Box design check for Dayton 12" HiFi

jonnythan · 9th February 2006, 06:44 PM

I'm designing a box (most likely a sonotube) for the Dayton RS series 12" High Fidelity woofer. It will be used in a home theater application in a room that's about 14 ft x 16 ft.

I'm using WinISD exclusively for the design. I'm very much a newbie at this.

I'd like someone to take a look at what I'm planning and tell me if everything seems in order.

General parameters:
3.75 cf enclosure
22Hz tuning frequency
20.59Hz at -3 dB

Here are the WinISD graphs. I'm confused about the group delay, as I can't quite tell what it is and what it should look like.

Also, how does one determine the volume the driver takes up inside the enclosure?

Thanks!

simon5 · 10th February 2006, 11:16 AM

You could try to update to WinISD Pro alpha, there's more options available.

You guesstimate the driver volume since the manufacturer don't give the volume. I'd guess 2 liters.

You could also design a slightly decreasing response curve because the room will amplify the lowest frequencies.

For example, I use a curve that starts at 80 Hz, then at 40 Hz I want it to be at -3 dB then -6 dB at 20 Hz.

Other than that, you seem to be on the right track!

sreten · 10th February 2006, 12:18 PM

Hi,

I agree with s5, a more overdamped response would be better.

The group delay is confusing, but you can compare your
design to the group delay of the same driver in a sealed box.

Group delay gives you some idea of bass transient response,
and its immediately obvious sealed boxes are much better in
this respect than vented.
But vented boxes have many advantages over sealed, not
least of all higher power handling and maximum output.

Generally try to keep GD at bay to as low a frequency as possible.

You''ll find the GD of an overdamped reflex is better than flat.

The driver has obviously been designed for ~ 2 cuft sealed.

When reflexed in ~ 4 cuft port frequency is very low, to get
some form of overdamped alignment port frequency ~ 18Hz.

/sreten.

jonnythan · 10th February 2006, 02:27 PM

Perhaps something like this?

I downloaded WinISD Pro Alpha, which gives me a slightly different response curve for the same parameters. It also lets me put in a crossover, so I put in an 80Hz crossover.

I assume this is what you mean by more overdamped... I eliminated the "hump" at the low end by tuning to a lower frequency.

I'm still confused by group delay, though. I get this huge spike of 40ms around 17.5Hz. Plotting the same driver in a sealed box gives me much poorer low end (F3 is 38Hz vs 19Hz for the ported box), but the group delay is better, I suppose? I'm still not sure what the group delay *is* and what effect it has on actual sub performance, though.

Thanks again for your help and advice.

jonnythan · 10th February 2006, 02:27 PM

Here's the group delay for the two (ported vs sealed)

jonnythan · 10th February 2006, 02:57 PM

Actually I just read a paper online and then found this review:
http://www.hometheaterhifi.com/volum...er-4-2005.html

Which indicates some baseline group delay numbers as well as a good definition of what it is and how it affects the sound. It would appear that my numbers:

27Hz / 18ms
33Hz / 12ms

Are below the reviewer's "audibility thresholds."

jonnythan · 10th February 2006, 04:31 PM

Now I'm thinking about a 10" sub in a much smaller enclosure at 2cf, perhaps an 18" diameter sonotube that's 15.5 inches long, or a cube with internal dimensions of 15.75" with a pair of 5/8" dowels as braces.

F3 will be more like 21.6Hz than 19.1Hz, and I'll get about 1.5 fewer dB across the board, but my room is only 1600 cf.. that should be sufficient, do you think?

In this config group delay would have a peak of about 33ms at 20Hz dropping to 17ms at 30Hz.

If I didn't mention it, this is primarily for home theater purposes.

Thanks to anyone who actually makes it this far

thalis · 10th February 2006, 05:50 PM

In these low frequencies group delay is not a big issue, I believe. It becomes more in the mid and high frequencies.
A good freeware utility to examine box alignments together with phase - step response - impedance etc. curves ishere
Regards,
Thalis

simon5 · 10th February 2006, 10:26 PM

I'd recommend 4 cu.ft internal net volume tuned with a 24" long 4" diameter pipe for the Dayton Hi-Fi with a 250W RMS amplifier.

Why changing to a 10" ?
Check for overexcursion, I think you might lose more than 2 dB or so.

jonnythan · 10th February 2006, 11:17 PM

Going to the 10" just for compactness and ease of construction.

4cf is really fairly large. 30-inch long, 18-inch diameter sonotube is manageable if I can orient it vertically, and 21.25" cubed is giant as well.

The 10" would also be a little bit cheaper.

If it's worth it, the 12" is definitely doable though.

10th February 2006, 11:16 AM	#2
simon5 diyAudio Member Join Date: Nov 2004 Location: Québec, Québec	You could try to update to WinISD Pro alpha, there's more options available. You guesstimate the driver volume since the manufacturer don't give the volume. I'd guess 2 liters. You could also design a slightly decreasing response curve because the room will amplify the lowest frequencies. For example, I use a curve that starts at 80 Hz, then at 40 Hz I want it to be at -3 dB then -6 dB at 20 Hz. Other than that, you seem to be on the right track! __________________ DIYaudio for President !

10th February 2006, 10:26 PM	#9
simon5 diyAudio Member Join Date: Nov 2004 Location: Québec, Québec	I'd recommend 4 cu.ft internal net volume tuned with a 24" long 4" diameter pipe for the Dayton Hi-Fi with a 250W RMS amplifier. Why changing to a 10" ? Check for overexcursion, I think you might lose more than 2 dB or so. __________________ DIYaudio for President !

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Design Check - Dayton Sonosub	mp3z24	Subwoofers	13	30th October 2006 11:27 PM
FS - Dayton 12" RS HiFi driver $120 shipped.	SightSeeker1	Swap Meet	1	3rd May 2006 02:59 PM
Dayton RS 12" HIFI	basham	Subwoofers	1	17th March 2006 05:32 PM
Dayton RS HiFi 12" Sub using Linkwitz Transform EQ--Design Proposal	dfdye	Subwoofers	23	24th January 2006 01:18 PM
Please check my design for a downfiring dayton 8"	Lyerigolfin	Subwoofers	2	9th August 2005 09:51 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

10th February 2006, 12:18 PM	#3
sreten diyAudio Member Join Date: Nov 2003 Location: Brighton UK	Hi, I agree with s5, a more overdamped response would be better. The group delay is confusing, but you can compare your design to the group delay of the same driver in a sealed box. Group delay gives you some idea of bass transient response, and its immediately obvious sealed boxes are much better in this respect than vented. But vented boxes have many advantages over sealed, not least of all higher power handling and maximum output. Generally try to keep GD at bay to as low a frequency as possible. You''ll find the GD of an overdamped reflex is better than flat. The driver has obviously been designed for ~ 2 cuft sealed. When reflexed in ~ 4 cuft port frequency is very low, to get some form of overdamped alignment port frequency ~ 18Hz. /sreten.

10th February 2006, 02:57 PM	#6
jonnythan diyAudio Member Join Date: Feb 2006 Location: NY	Actually I just read a paper online and then found this review: http://www.hometheaterhifi.com/volum...er-4-2005.html Which indicates some baseline group delay numbers as well as a good definition of what it is and how it affects the sound. It would appear that my numbers: 27Hz / 18ms 33Hz / 12ms Are below the reviewer's "audibility thresholds."

10th February 2006, 04:31 PM	#7
jonnythan diyAudio Member Join Date: Feb 2006 Location: NY	Now I'm thinking about a 10" sub in a much smaller enclosure at 2cf, perhaps an 18" diameter sonotube that's 15.5 inches long, or a cube with internal dimensions of 15.75" with a pair of 5/8" dowels as braces. F3 will be more like 21.6Hz than 19.1Hz, and I'll get about 1.5 fewer dB across the board, but my room is only 1600 cf.. that should be sufficient, do you think? In this config group delay would have a peak of about 33ms at 20Hz dropping to 17ms at 30Hz. If I didn't mention it, this is primarily for home theater purposes. Thanks to anyone who actually makes it this far

10th February 2006, 05:50 PM	#8
thalis diyAudio Member Join Date: Jan 2004 Location: Athens	In these low frequencies group delay is not a big issue, I believe. It becomes more in the mid and high frequencies. A good freeware utility to examine box alignments together with phase - step response - impedance etc. curves ishere Regards, Thalis

10th February 2006, 11:17 PM	#10
jonnythan diyAudio Member Join Date: Feb 2006 Location: NY	Going to the 10" just for compactness and ease of construction. 4cf is really fairly large. 30-inch long, 18-inch diameter sonotube is manageable if I can orient it vertically, and 21.25" cubed is giant as well. The 10" would also be a little bit cheaper. If it's worth it, the 12" is definitely doable though.