Quatro 15" as a Sonosub?

[MicM]

New guy with some questions... Just finished building my first set of HT speakers and am ready to build a sub. Am facing a fairly strict budget.

Using the calculators that Thomas posted reference to in another subwoofer thread, I worked the numbers on the Dayton Quatro 15", and unless I am not fully understanding all of the variables, they look pretty good to me.

Here's the Quatro specs:
Power Handling: 300 watts RMS/600 watts max
VCdia: 2-1/2"
Le: 3.5 mH
Znom: 4 ohms
Re: 3.45 ohms
Frequency range: 20-125 Hz
Magnet weight: 67 oz.
Fs: 21 Hz
SPL: 91.8 dB 2.83V/1m
Vas: 6.60 cu. ft.
Qms: 14.0
Qes: .42
Qts: .41
Xmax: 10 mm


Plugging the pertinent numbers in here:

http://www.carstereo.com/help/Articles.cfm?id=17

I get a recommendation for a box volume of 7.662 cubic feet, with a resulting F3 of 19.02 Hz and an Fb of 19.68Hz. Taking those numbers and plugging them in here:

http://www.carstereo.com/help/Articles.cfm?id=31

I get a minimum port size of 5.11". Rounding up to 6" then, I get a recommended port of 7.91".

Figuring on an 18" diameter tube, the length comes out a little under 5'.

Are the calculated numbers true, or is there more to this than I have taken into account?

Thanks in adance,
Mike

[ThomasW]

I probably shouldn't have posted those links ... ops:

That's a generic box design program, it doesn't show the performance of the woofer in the model. Those are fine if the driver has adequate Xmax. But the Quatro is a low Xmax driver....

To simulate the performance of a specific driver, many people use WinISD Pro, I prefer UniBox. If you use one of those programs, you can see the Quatro quickly runs out of excursion with a low port tuning.

If I have time later today I'll post a plot to illustrate this point...

Regardless of the alignment you can still put the Quatro in a tube.

[MicM]

OK.

I was afraid there would be no such thing as a free lunch.

Sounds then like I'm better off spending money on a smaller driver with a higher xMax? (a 12", maybe, like a Dayton RS High Fidelity?) (Another limitation is current availability of drivers)

I guess my goal is maximum happiness for minimum price, in a 99% movie watching situation.

[ThomasW]

Sounds then like I'm better off spending money on a smaller driver with a higher xMax? (a 12", maybe, like a Dayton RS High Fidelity?) (Another limitation is current availability of drivers)

How about the 12" TC2+ from www.oaudio.com?

[ThomasW]

Here's why the Quatro won't work in a 20Hz tuned 7+ cu ft port box. Look where the blue line crosses the red. That's the frequency where the driver runs out of excursion ~38Hz.

[MicM]

AHA!

A picture really is worth a thousand words!

Will the simplified modelling tools work for the TC2+, or should I enter the parameters in Unibox?

Thanks again!

[ThomasW]

If you can use UniBox it will give you a much more accurate model of the design.

[MicM]

OK, I *think* I have everything entered correctly in Unibox...

[WillyD]

I was also gonna use the Quatro in a Sonosub until someone pointed out to be that it is not a suitable driver to be downfired.

Oh, and I ended up building the Quatro in a tall box cabinet that was about 6.30 cuft, before subtracting driver/port/plate amp volume. It works out nicely.

[MicM]

Thomas,

Any recommendation for the "best" vented enclosure volume, etc. for that driver? I've played around with the parameters, but I'm not sure exactly the results I'm shooting for in F3 vs. Fb, max excursion, etc.

Thanks again for the time you've taken to answer my questions!

Mike

[ThomasW]

How big a box do you want to live with?

[MicM]

I've got ample space - I could do 16 cubic feet or more if it came to that.

[Marzen]

Mike,
I modeled both the sealed & vented mfg suggested enclosures for a quick comparison of the two. It's rather a no frills job as I was unable to succesfully import the Clio text file, at least not the amplitude, although the Z data came out fine. I tried it in BassBox & SoundEasy with the same failure, 1st time that's ever happened after an import
I'll add a link if ever get my remote site updated via FrontPage w/o timeout disconnects...
Ward
--Finally! at least got that page up. It's a large page & may take some time to load: Quatro enclosure models

[MicM]

** Addendum: I should add that I'm modelling the TC2+ now rather than the Quatro 15 *****


Well,

I've been playing around with the numbers.

It seems that a combination of 300L volume, with a port tuned to 20.5Hz yields the lowest F3 of 20.51Hz. With that configuration, the excursion doesn't cross the xMax line until down below 20Hz.

It appears that the larger I model the volume, the flatter the resulting response curve, but when I deviate much from 300L I can't seem to get the F3 back down.

Another thing I found... The measured specs of the driver seem to differ greatly from those published on the TC Sounds site... I take it the measured values are the most likely to be accurate?

[ThomasW]

Ward, the link is bad....
https://Quatro 15" Recommended Enclo...ealed & Vented

Another thing I found... The measured specs of the driver seem to differ greatly from those published on the TC Sounds site... I take it the measured values are the most likely to be accurate?

Use the parameters from the Oaudio website. TC-Sound will make changes to a driver according to the customers wants, and I'm pretty sure Todd has his drivers modded from the stock design.

It seems that a combination of 300L volume, with a port tuned to 20.5Hz yields the lowest F3 of 20.51Hz. With that configuration, the excursion doesn't cross the xMax line until down below 20Hz.

Don't get all that fixated on a F3 that low (room gain tends to fill in the lowest frequencies). For grins model a 130L, Fb 20Hz, Damping (walls covered), Leakage (minimal leak), Port Type (one flared end) box, with a port diameter of 14.81mm. Look at the air speed and compare that with your 300L simulation

[MicM]

I was using a port size of 15.24mm (6 inch) I looked at the 300L figures - there was an airspeed spike just under 20Hz that was well over the 26m/s line.

Changing to your figures drops that down almost to the 17m/s line on the graph.

[Dennis H]

14.81mm -- 15.24mm

You guys mean cm, right?

[ThomasW]

Yes 14.81cm...

Changing to your figures drops that down almost to the 17m/s line on the graph.

Yep.... :T

[Marzen]

Ward, the link is bad....
https://Quatro 15" Recommended Enclo...ealed & Vented

Sorry, mhtm single pages seem unfriendly, changed over to a std html page. Although to late to be of use I'm afraid.