Bass Response and concrete floors


I was talking to a Dynaudio dealer the other day and asking about the Confidence 5's in comparison to the rest of the Dynaudio line. The 5's are apparently being cancelled with two new models being released in the Confidence line, based on the Evidence technology.

Anyway, he asked what type of flooring the speakers would be on. I said concrete with thick pile carpeting. He said the bass response on a concrete floor, even with carpeting, would be muted, that the Confidence 5's need a floor with give to produce decent bass. He said that the bass would roll off around 50 Hz on a concrete floor.

I've seen so many very positive comments about the 5's, but I suppose that people who are satisfied may well be using them on a main floor built on joists. The dealer indicated that I'd be a lot happier with the 3's on my floor.

Anybody know why this would be? More importantly, is this a common behavior of floor standers on concrete floors? Is it a general "rule" that if you have concrete floors, you'll get better performance from a high quality monitor? Thanks for any info -Kirk

kthomas

Showing 2 responses by abstract7

Many speakers couple to the floor and resonate through the floor. Concreate floors don't resonate (or not at a useful frequency). You could consider a pergo floor over your concrete. I did this in my audio room and it worked remarkably well. I put in an oriental (wool) area rug for some sound absorption, but carpet on the concrete (which is what was originally there) sounded very muted.
I have to disagree that concrete is the "best floor". To me that's like saying solid state is the best amplifier (that might be true in some context--but not always). First consider that the speakers AND room work together to make up the listening experience. (of course all components matter--but these two are most significant in this context) How the speakers interact with the room is critical. Look at how much care goes into speaker placement--and it's not all about removing the room anomolies, it's also about working with them. For example, electrostatics must have a somewhat relfective wall behind them to create the imaging/soundfield.

The theory that concrete is best because it does not resonate or absorb base makes some sense, but not much. This theory needs to be taken into the context of the rest of the room. Bass losses are going to be much greater through sheetrock walls than from a wood covered (or pergo as I had mentioned) concrete floor. The concrete under the wood is great that it gives a rigid floor. Concrete as the supporting structure is probably always best. The best studios use concrete to support their floors under the speakers. But the whole floor is not concrete--it's wood. These are also rooms that use speakers with incredible bass response, which brings me to my second point. A non-resonating material (or one that resonates outside the useful audio spectrum) is also unforgiving. If you have near perfect responding speakers--then concrete might work. But again, the rest of the room has to be considered (more on that later). The speakers may need some resonance or warm reflection from a wood floor to sound their best. I think the guitar analogy mentioned above is a good one. The concrete in my opinion will be overly bright, but that is of course subjective and some people may actually like that. However, you don't see many symphonies playing on concrete floors do you? But you do have choral works in stone/concrete buildings like Westminster--hmmm??

The room and the speakers (or orchestra or choir) work in harmony. Westminster has highly reflective surfaces and very long delay times. It creates long delay times that decay relatively long (even with a large audience). But the first few decays are relatively high in terms of dB (only with a full audience). The result works very well for choral music--but you wouldn't want to hear a symphony there (neither would the orchestra players). Now examine some of the finest symphony halls. They also have long delay times, but try to attenuate ones beyond about 60ms as much (or realistically so) as possible. They don't want the echoic sound of Westminster--they want you to be able to hear every instrument. Why is this important when we are talking about concrete. It doesn't attenuate, and can create some real problems--but again, it must be taken into context of the rest of the room. It's possible that there is enough other attenuation, and that the relfection off the concrete does not create a "second sound image". Second sound images are reflections that are preceived as separate from the original sound that we hear.

So, in the end, I would not say that it is impossible to get good or even great sound out of a concrete floor, but it's highly unlikely to get the best sound with just a concrete floor that is not treated in any way (carpet, wood, or synthetic flooring--like pergo).