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Asking for help in modeling a cabinet and port size.

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DLStryker

Active Member
My Heresy IIs need a sub. I know I should learn WinISD, but I just don't have time to sit down and study the application. Crazy hours at work and it just never ends. Could I ask someone to model me the subwoofer cabinet and port size for a specific driver? I have three systems and the one I am working on is the least capable and has a very strange arrangement because of the physical limitations. The Heresy IIs are 36 inches in front of me and toed in. They are also 27 inches off of the floor. I don't listen to loud music any longer, so I do not need a subwoofer with high SPL. The sub(s) will have to sit 27 inches off of the floor as well. So, since I do not need high SPL and would prefer the cabinets to be on the smaller size, I have chosen the Wavecore SW215WA01-8 1/2 Balanced Drive Paper Cone driver(s). I have two. Since I do not listen at high volume, I do not believe I will need the shelf port (lower chuffing) and a round tube port should be fine.

The manufacturer says a ported 1 cubic foot cabinet is adequate, but a larger cabinet will provide lower extension.

I only listen to two channel music. So getting down to 20Hz is not a need at all. 32 to 35Hz would be great.

Again, could I ask someone to model a cabinet and port size?

Link below for specs. Specs attached as well.
Wavecor SW215WA01 8-1/2" Balanced Drive Paper Cone Subwoofer 4 Ohm

By the way, if you think my speaker placement discussed above is completely nuts, I can provide details why it is that way. My main listening system is Chorus IIs placed on the floor and 8 feet from the listening position. Tube pre amp and dual mono SS amps. 2nd system is La Scalas 12 to 15 feet from the listening position and driven by Marantz
 
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Here you go:

Vent size: One 3" port, 15" long
Wavecor 8 inch_2.png

Enclosure Volume: 1 cu ft, tuned to 33Hz
Wavecor 8 inch_1.png
 
It is hard to say. With such a small enclosure, you have to keep the port diameter small or the port length will not fit inside the enclosure.

A larger port diameter, gives a proportionally longer length.
 
Using info in above graph:

3" port

10L: 23" long
12L: 23.2" long
15L: 20.2" long
20L: 19.75" long
30L: 15.3" long
45L: 14.2" long
 
I decide to learn how to do this last night. Looks like the ideal ported cabinet size is 43.28 liters (1.53 sq ft).

Screenshot 2026-04-20 070056.png

Screenshot 2026-04-20 070117.png

It dawned on me that, if I did this right, one could retrofit this woofer into a ported Heresy and get bass down to 28hz??? I must have done something wrong.
 
mboxler said:
I decide to learn how to do this last night. Looks like the ideal ported cabinet size is 43.28 liters (1.53 sq ft).

View attachment 3746165

View attachment 3746166

It dawned on me that, if I did this right, one could retrofit this woofer into a ported Heresy and get bass down to 28hz??? I must have done something wrong.
Click to expand...
The trick with that one would be fitting nearly 16" of port length into a Heresy cab. (maybe I didn't understand the question, 8" sub for UNDER a heresy. gotcha.)


Favorite of mine for quick-n-easy is here, when Archive.org is up and running. Put in your driver's FS, VAS up top, and port size. Scroll down to the 'alignment' you want to use, and click on the driver's Qts. It'll spit something out. Usually start with the middle column. There's other calcs if you clear out the end of the URL, leaving it as /calculators

​
SC458.26Liters7.5cm
727.06Hz44.18cm2
0.4924.26Hz25.56cm

​


​
 
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WinISD is free and super easy to use with a lot of features. Much easier than HornResp for standard sealed or ported enclosures.
 
THD+N said:
@DLStryker has not replied since he posted.
Click to expand...
I've got the basics of WinISD! Took about 2 hours of watching a couple of tutorials and then clicking around in Win ISD. @THD+N, I was able to recreate your simulations. So I know I have the basics.

I see the port was basically too long for a 1 cubic foot box. I see your simulation, and mine as well calculates to a 15" long port. I adjusted the box size to 1.3 cubic foot with the same tuning of 33Hz and get a port length of 11.2". At this measurement, the opening of the port, on the inside of the box, would be 2" from the box wall. Is that acceptable?
 
In WinISD, I have clicked on Rear port-Air velocity. Is the number under the heading of Graph, meters per second?

A Google search say up to 17mps will not create chuffing. Do others agree with that measurement?

Quick question, when I click on Front port-Air velocity, I seem to get zero. What is the definition of Front port and Rear port in this application?


1777169962271.png
 
If you click-on the crescent wrench (tools) icon, you can go in and change the units. The only two units that can be changed are cone excursion and air velocity.

I believe the "front port" option is for a 6th order bandpass enclosure which is selected when designing your enclosure at the beginning of a "New" project.

The port being 2" from a wall might be a problem, but at low volume levels probably not. If you were pushing the woofer for max SPL and wanted to deliver maximum bass then that would be another consideration.

If you are not going to be able to see the port, you could leave a bit sticking out of the enclosure to give you more wall clearance. Just a thought.
 
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Curiosity once again got the best of me, so I ordered a 4-ohm version of this driver. To simplify things, I printed an adapter that will allow me to mount in into my ported Heresy. I'll compare it to the installed 3012HO, then print a 14" port and compare again.
 
Wish I could be there to hear it by degree. The only HO ewave I ever heard had positively lovely midbass but didn't extend enough and now of course they're gone. Thumpity-thump-thump :)
 
OK, so I now have more knowledge on WinISD and some ChatGPT guidance on selecting a port tune frequency. For my Wavecor 8 1/2 driver(s), the resonance frequency is 33 Hz. With ChaptGPT guidance that the port tuning frequency should be .8 to .9 of resonance frequency, I calculated a port tuning of 27Hz. With a 1.3 cubic foot cabinet, a 2" circular port will need to be 7.43" long. So, very doable. The modeled frequency response shows + or - 1.6 db from 30 to 80 Hz. The port velocity will be 6 yards per meter. My understanding is this port velocity is well below the threshold to create chuffing.

I modeled 1, 1.3 and 1.5 cubic foot cabinets.

The F6 is 23 Hz. I see that if I create a high pass filter at 23 Hz, the driver will be approximately 2mm (or 20%) below xmax. I will be using an electronic xover, so adjusting the high pass filter, if the voicecoil bottoms out, will be no problem. This subwoofer is for music, so I don't foresee any over excursion issues related to ultralow frequencies.

I have two drivers and will be building a divided cabinet.

The reason I chose Wavecor, is because all Wavecor drivers were 30% at Parts-Express and Wavecor seems to be built more for SQ than SPL. I chose the 8 1/2 inch, because "if" they sound great, I am going to replicate the same thing to install under the back seat of a pickup truck. 10" is too wide to fit under the seat. 8 1/2" fits perfect. Plus these Wacecor drivers get fairly low in a small cabinet.

Anyone see any issues here? Have any suggestion?
 
mboxler said:
Curiosity once again got the best of me, so I ordered a 4-ohm version of this driver. To simplify things, I printed an adapter that will allow me to mount in into my ported Heresy. I'll compare it to the installed 3012HO, then print a 14" port and compare again.
Click to expand...
You must have purchased the last one! I see, after the 30% off sale, Parts-Express had one 4 ohm and one 8 ohm driver remaining in stock. I wanted to exchange my two 4 ohm's for 8 ohm's, but they did not have the available inventory. I clicked 4 ohm by mistake when ordering. I can make them work though.
 
Chat GPT will likely give you more misdirection than good information. It doesn't know anything inherently, it just scrapes the intertubes and regurgitates what it finds, without regard to accuracy. Stop subcontracting your cognitive function to the Billionaire's Plagiarism Machine®.
 
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