Hi, I built a wo32 with the Dayton drivers and it's really nice.  it was a quick and dirty project.  now I'm going to build a nice one.

I've been looking at drivers.
     vifa ne      wo32dayton      wo32vifa      peerless
imp(ohms)      8      8      8      8
sens(db)      84      91.7      88.5      87
vc dia(in)      2      2.5      2      2
fs (hz)      23      41.1      26      27
re (ohms)      6.2      6.3      5.9      5.9
Le (mH)      0.53      1.23      1.8      2.7
Qms      10.33      9.94      2.82      4.33
Qes      0.31      0.32      0.36      0.43
Qts      0.3      0.31      0.32      0.39
vas(cu ft)      3.43      1.72      4.59      3.88
cms (mm/N)      0.69      0.3            
BL ™      14.7      16.03      11      10.9
mms(g)      74.1      50.09      45      51
xmax(mm)      9.35      5.5            
sd (cm2)      326.9      339.8            337


vifa ne is a newer driver
wo32dayton is the recommended driver
wo32vifa is the original vifra wo32 driver
peerless is very similar to vifa wo32 driver.

I think I want a driver with the lowest FS (vifa ne). But it's least efficient and heaviest.

What's the most important thing to decide on?  FS?  QTS? Efficiency?  vas?

the only reason I'm looking at other drivers is a thread that said response drops fast below FS.  but another thread said, the loading of the driver in a wo32 horn/tapered pipe means fs is less important.  

Any advice?

Thanks

Hi rx7mark,

Many months ago, vifa NE's went on sale from their previous price, so I got a pair.  They are still sitting in the garage.

After starting this thread, I did a bunch of reading about horn theory and thiel/small params.  I'm no expert.  Here are my takeaways from that research.

A driver's behavior in free air or open baffle is completely dependent on the theil/small params. (springiness/damping/weight).

But, take a heavy stiff driver, and a light loose driver... place them both face down on a table, so they are as loaded as they can be, and then their thiel/small params won't matter so much anymore.  it's the tiny pocket of air under them that controls their behavior.  extremely damped/loaded.  they behave the same.

About horns... the operating frequencies are determined by the length and mouth size of the horn (shape of the wo32), not the driver.

so, since the drivers in the wo32 sit so damn close to the opposing wall (very highly loaded), the thiel small params of the driver matter less. The horn(load) is controlling the driver.  This together with the sealed volume of air behind the driver are determining how the driver behaves.  the driver is kinda just a pawn, stuck between the resonance of a small sealed chamber, and the loading of the horn.

Also, comparing the specs of the original Vifa wo32 driver, and the current dayton wo32 driver... they are different enough to hint to me that the specs aren't critical.

That was my conclusion.

At decfest, I mentioned this theory to steve and bob and asked if the driver didn't matter as much because of this interplay between the horn and the sealed chamber.  Steve said it was generally true.  Bob said the driver needs to have a strong cone though.  because the high loading, the pressures of pushing lots of air nearly directly against a wall can destroy a weaker cone.  and of course beware of cone slapping the wall, etc.

The vifa NE's are physically stronger than the daytons I'm currently running.  though they have less efficiency.

This isn't going to be a problem though as the sub puts out so much sound... I only use 1/10 of it.  My sub amps is a Velodyne external amp with a remote and a display.  default level is 40. max is 80.  I play at 6 or 7.  I can afford to loose a little efficiency.

To be clear, I use this sub only to fill in the lower notes that the HDT's don't reach down to. not very much music has notes down there.  It's sometimes hard to notice when the sub is on or off.  On some songs, there's a real "wow, I'm missing half the song" experience.  I don't use this sub to thump the house.  So I'm not really putting any driver anywhere near it's extremes.  Except in one case:  the amp has a mic and built in automatic EQ feature.  it plays a bass tone sweep and calibrates the sub.  this happens at the default 40 volume level.  Like that cerebro(?) device in the xmen movie, I am suddenly and simultaneously aware of every piece of glass in my house.  everything rattles. and my feet feel every vibration in the floor.  The sub doesn't even sound like it's trying very hard.  

When playing music normally, I hear the lowest notes in balanced level with the main speakers... and it also happens to be when I can still just barely feel the bass thumps in the floor.  

wo32 is a beast.  but the magic is in the wood/shape, not so much the driver, I think.

The efficiency bandwidth product (EBP) can be used as a rough guide to see which enclosure is most suited for a particular speaker.  It is defined as fs / Qes and is a measure of how "stiff" a driver is.  

An EBP of less than 50 would indicate a sealed cabinet.

An EBP between 50 and 100 would indicate a ported cabinet.

An EBP of 130 or more would work best in a horn loaded cabinet.   200 or more should work very well in horn loaded cabinets.

The only one in your list that comes close is the Dayton with an EBP of 128.  I think the other three would yield disappointing results.


Dan

I wish I could find where I originally read about about a tightly loaded driver making the params less important, but no luck.   So I searched and found this.  http://pwkdesigns.com/?page_id=258

This guy is saying basically "my drivers EBP is low, but it's ok because I'm forcing it to breathe through a small straw (horn throat gap)".

oh well, again, I'm a novice with this stuff.  I don't really know what I'm talking about.

Mark, I'll keep the vifa ne's.  I will build the nice wo32 "some day"

Dan, Also, since I don't really push this sub to it's limits at all, I probably wouldn't notice if a driver was doing better or not.

In any case, when I finally build it, I'll let people know how it goes.

Another odd thing..the original vifa driver (above) that decware recommended for the wo32 has a lower ebp than the daytons.  it's coincidentally strange that the driver chosen first is "worse" than it's replacement when it became unavailable.  oh well.  this all reminds me that I should order those loudspeaker books I've always wanted to get and really learn this stuff.

fyi some of the test songs I use to stress sub is are:
http://www.youtube.com/watch?v=RqPfbqiS8aE
http://www.youtube.com/watch?v=P_OsuuMpO7g
and the beginning of
http://www.youtube.com/watch?v=418515KflfU

I've heard many woofers and subwoofers cough, spit, and give up trying to play these songs loud.  my wo32 at the levels matching my mains, plays these nicely and controlled.  I smile wide when this happens.

Lonely Raven, if you're reading, I'd like to hear what your 21in sub does with these.  be careful.