Dayton Rss390 As A Pro Sound Woofer?

[Ray Tremblay]

With the HO model having a 12mm Xmax and an 800watt RMS power rating, it seems that this may work as a pro sound woofer for a dance club in a ported enclosure.

This woofer has a comparable displacement to a typical 8mm Xmax 18" pro sound woofer.

Assuming I have more than enough power, (I have a 20,200 watt RMS amp rack) would they have similar max SPL?

[Sydney]

Fs: 18 Hz SPL: 90 dB 2.83 V/1m, 87 dB 1W/1m, Vas: 9.95 cu. ft
Compare that to a "typical" Pro 15" and the differences are that Pro models trade LFE for higher output by design, because LFE is not as important as SPL in a live context.
A Hoffman compromise:
Eminence 3015LF: Fs 45Hz ,SPL 100db, Vas 5.4 cu. ft.

[Paul O]

The primary factor seperating pro drivers from everything else is sensitivity and an 8-10db difference is massive. If you have never heard a proper pro audio sub like the PV Lowrider or Eminence 4018LF in action you owe it to yourself to experience it, if all you have ever heard is HT subs it'll be hard to believe you can get that much sound out of so little input power.

[Ray Tremblay]

If you have never heard a proper pro audio sub like the PV Lowrider or Eminence 4018LF in action you owe it to yourself to experience it, if all you have ever heard is HT subs.....

I'm far more familiar with pro audio than most on this site.

What I'm not familiar with is what factors determine the max SPL of a woofer.

Is it mainly a function of displacement (Xmax X Sd)??

Can different woofers with identical displacement produce the same max SPL at frequencies below 100hz?

[Ray Tremblay]

Fs: 18 Hz SPL: 90 dB 2.83 V/1m, 87 dB 1W/1m, Vas: 9.95 cu. ft
Compare that to a "typical" Pro 15" and the differences are that Pro models trade LFE for higher output by design, because LFE is not as important as SPL in a live context.
A Hoffman compromise:
Eminence 3015LF: Fs 45Hz ,SPL 100db, Vas 5.4 cu. ft.

I actually have a pair of 3015LF's. If I'm going to run Eminence pro audio specific drivers, I'd rather just go with 18's.

[Sydney]

Because it would take 10 watts to get a Rss390 to produce the same SPL as a Pro driver produces with 1 watt , That ratio would be 100 watts to 10 watts etc
The pro driver requires less power for desired SPL and reaches higher SPL before Power Compression causes diminished SPL and potential damage:
On JBL's site
http://www.harman.com/EN-US/OurCompany/Technologyleadership/Pages/ScientificPublications.aspx
is the paper by Douglas J. Button
Heat Dissipation and Power Compression in Loudspeakers (http://www.aes.org/e-lib/download.cfm?ID=7059&name=harman)
and the paper by Mark R. Gander
Dynamic Linearity and Power Compression in Moving-Coil Loudspeakers (http://www.aes.org/e-lib/download.cfm?ID=5251&name=harman)

The negative thermal effects of power flowing through the typical VC made of #29 wire sets in quickly and changes T/S parameters and the amount of wasted heat increases and SPL drops.

[AMC]

I couldn't argue with any of the cautionary statements that have been made, but will point out that the eminence lab 12, is considered a true pro sound driver and has the same limitations as the RS390. So it is possible. The question I would have to ask is, why on earth would you want to? Any of the eminence 'LF' drivers should get you as low as you need

And yes, a 15 in driver, running +/- 8mm, will give the same SPL, regardless of it's design intentions. One of the other differences between prosound and HF is a durability factor. Prosound drivers are DESIGNED to run at close to rated power for long periods, where HiFi are not. Also, the frame and general construction are designed to be moved and transported a lot, HiFi is NOT. And while I love my RSs390, one of the major defects on it is the mounting holes. They located very near the inside of the frame, leaving you very little wood to mount the driver to. Works fine in my living room, but I would NOT want to move it around much, there is just not much holding the driver to the box.

My rule is simple, use the right tool for the job, and you will be better off. Prosound application, prosound driver.

[Sydney]

I'd rather just go with 18's. The advantage of using an 18 is the 35% greater Sd. To move the same Vd the 15 has to move 35% more.
Paul Klipsch, is his papers on Modulation Distortion showed the relationship: Increased excursion - increased distortion.
Wolfgang Klippel analysis and papers:
http://www.klippel.de/uploads/media/Loudspeaker_Nonlinearities%E2%80%93Causes_Paramete rs_Symptoms_06.pdf
http://www.klippel.de/uploads/media/Diagnosis_and_remedy_of_Nonlinearities_00.pdf
Shows performance linearity issues with increased power and excursion.
Such as:
http://www.klippel.de/uploads/pics/voice_coil_position.jpg

[billfitzmaurice]

I couldn't argue with any of the cautionary statements that have been made, but will point out that the eminence lab 12, is considered a true pro sound driver and has the same limitations as the RS390.When used other than where it's intended to be used, in a horn, the LAB 12 won't work well in a pro-sound application, for the same reasons why the RS390 won't.

[AMC]

When used other than where it's intended to be used, in a horn, the LAB 12 won't work well in a pro-sound application, for the same reasons why the RS390 won't.

Agreed, although the OP has never mentioned an intended application for said driver. All in all, I think there are ample reasons not to do this.



Shows performance linearity issues with increased power and excursion.


And in other breaking news, water is wet! Smart-a$$ comments aside, Other things to consider are the problems that come from the increased size, i.e. as BFM has mentioned, they seem prone to damage in some horns, I have also heard, that as the cones get larger, it gets harder and harder to keep the rigidity, and this can bring in both distortion and reduced output with power. No such thing as a free lunch, for every plus there is a minus.

[Sydney]

And in other breaking news, water is wet! Smart-a$$ comments aside, Other things to consider are the problems that come from the increased size, i.e. as BFM has mentioned, they seem prone to damage in some horns, I have also heard, that as the cones get larger, it gets harder and harder to keep the rigidity, and this can bring in both distortion and reduced output with power. No such thing as a free lunch, for every plus there is a minus. I wasn't trying to be SA or condescending, but unfortunately many look at the published Vd face value as a means of guess-timation and don't consider all the factors.
Imagine the response; If a statement was made that 2 internal combustion engines of similar displacement were always equivalent in performance...
Totally agree - TANSTAAFL ( larger driver - more mass, inertia Newton's laws yada yada )
RCF makes a 21" LF21N451 ( used in the El Whappo bass cab; IIANM )
EV used to make a 30" woofer, but it had it's issues and wasn't commercially viable.

[Paul O]

what factors determine the max SPL of a woofer. All factors play a roll, the driver sensitivity, power handling, and displacement capibility, and of course the type of cabinet it's loaded in. If we just look at reflex designs then the pro driver has the spl advantage everywhere except at subsonic frequencies, and while that's nice to have that end of the spectrum is usually filtered out(with live sound anyway) as it often contains a lot of noise that just adds mud to the mix.

http://techtalk.parts-express.com/picture.php?albumid=394&pictureid=3654

[AMC]

I wasn't trying to be SA or condescending, ...

I was the one being a SA, It's what I do.:D

I always wanted to see one of those 30" drivers, the must look awful impressive, even if they don't sound good. Someone also made a 24" many years ago, heard it wasn't so good either.

Again, I go back to the "right tool for the job". I can use a chisel as a screw driver, it's just not smart. The RSS390 may work in the right application, but why try and re-invent the wheel.

[AMC]

http://techtalk.parts-express.com/picture.php?albumid=394&pictureid=3654

If a picture is worth a thousand words, that one about sums up the differences between a prosound driver and a HiFI driver in the low freq ranges.

Why would you need 20HZ output in a live show? you DON'T!
Why would you need 125db in your living room? you DON'T!

[billfitzmaurice]

Why would you need 125db in your living room? you DON'T!Clearly you don't share the views expressed here:
http://www.avsforum.com/avs-vb/forumdisplay.php?f=155

They not only want 125dB in their living room at the listening position, they want it at 10Hz.

[AMC]

Clearly you don't share the views expressed here:
http://www.avsforum.com/avs-vb/forumdisplay.php?f=155

They not only want 125dB in their living room at the listening position, they want it at 10Hz.

People like that are a reason to invest in hearing aid manufacturing. They should also look up the word 'habituation'. As someone on this forum mentioned a little while back, 105db is LOUD.

[Taterworks]

"Mr. Anecdotal" here,

A friend and I built a prototype of a Mass-Loaded Tapped Horn enclosure for PA applications using the 10" Dayton Reference HO subwoofer. It has a 3" coil, copper in the motor, and plenty of venting. That box worked very well down to 40 Hz, while having a very compact footprint.

The RS subs might not be right for a direct-radiating PA application, but if you are willing to investigate a tapped horn design, the Dayton Reference drivers can hold up under some punishment.

[AMC]

For some applications most anything will work, like the LAB12. But the question would remain, is it a better option then something like the Kappalite 3012HO (I use it because it similar in price). I'll take the extra 16db (yes, that's not a misprint 84 vs 100) sensitivity in the kappa lite, and take the money I save on amplification and buy about 3 more subs. For those who don't want to do the math, 15db sens would mean, to get the same output of the Kappalite 3012HO @ 100watts, the RSS would have to be run @ 3200watts.

[wg_ski]

You could probably *get* 100-102 dB sensitivity out of an RSS sub in a proper tapped horn. 105 out of it front loaded - but it would be a monster, possibly larger than a lab horn. And of course, you'd need 4 boxes or the low end droops. The questions that would need to be addressed are first, is it practical? (Labhorn-ish is about as big as you'd want any single cab to go unless it's peramanently installed.) And second, will the cone disintegrate from the resulting pressure? Somebody ought to run the numbers and see how it stacks up against a Lab-12, 3015LF, or 15TBX100. It may end up being favorable for 30Hz (or under) horns. Or be a dud.

[billfitzmaurice]

Somebody ought to run the numbers and see how it stacks up against a Lab-12, 3015LF, or 15TBX100. It may end up being favorable for 30Hz (or under) horns. Horn loaded the result is the same. If you need response below 30Hz the RSS works well, but with lower sensitivity than an appropriate driver in a horn that doesn't go that low. The same applies to the Lab 12 and for that matter Lab 15. They're very good in a horn with a 28Hz or lower Fc, but sacrifice broadband sensitivity to do it, and they don't work well at all in a higher fc horn.

[AMC]

You could probably *get* 100-102 dB sensitivity out of an RSS sub in a proper tapped horn. 105 out of it front loaded

16 to 21 db gain from a horn? I want to build wg_ski's horn, cause they are amazing.

Seriously?

[wg_ski]

The reason those home theater drivers are so low in sensitivity is because they are so poorly matched to the air load. Properly loaded to an expanding column of air you approach the same 105 dB/W with most drivers. It's got to be properly matched or you don't get this. For the RSS's in question, I'd suspected that the horn cutoff would need to be in the 20's to do this. It won't have this kind of gain on a 40 Hz horn, as BFM cautioned. Normal pro-sound drivers have a better match to the air load as a direct radiator to begin with, hence the sensitivity is "better" without any extra load.

[billfitzmaurice]

The reason those home theater drivers are so low in sensitivity is because they are so poorly matched to the air load. Properly loaded to an expanding column of air you approach the same 105 dB/W with most drivers. It's got to be properly matched or you don't get this. For the RSS's in question, I'd suspected that the horn cutoff would need to be in the 20's to do this. It won't have this kind of gain on a 40 Hz horn, as BFM cautioned. Normal pro-sound drivers have a better match to the air load as a direct radiator to begin with, hence the sensitivity is "better" without any extra load.Home theater woofers have lower sensitivity primarily because they have higher Mms. It's the same thing as which will go faster, a 300HP 3000 pound car or a 300HP 10,000 pound truck. Smaller load= higher efficiency.
Better impedance matching between the driver and air is a function of a horn, and what gives higher sensitivity. There is no difference in the impedance matching of HT versus pro drivers into free air, as they both see the exact same air mass load.