Calculating an enclosure with PRs - Home Theater Forum and Systems - HomeTheaterShack.com

Old 04-06-15, 03:03 PM Thread Starter
Shackster

Join Date: Oct 2014
Posts: 22
Calculating an enclosure with PRs

I am trying to calculate an enclosure using one or two PRs. I am using WinISD but it gives me an error and tells me it can not calculate this box.

Does anyone have any pointers on this?

I am using the following:

Eclipse SW9122

Re = 6.2342 ohms
Fs = 38.5112 Hz
Zmax = 98.0958 ohms
Qes = 0.6023
Qms = 8.8752
Qts = 0.5640
Le = 5.6909 mH (at 1 kHz)
Diam = 245.7450 mm ( 9.6750 in )
Sd = .0474m^2( 73.5177 in^2)
Vas = 20.5683 L ( 0.7264 ft^3)
BL = 25.7803 N/A
Mms = 265.3696 g
Cms = 64.3599 uM/N
Kms =15537.6152 N/M
Rms = 7.2350 R mechanical
Efficiency = 0.1833 %
Sensitivity= 84.6488 dB @1W/1m

TC Sounds VMP (2) 15" or (1) 18" (This is up in the air until I can calculate)

VMP 15"
• Fs: 28.8 Hz • Vas: 2.30 cu. ft. • Qms: 7.00 • Cms: 0.063 mm/N • Mms: 540 g • Sd: 855.27 sq. cm.

VMP 18"
• Fs: 21.8 Hz • Vas: 5.03 cu. ft. • Qms: 7.00 • Cms: .71 mm/N • Mms: 690 g • Sd: 1194.56 sq. cm.

Last edited by scparrish; 04-09-15 at 11:05 AM.
scparrish is offline

Old 04-13-15, 03:34 PM Thread Starter
Shackster

Join Date: Oct 2014
Posts: 22
Re: Calculating an enclosure with PRs

There seems to be little information out there on this.
scparrish is offline
Old 04-14-15, 01:00 AM
HTS Senior Moderator

Join Date: Sep 2008
Location: Newcastle Australia
Posts: 5,624
Re: Calculating an enclosure with PRs

I don't know how accurate these are as I haven't done a design using PR's before today. Also without the power handling and Xmax of the units I cannot work out what the usable output would be either.

Anyway, here is the 18" shown in red and the 15" in green.

Test 18 inch passive.wpr test 15.wpr

Silence is golden but duct tape is silver.

DIY completed:
http://www.hometheatershack.com/foru...-shelf.html
robbo266317 is offline
Old 04-14-15, 01:01 AM
HTS Senior Moderator

Russ

Join Date: May 2007
Location: The Inland NW, USA
Posts: 1,788
My System
Re: Calculating an enclosure with PRs

I will load up your data and post back. There's nothing to it aside from being slightly trickier to tune than a ported sub. As long as you have the needed specs, which you do, modeling a PR is not a problem. I modeled many subs with CSS APR radiators but never got around to building one.

 My Setup SI HT18, Sealed, NU3000dsp "HT 2.0" Monitors (704D, XT25) Flatpack Computer Speakers (ND91-8) The In-Walls
fusseli is offline
Old 04-14-15, 01:04 AM
HTS Senior Moderator

Russ

Join Date: May 2007
Location: The Inland NW, USA
Posts: 1,788
My System
Re: Calculating an enclosure with PRs

Robbo, yup the xmax/xmech of the PR must be considered based on power levels and tuning and qty of PRs. Adding mass to the cone of the pr is how you tune it. Look at PR cone excursion in the software. If it runs out of travel for the desired power level of the sub, add a second or a go to a larger PR.

 My Setup SI HT18, Sealed, NU3000dsp "HT 2.0" Monitors (704D, XT25) Flatpack Computer Speakers (ND91-8) The In-Walls
fusseli is offline
Old 04-14-15, 08:07 AM Thread Starter
Shackster

Join Date: Oct 2014
Posts: 22
Re: Calculating an enclosure with PRs

Power handling of the eclipse is 1500w rms.

I am going to see if I can figure out why I kept receiving errors, when trying to model the PRs.

I really appreciate the input so far.
scparrish is offline
Old 04-14-15, 10:14 AM
HTS Senior Moderator

Russ

Join Date: May 2007
Location: The Inland NW, USA
Posts: 1,788
My System
Re: Calculating an enclosure with PRs

A quick web search says the xmax for that is 23mm, xmech is likely 1.5" (38mm) as listed on Sonicelectronix. That should be a strong and capable driver, its only limitation is the high Fs. This would be a good SPL setup but not as ideal for reaching LF for HT use. It would be more than adequate for music. One VMP 15 should do it, with mass added, about 50L volume, and would take up to 1000W rms.
Attached Files 15 inch passive.wpr (1.8 KB)

 My Setup SI HT18, Sealed, NU3000dsp "HT 2.0" Monitors (704D, XT25) Flatpack Computer Speakers (ND91-8) The In-Walls
fusseli is offline
Old 04-14-15, 10:41 AM Thread Starter
Shackster

Join Date: Oct 2014
Posts: 22
Re: Calculating an enclosure with PRs

I originally used the sub in car audio but have since taken it out. So it is just sitting and it's a quality sub. I thought about selling and getting something else but the other items in it's price category are a lot more space hungry.

The sub models quite a bit better ported than with a PR. It will be a 50/50 split on HT and music.

This is the way I see them modeling:
ported > 18" PR > 15" PR

There isn't a big difference between the 18 and 15 PR. I may go ported if I can't achieve any gains with a PR, other than a slightly smaller enclosure.
scparrish is offline
Old 04-14-15, 04:39 PM
HTS Senior Moderator

Russ

Join Date: May 2007
Location: The Inland NW, USA
Posts: 1,788
My System
Re: Calculating an enclosure with PRs

That's right, the advantage of the PR is only a size savings. You can match the performance of a PR to ported sub by having adequate PR surface area and tuning. For a small box, low tuned sub the port will be huge, so the size savings can be substantial. You also have the added cost of PRs, however.

 My Setup SI HT18, Sealed, NU3000dsp "HT 2.0" Monitors (704D, XT25) Flatpack Computer Speakers (ND91-8) The In-Walls
fusseli is offline
Old 04-14-15, 07:15 PM Thread Starter
Shackster

Join Date: Oct 2014
Posts: 22
I was hoping to have a smaller enclosure. It seems that to not be the case here. I do appreciate the knowledge though, maybe my next less budget friendly build will see some PRs.
scparrish is offline

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