[JeffB]

I was looking at this article on infinitely baffled subwoofers.
http://white.hometheatertalk.com/tips/ib.htm

I noticed that the following sub-woofer driver was being used
DAYTON IB385-8 15" IB SUBWOOFER  $119.83
http://www.partsexpress.com/pe/showdetl.cfm?&User_ID=15362308&St=2182&St2=-81158273&St3=60835494&DS_ID=3&Product_ID=118185&DID=7

I noticed a comment on the parts express page:
"the IB series subwoofers are the only drivers on the market designed specifically for infinite baffle situations."

I wondered if it would also be appropriate for open baffle situations.
The frequency response graph looks better than most subwoofer graphs that I have seen.
http://www.partsexpress.com/pdf/295-455.pdf

And the original article had this comment:
"At 16hz, the sub was still putting out well over 75 db with ease"
So the drive seems quite capable.

I am mainly interested because of the frequency response graph.
I have not seen hardly any mention of this driver so I thought I would bring it to people's attention.

[justpoor]

That sure looks good on paper but for not much more you could get the Augie from Hawthorn which has already been proven and love by lot of folks.  Just my 2 cents.

[gooberdude]

Are there other subwoofers made that are suitable, if not flat out designed, for OB??

[JoshK]

These are the best bang for buck for IB useage.

http://www.mach5audio.com/product_info.php?products_id=56&osCsid=393aade90eec23873a79281352c163be

[JoshK]

Are there other subwoofers made that are suitable, if not flat out designed, for OB??

Yes...Qts of .5 is part of the equation....high xmax...low mechanical noise, such as leads woven in spider, appropriate pole venting etc.

[Russell Dawkins]

these aren't too shabby, either, for half the price:

http://tinyurl.com/2quyyg

I'm wondering what a couple of these (8 ohms), paralleled, per side would sound like in OB.

A pair of these would give 1200 W power handling, vs 800, 97dB efficiency vs 90, and cost the same, more or less.

[JoshK]

half the price, but only half the displacement also...also stamped frame...not sure that is a fair trade off, depends on whether you budget it that tight.

[Daryl]

A driver doesn't need to be designed especially for infinite baffle or dipole operation.

Smooth frequency response
Low distortion
Low noise

are what you are looking for.

If Q is too low you use a simple series resistor to adjust it or active parametric E.Q.

This driver is one of the best available and at $160.00 is too cheap to pass up.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-468

It has three faraday rings and a huge motor giving it very low distortion.

It's displacement is 2.4 liters

Good looking too.

Metal cone with it's first breakup mode at 1.6khz.

[warnerwh]

I built two sealed subs using the Dayton RS 15" suggested above. Bass is truly outstanding. The reason I went with that particular driver is because all the people who are extremely knowledgeable suggested I use it, this included 3 different forums. I'd been prepared to spend double the money.

I don't know what that's worth for an OB but the driver is an excellent quality driver, as good or better than most of the name brand drivers. This isn't a guess, these guys measure them to see how they perform. For 160 bucks they're a bargain.

[JohninCR]

Thanks for bringing up those Dayton Reference series woofers as candidates for OB bottom end duty.  Plus the Dayton stuff has free shipping, which is a significant consideration that we must consider when comparing prices. 

The Mach5 woofers are hard to ignore, especially since you get cast frames at those low prices.  I wonder how the Mach5's are on noise.  Has anyone here run them to big excursions with LF tones looking for noise?  It sure would be nice to see some measurements.

I have heard good reports from people using the Dayton IB for OB, but I think I'd go with the dual voice coil, DVC, version instead of the IB.  It is cheaper and appears virtually identical, except that the DVC gives you more flexibility using resistive damping (a plus for the Mach5's as well).

[mcgsxr]

I have no measuring gear, but have done sweeps at high volume with my Mach5 12's, and can report not hearing any chuffing or slapping etc, at deep excursion levels.

I think this one, for me, wins the bang for the buck award -

http://www.mach5audio.com/product_info.php?cPath=48&products_id=53&osCsid=393aade90eec23873a79281352c163be

USD - $70 plus shipping
Cast basket, rubber surround,
FS - 26Hz
XMAX - 13mm one way
QTS with one VC left open - 0.64

They appear to be as close to custom built for OB, on the cheap, as you are likely to find.  If I had it to do over again, I would have bought at least 2 of those, instead of 2 of these 12's...

http://www.mach5audio.com/product_info.php?currency=USD&cPath=48&products_id=41&osCsid=393aade90eec23873a79281352c163be

The high excursion 18's look interesting, but at 3x the price, I suspect the MAW15's are still the value leader.

[tubamark]

I have no measuring gear, but have done sweeps at high volume with my Mach5 12's, and can report not hearing any chuffing or slapping etc, at deep excursion levels.

I think this one, for me, wins the bang for the buck award -

http://www.mach5audio.com/product_info.php?cPath=48&products_id=53&osCsid=393aade90eec23873a79281352c163be

USD - $70 plus shipping
Cast basket, rubber surround,
FS - 26Hz
XMAX - 13mm one way
QTS with one VC left open - 0.64

Looks promising, but:
I notice that the Mach-5 site indicates that specs are with coils in series . . . More typically, DVC subs are spec'd with coils in parallel.
I'm not sure that your Q doubling is accurate.  If they were spec'd in series, then one coil alone would halve the Qes, not double it.
Not to quibble with your results;  I hope the manufacturer has typos on the site?

Anyone out there actually measured these drivers yet for Qes and Qts?

[scorpion]

tubamark,

I think Mark is right on this. Here is a very illustrative exemplary spec: http://www.visaton.de/en/chassis_zubehoer/tiefton/gf200_2x4.html

/Erling

[tubamark]

tubamark,

I think Mark is right on this. Here is a very illustrative exemplary spec: http://www.visaton.de/en/chassis_zubehoer/tiefton/gf200_2x4.html

/Erling

Hmmm - seems you guys are right;  so can anyone explain (to my now very confused head!) how the Qts can be almost the same whether in series or parallell? 
As I understood before now, Qts is a product of Qms and Qes . . . Qms should remain nearly constant (as the result of cone mass and suspension components being a constant), while Qes depends on what happens electrically in the long path between the + and - terminals.
 
I'm happy to be mistaken here -- as long as I can learn why!
Help!

[catapult]

Darren at PE has said the IB driver has too much mechanical noise (chuffing) to use on an open baffle although I'm sure it could be made to work fine as long as you don't push the excursion too much.

As Daryl said, the RS series woofers are excellent (quiet and low distortion) for OB and you can always boost the Q with a series resistor or some EQ. Qts really shouldn't be a factor in selecting a driver. Go for low distortion and low chuffing and adjust the Q as needed.

About the series/parallel thing with a DVC driver, they do indeed have the same Qes and Qts. Running a single coil doubles Qes and almost doubles Qts. I think Adire used to have a white paper about it but it appears MIA. This note from SL gives the general idea.

http://www.linkwitzlab.com/faq.htm#Q12

[catapult]

Okay, a bit more on the series/parallel thing.

Qes = Re*Sqrt(Mms)/(BL^2*Sqrt(Cms))

Mms (moving mass), B (magnet flux) and Cms (suspension compliance) don't change so we're left with

Qes ~ Re/(L*L) where Re is the DC resistance and L is the length of the voice coil wire in the gap.

Let's say each coil has an Re of 4. Series Re is 8. Parallel Re is 2.

Single coil L (length) is 1. Parallel L is also 1 (goes through both wires at the same time). Series L is 2 (goes through one wire and then again through the other one.)

Single: Qes ~ 4/(1*1) or 4
Series: Qes ~ 8/(2*2) or 2
Parallel: Qes ~ 2/(1*1) or 2

Six of one, half dozen of..... 

[PaulHilgeman]

I'll give testament to the Dayton RS Series drivers.

They are just about as good as anything else out there and I did quite a bit of testing when developing the Ronin which uses the 10" version.

-Paul

[JohninCR]

The Adire paper talked about RDO, Resistive Damping Operation.  While you give up 3db of sensitivity by running only one VC.  You can make the Q anywhere between the Q running one and running both by putting resistance across the open VC.  Making the short across the open terminals with a variable pot (variable resistor) gives you an adjustable woofer.  0 resistance gives you the damping of both VCs and very high resistance gives you the damping of just 1.  Adire suggested using a variable pot that could go up to several hundred ohms.

[JoshK]

A driver doesn't need to be designed especially for infinite baffle or dipole operation.

Smooth frequency response
Low distortion
Low noise

are what you are looking for.

If Q is too low you use a simple series resistor to adjust it or active parametric E.Q.

This driver is one of the best available and at $160.00 is too cheap to pass up.
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-468

It has three faraday rings and a huge motor giving it very low distortion.

It's displacement is 2.4 liters

Good looking too.

Metal cone with it's first breakup mode at 1.6khz.

Indeed a good woofer for OB...I think it depends a bit on what the usage is, for IB, the added Sd of the Mach5 18"s might be well greeted (sic?, doesn't look right).

[JoshK]

Mark's suggestion with the Mach5 15" is good, but I'd fear the Fs of 26hz if you used the IB for movies too...for music I wouldn't care.   Even if you love pipe organ music, the likelihood for the music to crap out this woofer is small...but if you use it for HT sub, this is a bit too high, which is why I liked the 18" at the pre-prod price.