Help finding 12" or 15" underhung drivers

[Jose Hidalgo]

Hi everyone,

I'm currently looking for bass or mid-bass drivers for a precise Hi-Fi application. This drivers will have to meet the following requirements (from more to less important) :

Main requirements :
- Size : 12" or 15" (not less, not more)
- Underhung motor

Secondary requirements :
- High BL
- Rigid membrane (but still light - we're not looking for real SUBs here !)
- Low Rms
- High Cms
- Xmax not too big
- High BL/Mms

Can you please help ? If we could only list the major 12" and 15" driver manufacturers that use underhung motors, that would be a good start.

Thanks in advance,

Jose

[MJL21193]

Hi.
AuraSound makes a 12" and a 15" underhung drivers which would meet all of your criteria. VERY expensive though.

[Jose Hidalgo]

Hi MJL21193, thanks. Aurasound drivers are beautiful, but their membranes are WAY too heavy, and their BLs are too low. These are real SUBs (low Fs, heavy membranes to lower Fs, low VAS to keep them "WAF compliant", very high Xmax...), and that's not what we want here.

Maybe I should explain just a bit : I'm a part of a small team working on a High-end, Home-Hifi, 3/4-way active, speaker project (max SPL about 105dB, not more, everything software-EQ'ed with IZotope Ozone). We are aiming to find some of the best modern drivers the technology has to offer today, regardless of their cost (well, *almost* regardless of course, lol - let's say about $4-5K for all the drivers, that's our budget). For example, for the mid we will probably work with the Accuton C90-T6, which seems to be just one of the best modern mids out there. Now we are aiming to find a bass or mid-bass driver that will go up to 200-250 Hz and catch up very nicely with the Accuton.

For this, our choices are as follows :
- 12" or 15" : not more than 15" because most 18" drivers will have trouble going up to 200-250 Hz. And not less because subjectively we do not want less than 12".
- Electromechanical specs close to Accuton's ones (this includes a rigid membrane, a high BL but also a quite low Mms, a low Rms, a underhung motor, etc.). Yeah, too bad Accuton doesn't make 12" drivers yet. ;-)
- The frequencies below 50Hz aren't really a problem, because either the driver can make them while going up to 200-250Hz, or else we will go 4-way with a real sub below (and that's probably what we'll end up doing). The priority is up, not down.

The aim of this topic will not be to question these choices (although you can ask questions if you want of course), but rather to see if there really are some High-End 12" or 15" drivers out there that will meet our requirements. They might be Hi-Fi drivers or Pro sound/Studio drivers / etc., we don't care because we are quite cartesian people and we mainly believe in the technical specs (physics are physics, no miracles), in the optimization process and in the final results.

Of course we're not professional people and we can make mistakes. But hey, that's just part of the fun of it don't you think ? ;-)

Thanks in advance.

[kelticwizard]

I don't have any off-the-shelf recommendations, but Morel, a large manufacturer, makes Supremo car components with an underhung voice coil up to 8"

http://www.morelhifi.com/products/mob_2way_supremo.html

Since Morel also makes 12" drivers and is generally regarded as a very respected hi-fi manufacturer generally, you might want to give them a call and see what they can offer in a very short production run of a few woofers.

Who knows, maybe they might get enthusiastic about the project and work with you on this. No guarantees, but they certainly seem to have the capabilities you would need for this, if you can't find suitable production models.

[Peter M.]

http://www.bd-design.nl/

15" underhung, light cone, neo magnet....

[tinitus]

I had not seen that the BD-bass is underhung, nice but designed to give high SPL with high Fs


These 38EX and 46EX will be be very expencive

http://www.jlbcreations.com/Fertin/produits_hp.asp


And this one might be interesting

http://www.aer-loudspeakers.com/eng/sc12-e.htm

[Jose Hidalgo]

Thanks for your answers.

@kelticwizard : Morel doesn't seem to make drivers bigger than 10" (see http://www.morelhifi.com/products/raw_woofers.html ).

@Peter M. : YES, the BD15 could be a good choice. I had already seen its specs, and I think we're going to take a very close look at it. It could be a winner !!

@tinitus : what problem do you see with the BD15 ? We don't need a low Fs because there will probably be a subwoofer below. And we only need 105dB. Again, we are looking for a bass or mid-bass driver that will go up to 200-250 Hz and catch up very nicely with the Accuton. And for that, the BD15 is looking good, don't you think ?

Yes, the Fertin are very renowned here in France... but you're right, they're very expensive (about €920 each, that's $1250 each !). Let's say they're too expensive for us.

As for the AER... it really is a SUBwoofer, probably with a heavy membrane, and besides it has a small Vas (WAF-oriented driver ? ) which also means a small Cms. I don't think it will do.

@everyone : now that we see that the BD-Design BD15 can be a potential winner, do you see any other similar drivers ? What about the JBL 1500AL for example ? Looks very nice but... it just seems impossible to find one anywhere ! (if you have any URLs...).

Thanks.

[Michail Bugaria]

Hi

Maybe "Flex Unit" (your own specification) from Mr. Skaaning?
http://www.audiotechnology.dk/

[454Casull]

I assume you believe that relatively high Mms means... poorer performance? In what way?

As far as the gap type goes, underhung/SGLC is merely a method to attain a flatter BL(x) function. Overhung configurations can also achieve a fairly flat BL(x) WITHIN a certain excursion. If you calculate the required excursion for your max SPL, you will find the necessary limit within which the BL(x) must be flat.

Or, since nonlinear BL(x) mostly (only?) affects nonlinear distortion, just look for a driver with minimal low-end distortion. Mid- and high-end distortion is less affected by nonlinear BL(x) because excursion lowers as frequency increases, and BL(x) tends to be flatter as you restrict the excursion.

A rigid membrane is not necessary. Again, just look at the numbers.

High BL is nice, and so is a high BL/Mms ratio, but instead of looking for those figures, you could just look for high sensitivity.

Even if you ignore everything I mentioned above, I would strongly advise that you consider well the good PA drivers, like from JBL, 18Sound, etc. The JBL 2242H, in particular, looks like an excellent driver, with predominantly (and still very low) 2nd-order HD throughout most of the midrange, at 80W, even.

[tinitus]

I see no problem with the BD15, and believe it to be a very nice driver at a fair price .... but you didnt mention anything about using subs

JBL 1500AL will probably cost almost like the Fertins

AER, I dont think that SPL of 97db with a 12" points in direction of a subdriver or heavy membrane, at all .... but low Fs of 25hz is more likely achieved by soft surround/spider

I dont know about your design ideas, but the moderate VAS would be very helpfull in a multi way system, especially if its a 4way, otherwise your cabinet will become unrealistic big and drivers too wide apart, or wrong listening height etc.