What material is based below a down firing sub?

I don't like down-firing subs over carpet, but a lot of people would say otherwise (to put it diplomatically). But if it must be on a carpet, just make sure it sits on spikes or cones that go all the way through the carpet and bite into the hard floor underneath.

Putting a hard platform on the carpet first will work (better IMO), on conditions that:

1. It's at least 16" bigger than the sub all the way around (to properly launch the wave) and
2. It's heavy enough (with the sub on top of it) to compress the carpet enough so that if you step on one edge, it won't tilt AT ALL.

Nsgarch is off base here. First, the carpet makes zero differnce in a performance standpoint! Infact, the carpet may benefit, in that it can help hide higher frequency distortion or overlap/crosstalk!. Bass waves in play here are so big, that any carpet depth laying over a hard foundation, is going to affect NOTHING, in terms of intended performance! That is fact.
Second, anchoring a downfiring subwoofer with spikes, as long as the sub is heavy enough, is fine in carpet. Actually, the woofer is moving against the weight that's it's secured to from the box above it! As long as the woofer is pretty stable, and even at that, you're not going to have any downsides on carpet. Placing a down firing woofer on a marble platform is not really going to improve here. Infact, unless the marble platform is exponentially heavy enough, it's probably not as good as spikes into carpet/subflooring.
I've heard many people worry about downfiring sub on carpet, or otherwise. If you wan't to know, just experiment and find out!

Subs radiate in all directions because they are only extreme LF bass frequencies - it makes little difference that it is down firing or not...as long as stuff is not rattling (floorboards) or the sub is on an uneven surface and wobbling then you are probably ok.

Down firing is actually an advantage as you are less likley to damage the woofer.

I called Vandersteen Audio with the same concern and got a response very similar to what Flrnlamb said, but the only downside to not putting it on carpet mentioned was the possibility that the speaker would be more capabale of movement ("microvibrations") if not solidly tied to the floor by spikes.
If you put in a platform that the speaker can get a real good bite on, and the system is very well anchored by weight as Nsgarch suggested, seems like it shouldn't degrade the sound.

I agree with Frnlamb in the sense that I tried various stuff -- slate, tile, glass, pavers -- under the subs (used with my former speakers), as well as various spiking arrangements and frankly couldn't tell the difference. Ended up firing directly into the carpet, which was on a concrete floor. Dave

I actually went trough a "floor upgrade" with the same sub about a year ago. I went from carpet to hardwood floor (real hardwood). To date I can’t say I have noticed any substantial difference with the subs performance. I have to be honest ... I was hoping it would be dramatic - but no. If anything - it seemed to add a lot of echo that creates a whole new problem to deal with on the upper frequencies.

I'm running the Sig S4's so I need all the bass I can get. I thought the sub would be a huge performance increase but I can’t get it to match up right for my taste. I’m kind of a bass junkie but I think my destiny lies on a different path. I'll keep the Seismic for movies it's a brute. I dont think you can go wrong with it if you can get it to match up with your speakers.

I wouldnt listen to us however - go to a gravestone shop or a shop that puts in counter tops ... see if they have some reject marble or better yet granite. I bought a 1" thick piece once for a different project for $15 it was 24" square but a little marred up. Give it a try - what the heck. Bricks, cinderblock, concrete squares ... it's cheap and worth a test.

Horseface, before you give up on your sub, try this simple test: Place the sub at your listening position (I know, I know) then with some good material playing at upper moderate levels, walk all over the room and note the spot(s) where the bass sounds best. Then relocate the sub to one of those places. 90% guaranteed (OK 85%)

what nsgarth said about finding the best location for your sub is also my method only after i walk around the room & note where i liked the bass best i also crawl around the room & compare locations.

Tanks all for your sincere replies. I have the signiture 40's and the 470 surrounds. I will see if the carpet works and take the advice offered of finding a chunk of Granite on the cheap if it doesn't.

Peace

TE

There ya go! Try and find out...the audiophile way...experiement! good luck

Hey ... that sub idea worked great.

Thanks guys - It made a significant difference and I'm warming up to my "new" speaker system. It ended up in a strange place but I'm not fighting with logic.

TE-
The 470's are pretty incredible ... I have a friend that has them and at times they freak me out. Master and Commander - holy cow - I just about wet myself. I went with the S2's in the rear and feel a little bad because they cost so much and never get used much. I have second guessed that purchase since the day I did it. I sure love the S4's especially with the female voice. I matched them up with a pair of Levinson amps (bi-amped) and a Levinson 360S DAC. My two channel sound has me pretty happy - especially now that I tamed my sub a little. I'm still considering the B&W Sig 800's but I think I can push it off for a while.

If you get a minute shoot me an email if you want to compare notes on your Paradigm equipment.

Don’t look back man...