How high should woofer be off floor?

toenail · 30th March 2003, 02:52 PM

I'm tinkering with a pair of DIY 3 ways that utilize a 12" woofer for low frequencies (150hz and down). How important is the distance from the floor?

Seems like close to the mid would blend the two drivers better, but I thought I had read that too high up off the floor did wierd things to frequency response.

I have the option of mounting it any where from at the floor to 2 feet above the floor, forward facing or side firing. I'm looking for minimal cancellations and resonances- flattest, most accurate frequency response.

Any opinions?

SY · 30th March 2003, 02:56 PM

If you want to minimize interference effects without using multiple drivers, the floor is the best place. Look around for some of Roy Allison's papers where he demonstrated this.

A good example of a speaker that uses this principle is the NHT 3.3, which has a reputation for excellent bass and seamless driver integration.

toenail · 30th March 2003, 09:31 PM

I read a few write-ups on the NHT's, quite a speaker. A google search didn't turn up too much on Allison.

I experimented by placing the two 12's in three different positions. 1) 2 feet off the ground facing front, 2) right on the floor facing front, 3) right on the floor facing in towards each other parallel (similar to NHT). All of this was with woofers separated by 8', up against front wall, room 12' wide, listening position 12' from woofers.

1) was by far the flatest response, with only a bit of a peak (+3db) at 42-44hz

2) gave nasty resonance at 70hz and again around 40hz, like 10db gain

3) recreated the 70hz sinkhole I had previously eliminated by moving the speakers in the first place

Guess I'll stick with #1 for the time being.

Any other good reading out there on the net for bass frequency behavior?

30th March 2003, 02:56 PM	#2
SY diyAudio Moderator Join Date: Oct 2002 Location: Chicagoland Blog Entries: 1	If you want to minimize interference effects without using multiple drivers, the floor is the best place. Look around for some of Roy Allison's papers where he demonstrated this. A good example of a speaker that uses this principle is the NHT 3.3, which has a reputation for excellent bass and seamless driver integration. __________________ If there's a sucker born every minute, where do the rest of them come from?

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30th March 2003, 02:52 PM	#1
toenail diyAudio Member Join Date: Mar 2003 Location: Cranston, RI	How high should woofer be off floor? I'm tinkering with a pair of DIY 3 ways that utilize a 12" woofer for low frequencies (150hz and down). How important is the distance from the floor? Seems like close to the mid would blend the two drivers better, but I thought I had read that too high up off the floor did wierd things to frequency response. I have the option of mounting it any where from at the floor to 2 feet above the floor, forward facing or side firing. I'm looking for minimal cancellations and resonances- flattest, most accurate frequency response. Any opinions?

30th March 2003, 09:31 PM	#3
toenail diyAudio Member Join Date: Mar 2003 Location: Cranston, RI	I read a few write-ups on the NHT's, quite a speaker. A google search didn't turn up too much on Allison. I experimented by placing the two 12's in three different positions. 1) 2 feet off the ground facing front, 2) right on the floor facing front, 3) right on the floor facing in towards each other parallel (similar to NHT). All of this was with woofers separated by 8', up against front wall, room 12' wide, listening position 12' from woofers. 1) was by far the flatest response, with only a bit of a peak (+3db) at 42-44hz 2) gave nasty resonance at 70hz and again around 40hz, like 10db gain 3) recreated the 70hz sinkhole I had previously eliminated by moving the speakers in the first place Guess I'll stick with #1 for the time being. Any other good reading out there on the net for bass frequency behavior?