what kind of db’s should i expect?
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=122781
Printed Date: April 29, 2024 at 12:31 AM
Topic: what kind of db’s should i expect?
Posted By: gman91
Subject: what kind of db’s should i expect?
Date Posted: July 21, 2010 at 2:01 PM
I have two eclipse 87121.8 12 " subwoofers, ( 300w RMS 600w peak ), running off of a rockford fosgate Prime R500-1 amp ( 320w x 1 @ 4 ohms ). Im thinking about getting them metered, what can i expect from them in a nice home build box designed for the subs?
Replies:
Posted By: roadshop570
Date Posted: July 21, 2010 at 6:41 PM
Nowhere near what you want, lol, what vehicle and location its in? Type of enclosure, sealed or vented?
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Chadillac
Posted By: gman91
Date Posted: July 21, 2010 at 7:56 PM
I would be happy with a 125, they are in a saturn SL 97 and a slot ported box.
Posted By: roadshop570
Date Posted: July 21, 2010 at 8:58 PM
Upgrade your big three, depending on your head unit you may want to add a line driver, but it will get you to your mark.
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Chadillac
Posted By: gman91
Date Posted: July 21, 2010 at 9:37 PM
I got an alpine CDE-100 HU, wth is a line driver? And Big 3 will be soon, but will it really be that much of a difference?
Posted By: roadshop570
Date Posted: July 21, 2010 at 11:05 PM
Alpine deck is great, always remember every little bit helps, it should sound good.
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Chadillac
Posted By: DYohn
Date Posted: July 22, 2010 at 1:00 PM
I was going to post that the OP could realistically expect SPL greater than 75db, but I didn't want to sound patronizing. The answer is impossible to tell you since it is a function of the enclosure and the installation as much as it's a function of the woofers and the amp. Build it, install it, then test it and report back what you have. ------------- Support the12volt.com
Posted By: DYohn
Date Posted: July 22, 2010 at 1:01 PM
gman91 wrote:
I got an alpine CDE-100 HU, wth is a line driver? And Big 3 will be soon, but will it really be that much of a difference?
IMO don't waste your money on a line driver, and upgrading the Big 3 never hurts even though your amplifier is quite small and a standard electrical system should be able to handle it. ------------- Support the12volt.com
Posted By: gman91
Date Posted: July 22, 2010 at 4:31 PM
I got it hooked up, my windshield wipers and windshield flex quite a bit.
Posted By: DYohn
Date Posted: July 22, 2010 at 5:20 PM
Uh huh... ------------- Support the12volt.com
Posted By: dukesrebelyell
Date Posted: July 31, 2010 at 4:41 PM
my wipers and windshield were bouncing also, i only have two subs alsoand one amp. i have two hcca 12.4's and a hifonics 4000.1. i think im at like 130db, maybe, possibly...
Posted By: soundnsecurity
Date Posted: July 31, 2010 at 7:48 PM
and i can bounce a cell phone off of my roof, but it doesn't necessarily have anything to do with how loud your subs are. and cheap vehicles usually flex more than others. my ranger looks like its about to fall apart when my 18 hits and i'm seriously waiting for my back window to fall out into the bed, but i only hit a 143. the fact that your car flexes actually takes away from the overall loudness unless ofcourse you hit the resonant frequency of your interior.
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Posted By: haemphyst
Date Posted: August 01, 2010 at 2:23 PM
Chassis and body flex indicate loss. The stiffer all those parts are the more SPL you will get/have inside the car.
Additionally, the line driver is a bad suggestion. All it will do is add distortion, and likely drive your amp WAY into clipping, potentially damaging your woofers. Don't go there, ever. It is NEVER necessary to use a line driver in a daily driver. Your deck will drive that amp as far as it will ever need to go.
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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: haemphyst
Date Posted: August 01, 2010 at 5:37 PM
I was unable to find any efficiency numbers for those woofers, Eclipse seems to be very NOT proud of that particular spec... (It does not surprise me, they've always been VERY low numbers.)
Based on all of the other specs I have seen, I would be very surprised if they exceed 87dB or MAYBE 90dB. I am actually inclined to believe that they are FAR more typical of the Eclipse woofers, and exhibit abysmal efficiencies... I would not be at all surprised to see them hover down around 83-84dB
Starting with 90dB, two woofers in parallel, we have a reference level of 96dB. For every doubling of power, you gain 3dB. Let's do the math...
2, 4, 8, 16, 32, 64, 128, 256, 512.
That is eight whole doublings of power, and a little bit.
8 X 3 = 24
96 + 24 = 120.
120 + 6 (cabin gain, at best) = 126dB
I have given EVERY benefit to these formulae, I personally think you'll probably JUST hit 120dB... Realistically, you really shouldn't think you'll get as far as 125.
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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: i am an idiot
Date Posted: August 01, 2010 at 6:25 PM
Gman keep us posted. Curious to see what it actually does. If your woofers are firing to the rear of your trunk, put me down for 130. Woofers firing forward, 127. Let us know.
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