dtr20 Posted June 14, 2016 Share Posted June 14, 2016 I figured I would start a new thread on this. I did a search and couldn't find a dedicated thread on this. I have read a lot on decoupling subwoofers lately and I am interested to try it. I want to make my own so they fit my subs perfectly. I know to use mdf, but what is the best foam to use underneath? I have seen people say open cell, others said closed cell, etc. So I came to the experts. Thanks Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 Jeff Mier from AccuCal swears by air compressor isolation pads, for whatever that's worth. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 14, 2016 Share Posted June 14, 2016 Cut 2 tennis balls in half and put one piece under each corner of your platform for a cheap experiment to see if you like the effect. 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 I just think it is odd that the full range tower crowd tries to use spikes to purposely attempt to couple things, while some of the subwoofer crowd does the exact opposite... for the same frequencies. 1 Quote Link to comment Share on other sites More sharing options...
jason str Posted June 14, 2016 Share Posted June 14, 2016 Soft rubber feet, screw on type. MDF sucks. 1 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 14, 2016 Share Posted June 14, 2016 I just think it is odd that the full range tower crowd tries to use spikes to purposely attempt to couple things, while some of the subwoofer crowd does the exact opposite... for the same frequencies. I've always thought that decoupling the sub from the floor decreases output by allowing energy to be wasted by the driver moving the cabinet as opposed to anchoring the enclosure and have the driver put that energy in the room. 1 Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 I've always thought that decoupling the sub from the floor decreases output by allowing energy to be wasted by the driver moving the cabinet as opposed to anchoring the enclosure and have the driver put that energy in the room. Yeah personally I think your subs ought to be heavy enough to not move in the first place. If it vibrates at all then put some heavy granite on top or something, not that anybody would be crazy enough to do that. 2 Quote Link to comment Share on other sites More sharing options...
jason str Posted June 14, 2016 Share Posted June 14, 2016 I have built heavy braced 1/2" stock specialty subs (3/4" motorboard) and never had a issue with walking or moving around. Quote Link to comment Share on other sites More sharing options...
dtr20 Posted June 14, 2016 Author Share Posted June 14, 2016 I didn't think the purpose of this was to prevent walking around. I thought it was to prevent the vibrations from going through the floorboards, walls, etc because they are sitting directly on the floor. Sent from my SM-G920V using Tapatalk 1 Quote Link to comment Share on other sites More sharing options...
twk123 Posted June 14, 2016 Share Posted June 14, 2016 I just took one of those foam rollers from amazon and cut it into 4 different 4'' pieces then had the sub woofer rest on them like pillars. It actually works really well to clean up the base if you are getting vibrations into the floor if its wood. Quote Link to comment Share on other sites More sharing options...
jason str Posted June 14, 2016 Share Posted June 14, 2016 If your sub vibrates you have built it wrong. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 (edited) If your sub vibrates you have built it wrong. I think the question is more like how much vibration is acceptable exactly. Look at Deep Sea Sound, dude exclusively uses baltic birch, his baffle is 7 layers thick, their single 24 weighs 210 pounds... still vibrates a little. Up at the Klipsch factory I felt all around a KPT-1802-HLS while in action, it had a surprising amount of vibration. Most designs are simply going to vibrate to some degree no matter how nice it is. A typical 18 for example could have a pound and a half of reciprocating mass moving 2" or more, that's just a lot of mechanical energy. You're never going to completely counteract it without insanely overbuilding the box. Edited June 14, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
jason str Posted June 14, 2016 Share Posted June 14, 2016 Weight is a non issue. Throwing weight on a vibrating sub is band-aid fix. Quote Link to comment Share on other sites More sharing options...
babadono Posted June 14, 2016 Share Posted June 14, 2016 Yeah personally I think your subs ought to be heavy enough to not move in the first place. If it vibrates at all then put some heavy granite on top or something, not that anybody would be crazy enough to do that. 'cepting you 1 Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted June 14, 2016 Share Posted June 14, 2016 The best way to keep them in one place is to build them into a wall Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 (edited) Weight is a non issue. Throwing weight on a vibrating sub is band-aid fix. Sure weight is an issue, it's basic physics. It's like saying a light rifle (bolt action or muzzle loader) will recoil the same as a heavy one of the same caliber. Just not reality. Consider competition pistols, an easy way to reduce recoil and muzzle flip is to add a weight on the rails where a light would normally go. Subs aren't immune to physics. If it weren't an issue, dual-opposed designs would not exist, there would be no need for them. Edited June 14, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
Pete H Posted June 14, 2016 Share Posted June 14, 2016 My F-20 is on casters and doesn't move at all, but it has some weight to it and another 300+ lbs of gear sitting on top of it. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 Newton's third law of motion: "For every action, there is an equal and opposite reaction." The question here is whether the vibration is coming from a panel resonating, or is the entire enclosure moving back and forth. If your panels are flexing, sure, you didn't build it right. However, at some point, the energy of the reciprocating mass is going to move the entire box back and forth to some extent unless there's something holding it in place. Weight, spikes, bolt it to the wall, dual-opposed, whatever, but there is in fact a large force acting upon the box in both directions and something has to mitigate that if you don't want it to vibrate at all. Going in the opposite direction by trying to reduce friction so that a box can easily reciprocate more just doesn't make a lot of sense to me. Quote Link to comment Share on other sites More sharing options...
jason str Posted June 14, 2016 Share Posted June 14, 2016 Weight is a non issue. Throwing weight on a vibrating sub is band-aid fix. Sure weight is an issue, it's basic physics. It's like saying a light rifle (bolt action or muzzle loader) will recoil the same as a heavy one of the same caliber. Just not reality. Consider competition pistols, an easy way to reduce recoil and muzzle flip is to add a weight on the rails where a light would normally go. Subs aren't immune to physics. If it weren't an issue, dual-opposed designs would not exist, there would be no need for them. Never had a cabinet i built walk across the floor. I have seen it with store and on line purchased models. The cabinet resonates causing it to walk across the floor. My car rides too rough, i will throw 300 pounds of weight in the trunk. Opposed models are great countering each others actions. Band aid fix. Quote Link to comment Share on other sites More sharing options...
Paducah Home Theater Posted June 14, 2016 Share Posted June 14, 2016 (edited) Never had a cabinet i built walk across the floor. I have seen it with store and on line purchased models. The cabinet resonates causing it to walk across the floor. My car rides too rough, i will throw 300 pounds of weight in the trunk. Opposed models are great countering each others actions. Band aid fix. Whether it walks or not is not an indicator of zero vibration, it simply means that the given force isn't strong enough to overcome the friction involved with whatever is touching the floor on the bottom of the box. It's basic physics. It's like looking at a washing machine on spin cycle and saying there must be zero vibration since it doesn't walk around. Edited June 14, 2016 by MetropolisLakeOutfitters Quote Link to comment Share on other sites More sharing options...
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