kept 10 feet away from my 27" Sony TV. There is no other electronic stuff close to the sub. Can you please elaborate on the "conditioner" mentioned in your reply?

    2. There is cross frequency adjustment in my receiver (100-150-200). This is set to 100 (default). The sub also has a cut over frequency knob (from 50Hz to 200Hz). If this is set to 50, I don't hear much noice. Infact there is no sub effect at all. My speakers are somewhat small (entry level from sony). Front speakers are floor standing model, 100W power. Sorround & centre speakers are small bookshelp type (100W each). With these setup, can you please suggest the best adjustment for cross over freq? The sub's volume level is kept very low (25%) to avoid the vibration & boom sound.

    3. My budget is limited (max CAD$200). Can you suggest any other model for this price?

    Thanks again for your help.

    Cecee ([email protected])
     
  5. Tom Wyatt

    Tom Wyatt Extra

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    1. The sub being too close to your TV won't cause your sub to have interference, it will cause the TV to have interference. It was a good move to get an aftermarket sub cable. Look at the individual cables / wires running between your tv, receiver, sub, speakers, and any other equipment you might have. What you ideally want to do is keep the wires in 3 distinct groups, away from the other groups of wires. They are:

    (1)interconnects (these are the wirest that run from your tv or other components to the reciever, and from the receiver to your subwoofer - typically they are "rca" type plugs.) They conduct "low-level" signals.

    (2)speaker wire - these run the high-level (post-amplification) signals from your receiver's amplifier to the speakers.

    (3)power wires - power wires from all your components.

    You want to keep these separate, but if you have to, you can have the speaker wires and power wires running somewhat close to one- another. Just make sure the interconnects (low-level signal) are separated from the others (high-level signal) by a few inches (as much room as possible ideally). The reason for this is that the high level wires have a magnetic field around them, and the low level conductors will pick up this magnetic field, and transmit this "noise" with the other sounds.

    2. In your situation, I would keep it at 100Hz cutoff on the receiver, and put your sub's crossover between 100 and 150. With the sub at 50Hz, it is way too low for your setup, and not much will be going to it (as you said is happening). Keep all your speakers set to "small" as well. Also, make sure that the sub level in your "speaker level setup" is set to between -2 and +2 (this has worked best in my experience).

    I run my sub at 150 Hz on the sub's crossover, 100Hz on receiver's crossover, subwoofer gain at approximately "1-2 o-clock" (pretty high) on the sub and at +2 on my receiver. This nets me the same level as the rest of my speakers in my setup (setup done at reference level (75dB) at watching position)

    3. The power conditioner should take out any noise that your house's electrical system may transmit (typically around 120 Hz I believe). Again, this is all from memory, and could be wrong - do a quick search in this forum, you should come up with something. (search for "electrical noise" or "power conditioner")

    4. For your budget (and my budget) this is about the best sub one can get I believe. You have to realize that the sub will transmit whatever signal it gets - whether that is a good signal (low frequency effects from a dvd, for example) or a bad signal (from electrical noise, or from a poor tv broadcast, for example).

    Good luck
     
  6. GregLee

    GregLee Stunt Coordinator

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    Suggestions:

    Listen to dialogue that has these booms and buzzes, and turn the sub's power off and on, to make sure it really is the subwoofer that causes the problem. If it is, turn down the sub's volume and/or the receiver's sub volume control until the problem goes away. If at that volume adjustment you can't hear the sub at all (try the receiver's calibration test tone), you might seriously consider the possibility that the sub is defective.

    In any case, if you can return the sub and exchange it for another, consider the larger Sony SA-WM40, which has a considerably better reputation. It discounts to a price not that much more than the WM20.

    I still think the sub's crossover should be set to the max, 120Hz, but if you can make it sound better by turning it down, by all means do.
     
  7. Tom Wyatt

    Tom Wyatt Extra

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    I misread your original post... and thought that you had the sawm40, not the 20. I have the SAWM40. I don't know much about the 20, though I think that the rest of the information I gave you would apply to both.

    SOrry for any confusion.
     
  8. Cecee Green

    Cecee Green Auditioning

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    Tom / Greg,

    Thanks very much for your suggestions (with a lot of details). I'll do some more R&D and try adjusting the setup.

    Thanks again.

    Cecee ([email protected])
     

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