Harmon Sub Placement White Paper

[richie00boy]

Anybody got a copy of this or even better, can provide me the link on the Harmon-Kardon site? I seem to have 'cleaned it up' from my machine.

 

[TwisterZ]

I think this is what your looking for

http://www.harman.com/wp/pdf/multsubs.pdf

or this one

http://www.harman.com/wp/pdf/LoudspeakersandRoomsPt3.pdf

 

[richie00boy]

Many thanks, I couldn't see any way to find them from the website.

The second one is 'part 3' - is there a part 2 relevent anywhere? Is part 1 the first document?

 

[TwisterZ]

Here is the White Paper index page

http://www.harman.com/about_harman/technology_leadership.aspx

 

[Rybaudio]

I've been reading this paper and I'm wondering about the LF factor they use. It seems like they use 0 dB as the amplitude of the direct sound, but what exactly does this mean? Is that full space SPL from the source at the distance that the listener is at in the room? Is it " " " 1m? Is it not full space? Can anyone help me here?

 

[TwisterZ]

0dB is used as a reference point, This way you can compare different signals on a uniform scale. In the recording industry 0dB FS (full Scale) is the max level of the AD-DA circuit without clipping. For home theater receivers a volume setting of 0dB should produce 105dB at your listening position and a 10dB boost below 80Hz to hear a DVD or CD at the level the recording engineer intended. As you may know this is very loud for most people but you will hear when actors who are whispering in the movie.

Hope this helps

 

[Rybaudio]

I know it corresponds to some reference point; what I'm asking is what is the reference point in their study? I want to know what 0 dB means in their study. Judging from a couple graphs and how they talk about it in the paper, it is the "direct" sound from the subwoofer, but what is meant by that. Here are the two main questions that if answered would provide enough information to get what I want:

What are the radiation characteristics of the sources? I'm assuming they are point sources with 4pi radiation.

At what distance from the sources is the direct sound taken to be? Is it some standard distance such as 1m, or is it the actual distance in the room? I would think a standard distance would be preferable, because each of the setups would have the same volume velocity per source, but then using the phrase "direct sound" is a little bit misleading.

BTW, thanks for the information on the recording industry standards. I wasn't aware of those standards, but they are very close to what I have found over the years as a good target to start with as far as output goes: for above 80 Hz, I need to hit peaks of 110 dB at 3m anechoic. For the subwoofer, I need to be able to hit peaks of 125 dB from 30-80 Hz at the listening location. These targets insure I am below the limits of the system under normal operation and I always have a little extra if I want to lean on her a bit.

This gets to the heart of why I want answers to the questions above. I want to be able to use the data to estimate what I need out of a subwoofer when I am designing a system. I know what I want at the listening position, but what does this translate into 1m half-space anechoic? That is what I am looking at in a modeling program.

I hope that clarifies what I am looking for.