3-Way/Side-Firing Woofer?

[Robert Dunn]

I've been working on a three-way with the following driver configuration:

SB29NRX75-6 10" (2.5cf, ported, tuned to 23Hz)
SB15NRXC30-8-UC 5" (somewhere between 0.25 and 0.5cf, sealed)
Hiquphon OWI-Fs/OWIIx-Fs 3/4" dome

Mid/woofer should cross over somewhere in the 150-250 range.

Problem is that the woofer driver flange (11.5") + a grill frame (say 1.5" total) + 3/4" round-over (another 1.5") requires a minimum 14.5" baffle width. Simple rectangular boxes with a 14.5" wide front baffles are going to have a very low WAF.

So I'm considering moving the woofer to a side baffle to allow a narrower, taller box. It will look "better," of course, but the goal is fidelity. Among other things, I worry that the long dimension will start coming close to the cross-over wavelength potentially creating undesirable woofer/box resonances.

Anyway, I'm not sure whether this is a smart thing. What do you guys think about "side-firing woofers" and what should I pay attention to or worry about?

[michiganpat]

Re: 3-Way/Side-Firing Woofer?

if you can lower the crossover point to 100-150 hz, and maybe even do it more as a 2.5 way, with no high pass ( or a minimal high pass, say, maybe a 1st order butterworth at 100hz), then I think you'll be fine....AR and NHT implemented the concept successfully more than a few times over the last 35 years....

[fuzz092888]

Re: 3-Way/Side-Firing Woofer?

I don't have the speaker knowledge of majority of the guys around here, but I have a pair of towers with side firing woofers and they're great.

I agree the crossover to the side firing woofers should be kept low, around that 100-150Hz mark.

[billfitzmaurice]

Re: 3-Way/Side-Firing Woofer?

I agree the crossover to the side firing woofers should be kept low, around that 100-150Hz mark.

IME you can go to 200Hz with no issues.

Among other things, I worry that the long dimension will... wavelength potentially creat undesirable woofer/box resonances.

A few inches of foam top and bottom will take care of that.

[tc]

Re: 3-Way/Side-Firing Woofer?

What about using a bipole setup on the woofers? One could almost back the magnets together and elminate bsc? Opposing forces negate a lot of problems too.

[PEB]

[J Fallows]

Re: 3-Way/Side-Firing Woofer?

What about using a bipole setup on the woofers? One could almost back the magnets together and elminate bsc? Opposing forces negate a lot of problems too.

That's how it's done on the KEF Blade

[michiganpat]

Re: 3-Way/Side-Firing Woofer?

good to know...I know the AR9, 90, and 93 all had a ~200hz crossover point from the side firing woofers to the midwoofs, but newer designs pushed the crossover lower, I had presumed because by 200hz things start to become too directional--my AR312HO's cross the side firing 12" woofers at 100hz.

[billfitzmaurice]

Re: 3-Way/Side-Firing Woofer?

good to know...I know the AR9, 90, and 93 all had a ~200hz crossover point from the side firing woofers to the midwoofs, but newer designs pushed the crossover lower, I had presumed because by 200hz things start to become too directional--my AR312HO's cross the side firing 12" woofers at 100hz.

200Hz is too directional when you have subs and tops that don't share the same vertical plane. When the drivers are within the same vertical plane, or very close to it, you still get all the directional cues from the midbasses and tweeters, as your ear/brain doesn't have enough processing power to triangulate the woofer position as a separate source.

[Paul Carmody]

Re: 3-Way/Side-Firing Woofer?

Super-cool. Good to know.

How does the 90' fare as the frequency goes up?

[Jonathan Anspach]

Re: 3-Way/Side-Firing Woofer?

I agree with Bill. You should be able to go up to 200Hz just fine.

[Kingo]

Re: 3-Way/Side-Firing Woofer?

In a related question,,should the woofers be pointing inwards or outwards?

[michiganpat]

Re: 3-Way/Side-Firing Woofer?

depends on how close you are to a boundary.....the AR 9. 90, and 93 had dual side firing woofers, one on each side....my 312HO's have a single side firing 12, I've tried them both ways, and they sound better outwards, where there's ~3' to the room wall (boundary) vs. inwards, where they were 6" from my entertainment center....

[Robert Dunn]

Re: 3-Way/Side-Firing Woofer?

Thanks to all. I think I'll do some simulations before proceeding.

[billfitzmaurice]

Re: 3-Way/Side-Firing Woofer?

In a related question,,should the woofers be pointing inwards or outwards?

Since their radiation will be omni-directional it doesn't matter all that much.