Custom Enclosure: Downfiring
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=48032
Printed Date: July 05, 2025 at 8:04 AM
Topic: Custom Enclosure: Downfiring
Posted By: uthinkuknoaudio
Subject: Custom Enclosure: Downfiring
Date Posted: January 18, 2005 at 6:34 PM
Well, obviously that didn't work... Never copy and paste that again... Hey guys, i wanted to take my two Nakamichi SPW120's and put them in a downfiring box, preferably sealed. Well, the stats say the following: Subwoofer Specifications 12" subwoofer Impedance 4 ohms Sensitivity (@ 1 watt/1 meter) 90 db Power Handling 300 watts RMS, 600 watts peak Frequency Range: 25 Hz- 250 Hz Mounting Depth (approx.) 5" Recommended Box Volume 0.85 cu. ft. So do that times two for two woofers and let me know exactly what the box should look like and how to do it. Length x Width x Height. Don't send me the link to the Woofer Enclosures page, as it was no help of me, i already tried. It don't say crap for downfiring... Let me know. - Tony ------------- "I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Replies:
Posted By: uthinkuknoaudio
Date Posted: January 18, 2005 at 10:11 PM
Wow, is everyone clueless and lost in the dark?
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"I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: bullman96
Date Posted: January 18, 2005 at 10:49 PM
maybe its just a dumb question and you are clueless and lost in the dark. design the box the same way you would for the subs, give the box some feet so the subs arent hitting the floor, and you might have to reverse the phase depending on the situation. nothing else changes you clueless, lost in the dark soul
Posted By: kfr01
Date Posted: January 18, 2005 at 11:26 PM
Stevdart, I saw that, and I shared your thoughts. ;-)
Otherwise, no comment.
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New Project: 2003 Pathfinder
Posted By: stevdart
Date Posted: January 19, 2005 at 12:34 AM
heh...yeah, once the hole starts getting dug, I just sit back and wait till it's done. Hope it comes out to specs!
Posted By: heavilymedicate
Date Posted: January 19, 2005 at 1:57 AM
Somethings fishy here... Do you smell the fish, Tony? ------------- What will you get for Christmas, bad boy? Coal........or Visonik?? - stevdart
Wow, is everyone clueless and lost in the dark? - uthinkuknoaudio
Posted By: KarTuneMan
Date Posted: January 19, 2005 at 2:20 AM
You guys are F ing cruel!!! Just the facts mayam, just the facts -------------
Posted By: DYohn
Date Posted: January 19, 2005 at 8:22 AM
Don't be rude, uthink, or so impatient. To know if a woofer can be mounted downfiring, you need to calculate the % sag, which is the effect gravity has on the woofer. You can calculate the sag of a driver from: Percentage of Sag = 24,849 / ( Xmax * Fs²) - 24,849 is a constant value based on the relationship of acceleration due to gravity and Pi.
- Xmax (mm).
- Fs (Hz). As a general rule of thumb, any time the sag exceeds 5% of the driver's Xmax, it's not recommended for a down-firing subwoofer application. ------------- Support the12volt.com
Posted By: haemphyst
Date Posted: January 19, 2005 at 10:52 AM
Checked my Thiele-Small database, and nothing there... If you don't know the parameters, you can't figure the sag.
For anybody interested, and for those of you that might not have it yet, here is a pretty decent Thiele-Small database. I am usually able to find enough parameters on a given driver to help. No Nakamichi, tho! 
Nakamichi does not seem TERRIBLY interested in sound quality to me, otherwise they would provide ALL of the required parameters for a driver. NOBODY can build a proper SQ box without having all of the information. I guess I should shut up, tho, bacause by this qualification, I can say the same of Eclipse or Diamond, sorry to say. maybe what I AM trying to say is if Nak was THAT great a comapny, they would provide enough information to make themselves stand head and shoulders above the rest. Is it POSSIBLE that Nakamichi is JUST another car audio manufacturer? Yes, that is a jab! ------------- 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: uthinkuknoaudio
Date Posted: January 19, 2005 at 3:40 PM
No, Nakamichi is not just another company. Its a fantastic company, which is near top of the line if not the best when it comes to certain products. My comment was not made to be insultful or to belittle, but i really don't screw around with downfiring enclosures and i'd figure i'd ask. When you build it, is there a special way you are supposed to brace it, mount it, or change dimensions? How exactly should i build it above the floor with what and how do i mount it to keep it from moving? This is some stuff i need to know okay. Xmax is pretty pathetic (8mm) but hey, thats why this is experimentation. I gave the other specs, but you guys need to get me here. I can't find the Fs on it, but lets say we didn't need that for a second... I can tast a stab at it as this is experimentation... Someone just guide me on the path of enlightenment to downfire enclosures. Thanks you - Tony
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"I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: kfr01
Date Posted: January 19, 2005 at 4:08 PM
Contact the wizard of oz at Nakamichi and ask them if you can mount it downfiring. Also tell them to send you all the other t/s parameters for the speaker. You probably can. As everyone else said, the box design is otherwise EXACTLY LIKE NORMAL. All you need is feet, 1 inch or high would do the trick. Also, what's the deal with Naks home stuff? It all looks so B&O. ------------- New Project: 2003 Pathfinder
Posted By: uthinkuknoaudio
Date Posted: January 19, 2005 at 4:39 PM
B&O? Anyways, i've tried contacting the wizard of oz at Nak and they never respond. How ould you keep it stuck to the floor though? When you hit a note, i don't want the enclosure to move...
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"I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: kfr01
Date Posted: January 19, 2005 at 5:21 PM
Hmm.. What kind of company doesn't respond to customers? ;-) Be creative. I can think of at least a dozen different ways to keep it from moving. Brackets at each end. Brackets on each foot. A bracket on one foot. Velcro. A base built onto the box. Make it freaking heavy. Bolt it to the rear seat. Bolt it to the side of the car. Glue the feet to the carpeting. Rope. Bungie cable. Duct tape. ;-) Half of those were kidding. But seriously, take a pencil and a napkin and take 5 minutes to come up with some ideas. https://www.bang-olufsen.com/ B&O makes "high end" *cough-over priced-cough* stuff they sell in fashion mall stores you see next to Gucci and Coach. They seem to care more about form over function. On first glance Nak's home stuff strikes me as having some of the same priorities. Although, to be fair, both companies do have some innovative designs. ------------- New Project: 2003 Pathfinder
Posted By: DYohn
Date Posted: January 19, 2005 at 5:52 PM
I had a chance to test these B&O loudspeakers. Amazing technology, amazing sound, everything they say they do is true, and if I had the money they'd be in my house right now. But having the money is of course the problem! ------------- Support the12volt.com
Posted By: uthinkuknoaudio
Date Posted: January 20, 2005 at 9:48 PM
I tell you what, those Nakamichi Soundscapes are fantastic. They really are. They are very expensive, but they are very good. I don't think its fair to say that they do form over function. Why would they make the CD-45z? Its a plain head unit, looks like stock, and functions fantastically. Sounds crystal clear too even at high volumes. Either way you go, Nakamichi is a very good and reputable company. BTW, Nak did get back to me on my email to them and this is what they told me: Box - 1 to 1.25 cu ft. FS - 25-30 Hz Qts - 0.35-0.45 Vas - 2.5 - 3.5 cu ft. Xmax - 8mm Got it everyone? Well i hope this helped determine how to make this box! -Anthony ------------- "I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: stevdart
Date Posted: January 20, 2005 at 10:01 PM
uthink, you'll have to get back to your Nak friend and tell him those parameters are the skimpiest list we've ever seen. And ask him what's up with variable Qts, Fs and Vas? Tell him to ask somebody what parameters are needed to construct a box for SQ.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: uthinkuknoaudio
Date Posted: January 20, 2005 at 10:08 PM
Well here you go: For SQ Box - 1 cubic foot FS - 28 Hz Qts - 0.35 Vas - 3.0 cu ft. Xmax - 8mm Does that make sense to you now? ------------- "I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: stevdart
Date Posted: January 20, 2005 at 10:41 PM
Everything you say makes sense, uthink.
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Posted By: kfr01
Date Posted: January 21, 2005 at 12:11 AM
DYohn] wrote:
had a chance to test these B&O loudspeakers. Amazing technology, amazing sound, everything they say they do is true, and if I had the money they'd be in my house right now. But having the money is of course the problem!
Hmm... I have to admit I'd developed a bias against them because of the external designer feel and the store fronts in fashion malls. (I also get more than slightly turned off when some young metrosexual employee with too much gel in his hair is snotty to me because I don't fit the demographic he usually sells to.) I downloaded the pdf file on the speaker. I eat my words, my hat, put my foot in my mouth, whatever. Wow. Fully active design, on board adaptive dsp... looks very impressive. How much is that speaker? ------------- New Project: 2003 Pathfinder
Posted By: kfr01
Date Posted: January 21, 2005 at 12:56 AM
uthinkuknoaudio wrote:
I tell you what, those Nakamichi Soundscapes are fantastic. They really are. They are very expensive, but they are very good. I don't think its fair to say that they do form over function. Why would they make the CD-45z? Its a plain head unit, looks like stock, and functions fantastically. Sounds crystal clear too even at high volumes. Either way you go, Nakamichi is a very good and reputable company. BTW, Nak did get back to me on my email to them and this is what they told me:
I wasn't talking about their car stuff. I was talking about the home stuff. Most of the home stuff seems very form over function. This is an opinion and based on my observation. I don't think there is anything unfair about making such a statement. Let me ask you this. What is the marginal utility for each dollar spent on a soundscape system over the average price of a similarly performing unit? i.e. For every extra dollar spent on the soundscape, how much added utility does it buy you? What portion of that dollar is form? What portion is function. Returns diminish very fast at the high end. They do in just about every consumer product market. This isn't new. With Nakamichi's current home product line, I say with a reasonable amount of confidence that returns probably diminish faster than the average - because of their focus on form in the home line. Their car stuff is quite the opposite. I love it. No glitz. No glam. Just function. Bravo to their car group.
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New Project: 2003 Pathfinder
Posted By: DYohn
Date Posted: January 21, 2005 at 8:34 AM
kfr01] wrote:
QUOTE=DYohn]I had a chance to test these B&O loudspeakers. Amazing technology, amazing sound, everything they say they do is true, and if I had the money they'd be in my house right now. But having the money is of course the problem!
Hmm... I have to admit I'd developed a bias against them because of the external designer feel and the store fronts in fashion malls. (I also get more than slightly turned off when some young metrosexual employee with too much gel in his hair is snotty to me because I don't fit the demographic he usually sells to.) I downloaded the pdf file on the speaker. I eat my words, my hat, put my foot in my mouth, whatever. Wow. Fully active design, on board adaptive dsp... looks very impressive. How much is that speaker? [/QUOTE] I certainly know what you mean. I get the same snotty attitude sometimes when I go into Magnolia HiFi and they are one of MY customers... The Beolab 5 is only $18000. But you do get a matched pair...  ------------- Support the12volt.com
Posted By: Francious70
Date Posted: January 21, 2005 at 1:35 PM
This Axiom Audio sub has a built-in DSP. It also makes the claim of reaching 10Hz.
https://www.axiomaudio.com/epicenter600.html
Paul
*EDIT*Oh yea, Tony, why exactly do you want a down-firing enclosure?? Seems kinda pointless in a car environment to me.
Posted By: uthinkuknoaudio
Date Posted: January 21, 2005 at 6:42 PM
Well krf01, the advantage of the dollar spent is the quality of sound. Never before have i head such sound quality reproduced before (price does reflect of course). I still disagree, but i respect your opinion. Everyone says my nak head unit is ugly as hell and i love it! Francious70, i want a downfiring enclosure because i've always been curious how they would sound in my Explorer, and i happen to have to Nak subs laying around to try it out with. It isn't pointless, as a matter of fact downfiring enclosures are quite common. I figured i'd try it once and see if i take a liking to it. Tony ------------- "I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: kfr01
Date Posted: January 21, 2005 at 7:11 PM
uthinkuknoaudio wrote:
Well krf01, the advantage of the dollar spent is the quality of sound. Never before have i head such sound quality reproduced before (price does reflect of course). I still disagree, but i respect your opinion. Everyone says my nak head unit is ugly as hell and i love it!
Did you read my post? I wasn't talking about the car audio stuff. I was talking about the soundscape stuff. Also, your post shows a simple lack of understanding of my question. Here, I'll repost it so you can actually read it this time: kfr01] wrote:
strong>I wasn't talking about their car stuff. I was talking about the home stuff. Most of the home stuff seems very form over function. This is an opinion and based on my observation. I don't think there is anything unfair about making such a statement. Let me ask you this. What is the marginal utility for each dollar spent on a soundscape system over the average price of a similarly performing unit? i.e. For every extra dollar spent on the soundscape, how much added utility does it buy you? What portion of that dollar is form? What portion is function? Returns diminish very fast at the high end. They do in just about every consumer product market. This isn't new. With Nakamichi's current home product line, I say with a reasonable amount of confidence that returns probably diminish faster than the average - because of their focus on form in the home line. Their car stuff is quite the opposite. I love it. No glitz. No glam. Just function. Bravo to their car group.
See, I gave credit to the car line. You do not need to mention it again. I bolded the important parts. In otherwords, what PERCENTAGE of each extra dollar OVER AVERAGE goes to form? Function? The smart and logical answer cannot be 100%.
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New Project: 2003 Pathfinder
Posted By: uthinkuknoaudio
Date Posted: January 22, 2005 at 6:47 PM
I wasn't talking about their car audio. If i was i would have said so. I was talking about the soundscape. Once again, the dollar extra goes to sound quality, as i have never heard such clarity before in a home unit. It is great stuff, and very well worth it (if you got the money). I think it is very well made and easy to use. ------------- "I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
Posted By: kfr01
Date Posted: January 22, 2005 at 6:53 PM
You still didn't answer my question. But that's ok, I can see you don't want to play my game or don't understand. Either way, this thread is dead in my opinion. Cheers.
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New Project: 2003 Pathfinder
Posted By: uthinkuknoaudio
Date Posted: January 22, 2005 at 8:23 PM
cheers!
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"I don't play games. I play Nakamichi and that for real yo" - Probably some japanese kid said this in the early 80's trying to sell stereo out of his trunk lol.
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