My First Sonosub/WinISD effort...

[howdogg]

Hello everyone,
This is my first time posting here, so please bear with me . Anyway, for the past few weeks I've been reading up on Sonosubs. I really like what I've seen so I decided to attempt one of my own. I'd like to use a 15" TC-9 hybrid 2 ohm DVC subwoofer I have thats just taking up space in my basement. I downloaded WinISD, loaded all the sub t/s parameters and I think I understand what I need to do. However, being that this is my first HT build and my first time using WinISD, I was hoping someone could double check me.

Here is the subwoofer information:
Revc = 4.0229 ohms
Fms = 27.3089 Hz
Zmax = 38.5442 ohms
Qes = 0.3948
Qms = 3.3876
Qts = 0.3536
Le = 4.0277 mH (at 1 kHz)
Diam = 325.7550 mm ( 12.8250 in )
Sd =83343.5655 mm^2(129.1828 in^2)
Vas = 152.9121 L ( 5.4000 ft^3)
BL = 19.5766 N/A
Mms = 219.1788 g
Cms = 154.9648 uM/N
Kms = 6453.0791 N/M
Rms = 11.1017 R mechanical
Efficiency = 0.7412 %
Sensitivity= 90.7176 dB @1W/1m
Sensitivity= 93.7030 dB @2.83Vrms/1m
Xmax = 22 mm

Ideally, I'd like to use a 24" diameter by 36" long sonotube, (I can go much higher than 3 feet else the wife will probably void the entire project), double 3/4 inch MDF endcaps (3/4 inside the tube, 3/4 inch outside) which would result in a net volume of about 255 L (before port/driver displacement).
From what I've read, 18 Hz seems like a good tuning frequency. So, I punched all this data into WinISD and it calculated a port size of 4" diameter by 8.63" length.
I looked over the various graphs that WinISD calculates and although they looked ok to me (based on other people's WinISD graphs I've seen online), I'm not experienced enough to know if what I'm looking at are the results I want.

Does all of this sound reasonable? Due to a lack of experience, I'm not sure about a lot of it, especially the port length, enclosure volume, and tuning frequency. Anyway, if anyone more experienced could critique my first effort to build a sonosub with WinISD, I would be forever grateful.

Thanks in advance!
Jason

[Mike P.]

You are on the right track. You need to know the maximum power handling of the sub to figure out where maximum excursion occurs in this setup. From there we can figure out the port air speed and what diameter port will keep the air speed to an acceptable limit.

[howdogg]

Thanks! I'm excited that I wasn't totally off base with this.
The person I purchased this sub from said it's 1000 watts RMS, but he had tested it with up to 2000 watt burps.
Anyway, I entered 1000 watts into the WinISD project under the "signal" tab. Then I checked the graphs for cone excursion and read port air velocity, but again I'm not sure how to interpret them.

Here are the graphs:




I'm not sure about the excursion, that might be ok as is, but I know the port air speed is way too fast. Whats my next step?

Thanks again!
Jason

[Mike P.]

Excursion looks good with 1000 watt input. Airspeed is extremely high at this much power. Try to keep airspeed under 20 m/s by using larger ports or multiple ports. Maximum port length should be under 36 inches. What amp will you be using?

[howdogg]

Thanks again for the response!
I was planning on using the Dayton HPSA1000 1000 watt plate amp, unless, of course, there is something better out there for the money .

Question, at what frequency should the air speed be under 20 m/s? I assumed 18 hz (which is the frequency the box is tuned to).

Using one 6" by 22" port, the air speed is 45 m/s at 18 hz. Using two 4" by 21" ports, it's even higher. Two 6" ports would require a length of 48" so thats out. Whats my next step now, how do I get that airpseed down? Do i need to increase the volume of the enclosure or what? All suggestions greatly appreciated!

Jason

[Mike P.]

I'm curious where you got the specs from. The TC-9 specs I found are alot different from what you posted.

http://web.archive.org/web/200408302...15tc9_2570.pdf

[howdogg]

The specs came from the person I purchased the sub from. It's kind of a grey area since the subs are not true TC-9's. Here's a link to some info about them.

Anyway, the person i bought it from (and took the measurements) owns a car audio company named Sundown Audio, so he is experienced and knowledgable in this area. He said in a post in that link that these arent true TC-9 subs, they are TC-9 "based" subs so I suppose that is why the parameters are different although I'm no expert by any means.

Do you think I should use the parameters you found? or is there anything else I can do with the parameters I have to get the port airspeed down to where it needs to be?

Thanks again!
Jason

[Mike P.]

Use the parameters you posted since the subs are TC-9 OEMs and they were measured by Sundown Audio. As for the air speed issues, all I can suggest is a bigger cabinet as in a LLT design or the use of passive radiators.

[Ricci]

Howdogg,
Try using a slot port or 3 4" ports. You can increase your port area to reduce your airspeed. Just keep your length at 36" or less due to resonance issues.

[Mike P.]

I've been modelling this sub in WinISD and the best I can come up with is 350 liters tuned to 16.5 hz with one 8 inch port 32 inches long. Max power would be 500 watts to keep the air speed within limits. Hopefully someone else will chime in here if they have any ideas on this sub.

[WillyD]

Well considering this is a 15" driver with 22mm xmax, there is no need to be overly worried about the simulated port air speed. If possible, it is certainly nice to use a larger port than 6" for high excursion 15s, but plenty of folks get by ok with one 6" for drivers like SDX-15s, Rl-p 15s, and 15" TC-2000s.

The key is to not get caught up in the simulation. During most real world listening and material the sub won't be asked to play sine waves in the 13-19Hz region. And you probably won't be listening loud enough in the first place.

Ricci is right about using 3 4" ports (better). I'd either do that or use one 6.

And in using those parameters provided, to me, 220 liters net tuned to 17Hz (6inch port) or tuned to 18Hz (3x4inch ports) with a looks like a good FR. And don't forget, if a highpass is utilized, that'll cut the air speed right down.

[Mike P.]

Thanks for the info, Will.

[howdogg]

Thank you all for your responses! The 222 liter, 17 Hz model will work nicely for me me since it'll allow me to stay at about a 36 inch total height. ...and, unfortunately, i must agree that the wife probably wont let me listen to it loud enough to hear port noise .

I do have some other questions about actual construction.
First, is it necessary to use bracing for a sonotube? I have seen conflicting information about this topic and was wondering what anyone here thought. Second, should I line the tube with some form of sound damping? and if so, what form do you suggest?

Thanks again to everyone for your help!
Jason

[Mike P.]

Bracing would not be required. Sound damping is done by using egg crate foam, known as a mattress pad, which is cheap to buy at WalMart. There are some sonotube pics here in John's thread to give you an idea.

http://www.hometheatershack.com/foru...5-order-2.html

[WillyD]

No bracing necessary. And the foam that Mike mentioned can be used, or you can line it with a thin layer of R13 insulation (well, relatively thin).

And actually, 220liters @ 17Hz won't work for you with a 24" dia/36" long sonotube. The port will be too long to fit. You'll need to raise the tune to just above 19Hz. Which isn't that big of a difference. Then I'd put a highpass in at 18Hz and give 'er 1000W. This amp would give you both. Among other things..and its on special with free shipping and has a good warranty.

Or you could go the pro amp route like a lot of other folks (including myself) go.

edit: Ah, you were already looking at the Dayton amp. Well ok then.

[howdogg]

Thanks again to everyone for the responses! You guys are all extremely helpful!
It'll take some time for me to gather all the materials, but I'll make sure to post updates here with pics once I start construction.

Jason