SQ Question
Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=57136
Printed Date: May 17, 2025 at 8:21 AM
Topic: SQ Question
Posted By: Kawoogie
Subject: SQ Question
Date Posted: June 05, 2005 at 11:38 PM
Hello, I recently purchased a Diamond Audio D912D4. I was wondering if anybody here has had any experience working with this woofer, and could recommend a SQ enclosure for it. I ran it through WinISD and it seemed that an enclosure that is 2.526^3, with a 4.02 X 17.76 vent would give me a nice flat transfer function with nice low end extension. I will be running it at 800 Wrms. I would love some outside opinions and Ideas. Thanks, Lee P.S. The Theile/Small Paramaters are located at https://www.diamondaudio.com/products/pdfs/D9%20Woofer%20Tech%20Sheet2.pdf
Replies:
Posted By: haemphyst
Date Posted: June 08, 2005 at 7:00 AM
I'm workin on it... trying to find my JBL after a format...
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: Kawoogie
Date Posted: June 17, 2005 at 3:39 AM
Hey haemphyst hows it going? Have you found your JBL?
Posted By: Nodestiny
Date Posted: June 17, 2005 at 10:37 AM
WinISD works great. Though remember cabin gain plays a large role in car audio. honestly, in most car setups, it seems that a large sealed box is fairly unbeatable in SQ over even a good ported box. It takes a LOT of fine tuning and what not to get a low tuned ported box to sound truely good in the car... I would try out the recommended sealed box first, then compare to the ported and see what works better for you. My Matrix Elite subs sounded a lot better to me sealed than any porting i could do. They blended with my front end and had a cleaner drop than the ported... but everybody has their opinion... PLUS vehicle makes a differance as well.
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04 dodge neon SXT
(2) Oz Audio Matrix Elite 12"s sealed in 4 cube fiberglass enclosure, powered by HiFonics BX1605D
Oz Audio Matrix 180cs 6.5" component set power by HiFonics ZX4000
Posted By: haemphyst
Date Posted: June 17, 2005 at 10:51 AM
Yep... found it yesterday, but I was busy. I'll plug the numbers in tonight when I get home. Seriously, though, thanks for reminding me!
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: Kawoogie
Date Posted: June 18, 2005 at 3:35 AM
Nodestiny, I agree with you that sealed enclosures sound really good. My last few systems have all been sealed. What made me want to try ported was a few things. I heard the driver in a transmission line enclosure in the store and it sounded amazing. Not exaclty what I will be building, but I was very impressed with it. I have also never made a ported box before and am looking forward to the challange., and last, I want something that will go lower, and louder as well. I find the sealed boxes don't always cut it. But, if my ported doesn't sound good, I definitly will rip it out and build a sealed. Cabin gain is one thing I don't know much about. I have a background in electronics so I don't know much about acoustics. I know it is usually around 50 Hz, but I don't know what it is for my car (92 Dodge Spirit). haemphyst, thank you for offering to take a look at this. Your input would be appreciated and respected. Lee
Posted By: DYohn
Date Posted: June 18, 2005 at 10:07 AM
I ran your woofer and came up with different numbers. It looks to me like a 1.84 cuft (52.02 litre) enclosure ported for 27Hz is the best alignment. The dimensions would be something like 21" X 17" X 12" (0.75" MDF) with a 4" port 21.25" long or a 3.5" port 17" long. Realize that the T/S parameters given are with the speaker at 8 ohms (VCs in series.) They do not give you the T/S at 2 ohms. This speaker is best suited for a sealed application (0.9 cuft) however, as the EBP is 55.73. It'll work ported and probably sound just fine. ------------- Support the12volt.com
Posted By: haemphyst
Date Posted: June 18, 2005 at 10:43 AM
Those numbers came really close for me as well... My tuning hit at 28Hz, though... Close enough for government work...
Use the bigger port - less chance for port noise. Add additional space to the box to allow for the port volume. The volume DYohn came up with is NET volume, this means you have to know the displacement for all of your bracing, woofer volume, and port - then add it to the internal volume of your box. DO NOT SKIMP on bracing. This is especially important for a vented enclosure, as the pressures exherted are higher in a vented box at resonance than they are in a sealed box. Panel flex will also change your tuning. When you think you have enough bracing, find a way to add more to your design... If you think I am kidding, come over to my house and give a rap to the enclosure of ANY woofer here. They sound like you're knocking on stones. You CANNOT have too much bracing.
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: Kawoogie
Date Posted: June 18, 2005 at 3:03 PM
Thanks DYohn and haemphyst. Ya, I noticed the EBP of 55.73. i was hesitant to put it in a ported enclosure, but listening to the transmission line sold me. How much of a difference will it make having the T/S parameters at 8 ohms instead of 2? Not that I am concerned; I am just curious. About the bracing, I am building this out of fiberglass, any hints, suggestions for bracing? This is the largest fiberglass project I have undertaken yet, so anything will be helpful. I have learned about improper bracing before in the past. Trust me, I don't want to make that mistake agian. Thanks Lee
Posted By: haemphyst
Date Posted: June 19, 2005 at 10:26 AM
I got nothin'... Maybe some others could help out. Personally, I have never undertaken any fiberglass projects. I'm escared... Just never had the time or desire, and never really wanted to do the "trick" thing...
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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."
Posted By: DYohn
Date Posted: June 19, 2005 at 10:47 AM
Kawoogie wrote:
How much of a difference will it make having the T/S parameters at 8 ohms instead of 2?
The T/S parameters given by Diamond are at 8 ohms (VCs in series.) This is true for most loudspeaker manufacturers' ratings for DVC woofers. When you put VCs in parallel, the Qts changes. Here is the formula for parallel VCs: Qts = Qms*Qes/(Qms+Qes). The difference is generally not so significant to cause major changes to enclosure design in car subwoofers from what is achieved using the standard series number. ------------- Support the12volt.com
Posted By: Kawoogie
Date Posted: June 20, 2005 at 2:55 PM
Thanks, I figured it was something like that. Just take the Qms and Qes and treat them as if they were in parallel. I guess it's time to hit the drawing board. Thanks guys, I appreciate it. I'll let you know how it turns out. Lee
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