Major SPL
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=43063
Printed Date: May 08, 2024 at 2:03 PM
Topic: Major SPL
Posted By: dubb
Subject: Major SPL
Date Posted: November 15, 2004 at 6:46 PM
One of my homeboys got some subs installed in his car.Two seperate sealed boxes. One box wit two 10's placed behind the other box with two 12's. i mean it looks crazy two but the spl is crazy. His trunk hits, the two boxes take up all trunk space. I was wondering what are the pros and cons of this set up. what do you lose and what do you gain. i have two extra 12 sitting in my room and his spl made me wanna throw that box in behind my 15's. Give me info before its too late and i explore my curiousity. LOL. Where u at RUSHMAN.... ------------- 2005 Ford 500 SEL. 3 Kicker CVR 15"s. 2000 watt Quantum Audio AMP.
Replies:
Posted By: boostedcivic
Date Posted: November 15, 2004 at 6:56 PM
I would be careful running subs that are different sizes because you can end up with alot of cancellation. the only way I would do anything like that is with two amps and an external crossover. Jason
Posted By: customsuburb
Date Posted: November 15, 2004 at 8:02 PM
You shouldn't run subs of different sizes, unless you have them properly crossed over so that they arn't playing the same frequencys. If you didn't cross them over cancellation would probobly occur. I would just stay with either 12s or 15s, Not both.
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Posted By: kfr01
Date Posted: November 16, 2004 at 12:24 AM
I agree with the above. It is generally a bad idea.
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New Project: 2003 Pathfinder
Posted By: haemphyst
Date Posted: November 16, 2004 at 12:29 AM
I hear all the time "Don't use different size woofers, blah, blah, blah..." go ahead and use 'em... the difference in size between a 12 and a 15 is SO insignificant at the wavelengths you will be reproducing, it will be such a non-event, to even TRY to measure the difference, it would be pretty close to impossible to quantify any "cancellations" you MIGHT get. I wouldn't recommend an 8 and an 18 running the same frequency band, but a 12 and a 15? No problem. The important thing to remember is: MAKE SURE THE PHASE OF EVERY DRIVER IS CORRECT! If you do not do this, then you WILL end up with cancellations that will destroy (if not, limit) your maximum SPL... If you were doing this in a competition vehicle, it might not be the BEST idea, but a daily driver, looking for "bump", you'll be fine!
I have installed multiple size drivers (subwoofers, specifically) in many cars in my day, always with FAR more than "acceptable" results, BUT, if somebody can prove to me that I am wrong, with empirical evidence, I'll recant my ravings, and admit defeat. Until then, go ahead and use the drivers you have!
I might mention, that it is also VITAL that the drivers all have their own airspace, completely separate from the other drivers. I am thinking this may be where people are believing that you shouldn't mix driver size. In a common enclosure, the driver with the STRONGER MOTOR STRUCTURE (it has NOTHING to do with the driver size) will cause the other driver to perhaps (ok, LIKELY) function out of phase, due to the compression of the air inside the enclosure... this IS bad... but as I said, separate enclosures will prevent this from happening.
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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: boxmaker85
Date Posted: November 16, 2004 at 9:58 AM
haemphyst does have a point. This concept applies to you're normal speakers. You've got 5.25" and 6.5" or 6x9. Different speakers but same music. But as far as subs you're dealing with a much larger wave (in wavelength and height) so wouldn't you get more cancelation espceially when they are so close together? The might play with a slightly smaller wave and therefore cause a different sound. And not arguing but if it makes such a small difference then why do you hardly ever see the mixing of sub sizes, especially with the competition cars? I think it's kinda cool to have like one 15" surrounded by a ring of 10" subs, but will it work? (hm... sounds good for a show car). Just my $.02
Posted By: haemphyst
Date Posted: November 16, 2004 at 10:42 AM
The wavelength is NOT based on the diameter of the driver, it is based on the frequency being reproduced. 1100 Hz is one foot long, whether it is coming off of an 18 inch woofer or a 1 inch tweeter. It will make no difference. There is no "height", as you refer to it. Sound actually radiates off of a diaphragm as a half sphere of pressure/rarifaction waves. The interaction of these waves can be destructive or constructive, again from whatever size the driver is. If your drivers are reproducing different frequency bands, then this will actually cause more destructive interference.
As far as "competition cars" using different size drivers, why would they? They are usually sponsored, so why not use as many of the biggest drivers they can? There is no NEED to mix driver sizes. It would not matter if the did, though.
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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: heavilymedicate
Date Posted: November 16, 2004 at 11:25 AM
Your not getting enough from the 2 15" Kicker CRV's? Well after reading your sig I can see you all about loud, and thats it. So sure throw those 2 12's in the trunk, you'll be louder. I would not worry explicityly about cancelation in your case (although it is a legitimate argument) cause you are going for spl and no resembalence of SQ. I still can amagine those 2 15 kickers are not doing it for ya, unless there is something wrong with the setup... My first question would be what are these "2 1000 watts 2 channel amps"? I run a JBL 1200.1 (600@4ohm 1200@2ohm) and my electrical system is taxed to the limits when I push the amp hard. So how are you running 2 1000w amps and a 400w? You may benifit from a new alternator, something like 200amps with that kind of wattage in your system. My second would be-check your enclosure design. I checked the specs and Kicker recommends a 5cu. ported enclsoure for max SPL, thats allot of trunk space. (I know how big a 88 is) How big are the power/ground cables to those amps? You should be running 1-1/0 then split into 2-4 to each amp or 2-4 guage to EACH sub amp. Personally I run a 4 guage to the sub amp and a 8 guage to the 4 channel component amp. ------------- What will you get for Christmas, bad boy? Coal........or Visonik?? - stevdart
Wow, is everyone clueless and lost in the dark? - uthinkuknoaudio
Posted By: boxmaker85
Date Posted: November 16, 2004 at 12:05 PM
Uh actually a wave does have a height. They call it an amplitude. And the louder a sound the larger the wave. And why not mix drivers? The same reason there are different setups. It would suck if everyone had the exact same setup, but I would bet there is something to do with the way it souds. Why not have 4 10" and 2 12" subs (and heck why not a 15")? Probably for the same reason.
Posted By: kickerstang
Date Posted: November 16, 2004 at 12:26 PM
do it
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what!?!?! you want some??
Posted By: dubb
Date Posted: November 16, 2004 at 1:35 PM
Thats what im sayin...it cant be that bad..im not entering any comps. so perfect sound is not a nessecity. I do love SPL. rattling, earthquake bass is what i like. my 15's are crazy as they are but i figure why stop there. its not like im makin another purchase im puttin goods that i have already to use. i dont see my system gettin no worse jus better. i thank you all for your opinions. ima try this sh*t out and let you all know how it goes. ------------- 2005 Ford 500 SEL. 3 Kicker CVR 15"s. 2000 watt Quantum Audio AMP.
Posted By: haemphyst
Date Posted: November 16, 2004 at 2:52 PM
boxmaker85 wrote:
Uh actually a wave does have a height. They call it an amplitude. And the louder a sound the larger the wave.
Umm... have to disagree with you there... what you are thinking of as a height (because you have always seen it represented on an oscilloscope as yes, an amplitude...) is only the visual manifestation of sound. The amplitude you are referring to, which is perceived as loudness of a sound, is NOT a height, physically, but the DIFFERENCE in pressure between the negative swing (rarifaction) and the positive swing (pressurization). The GREATER the differences between these two points, the greater the loudness of a sound - RATE OF CHANGE determines loudness... not "height". The wavelength is ALWAYS the same size, in both length and "height". The physical dimensions occupied by a sound is always the same, in height, width, depth, and time. ------------- 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: Steven Kephart
Date Posted: November 16, 2004 at 4:56 PM
haemphyst wrote:
I have installed multiple size drivers (subwoofers, specifically) in many cars in my day, always with FAR more than "acceptable" results, BUT, if somebody can prove to me that I am wrong, with empirical evidence, I'll recant my ravings, and admit defeat. Until then, go ahead and use the drivers you have!
Hmmm, I may have to play devils advocate on this one. Although I really haven't ever fully thought this one through. So let's break this problem down. We will assume that we are using the same model of speaker, each using an identical motor with just different sized cones and baskets on them. We will also assume the alignment of each size will be the same. First of all, what are the differences you will see? Well the larger driver will have a higher Vas, but that won't be an isue as the speakers are using different enclosures. The larger driver will have a lower Fs, which means that it will play lower for a given alignment . This means that you will probably have an odd stepping down in the low end of the frequency response. Although it will likely be low enough to be fairly inaudible. Q differences will be so close as to not be audible. Yup, I will have to agree that it won't matter as long as the assumed points are true. But my question is why? Why not instead just get all 4 of them to be 15's and know that you will have an ideal response? Now if you are using two completely different subs (different manufacturer and different design), then the results will probably not sound very good. Steven Kephart Adire Audio -------------
Posted By: heavilymedicate
Date Posted: November 16, 2004 at 5:00 PM
dubb]< wrote:
>ima try this sh*t out and let you all know how it goes.
You do that. ------------- What will you get for Christmas, bad boy? Coal........or Visonik?? - stevdart
Wow, is everyone clueless and lost in the dark? - uthinkuknoaudio
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