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12-15 inch pro woofer choice?
12-15 inch pro woofer choice?
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Old 10th February 2019, 03:33 AM   #21
fullrage is offline fullrage  United States
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Godzilla swore by this driver as a fullrange end all woofer. love to hear all updated ops. on this driver. ( 12lta).
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Old 10th February 2019, 05:12 AM   #22
ScottG is offline ScottG  United States
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..not much xmax:

Peerless by Tymphany FSL-1220R02-08 Professional 12" Woofer Driver 8 Ohm
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Old 10th February 2019, 12:32 PM   #23
lowmass is offline lowmass  United States
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Quote:
Originally Posted by ScottG View Post
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

Last edited by lowmass; 10th February 2019 at 12:43 PM.
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Old 10th February 2019, 01:24 PM   #24
Scott L is offline Scott L  United States
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12-15 inch pro woofer choice?
Quote:
Originally Posted by lowmass View Post
looking for 12-15 inch woofer selection experience/ advice ...
Given your 2 sets of design circumstances, I don't see where one choice would be suitable for both. Maybe something from Acoustic Elegance, but, it won't be cheap.

Last edited by Scott L; 10th February 2019 at 01:25 PM. Reason: added text
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Old 10th February 2019, 01:35 PM   #25
mortron is offline mortron  Canada
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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!
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Old 11th February 2019, 03:50 AM   #26
ScottG is offline ScottG  United States
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Quote:
Originally Posted by lowmass View Post
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.

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).
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Old 11th February 2019, 02:53 PM   #27
lowmass is offline lowmass  United States
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Quote:
Originally Posted by mortron View Post
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
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Old 11th February 2019, 03:31 PM   #28
lowmass is offline lowmass  United States
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Originally Posted by ScottG View Post
Rubber's not great for this. <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.pdf

Last edited by lowmass; 11th February 2019 at 04:00 PM.
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Old 11th February 2019, 04:10 PM   #29
lowmass is offline lowmass  United States
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BTW for the price this one seems quite good! very high sens, quite linear, and good x max
https://www.parts-express.com/pedocs...ifications.pdf
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Old 12th February 2019, 06:17 AM   #30
ScottG is offline ScottG  United States
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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.
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