New Subwoofer project...

[RuiSilva]

Hi there guys!

I'm making a ported subwoofer for HT appliance with a following specs.

Hardware:
Driver - Peerless XXLS 12" model 835017
http://www.tymphany.com/files/XXLS-P...0Rev%201_0.pdf

Plated Amp - BASH 500
O Audio - 500W BASH Subwoofer Amplifier

Enclosure dimensions:
Volume = 2.5 cft (~70dm^3)

Port vent:
diameter = 3"
Length = 13"

Ok, so I have this to begin with, but, if some of you could lend me a hand on the box size and vented port it would be very nice!
I tried to use the WinISD Pro for the box dimension calculation but I couldn't find some values of the driver for the program so... I did it on paper, and compare it to a DIY project I found that had the volume and port dimensions and my values are a bit smaller than the project I found.
(The values above are from the project I found, and yes the project is with the same driver)
I've read that the enclosure shouldn't be cubic but instead rectangular (or other format) so that the frequency curve response should be smoother. So I'm also opened to opened to suggestion...

Hope the information a gave was enough!
Thank you guys!

[Zero D]

@ RuiSilva

Hi, i looked at the PDF, & ALL the required data needed for designing a project in WinISD is included in there. I guess you must be thinking that ALL of the boxes for data shown in WinISD, have to be inputted manually. This is NOT the case, & is often the cause of confusion. Only a certain amount of Data needs to be inputted manually, the rest is automatically arrived at by WinISD

First of all, make SURE that WinISD is set to automatic.

I made a thread with Lots of screenies, to help people with WinISD here - How to correctly use WinISD

It's up to you how big/small the box will be, & what you tune it to. Experiment with different sizes until you find something suitable.

All the best

[johnr66]

Use a larger port or flares at both ends. Even with modest power, that thing is going to chuff something awful. A cube shape is fine for a sub as cabinet standing waves are a non issue at subwoofer frequencies.

Don't be afraid of sealed designs. I used to be a fan of ported speakers until after trying a couple sealed subs. My latest is a 15" driver in a 3 cu ft box. I'm quite surprised at the SQ and impressed with the bass it can make and how low it plays with modest power.

[RuiSilva]

Thanks for your input Zero D.
After working on the WinISD software, I didn't find the cone displacement curve so I went for the "BassBox 6 Pro" software (I'll post some of my configurations).
After reading a bunch of stuff I started to input some data and here are some of my results.
I used 2 kind of systems, Vented and with Passive Radiators for two types of Drivers:

Passive Radiator:
Scan Speak Discovery 12” model 30W/0-00-00
http://www.scan-speak.dk/datasheet/pdf/30w-0-00-00.pdf

Drivers :
ScanSpeak DISCOVERY 12" 30W/4558T00 (150W RMS)
http://www.scan-speak.dk/datasheet/pdf/30w-4558t00.pdf
Peerless XXLS 12" 835017 (120W RMS)
http://www.tymphany.com/files/XXLS-P...0Rev%201_0.pdf

Ok, so I'm going to post now some pictures of the 4 systems...
For each Driver I did the passive radiator/vented system calculation so that the F3 value would be the lowest possible without degrading the curve response, I also didn't want a BIG box so I tried to create a medium size box.
Attachment 263313
Design 1 (RED)- Scan Speak with one PR (F3=25,67Hz; damping= typical)(Venclosure=73L);
Design 2 (ORANGE)- Peerless with one PR (F3=24,09Hz; damping= typical)(Venclosure=97L);
Design 3 (WHITE)- Scan Speak vented (F3=28,22Hz; damping= minimal; vent type - one flared end with a diameter of 8,5cm and the length of 30,1cm Fb=24,12Hz)(Venclosure=85L);
Design 4 (BLUE)- Peerless vented (F3=29,48Hz; damping= minimal; vent type - one flared end with a diameter of 8,5cm and the length of 30,1cm Fb=22,86Hz)(Venclosure=94L);

Ok so I tried to compare each driver with the PR and the response curves are as fallow... (I peaked the power to 120W for each driver because the ScanSpeak as 150Wrms and the Peerless as 120Wrms).
But... moving on...
PR.jpg
Now comparing the drivers in vented mode...
Vented.jpg
And finally the comparison of the costume amplitude response for the Vented and passive radiator boxes.
Vented_vs_PR.jpg

Ok, so to my conclusions:
Between the PR enclosure I think that the ScanSpeak is better than the Peerless driver.
Between the vented both the drivers perform as I expected.
Between the PR and the Vented enclosures the ScanSpeak is the one closest to the vented enclosure.

Now for the final thoughts:
I think the PR with the ScanSpeak driver is a very good choice... but I also think the Vented for both drivers are very good...

Some questions:
Is the 120w and 150w enough for my system? I have an home cinema with 4 beyma DIY 3 way with 120Wrms in them, and a central (Beyma also) with 100Wrms.
I don't know if this drivers have enough power in them to my system!
Maybe other driver? I was thinking about the RSS390HF-4 15" Reference HF Subwoofer 4 Ohm (250Wrms).
http://www.daytonaudio.com/media/res...ions-46176.pdf
But only if you guys feel this would be the right way to go! (Meanwhile I'm going to make some calculations!!)

Thanks for everything guys! hoping on earing from you!

PS: My conclusions/statements can (most likely!!) be wrong!

[RuiSilva]

Originally Posted by johnr66

Use a larger port or flares at both ends. Even with modest power, that thing is going to chuff something awful. A cube shape is fine for a sub as cabinet standing waves are a non issue at subwoofer frequencies.

Don't be afraid of sealed designs. I used to be a fan of ported speakers until after trying a couple sealed subs. My latest is a 15" driver in a 3 cu ft box. I'm quite surprised at the SQ and impressed with the bass it can make and how low it plays with modest power.

Thanks Johnr66 I'm going to see that!!

[RuiSilva]

There's missing one attachment....
"Ok, so I'm going to post now some pictures of the 4 systems...
For each Driver I did the passive radiator/vented system calculation so that the F3 value would be the lowest possible without degrading the curve response, I also didn't want a BIG box so I tried to create a medium size box."
4Types1.jpg

[Zero D]

@ RuiSilva

Your last screenie "some pictures of the 4 systems" is too small to view/read. Can you upload it again, but larger

Here's where you'll find "cone displacement curve" in WinISD

[revboden]

Originally Posted by RuiSilva

Some questions:
Is the 120w and 150w enough for my system? I have an home cinema with 4 beyma DIY 3 way with 120Wrms in them, and a central (Beyma also) with 100Wrms.
I don't know if this drivers have enough power in them to my system!
Maybe other driver? I was thinking about the RSS390HF-4 15" Reference HF Subwoofer 4 Ohm (250Wrms).
http://www.daytonaudio.com/media/res...ions-46176.pdf
But only if you guys feel this would be the right way to go! (Meanwhile I'm going to make some calculations!!)

Thanks for everything guys! hoping on earing from you!

PS: My conclusions/statements can (most likely!!) be wrong!

Enough power depends on the design, With a BR/PR design Excursion will be the limiting factor. How loud and low do you want a sub to go? How large is the room this will go in? How large a box are you willing to build, are you open to make two if large (200-300L) is not an option?

[RuiSilva]

Hello fellowship of the DIY!

Sorry Zero D I don't know why but that image is really small, here is a new one.
4Types1.jpg

Revboden thanks for your reply, I am thinking on a Cubic design (I know it's not the most appropriate design) the room as 42m^2 (452ft^2). The sub will mainly be used in Home Cinema, the box should be between 100-150L.

After johnr66 post I read more about vented and closed enclosures designs and I did some analysis on some of the parameters of these three drivers.
First of all I read that closed design is better suited to the Home Cinema buff then the vented one. What I read is that closed boxes is for listeners looking for sound quality driven system that is clean across the entire frequency band, something that a vented one can't do without engaging in a big volume enclosure.

I know now (always learning new things!) that if the EPB is lower than 50 it's recommended to use a closed enclosure, and if the EPB is higher than 100 you should go vented, and everything between this values is your choice.

The Effective Bandwidth Product (EBP=Fs/Qes) for the given drivers are:
Peerless - 55
ScanSpeak - 50
Dayton - 36,7

I'm going for the closed design, seems to be a better choice due to the fact that I want a better sound quality across the entire frequency band and I don't want a big box in the room.

Now for some numbers:
Peerless
-12dB @ 22,48Hz
F3 = 45Hz
Max dB(@120Wrms)= 110.6dB
Maximum X(@120Wrms)=9.05mm
Xmax = N/a

ScanSpeak
-12db @ 21.68Hz
F3=42.7Hz
Max dB(@120Wrms)= 110.8dB
Maximum X(@150Wrms)=10.1mm
Xmax = N/a

Dayton
-12db @ 17.44Hz
F3=34.3Hz
Max dB(@250W)= 112.2dB
Maximum X(@250W)=10.9 mm
Xmax reached at 415W

Maintaining the input power at 120W and comparing the acoustic power at 20Hz the Peerless and the ScanSpeak will give 96dB and the Dayton will give 99db.
Now analyzing at their maximum input power (for the Dayton I will use the 250W and not the 500W because Xmax was reached at 415W and I think this input will be enough!) at 20Hz the Peerless gives 96dB the ScanSpeak 97dB and the Dayton gives 102dB.

I'm going to post some images of the amplitude curves and cone displacement for these three drivers at an input of 250W, this is only to show the difference between the three drivers.
Untitled.jpg

My thoughts are that the ScanSpeak/Peerless are two very similar drivers in closed enclosures.
The dayton has a better amplitude response with a better cone displacement within the same power input.

Because I'm leaning to a closed design I think the dayton will suite me better, mainly because it has more power in it and slightly better amplitude response.

Note: All the above designs are for Hi Fidelity in order to have best flat response as possible.

[revboden]

Looks good,

I know the rss390HF-4 very well and something is wrong with the BBP model, you'll need 158L to get a Qtc of .707 a external box with external 23"h x 23"w x 24"d box with a double thick baffle board would get you that.

With a little EQ to bring the top end (30-80hz) down a bit The 390hf makes a monster HT sub.

You can make a BR box sound as good as a sealed box but you have to tune it very low (14-16Hz), so you are correct, that requires a large box.

edit: If you want an example of a very good sounding ported sub using 6.3ft^3 and a rss315hf-4 I made one. my "little" build