Inexpensive OB woofers from Parts-Express ?

[MisterD]

Hey folks I’ll be wanting to buy four, inexpensive woofers from PE, either 15’s or 18’s. Wondering about Eminence Alpha, Goldwood or..? These are intended for use in some open baffles, two per side. What is the best sounding for the price?

Thanks!

[fpitas]

I'm no expert on OB woofers, but the Xmax is particularly important, since a lot of bass will be lost to front-rear cancellation, and you'll have to EQ them up to compensate. Depends on how loud you listen of course.

[LOUT]

The GRS 15PF-8 is probably worth looking at. If its T/S specs are accurate its OB bass response with a pair should likely able to hit 100db down to 50hz if you have protection (active or passive) below 40hz.
The smaller 12" GRS 12SW-4 might also be worth checking, if its much higher XMAX is truthful that should allow a smaller and cheaper OB build to reach similarly loud and deep.

[MisterD]

The GRS 15PF-8 is probably worth looking at. If its T/S specs are accurate its OB bass response with a pair should likely able to hit 100db down to 50hz if you have protection (active or passive) below 40hz.
The smaller 12" GRS 12SW-4 might also be worth checking, if its much higher XMAX is truthful that should allow a smaller and cheaper OB build to reach similarly loud and deep.

Thanks for suggesting the GRS.

[Chris Roemer]

For an OB setup, I think it's fairly common to target drivers w/a Qts near 0.70 (0.6-0.8 range).

[Billet]

I agree with Chris on this one. 0.5 Qts is critically tuned bass, 0.707 is often used as a compromise to help extend bass response. The higher Qts (over 1.0) for OB might help extend bass response, but only if it is at the correct frequency. If not, I think it could sound under damped. Properly damped bass can sound very realistic, but quieter and less obvious. I guess it really depends on the type of bass response that you prefer.

I have used the Beta 15 in the past in moderately large baffles. My most recent smaller OB project used an Alpha 10 for bass along with an Alpha 6 for extra mid bass. Sounds good to me!

[Brian Steele]

The "ideal" OB driver should have a long coil (good Xmax), not necessarily designed for high power, a high Qts, and a low Fs, and fairly cheap. Unfortunately it's not that easy to find a driver that meets all of those three ideals.

[jhollander]

First question is this passive as part of a 3-way or active with a plate amp or amp with DSP? Active: go straight to the most swept volume xmax x SD. GRS 12SW wins when amplified.

Passive IMO go for the highest QTS with the lowest FS 15 inch woofer. With ABC Dipole you can look at the roll off and baffle size.

[a4eaudio]

Hey folks I’ll be wanting to buy four, inexpensive woofers from PE, either 15’s or 18’s. Wondering about Eminence Alpha,

I'm not sure where the Eminence Alpha stands based on the suggestions you have received so far, but there are 2 restocked Eminence Alpha-15A drivers in stock for pretty much 50% off.

[MisterD]

Thanks, guys. My plan is to use two woofers each speaker,, facing each other behind the open baffle and ported through the baffle face; essentially still open..
Nelson Pass shows something similar but his used six, smaller woofers each side.

Something like this picture, but with two, larger woofers. Planning on making a two-way passive using the Dayton PS220-8 as a full-range above, and a low-pass filter so the woofers blend in smootlhly.

[jhollander]

Slot loaded OB. The slot resonance will dominate the frequency response. You can model in Horn response but IIRC there's no way to get the response high enough to reach a tweeter.

[Billet]

Is that also called a Ripole? If tuned correctly, it seems like it could add some bass where the full range is rolling off.

Are you planning to use a contour filter to attenuate the mids and highs on the full ranger?

Visaton has plans for a similar design, they call it the Grand Orgue.

[MisterD]

Is that also called a Ripole? If tuned correctly, it seems like it could add some bass where the full range is rolling off.

Are you planning to use a contour filter to attenuate the mids and highs on the full ranger?

Visaton has plans for a similar design, they call it the Grand Orgue.

I can attenuate the full-range driver if needed; hoping not to.