Multiple Small Subs - Geddes Approach

[goskers]

For me there are two very important things that people need to remember when attempting this. Two of the three subs should be able to be located fairly easily within the listening environment; the corner and adjacent wall subwoofer. Don't forget the third on which is for non-corner above centerline height placement. I have not modeled any rooms but this makes complete sense to me because we are attempting to even out a frequency response that is room dominated in a 3-D space. To do this best makes me think that something above the centerline would be of great advantage.

The second item is that some people state that doing level setting by ear is fine. Having seen a setup performed confirmed the fact that measurements are a huge benefit. Having so many variables from placement to levels to phasing just leaves too many possibilities for ear tuning. I would guess that most people who do tuning by ear end up with a very bass emphasized playback.

[PeteMcK]

Interesting paper Earl, Markus, thanks.
I mis-read ‘Schröder’ as ‘Schrödinger’ – thought I was going to have to kill a cat for a moment there…

‘Our hearing needs a couple of cycles before it can determine a sound timbre’ –guess that’s why group delay is relatively unimportant?

[markus76]

Originally posted by Wayne Parham
I've been using CARA for a few years and really like it. You can model your room to whatever level of detail suits you, then positioning subs within it is easy.

Have you verified the LF results from CARA with measurements?

[Wayne Parham]

Yes, I did. First thing I did was to compare the models of a small room to measurements at various places inside the room. I was impressed, the model showed the locations of nulls very well.

[markus76]

So you ended up placing the subs at the locations you found in the CARA model? How good was the LF frequency response?

[HiFiNutNut]

Markus,

Thanks for your write-up. It is excellent.

It would be very helpful if you could provide a bit more information about the final XO points, XO slope and EQ you used in setting up your subs resulting in the 4 graphs shown in your write-up.

A number of questions regarding the XO points and XO slopes were previously raised by a few people but I have found no descriptions about those yet.

Regards,
Bill

[markus76]

Thanks Bill. I left out the final settings intentionally because the average websurfer simply doesn't read and in the end there will be people that use my settings and wonder why they don't get a flat low frequency response...

[Wayne Parham]

I'll tell you what. I just moved into a new home, so I have to do it all again anyway pretty soon. Maybe it would be interesting to document the process, saving the models and measurements. I'll do that, and post the results on my website.

[markus76]

Great idea. Would be helpful to compare the benefits of each method.

[otto88]

Hi Earl

> I do favor "sealed", but sealed bandpass, not direct radiating.

Do sealed BP avoid the poorer transient decay of that vented BPs can have?

Cheers