[uncola]

https://www.ebay.com/itm/10-Audiofile-UnderHung-IB-Series-Dipole-Woofer-Made-in-USA/392177947904?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

I saw the dipole woofer in the ebay title and decided to get a couple.. I noticed the sensitivity is low, but I plan to bi-amp with dsp active crossover to level match via dsp, also I can wire them in parallel 2 per side to help.. what do you guys think?  For my first speaker build with fast 8 full range driver and these 10.5" woofers to help with bass

[JLM]

Well they sure look the part.  Not familiar with how the Qts is stated.  Note that Fs is only 35 Hz and mention of going down to only 27 Hz (relatively flat, whatever that means) wouldn't call that "extremely low frequency response" as the ad states. 

Will certainly help add bass.  Will need a beefy amp to reach live performance levels.  Not a fan of fixing drivers/speakers with DSP, would rather start out with good "bones".  As Earl Geddes says, "Fix physical problems via physical means".

[lokie]

high xmax is the spec you need to focus on... then,  bandwidth and efficiency to match other drivers.

[FullRangeMan]

The Qts = 2.680 is surprising hi 
The Alpha15A Qts are 1.26 and the bass already too soft for most listeners, so rule of thumb was about 0.8 - 1.0

[uncola]

thanks guys.  yeah I'm excited to just start cutting wood and give things a shot.. just need the dsp active crossover to arrive

[uncola]

@FullRangeMan the only thing I found out about super high qts and mention of flat frequency response in the very low bass is some stuff about the Carver Amazing Woofer..   any light you can shed on it would be welcome

"The Carver "Amazing" OB speaker started with specifically designed 12 inch woofers (built by Sony to Carver specs) with a Qts of about 3.12 or so and, IIRC, a Qms of about 10. This allowed the woofers to remain flat without EQ'ing down to about 20 Hz.

Later versions used a Tonegen woofer with a lighter cone and a Qts of about 2.85 and were targeted at 28-30 Hz, again without EQ.

This was the result of original research conducted at Carver, as there really wasn't any information available and the driver build houses had never attempted anything like this before.

Best Regards,
TerryO"

[FullRangeMan]

I have the Amazing Silver Edition, it use three 12'' woofers and a damping Q correction to adjust the bass to Soft to Dry/hard, I cant tell its flat on listening bass music, but I have noted there is a gap betweem the woofers and the 48'' ribbon in the bass, maybe 150 - 200Hz.

Alpha15A direct with no correction have soft bass as are know.
The rule of thumb was become QTS about 0.7 - 0.9 as some Acoustic Elegance or PAP.
http://aespeakers.com/shop/dipole/dipole15/

http://www.pureaudioproject.com/product/15inch-open-baffle-bass-woofers/
As everything in music are personal taste I hope you like your purchase.

[uncola]

thanks when I actually build it and have news I'll post again