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Posted By: player8 Need some room assembly help... - 07/13/04 05:36 AM
I will be making some stands for my surrounds for my dorm room that I will be entering in a month. I need some suggestions after I explain my situation.

I want to play my sub as loud as possible and I understand that the closer you place the sub to your listening position the lower you have to play it to achieve desirable results. I will be installing shelves on the front wall to place my M22's and I was hoping on putting the stf-2 under one of the shelves, but I was thinking I would be better off if I put it beside the couch which will be against the back wall at only 6 feet from the M22's (remember this is a one bedroom apartment style dormroom). My question is, that because room is so tight, will I be okay if I make one stand approximately half the size of the other one and place it on top of the sub? I'm worried that the small radioshack surround will fall off of the stand because of the vibration. Can you guys give any tips?
Posted By: JohnK Re: Need some room assembly help... - 07/13/04 06:18 AM
Matt, although sound level theoretically drops by 6dB every time the distance from the speaker to the listener is doubled, this is really only true under anechoic conditions. In a small, live room there's surprisingly little falloff say from 3 feet to 10 feet. I'm suggesting that you use the front wall or even better, corner. There'd be very little volume level increase needed.
Posted By: player8 Re: Need some room assembly help... - 07/13/04 03:49 PM
Thanks, because the room is so small, the sub (in either position) would be about 18 inches from a corner so i figure either position should sound good. I was just trying to save some space and think of my neighbors as well. I live between two other rooms and one side of my neighbors are totally cool with the music and the other side always complains so I was trying to do what I could, but since little difference is made I will stick with my original plan. Plus, it will be alot easier set up because the sub will then be placed closer to my reciever.

The previous leads me to my next question, because of room constraints I will have my cd player on the floor. With the sub theoretically sitting about 1 foot from the player is there any inexpensive (not audio snake-oil) ways to reduce vibrations?
Posted By: Capn_Pickard Re: Need some room assembly help... - 07/13/04 04:13 PM
put a towel under the cd player, or the foam from a pillow. That said, if the cd player is on a carpet, it might not make a difference. Hardwood or concrete might necessitate some damping.

Posted By: alan Re: Need some room assembly help... - 07/13/04 04:17 PM
Hi player8,

Depending on the brand and sensitivity of the CD player to mechanical vibration, it may not affect your CD playback at all. There's a lot of audio voodoo and nonsense perpetrated about mechanical vibration affecting sound quality with solid-state components. Normally, there is no effect whatsoever.

But there is a mechanical aspect to CD playback. The optical pickup is usually on a mechanical sled that is servo-driven across the radius of the disc, so it can be knocked off-course by fairly blunt jarring. Minor vibration doesn't usually cause any effect.

There are two types of vibration generated by your subwoofer-- mechanical, transmitted through the subwoofer's feet to the floor, and then through the floor to the CD player. If the floor is concrete, or wood parquet over concrete, that is unlikely to occur. It will happen with older, springy wooden floors.

Then there's acoustic energy generated by the sub's acoustic output and standing waves in the room. Insulating the sub's mechanical vibrations won't do anything to damp the acoustic energy and resonances that may result..

You can use compliant pads of rubber or old squishy tennis balls under the feet of the sub to isolate mechanical vibrations. Most CD players are quite resistant to acoustically born vibration, so try it out first.

Acoustic and mechanical vibration really only become a serious issue with turntables and tube gear, where the tubes often become microphonic and susceptible to acoustic and mechanical feedback--yet another liability of tube equipment. The plastic dust covers on many turntables used to function as a primitive microphone feeding acoustical energy to the turntable base, tonearm, and cartridge, especially at high volume levels.

Regards,
Posted By: mhorgel Re: Need some room assembly help... - 07/13/04 05:04 PM
In reply to:

You can use compliant pads of rubber or old squishy tennis balls under the feet of the sub to isolate mechanical vibrations.




Alan;

That is quite interesting...exactly how would you use tennis balls to accomplish this. Do you have to cut the balls in half or what? Please give more details!

Mark
Posted By: player8 Re: Need some room assembly help... - 07/13/04 06:12 PM
Thanks for the replies guys. The reason I'm worried is because the CD player is a 12 year old Sony 5 disk changer and skips on occasion during a really bass heavy peak (and these were through my old Bose 301's) or when one of my roommates would stomp (jump) his feet on the floor. The reciever is gonna be shelf mounted so that shouldn't be a problem. I'm also intrigued by this Tennis ball solution. I just want to play it as safe as I can with spending the least amount of money possible.
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