12-15 inch pro woofer choice?

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You should be looking for drivers with higher Qts.. (..and not to large of a Vas.)

OR

Looking for something with a LOT of efficiency near 150 Hz and then adding resistance (usually in combination with inductance).

You can often linearize a choppy higher freq. response with a damping compound on the surround and cone junction. (..usually several coats of stretch fabric glue.)


understood, the last time I played with this I had some old radio shack 15 " polyprop woofers. Vas was quite large ( light cone, low fs. foam surround) and it was a roller coaster above about 600 hz.
Applied a few layers of rubber to surround and played with adding stiff ribs of various size/shape, and materials to cone. Got Vas low and smoothed cone action to about 2 k and all was well in dipole land except the pathetic X max

This was one of the light woofer cone experiences. Very light cone /motor for a 15". Once the issues were overcome that cheap woofer was very good used below about 300 hz.


One of my biggest concerns is the area between 300 and 2 khz. Seems to me to get these larger cones to sound uncolored through the handoff at 1 k you need a lot of refinement in cone. Throw too much at it and its flat but veiled, too little and its got sharp peaks in the cross
 
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I would think that for a "cheaper" driver that can do it all, that the Beyma 12BR70 would be up your alley.

It's got a highish QTS and a good deal of xmax so it could be manipulated via EQ too. While it doesn't stand out as a great OB woofer, it's got a low Fs and about 7-8mm xmax IIRC. Would work well in a sealed or maybe ported box then play nicely in OB with a little EQ. It's noted to play up high, light cone, so should be able to go high enough for the other application.

All you need to do is accept the 93db sensitivity ... 2/3 rule strikes again!
 
Applied a few layers of rubber to surround and played with adding stiff ribs of various size/shape, and materials to cone.

One of my biggest concerns is the area between 300 and 2 khz. Seems to me to get these larger cones to sound uncolored through the handoff at 1 k you need a lot of refinement in cone. Throw too much at it and its flat but veiled, too little and its got sharp peaks in the cross..

Rubber's not great for this. :eek:

This is the stuff for surrounds: Aleene's(R) Flexible Stretchable Fabric Glue™

2-3 coats applied: once-at-a-time waiting for each coat to dry; at the junction between paper and surround up to the surround's first (if it has more than one) roll apex.

You do need to start with a decent cone (or at least the "base" cone if it's one with one or more whizers).

My guess is that the Peerless driver (1220R02-08) I mentioned would work well for your dual purpose (..I think based on your *description), despite the lower linear xmax. It's already pretty clean to 1.6 kHz, it just has a response that needs some "shelving": FSL-1220R02-08 - Tymphany

*this is if your description means a high-pass near 200 Hz for the woofer. If you mean low-pass then your plan needs to be scraped, because there isn't anything that would meet your requirements (in total). :eek:
 
I would think that for a "cheaper" driver that can do it all, that the Beyma 12BR70 would be up your alley.

It's got a highish QTS and a good deal of xmax so it could be manipulated via EQ too. While it doesn't stand out as a great OB woofer, it's got a low Fs and about 7-8mm xmax IIRC. Would work well in a sealed or maybe ported box then play nicely in OB with a little EQ. It's noted to play up high, light cone, so should be able to go high enough for the other application.

All you need to do is accept the 93db sensitivity ... 2/3 rule strikes again!

yep 93 is about 3 db low unfortunately
 
Rubber's not great for this. :eek: <snip>
Understood about rubber not good damping of mid range. It was more to raise Fs from 20 hz to about 40 hz AND to raise Qm quite a bit. The "rubber" was also layed on in a way that made the suspension of the woofer a more progressive acting spring. Idea was to keep the puny VC in the field under harder drive .This made it a much better OB woofer below 200 hz anyway. The thing went from flabby mush to some of the fastest bass Ive ever heard. A revaluation of how sometimes the simplest things can make a world of difference in speaker land.

The woofer for this latest project will be used UP TO 200 hz in the OB speaker and UP TO about 1khz in the monitor. Monitor needs to be around 96 db sens and dipole can be down around 87-90 db sens

Now someone mentioned I should be looking at higher Qt for OB use. This is a question to me still. On the one hand I understand the high Qt to help with the SPL roll off below baffle cutoff, question is how much??

I see a number of OB designs now that use a LOW Qt pro style woofers. I assume to get the response levels at low freq they are just using the higher sensitivity to advantage and with the low crossover of 150-200 hz typically done in these designs we end up with the rise in low freq spl below about 150 hz to make it work on the OB.

In my calculation I can take a 96-97 db sens low Qt pro woofers on an average size baffle crossed at 200 hz and end up with a system sensitivity around 87 db which will be useful with majority of mid/ tweeter. OR is there simply too much damping in the really low Qt woofers to make any bass down to say 50hz on any open baffle?? How does Trolls Graveson and others get a good result with a woofers with .3 Qt on open baffle?

With many of the High Qt woofers im not sure I will get this same type of rise in low freq, AND overall sensitivity of these drivers is often around 85 db sens AND/OR have limited Xmax.

The Eminence Alpha 15 looks good with a High Qt of about 1.3 BUT according to graph its overall sensitivity is really more like 93 db ( not the 97 they say) which puts overall system sens around 83 db.

In the end I really would like to see a close mic ( within an inch) of a High Q ( greater than 1) and a LOW Q ( less than or equal to .35) woofer . This would help know what to do here.

measurement in link below of high Qt/ highish sensitivity woofer is interesting. They say its "HALF SPACE" measurement. Sooo I assume a huge baffle?? The response does rise a useful amount below 100 hz. This 5 db rise , plus take another 5 db off of level region and end with around 88-90 db sens with a 10 db rise down to low freq resonance. https://www.parts-express.com/pedocs/more-info/290-394-goldwood-gw-1538pa-more-info.pdf
 
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The problem here is gain vs. enclosure volume.

You can purchase a woofer with a high Qts for your gain (dipole compensation), BUT for a sealed (or worse: bass reflex design), that driver will require a cabinet volume that doesn't come anywhere close to what you have asked for. (..the 1.1 Qts of the Fane fullrange driver I mentioned might make it in a sealed design - particularly if it's done with an aperiodic vent).

The alternative is boosting the low-end with *lots* of xmax, but I can't think of any woofers with an average spl of more than 95 db (1 watt/meter) that has lot's of xmax (like more than 12mm linear each way) and that will also do what you ALSO require in a (relatively) small volume enclosure.
 
yes I understand about the high Q and huge box.

I guess my question is ...

With the mic at only 1 inch from the cone and cone in open space, what does the freq response look like on a high Q and low Q woofer. No box, no baffle , infinite baffle is OK, and mic at 1 inch or less from cone surface, what does freq response of these two drivers look like as we approach low freq resonance?
freq response from about 300 hz on down, what does close mic measurement look like?


Is there a way to calculate w/o measure?


I have built countless planer magnetic dipole woofers and understand the critical nature of that rising response into lower bass region. Not just the peak but the shape of peak and where it begins. BUT Im not sure of the response og high Q cones vs low Q cones at close mic measure. I believe I need this info to make informed judgment for what Im trying to do.
 
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>>> I use 2 pa310's per channel in open baffle, and still need quite a bit of bump in the lower frequencies

Curious, do you also use additional bass support like a powered sub?


>>> Godzilla swore by this driver as a fullrange end all woofer.

I do enjoy the 12LTA but having tried it in various ported boxes between 2 and 3cf I never thought it provided deep enough bass in a reasonably sized box to sound balanced. IMO it's tradeoffs are best left for either small sealed applications with bass support or open baffle with bass support. It needs a tweeter too. I think the 12LTA is a fantastic driver for home use with low powered amps.

Unfortunately, having purchased and returned the PA310 - because they seemed so delicate compared to the Eminence drivers - I never played the driver before returning it so I can't say I know its sound. They spec out nicely for home speaker projects - typically requiring smaller boxes than many other Pro Audio woofers from other manufacturers and reaching deeper in the bass.

As for the OP, I think he's on the right track with the Eminence Delta 12LFA - which I understand is commonly used as a Klipsch Heresy woofer replacement (which uses approx 2cf sealed box). Unfortunately, I have found this an exhausting exercise since many 10" pro drivers provide deeper bass in similarly sized cabinets between 2 and 3cf.

Regardless, the Dayton PA310 certainly specs out nicely but I'd like to hear it compared to the Eminence Delta 12LFA.

If you are willing to go to 15" then consider the

Delta 15LFA
https://www.parts-express.com/pedocs/more-info/290-417-eminence-delta-15lfa-more-info.pdf

or the

Legend CB158

https://www.parts-express.com/pedocs/more-info/290-497-eminence-legend-cb15-more-info.pdf

Sorry for adding to the confusion.
 
yes I understand about the high Q and huge box.

I guess my question is ...

With the mic at only 1 inch from the cone and cone in open space, what does the freq response look like on a high Q and low Q woofer. No box, no baffle , infinite baffle is OK, and mic at 1 inch or less from cone surface, what does freq response of these two drivers look like as we approach low freq resonance?
freq response from about 300 hz on down, what does close mic measurement look like?


Is there a way to calculate w/o measure?


As you enter the nearfield pressure rises at lower freq.s compared to the average and (depending on where you place the mic.) at higher freq.s (due to fresnel diffraction effects that change with freq. and mic placement).

Testbench seems to do a lot of their testing in the near-field, you might be able to find a higher Qts driver in their list:

Items tagged with: Test Bench | audioXpress


As for simulation:

XLBaffle/ Edge - amateur audio

Martin King's spreadsheet also had this..
 
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