rough figure for db’s of my setup

I have a 94 gmc sierra ext. cab and I am thinking of running 4- 10 inch MTX 8000's single voice coils wired in a 2 ohm load and pushed by kicker kx800.2 amp, was wandering of about or any idea of the db's that might come out of this?

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live in your world, come play in mine

any where from 0-135 would be a rough figure    Its impossible to give you a close estimate.

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2003 Chevy Avalanche,Eclipse CD7000,Morel Elate 5,Adire Extremis,Alpine PDX-4.150, 15" TC-3000, 2 Alpine PDX-1.1000, 470Amp HO Alt.

Ditto to the "impossible to tell" comment from Alpine Guy.  But before you hook up your system and start trying to hit ANY db number, realize a couple of things: That Kicker amp cannot be bridged into a single 2-ohm load.  It is only capable of sustaining a 4-ohm load when bridged.  Also, the SVC MTX 8000 series is a 4-ohm speaker, so you cannot connect 4 of them togehter to achieve a 2-ohm net load.

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Actually, guys, it IS possible to tell a rough estimate of how loud he will get.

1: Take the efficiency specification of the driver in dB/1w/1m. Call that number X
2: Add 6 (because there are 4 drivers) X+6=Y
3: Starting with 4 (1 watt per driver) count how many steps it takes to get to 400 (which AFAICT is the 4 ohm bridged power of this amp) Call that number N
4: Take that number, multiply by 3 N*3=Z
5: Add that number (Z) to Y

Example:
X=90
X+6=Y=96
4,8,16,32,64,128,256 (The remaining 128 watts available from the amp will add about 1.5 dB) 7 doublings * 3dB per doubling = Z = 21dB additional output.
96+21=117 dB, give or take a couple.

Alpine Guy, you ARE correct, it IS between 0 and 135dB, but I think shane7643701 was looking for something a little closer... I just wanted to show that it is possible, given at a minimum, the number of drivers, the amplifier power, and the efficiency of the driver, you CAN indeed get an estimate of the system output. I do want to mention, though, these ARE anechoic numbers, and the cabin gain (and cabin gain IS dependent on the cabin, obviously) can add as much as 12dB at various frequencies, but NOT across the board.

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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."

Ok, here is the problem with your formula. First, it is correct for home audio where you are dealing with sound waves, but in cars you deal with sound pressure (notice why soundoffs are called SPL not DBL), but since you know the formulas you should know this already. Out in the open or in a warehouse these formulas would probably work rather well to get an estimate. Also, we have no idea what kind of box he has the subs in, which will affect the sensitivity of the sub greatly (remember that sensitivity is done in a warehouse, free air, with a mic that is 1 meter away with 1 watt of power). The sensitivity of the sub is a rather useless number unless you are going for sq+. This is just my 2 cents from experience.

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Certified Security Specialist
Always check info with a digital multimeter.
I promise to be good.
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I've been sick lately, sorry I won't be on much.

ALL SPEAKERS MAKE SOUND WAVES. Sound in measured in SPL WHEREVER you measure it. Yes you DO deal with sound pressure, but in the home (or warehouse or wherever) you also deal with sound pressure, WHEN THE WAVELENGTH IS LONGER THAN THE ROOM... it is still sound! (I think you are getting confused between sound and sound pressure... they ARE the same thing) The same rule applies in the car, this is called room (or, in the car, CABIN gain). The numbers above, are (yes, I admit, I should have specified the TYPE of enclosure) for a sealed enclosure. Add 3 dB for a vented enclosure, or 6dB for a bandpass enclosure, but also remember that when you vent a small (required for automotive use, because of the physical limitations of the CAR) you will sacrifice low frequency extension for output. Ya canno' change the laws o' physics! You will also notice that I did refer to cabin gain, and I also mentioned that cabin gain is not a uniform boost across the spectrum. It will be based on the HARMONICS of the cabin. Smaller cabins, such as trucks, will enhance higher frequencies, and larger cabins, such as an Explorer or the like, will enhance lower frequencies. Also, most manufacturers base their sensitivity ratings on the Theil-Small parameters of the driver (mathematically derived, based on MMS, BL, and other parameters that are relatively fixed values), they do not put the driver in a box, and test it - they can't, because of the tens of thousands of drivers they make, and I can tell you this is true, because I have measured literally hundreds of drivers, and VERY few ended up being right on the mfr. spec. for efficiency. It actually comes closer to an infinite baffle sensitivity, also. The spec will change, based on the tolerances allowed in the manufacturing process, usually + or - 10 percent. More expensive drivers will usually use higher tolerance parts, and therefore come closer to mfr spec.

I really am curious, what makes you believe that a woofer does something different in an automotive environment than in a home environment? All loudspeakers, from tweeters to woofers, to full range drivers, are electromechanical devices that do nothing more than excite air molecules in a compression/rarifaction pattern, based on the frequency being reproduced. It does not matter where it is measured, as long as you allow for room gain. You will get the output of the driver. The space (distance) between the wave (the outward movement of the cone - high pressure) and the trough (the inward movement of the cone - low pressure) is called the wavelength, and it is the same in a car as it is in a non-moving rigidly placed building. The room (or cabin - interchangeable, both verbally and physically) has an effect on SOME of the frequencies more than it does on others. These are called standing waves, and you can figure these as well, AND say how much the gain will be at a given frequency, as well as the harmonics of that peak frequency, with relative precision.

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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."

Oh, and efficiency has NOTHING to do with whether a driver will be an SQ driver or a high output (I do not want to say SPL) driver in a perticular application. I have seen extremely inefficient driver simply BLAST with enough power, and I have seen very efficient drivers sound simply PHENOMENAL. I have also seen extremely inefficient drivers sound like CRAP, and very efficient drivers not play as loud as one would expect, because they cannot handle any power to speak of. Play around with Tractrix horns and transmission-line enclosures, before you say something like "efficiency is a useless number except for SQ drivers"...

Sorry for the tone... sometimes I get a little passionate about my audio, AND my actual schooling in the audio world, as well as my years of hands-on experience. I admit I do not know everything, but I am quite knowledgeable in what I do know, and I am always looking to learn more.

I do know that if Steven Kephart is reading any of these posts, he will correct me, and I hope that he does.

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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."

 This may have just been covered in the above posts, but I have done some tests with woofer location in the vehicle (only 1 vehicle, actually- a 1994 Buick Regal. A pretty avererage sized car) and we found that if using two woofers in seperate boxes, placing them at the rear of the trunk w/ 1 on each side behind the tire wells gave us the highest output on the db meter (I know there's a proper name for it but it escapes me right now). Even having two subs in one box, measuring with the box all the way towards the back of the car yeilded  1.2 db higher than when the box was pushed all the way towards the front of the car (but still in the trunk.)  This is supposed to be because of the way the sound waves bounce off of the solid panels of the car and the distance they must travel before they get to your ear (or the mic.) Someone else will be better at explaining the specifics of this theory.   I am currently using a q logic box under the driver side rear set of my 97 ext cab chev. I have tried having the box in every nook and crannie in every possible position, and have found that spot to be the best. Obviously when using 4 subs you have a lot less options as to placement.

So anyways- If this is what haemphyst was referring to as "cabin gain", then I just typed my fingers raw for nothing. If this is not "cabin gain", haemphyst, could you please elaborate on what it actually is? I too like to continually learn at every chance I get. 

Thanks, and hope my $.02 helps. 

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

cabin gain...

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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."

sorry, had to leave the room for a few.

Yes, this is an example of cabin gain. You get more output with the woofers closerto the back of the car, bucause the sound loads up, the same way a woofer loads up in a house when you shove it all the way in the corner, but you will always get a smoother output (in the car or the house) if you minimize the number of hard surfaces the sound waves interact with. I know, they will interact with ALL the surfaces, I am referring to loading interaction. Infinite baffle yeilds zero dB gain, an enclosure on the floor will yeild 3dB gain, in the corner of the wall/floor boundary will yeild 6dB, and in a corner on the floor will yeild 9dB, but again, these figures are not hard and fast, they will change, based on the boundary surfaces, and frequencies being reproduced.

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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."

 Thanks! Can I ask-- what classes and coursework did you take to learn all the minute details of car audio like this?  I took a basic electricity and automotive elec. classes when I was in an Auto. Technicians course 8 years ago, though I do not work with cars professionally. I love to work with car audio whenever I have time, though, and want to know all the little details and what actually makes things work and why. I have been picking up a lot since I joined this forum, but a lot of times on here the surface just gets scratched and I am still left curious about what was being talked about between other members. I live sort of in the middle of nowhere, so I don't have access to any decent tech. schools (unless I quit my job to commute full time, but it gets hard to make a house payment with no job.)

Just wondering I guess...

Thanks

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

I gotta point out 2 things. First off the 8000 are avalible in dual 4 ohm so if he has those then he can get his 2 ohm load. Second of all even if the kicker amp was 2 ohm stable its not near enough power. Those subs are pretty power hungry and since they are inevitably in a small sealed box he is gonna need more power

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double-secret reverse-osmosis speaker-cone-induced high-level interference distortion, Its a killer

We use a very similar formula, and find it a very quick way to get an spl number.  With enough use you can be close on cabin gain.  We used it when competing, helpful to verify meters, and if your compeditor was "legal".  When you get good at it, you can be within 2 dB.

well I have'nt got the subs yet , I was trying to decide on the voice coil, single or dual, also I know that one of the kicker kx800.2 is not enough power for 4 of the subs, they are 400 watts rms each, so I will probally be running 2 of them(amps) also the subs will be in a sealed enclosure under the rear seat of a 94 gmc sierra ext. cab, but here is another idea that I came up with, would it be better for me to run different subs such as alpine's rather than having to buy another amp plus my subs? And I got one more ? I temporarley have 2 12" kick comp cvr'r (dvc 400watts rms) but they wont fit all the way under my seat(looks like crap sticking out) I had this setup in my 89 camaro and the bass was hard hitting, but since I put it in my truck, the bass dont hit as hard anyone have any idea of this? oh but what I was asking is right now I have the 12's in my truck and if I bought like 4 of the alpine's which ever ones have the rms of about 800 watts toal for 4 subs and ran them would'nt I actually have better bass because of moving more air? Thanx for all the help, Is close to 135db's pretty good for daily driver? I dont enter in comps, I just love my tunes! lol

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live in your world, come play in mine

How do you gain this kind of info chevyman26, years and years of experience cough cough, oxygen mask please......and most importantly asking a questions to which someone will answer. Stephen Kephart is fairly new to the game (age wise) I would summise (sorry if I am wrong dude), but he has also lined up with a manufacturer that can teach him the proper information and how to use it as well. There should be way more people like that in this industry. There is no substitution for learning something yourself when taught by the proper person or company.

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Top Secret, I can tell you but then my wife will kill me.

shane7643701- I'm not able to accurately answer your questions as the others here are, but hey- if you find a way to fit 4 subs under your rear seat without them "sticking out and looking like crap" please let me know. No sarcasism intended here! I want to do something similar in my 97, but don't see it possible without moving the seat or having it stick out. Any new ideas would be appreciated!

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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."

chevyman26- 10's will fit under the seat, and if you make them front firing you can get 4 in there and still get the box under the seat, and the box will set right under the edge of the seat, so I dont see how this hard to understand, would you like me to build the box for you?

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live in your world, come play in mine