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Discussion Starter · #1 ·
I'm sure I've seen this here before, but I must be using the wrong words in the search. Oh well...


My HT is in my loft, and because I don't want to rattle my roof tiles from the roof, I decided to use bass shakers instead of a sub.


I've got the shakers working quite well via a stereo amp and the LFE out from the 3802, but I did try my Paradigm PDR10 in the loft 'just to see' and I found that although the front speakers go down to 38hz, I do need a sub to fill in the lower frequencies. It also makes the shakers feel more 'correct'.


So I need to get a sub, but I also want to isolate it from the floor - I want to hear it, not feel it.


I'm thinking of using a thick piece of kitchen work-top (about 1.5ins thick) with a layer or two of very thick rubber matting (about a third of an inch thick) to sit it on.


Any other suggestions appreciated, along with sub suggestions in the £200 ($300) range.


TIA


Gary.
 

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A good sub will set up vibrations through the floor even using the mat. You can decouple the sub by using little rubber feet though I don't think this will help much either. Most people think having the ability to crack the foundation is half the fun. Probably the best way to achieve your goal is to keep the volume at a reasonable level.
 

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My Paradigm PW 2200 (12" 250 w) sub was pouring its energy into the floor instead of the speakers. I bought some tip toes. These are cones made of some hi teck material used to eliminate vibrations in the hull of racing boats. I put three under my sub, pointy end down, and this completely eliminated vibration going directly from the sub into the floor. They are really good at isolating a sound source. Low frequency sound waves will still get into the floor and walls after travelling through the air. The tip toes also increase the efficiency and acoustics of the sub.
 

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Denis,

Could you tell me where you got the "Tip Toes"?

Thanks
 

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Discussion Starter · #5 ·
I'd like to know too please. :)


They sound like just what I'm after.


Will ordinary isolation spikes do a similar job? They're easier to buy or make if I can't get them here in the UK.


Thanks.


Gary.
 

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You should understand the true fundamentals re the purpose of the subwoofer.


You should never really hear the sub you are meant to feel it!!


You could watch a dvd I guess that is your medium and use the dynamic compression of audio the dvd allows you to do (DRC).


This may alleviate the sound levels see your dvd player manual.


Perhaps another possiblity is to adjust the crossover range on your sub (not sure if it has one)

I use a velodyne f1500r and calibrated at 75dbspl using sub pink noise at the frequency of 40htz. CRACKS FORMING IN THE FOUNDATIONS GREAT!!!!

This provides a truly visceral effect.:D :D :p
 

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Discussion Starter · #8 ·
Darien: they look just the job too - I have similar things at work, so I could try those to see if they work. :)


Benthx: Despite what you say, I CAN hear the sub bass below that of my main speakers.


My mains go down to 38hz, and I get more than enough vibration out of the bass shakers, so I don't need to feel any more bass. I may be getting some frequencies above where I want them in the shakers too - I want to elimanate the 65 to 80hz from the shakers, so I might look out for an external crossover.


Using the PDR10 as well as the bass shakers gives an audibly lower bass sound. Where the sub was situated, I couldn't feel it in the chairs - they are isolated from the floor using rubber, but when I went over to it, I could feel the floor and wall responding to it, which is what I don't want.


You can hear bass down to 20hz IIRC, but can feel it lower than that. I even placed the sub on one of the chairs, and the sound was still noticably lower.


So getting a sub and isolating it from the floor is what I need to do, but I need an effective means of isolation.


Cheers.


Gary.
 

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I had the pleasure about a year ago of listening to a THX certified theater in a Hi-Fi store. The speakers, including subs...were all M&K. My memory isnt the greatest...I do remember that the 2 subs were mounted in the ceiling. They were small either 7 or 8" M&K's. They sounded great. Maybe this is an option for you....I dont think they would vibrate your roof....
 

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Gary:


I have my two Aerial SW12 subs mounted on custom-made acoustical stands by ASC ( www.tubetrap.com ), with excellent results.


Here is the detail: each SW12 is mounted on a matching, spiked, sand-filled stand by Sound Anchors. The spikes of these stands are coupled to the top of the ASC stands.In turn, the bottom of the ASC stands rest of four large, height-adjustable cones by CustomHouse, which guarantee perfect stability on the carpeted floor.


Just by 2 cents.


J.V.
 

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Discussion Starter · #11 ·
Hi JV,


I take it that by isolating the subs, you hear all the bass, but without transmitting any vibrations through the floor?


This is what I'm after doing, and as your set-up works, I know I wont be wasting my time if I devise a similar set-up.


Thanks to all who contributed, you've given me some good ideas that will solve my problem.


I love this place. :)


Gary.
 

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Gary:


You're right, isolating the subs resulted in virtually eliminating vibrations to the floor. Bass became cleaner, crisper, and smoother.


I took notice of ASC through my trusty dealer. He let me know ASC can make custom-sized acoustical stands for subwoofers, based on basic information about the subwoofer and the room (in this last respect, the height of the ceiling is a key parameter for ASC sizing the stands).


For the dimensions of my room, the resultant acoustical stands were exactly 12 inches (14 inches with CustomHouse cones adapted) in height. I don't know whether the sonic benefits were a result of simply lifting the subs 14 inches from the floor or because of the material/construction employed for the stands. However, the fact is that the sound improved in a significant way.


Good luck in your search.


J.V.
 

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&nbsp &nbsp &nbsp Spikes / cones / etc. will couple your sub to the floor, not isolate it! This has the benefit of keeping the sub's enclosure from moving during driver or PR excursion (resulting in better performance). Paradigm sells a spike kit for their Servo-15... perhaps something similar exists for the PDR10 (you can also get this stuff at a hardware store).

&nbsp &nbsp &nbsp If your floor is rattling due to low bass transients, isolating or coupling the sub to the floor is not going to help. You will need to find the rattle and fix it. You other option is to turn down the volume...


Greg
 

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Discussion Starter · #14 ·
Hi Gregg,


The reason I want to isolate the sub from the floor is because my HT is in my loft, and any vibrations will transmit to the roof tiles. I want to keep them on the roof!


I'm using bass shakers for all the vibes I want, and the seats are isolated from the floor via thick rubber strips under the beams of the frame to which the seats are bolted.


I just need the extra bass sound I got from the PDR10 (or whatever sub I settle for), but without it transmitting these vibes to the roof joists (which are attached to a purlin, then a wall, then the floor).


According to some posters in this thread, they have successfully isolated the sub using cones or similar. So now I'm a tad confused.


Gary.
 

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Pinnacle also makes a number of subs that come with the inverted cone feet. Their purpose, according to Pinnacle, is to prevent the sub from moving and couple it to the floor to tighten the bass. It sounds to me like you would be better off using some type of in ceiling sub. Niles & Speakercraft both make them (some are powered, some are not. On commercial jobs, we have used the JBL and the Soundolier which are mounted to the ceiling and are in a particle board box. The Soundolier has a separate power amp that is quite nice. In my M. bedroom, I have an in ceiling sub which is made by AES (audio Electronic Systems in Florida.) It looks like a 6 X 9" driver, except that it has a polypropylene clear cone, an 80 ounce magnet, dual speaker level inputs and its an 8 ohm version. Its got quite a kick if you give it some power. They were also marketed under the Phillips name. I don't know whether or not they are still being made. Bass under 100 hz is nondirectional, so that ceiling placement is fine.
 

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Hi Gary,

You may want to try Vistek's Aurios MIB's which are basically two

shells enclosing a ball bearing within. I use these under all my Equipment including speakers. These cost $299 for a set of three (basic model). Info: www.vistek-inc.com

However you will find that the bass seems to be reduced initially but eventually find it more detailed and refined. Some peple do not like this though. It's a trade off for quality vs. quantity.

These devices will really decouple your sub from the floor.

There have been a quite a few reviews regarding the Aurios including Stereophile, Stereo times and have yet found a negative

report. I swear by it. Though a bit pricey, you may want just to buy a set and put it under your sub and if not happy with it then pop it under your source. You will definitely hear a worthwhile improvement.


Regards


CCWong
 

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I do not wish to appear sinical but hay many of these add ones.


Does one think that what they hear are a result of a PLACIBO affect? ie. cones


double blind fold test would be nice!


:D
 

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Discussion Starter · #18 ·
Benthx: judging by your contribution to this thread so far, I've started to think you're a bit of a placebo yourself. :)


As for isolation etc, I'm going to try different methods myself, and see which ones work and which don't:


I can make a platform and screw some spikes into it - spikes facing down into the floor, then sit the sub on that and see how that compares with the sub on the floor.


Try the above with a rubber mat on it, and the sub on that.


A heavy slab or wooden worktop (cut to size) with rubber matting on it, then the sub, more matting and a weight on that. I remember somebody mentioning this method once before, and it greatly reduced sub vibrations going into the downstairs flat. I didn't really want to have to take anything too heavy into the loft, as it's not always that easy to get the stuff up there!


I can't put anything into the ceiling, as the ceiling is directly attached to the roof joists, and that will definately loosen the roof tiles.


Over the w/e I can try a simple isolation of the sub - two pieces of wood 70mm long, and the width of the sub, with rubber strips on them, sat on the floor, and the sub feet sitting on the rubber strips. This is how I've isolated the theater seats from transferring the bass shaker vibrations to the floor, so I know it works in this case. It'll be interesting to see how effective this cheap and simple method is for a sub.


Film at 11 !


Gary.
 

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Gary


You say you wish to fill in the lower frequencies.


So what frequecies do you wish to reinforce buy using a sub?


What do you mean by me being a bit of a placebo?


I dont see any mention of what your main speakers are or perhaps I'm mistaken.


Its seems you want the sub to do its job but not experience the charateristics of it.


Your last chance you could ask the good people at www.widescreenreview.com


They will sort you out:D

Have fun:rolleyes:
 

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Discussion Starter · #20 ·
Hi Benthx,


My speakers go down to 38hz, and the PDR10 sub goes down to 27hz. I can hear the difference, so I would like to add a sub to the system.


I currently have 4 bass shakers fed via a 60w/c stereo amp which gets its signal from the LFE out of the amp. the seats are isolated from the floor using rubber strips. The shakers give lots of vibration and really enhance the experience. Because my ht is in my loft, I don't want to send any vibrations into the rafters and risk loosening any roof tiles. None of the vibes from the seat platform get into the floor, so the roof is safe, and I'm happy.


I want to add a sub to fill in the lower frequencies that I know are missing, but I don't want any vibrations getting into the rafters, hence my initial post.


I thought that isoloating a sub would be different to isolating the seats due to the extra sound waves produced by the speaker cone and baffle. I don't think I'll get a down firing sub for this reason.


There have been some good ideas using decouplers or rubber isolation 'feet', so I have something to be getting on with. Failing that, I'll have a mosey on down to the link you gave me. Thanks.



Gary.
 
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