RE: The forgotten factor.

Posted by Thorsten (M) on July 12, 2012 at 09:09:29

In Reply to: The forgotten factor. posted by Belgarchi on July 11, 2012 at 22:04:18:

Hi,

> The baffle step, killer of DIY speakers by beginners, is pretty
> well known,

Actually, here is a fun fact. The "baffle Step" only exists in anechoic on axis response, in the speakers power response there is no baffle step.

Now why is that? And what do you tink you hear when you lkisten to a given speaker in your living room, the power response or the on axis response?

Secondly, it is true that many small speakers sound subjectively "better" with several decibel bass lift in the power/in room/actually heard response. However, it must be understand why that is (Hint - read up on Robinson-Dadson and/or ISO 226:2003).

> but something very important is often ignored / underestimated /
> overlooked: destructive interference, often in the critical 100-160
> Hz region, between the direct wave from the woofer and the reflected
> wave from the floor.

Again, this supposed "interference" only exists on axis. Not in the diffuse field, which is what you actually hear, it is not present.

In other words, this "interference" is a simple result of misinterpreting the measured results and of being unaware of basic acoustics.

> It is a difficult problem to solve:

Hardly. The imple solution is to switch from single point, pseudo-anechoic gated measurements to multiple point room averaged measurements appropriate to the subject being investigated and voila, the problem has miraculously vanished.

This in fact is covered by acoustics 101...

> Do you know other examples of good solutions?

Use appropriate measurements and/or be aware of the limits and peculiarities of the method you use to measure?

BTW, a real problem in most domestic rooms is the vertical mode, as seated at around 1m Ear Height you are peripously close to the null of the mode of a 2.4m high ceiling, which happens at around 140Hz for common 2.4m high ceilings.

Thankfully my living/listening room is blessed with a over 4m high cathedral ceiling, so I simply do not have this problem and of course, if I did have this problem I would not mistake it for ïnterference from the floor reflection".

Ciao T

Thor

At 20 bits, you are on the verge of dynamic range covering fly-farts-at-20-feet to intolerable pain. Really, what more could we need?

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Follow Ups Full Thread

Topic - The forgotten factor. - Belgarchi 22:04:18 07/11/12 (25)

RE: The forgotten factor ?? - jedrider 16:36:50 07/18/12 (1)

RE: The forgotten factor ?? - layman 20:01:54 07/18/12 (0)

Serious Problem - layman 05:21:28 07/14/12 (5)

RE: Serious Problem - Thorsten 08:39:11 07/14/12 (4)

Again confused - Belgarchi 17:59:08 07/15/12 (1)

RE: Again confused - Thorsten 23:41:37 07/15/12 (0)

Here we go again... - villastrangiato 11:03:17 07/14/12 (1)

RE: Here we go again... - Thorsten 11:17:41 07/14/12 (0)

BDS is not that big a problem if spkrs are positioned to get maximum and smooth room gain. - Timbo in Oz 20:54:22 07/13/12 (0)

Nodes are worse yet... - Scholl 17:59:39 07/13/12 (1)

RE: Nodes are worse yet... - Kloss 08:06:26 07/14/12 (0)

How about... - Presto 11:20:59 07/12/12 (1)

Should work well. (nt) - Belgarchi 16:42:25 07/12/12 (0)

RE: The forgotten factor. - Thorsten 09:09:29 07/12/12 (8)

Don't agree at all - Belgarchi 16:40:24 07/12/12 (7)

I agree lets get rid of floors who needs them - Kloss 08:04:16 07/14/12 (0)

I agree with Duke and Thorsten - djk 23:42:46 07/13/12 (0)

RE: Don't agree at all - Thorsten 22:12:37 07/12/12 (0)

I agree with Thorsten - Duke 21:30:27 07/12/12 (3)

I don't agree or disagree - just have a more insightful, maybe even more useful comment... - villastrangiato 10:20:47 07/14/12 (2)

insights - Duke 11:21:17 07/14/12 (1)

RE: insights - villastrangiato 12:05:54 07/14/12 (0)

Paging Roy Allison.......nt - viridian 08:08:02 07/12/12 (2)

Great Roy Allison Interview - layman 20:08:03 07/18/12 (0)

Yep, I forgot him, good point. (nt) - Belgarchi 16:41:24 07/12/12 (0)

Follow Ups

RE: The forgotten factor. - Thorsten 09:09:29 07/12/12 (8)

Don't agree at all - Belgarchi 16:40:24 07/12/12 (7)

I agree lets get rid of floors who needs them - Kloss 08:04:16 07/14/12 (0)

I agree with Duke and Thorsten - djk 23:42:46 07/13/12 (0)

RE: Don't agree at all - Thorsten 22:12:37 07/12/12 (0)

I agree with Thorsten - Duke 21:30:27 07/12/12 (3)

I don't agree or disagree - just have a more insightful, maybe even more useful comment... - villastrangiato 10:20:47 07/14/12 (2)

insights - Duke 11:21:17 07/14/12 (1)

RE: insights - villastrangiato 12:05:54 07/14/12 (0)

RE: The forgotten factor.

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