[Bumpy]

I seem to be going round in circles in my head with this one, so would appreciate a different perspective.

I want to run a 15" driver in OBs with 100Hz low pass, so what is it specifically that makes the best driver.

Lot of discussion on Qts and Fs but these can be similar on a £50 driver and £1000 driver, so what else is important?

[JohnR]

You can't really separate the driver from the rest of the design like that - in other words, "best" depends on how it's going to be used. Still, one thing that is more important for OB than boxes is low noise from the motor and air moving through it. Although if you're using a 2W amp, this probably doesn't matter...

FWIW you can't design a speaker by swapping drivers, I think the money would be better spent acquiring some measurement gear so you can optimize what you already have

[FullRangeMan]

For my view woofers must have a light cone, accordion suspension, neo magnet, cast frame and hi sensitivity as some Eminênce.
Avoid dual VC as AE.

[Early B.]

This one:  http://aespeakers.com/shop/lo-woofers/lo15/

[EIEIO]

Don’t get so hung up on the numbers… I’m running a single Faital 15PR400 with an Alpair 12P (per side) with a MiniDSP for fine adjustments. Roughly based on the OBL15 www.troelsgravesen.dk/OBL-15.htm

Tho the numbers don’t tell, they sound pretty sweet to my ears.

[FullRangeMan]

Hi EIO,
Before digital audiophiles used only an 4.7mH inductor or a higher/lower value. Do had tried this old-fashioned solution from the past before the DSP ?

[Bumpy]

Hi EIO,
Before digital audiophiles used only an 4.7mH inductor or a higher/lower value. Do had tried this old-fashioned solution from the past before the DSP ?

This is how I run mine. 

[Bumpy]

For my view woofers must have a light cone, accordion suspension, neo magnet, cast frame and hi sensitivity as some Eminênce.
Avoid dual VC as AE.

 Why is this?

[Bumpy]

You can't really separate the driver from the rest of the design like that - in other words, "best" depends on how it's going to be used. Still, one thing that is more important for OB than boxes is low noise from the motor and air moving through it. Although if you're using a 2W amp, this probably doesn't matter...

FWIW you can't design a speaker by swapping drivers, I think the money would be better spent acquiring some measurement gear so you can optimize what you already have

I have been using a UMIK microphone with REW for some time now. Its proven useful for balancing driver volumes and crossover points, but there seems in my system to be poor correlation between a flat frequency curve and sound quality.

[Bumpy]

It may help if I define my actual conundrum.

In my 3 way baffles I am running the 15" driver through its own dedicated SS amplifier with good damping factor, and using a crossover about 100-120Hz. Neither of the drivers I have experimented with, has hit my sweet spot. There are two areas I have focussed on. One is the ability to produce bass slam and the other is the ability to deliver the frequencies above 100 Hz that can match the sound quality of the midrange, and not trample all over it destroying the magic.

Eminence Alpha
Producing some of the bass slam I wanted (high Qts), but has a negative effect on the midband. This is not meant as a criticism of the Alpha but in reality it is working outside of its price range.

Altec 416B alnico vintage
This integrates perfectly with the midband and is more listenable with much better sound quality. It is however less impactful than the Alpha. (low Qts)

Hence my question.

[JohnR]

According to the datasheet, the Alpha 15A has a hefty resonance at 2 kHz. If you measure just one woofer, is the peak evident?  If so, I suspect that (and an inadequate crossover) are the cause of your issue.

[Early B.]

Like any other product, "good" refers to quality of parts, materials used, longevity, design, etc.  You guys are mostly talking about measurements which is only one minor parameter that may affect how good a driver is.

[JohnR]

I think you've completely missed the point.

[Bumpy]

According to the datasheet, the Alpha 15A has a hefty resonance at 2 kHz. If you measure just one woofer, is the peak evident?  If so, I suspect that (and an inadequate crossover) are the cause of your issue.

Thanks JohnR

My low pass filter is a Jantzen 3.9mH C Coil in series and a 150uF paper in oil capacitor in parallel. Where should I look for the weakness in this set up?

[MarvinTheMartian]

Best place to start is with current OB manufactures.
Both Spatial  and Pure Audio Project source custom open baffle drivers from Eminence.
The Pure 15” driver parameters are available on their site .

https://www.pureaudioproject.com/product/15inch-open-baffle-bass-woofers/

Clayton hasn’t done the ST15 big reveal yet, but if this Circle asks politely.
Shawn

[Bumpy]

Best place to start is with current OB manufactures.
Both Spatial  and Pure Audio Project source custom open baffle drivers from Eminence.
The Pure 15” driver parameters are available on their site .

https://www.pureaudioproject.com/product/15inch-open-baffle-bass-woofers/

Clayton hasn’t done the ST15 big reveal yet, but if this Circle asks politely.
Shawn

Unfortunately they don't seem to sell drivers separately.

"We currently no longer offer the OB-A15SEN (NEO) as components.
These custom woofers were designed specifically for our speakers and are used in all Trio15 and Quintet15 models."

[DaveC113]

I would cross over the woofer with a steeper slope, try 24 dB. That should reduce the contribution of the woofer to the lower mids. Woofers with too much Le tend to not have the best higher frequency performance as well.

As far as slam, IMO that is OB bass' weak point and I might try a bass reflex design instead.   You'll also get less excursion, lower extension and better efficiency.

As far as quality, the AE woofer Early B. linked to is indeed one of the best and will play higher up in the frequency range with good clarity. Your current 2nd order xo would work better with this woofer than the Alpha as well. AE woofers are used in many cost-no-object speakers. It's a small company so plan on waiting a while though.

[MarvinTheMartian]

Unfortunately they don't seem to sell drivers separately.

"We currently no longer offer the OB-A15SEN (NEO) as components.
These custom woofers were designed specifically for our speakers and are used in all Trio15 and Quintet15 models."

True, but the Pure custom driver parameters are available.
How do the parameters differ from your current drivers ?
Understand the OB targets and possibly "What makes a good 15" bass driver?"

Then find an off the shelf driver that leans in the same direction.
Shawn

[mcgsxr]

I’d agree that the most commonly sought specs are QTS, XMAX, and FS.

Many overlook that a dual voice coil woofer can be used with only one voice coil, effectively doubling the QTS.

I enjoyed some car subs this way on OB for a decade.

There are some excellent dual VC Dayton woofers that would qualify too, and 15’s.

And for me if you’re going to biamp , then the sensitivity is way less critical. 

[Rusty Jefferson]

...In my 3 way baffles I am running the 15" driver through its own dedicated SS amplifier with good damping factor, and using a crossover about 100-120Hz. Neither of the drivers I have experimented with, has hit my sweet spot. There are two areas I have focussed on. One is the ability to produce bass slam and the other is the ability to deliver the frequencies above 100 Hz that can match the sound quality of the midrange, and not trample all over it destroying the magic....

A lot of woofers can certainly screw up the lower mids, but generally not below 100hz unless the gain is too high compared to the mids.  The 24db slope (or steeper) as mentioned would be the 1st thing to try with the Alpha woofer. What's your midrange driver that can play down that low?