How do I get my system louder?

Posted on 27. Jul, 2009 by in Industry News

One of the greatest tools in the audiophile toolbox is math. What? Math sucks you say. Well I say get your calculators out and start working your brain. This will be fun, honest.

In retail, chat forums and lunch rooms across the country the single most common questions are “how do I get my system louder” or “how loud will these subs be”. I can personally guarantee you that you ask ten people this question, including the guys at the stereo shop, you will get 13 different answers and none of them will be basing their answers on facts. They simply do not know how it works. There are some basic physics at work here.

Volume, which is measured in decibels (expressed by dB), is a function of power, cone area, enclosure design, and transfer function. Oh, you knew that already? Ok, sure that last statement might seem a little obvious, but undestanding how they interact togethr is critical to calculating volume. That’s right, you can calculate exactly how loud you system will be. Enough BS, here is the worksheet. You won’t find this anywhere else, send your friends.

This formula requires a few specs. First, you need the sensitivity of the sub(s). This listed on the woofer spec sheet in dB. It is sometimes notated as the SPL of the sub. Next, you need to know how much power your amp puts out. An amp birth-sheet (usually included in the box) will have the actual power the amp displayed when it was tested at the factory. Not all amps come with these. If you do not have such a sheet, you can use the power ratings, or even better, you can test it yourself (that is whole other enchilada and we will get into that another time). Other specs you need are more simple- what type of car do you have- truck, hatchback, or sedan; and what kind of box is it installed in. The enclosure will make a big difference, if it is a crappy home-built box with lots of leaks, held together with carpet and liquid nails, it probably won’t function as well as a professionally-built enclosure (like the Q-Logic pre-fab enclosures- shameless plug) and how many woofers you have. Have fun.

Sensitivity =

Every time the cone area doubles, the output of the system increases by 3 dB, which is relative to a doubling of volume. If you have 4 subs, you would add 9 dB to the sensitivity rating of the subwoofers.

add 3 dB per doubling of cone area

i.e. 2 subs, 3 dB, 4 subs, 6 dB

Let’s consider sub sensitivity, with 3 dB per sub added and calculate the SPL. Each time the output power (wattage) of the amplifier doubles, the SPL increases by 3 dB. To figure this, use the following figures.

This represent 3 dB added per doubling of power starting at 1 watt/meter SPL.

1=0

2=3

4=6

8=9

16=12

32=15

64=18

128=21

256=24

512=27

1024=30

2048=33

4096=36

8192=39

Next we add in Transfer Function

add 12 dB for a standard car/truck

add 16 dB for a hatchback car

Now we figure in box type

For a sealed box, 0 dB, sealed offers no dB gain.

For a ported box, 3-9 dB depending on tuning frequency and air ripple. The higher the ripple, the more gain but at a cost of sound quality.

For a bandpass box, 6-12 dB again depending on the tune freq. and ripple.

For example, a 12″ Rockford Fosgate subwoofer has a sensitivity of 86 db at 1 watt/1 meter, and is capable of handling 300 watts.The sub is installed in a ported enclosure, so we are going to use a the lower output rate for the ported box at 3 dB. Powering the subwoofer is a Rockford Fosgate Punch 300-1, which is rated at 300 watts to a single 4-ohm load. All of this is installed in a 2006 Honda Civic Si, which is a hatchback and gets a boost from the 16 dB transfer function. Using the formula, we get the following results-

86+ 24 (at 256 watts, it is close, but you could add in an extra dB if you want) + 16 (trans function) + 3 (box gain) = 129 dB estimated output. This estimation will be within +\- 3 dB of the measured output. This is simple physics, and it works.

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66 Responses to “How do I get my system louder?”

  1. norman

    13. Sep, 2009

    hello I have a single 12″ bandpass box with a alpine swe-1242 sub.is this encloser good for my sub.my amp is a profile california ca 400m

  2. JeffersonBryant

    13. Sep, 2009

    The Alpine SW-1242 is a great subwoofer. While the typical enclosure for this sub is a type 1 or 2, a bandpass enclosure will get you the most boom for your money. If you just want big boom and don’t really care about tonal accuracy or muscality, then it will get you there. The 1242 is not designed for a ported enclosure, so you are limited to a sealed enclosure or bandpass for that one. While you will lose some bass (to the tune of about 6 db), the Alpine subwoofer is more of a sound quality sub versus SPL, and a sealed enclosure will sound better. Good Luck with your system. Send us a pic and we will put it up with you comments.

  3. Curtis

    19. Oct, 2009

    hi…

    Im starting my first system and i do want some spl in there but i dont have enough money for 18s or 22s, so (to some people this might be sad but i got 2 12s from wallmart and a 200 watt peak 85 watts rms amp. the subs are VR3 VSW120, 400 watts peak and 50 watts rms. they recommend a seald enclosure but i want to try ported with them but i fiqured i would ask someone about enclosure types and tuneing freq.s. i have a 95 jeep grand cherokee if that helps any. also i have designed and built some ported enclosures for 8s and they turned out pretty good. i use 3/4 inch MDF seald with wood glue, culking and screws, L port instead of round or tube.

    thanks….

  4. JeffersonBryant

    21. Oct, 2009

    Curtis,
    Hey, we all have to start somewhere! My first system consisted of a set of Pioneer 10″ subs from Sears, a pioneer tape deck and a Jensen amp, so I am right there with ya. As far your subwoofers, the only info I could find was basic installation directions, there were no specs. Without specs, it would be hard to build the perfect box, but I would suggest a ported enclosure. The nice thing about a ported enclosure is that it can be tuned to match the subwoofer, so once you upgrade to better subs, you can keep the same enclosure, as long as they are same size.

  5. barry

    15. Nov, 2009

    Hi Jefferson,

    I am getting two Kenwood KFC-W3012 subwoofers and Kenwood KAC-8104D 100 w amp. I am considering Scosche SEV122 ported dual or Atrend E12Dsv B Box Series 12-Inch Dual Vented Enclosure with Shared Chamber and even a simple Atrend E12D B Box Series 12-Inch Dual Sealed Bass Boxes. What would you do? I am a newbe.

    Thank.
    Barry

  6. Jefferson Bryant

    16. Nov, 2009

    Barry,
    I am a big fan of Kenwood gear, I used to compete in DB Drags with Kenwood back in the day. The 3012 is good sub, and with a dB rating of 86, with two subs and a ported box you will be looking at about 134 dB with that amplifier in a typical car or truck, if you have a hatchback, it will be even louder. 134 is dang loud. While the Atrend looks good, I can’t find any specs on the volume. That is a key part of the equation. Personally, I would go for an enclosure that you knew had the right internal volume, like the Q-logic dual 12″ Type 2 vented enclosure. This enclosure is spec’d at 1.5 cu ft per sub, which is the recommended vented spec for those subs. It would sound really good. If you want volume, go for the ported enclosure. I rarely run a sealed enclosure unless I either have no room for the added airspace OR it is for an SQ only system (even then I can still get loud). But I like the big boom, and its your call. Either way, have fun with it. Good Luck!

  7. Brandon

    17. Nov, 2009

    Jefferson,

    With a rockford P1000-1bd amp and two rockford P3D212 subs, what am i looking at for dB’s? And whats your recomendation on a box? I’m looking at getting a different box and would like a direction to look.

    thanks brandon

  8. andre

    19. Nov, 2009

    hey jefferson i stumble on this sight cause im building a spl system for my 1997 suburban i have 3 xplod 1300 w subs now with a 1600 power acoustic amp but im ready to but some 18″s i dont know if i should go with the four or two im not worried about the trunk space now since i have three rows of seats (just relize that.) but i seen this 01 tahoe on the net and im hooked could u give me some pointers oh yeah im upgrading everything amps,alts,battery cells and all well thanks looking forward to see what help u got if any thankx dre from south jersey!

  9. Glen

    01. Dec, 2009

    Hello Jefferson
    I am hopefully starting my first system in my 1994 S10 Blazer. I am looking at the Alpine type R 10′ sub model # SWR-1022D powered with the Alpine Mono block amp # MRP-M500. I was looking at your enclosures and wondering which should I go with. I noticed the Q Logic Type 2 QLH-10S110SV has a volume of 1.10 cu ft. the subwoofer specs call for a .5-.8 cu ft ported box. Would this box work? some people told me of the volume that the actual sub will take up. Is that important. I also noticed the type 4 enclosure QB-110.3 with a .58 cu ft volume, would that enclosure be large enough? I just don’t really know which enclosure would work properly. Any help would be greatly appreciated.
    Thank you
    Glen

  10. Glen

    02. Dec, 2009

    Hello Jefferson
    I will be setting up my first audio system with a sub in my 1994 S10 4D Blazer. I am going with the Alpine 10″ 2 OHM Type R subwoofer, Model # SWR-1022D. I will be using the Alpine Mono Amp, Model # MRP-M500. I was on the Q Logic site and saw two enclosures I am interested in. One is the type 4 QB-110.3 and the type 2 QLH-10S110SV. Which enclosure would you suggest. and is my calculated 128dB rating somewhat accurate? The suggested enclosure volume for a vented box is .5-.8 cu ft. is the type 2 box too large at 1.1 cu ft? is the type 4 too small at .58 cu ft? I have heard you must accomadate for the volume that the sub takes up. Is that true?
    Thanks
    Glen

  11. steven

    11. Dec, 2009

    i have two power acoustik mofo 12s with a stax 5500 d mono amplifier in a seal enclosure how many db should i be hitting?

  12. Miguel

    08. Jan, 2010

    Hi jefferson
    I have a 2003 F150 extended cab. i have all kicker audio. I lifted my back seat 4″ and i have 2 12″ kicker cvr subs 2ohm each. and powering them is a kicker zx750.1 i have 61/2 kicker components in the front and kicker 6×9′s in the back powering them is a kicker zx350.4. my problem is i have each sub in there seperate box a cubic foot each and they sound alright but i want the bass to hit harder. i was thinking of rebuilding my box and taking the amp out from the middle of the two boxes and making the box just one as long as the back seat and just dividing it in the middle of the box. i wanted some experties from you. will this help my subs hit the lows better and i hear boxes in trucks sound better upside down? Or do you suggest some diffrent subs? i willing to try new stuff. thanks!

  13. tim

    13. Feb, 2010

    i am getting 2 phoenix gold rsd 124 12″ competition subs and running them off a lanzar vibe 286 4000 watt 2 channel amp in a car with the back seats down so technically a hatchback? what is the decibels that i can achieve the subs are rated at 94db.

  14. Mary

    09. Mar, 2010

    i have a 97 s10 blazer with 2-15 xs15D with 2-5500 spl gorilla series amps on them. i have three batteries and my alternator has been beefed up. the specs for the enclosure says 4.5cuft per sub. i have a 9.1cuft enclosure that is ported with 4×5″ ports two for each sub. i am at a 148db on the window but i am concerned that the enclosure is what is keeping me from getting the 150db that i am after. any suggestions?

  15. Jason

    22. Mar, 2010

    Hello, I was wondering if I use a bigger box, will I get more DB for SPL woofers. I have 2 12” Orion HCCA 12.4 woofers. I wanted to fiberglass a box but im not sure if ported out of MDF is better and how big should this be? This will be going into a 05 Durango with 3rd row seat removed I have L 47.5” x H 30” W 22”. These are going to be powered by 2 HC2000 Kenitik batterys on a 250 amp alternater. Amp will be a power accoustic BAMF 5500/1. How would this sound? Thanks for your help.

  16. Rodrigo

    20. Apr, 2010

    Hi jefferson
    i just installed two re se 12″ 600rms watts each dual 4ohm. Im running them with a hifonics 1610d. the box is ported i dnt really know its turning. but i thinks its around 2.0cu ft. each of these subs are rated at 86bd. how many db you think i should be hitting? Thanks.

  17. ethan

    09. May, 2010

    i have 2 12″ vr3 vsw120 in a ported box and i was wondering what would be the best budget friendly amp to buy.

  18. Ryan

    14. Jul, 2010

    Hi Jefferson,
    I have 2 12 in. Alpine Type R subwoofers in a sealed box in the back of my 2002 Kia Spectre Gsx hatchback. I am running a 3000 watt (so I was told) Alpine amplifier to them at about 3/4 gain and 4 gauge power and ground wire. Do you think there is anything I can do to make it better or improve it if I didn’t do it correctly? And how many dB do you think I’m getting? (I don’t know the specs on box sorry) Thanks.

  19. sean

    06. Aug, 2010

    hey jeff ive got 2 new 12″ KENWOOD 3012 single 4 ohm 2010 series both are 1200w peak power and 400rms in a sealed box! but what i cant figure out is whats the best amp i can use for the least amout of money to be able to push them hard enough to where its actually worth listening too i mean i dont know how bout i had a 2700w single channel class d mono block legacy ion amp and for some reason it fried on me and i only had it for 5 days =( so what amp would you suggest???? thank you!

  20. Jeffsron

    09. Aug, 2010

    Ryan,
    If you plug in the SPL or sensitvity rating from those Alpine subs into the formula, and do the math, you will have your answer. A sealed enclosure does not give you any dB gain, but the hatchback does, so add in about 9 dB for the hatch and you should be really close to you actual overall dB. As far your gain, you should set that by turinng the head unit up until it distorts, then back it off a little. Then adjust the amp gain till the subs distort and back it off. That is your max output, don’t turn the head unit up past that point, or you will distort you gear.

  21. Jeffsron

    09. Aug, 2010

    Sean,
    The problem with Legacy is that is a pawn-shop brand, they are cheap because they use cheap parts. I would visit your local car audio shop and ask about their entry-level amps. these are usually good quality, but at a fair price, you are not paying the big-name brand. They will likely try to sell you the next-level gear, which is not a bad thing either, as the quality typically goes up with the price. Just make sure it has a good warranty and that you hear it first, and don’t buy it at a swap meet or pawn shop. You have Kenwood subs, why not get a Kenwood amp to match?

  22. dlong66

    16. Aug, 2010

    Hey guy’s thought I’d let you know what I just had installed. I have a 93 S10 4dr blazer. The radio is a Pioneer AVHP4200DVD Touch screen. I have 4 sets of the Kicker QS652 6.5″ speakers, 2 sets in the front doors, 1 set in the back doors and 1 set mounted in the upper corners of the rear of the vehicle. These are powered by a Kicker ZX850.2 amp. The subs are 2 S15L5-4 15″ Solo-Baric (dual 4 ohm) these are powered by a Kicker ZX1000.1 mono block. If there are any mistakes in any of these specs, I’m typing it straight off of my invoice so I’m just typing what I’m seeing. Anyway that’s about it. It really rocks, I’m sure I have permanent damage already. Ears have a constant ringing pretty much all the time now, but it’s the only way to listen to it right. Let me know what you think. Tuning it is a bit of a pain, like you said everybody, even every tech and salesperson at the audio shop has a different answer for everything.

  23. Cobb

    11. Oct, 2010

    Hey Jefferson, I have a set of used alpine 12e subs and the specs say they should be used with a Q-Logic Box Type: 1, 2. I did a search and came across your page. Id love any help you can offer.

    Basically I just replace car stereos and replace oem speakers with something better from the local store. Ive used the bazooka tube in my past 2 scions and wanted to do a bit more. Long story short I have been through 2 amps, added a second battery, destroyed 1 box, 2 subs and spent a lot of money. My current setup is an alpine m450 amp with 2 jbl gto 804 in a bandpass box from ebay where hte subs are angled and facing each other. Its 90% of what i want. I want to feel the beat in the steering wheel, back of the seat and floor. I can do this at the highest setting. The alpine 12 e’s can rattle the head liner, but you can see them move at an angle in videos as I have a sealed box with an angled back. I had one friend tell me I need a bigger box, another said just save hte dough for a w7. Thanks for help with my current subs, boxes and next step. PS, this is for a Hybrid, LOL.

  24. Mitchell

    25. Nov, 2010

    I have recently purchased a 12 inch mtx-tr7512-44 sub and I am looking to put it in a sealed box. MTX calls for a 1.25 cubic ft. and I am having a really hard time finding a good box with that exact volume? Does it have to be exact and if not am i better off going smaller or bigger with the box??? Any help would be nice. -thanks

  25. Luke

    31. Dec, 2010

    hi, i just bought two 12 inch subs from walmart at a rating of 250 watts and a sub at 600 watt. but i want my system to “bump” harder. how do i do this? is it a higher voltage amp? im so confused becuase this is my first system. my friend has a similar set up but his hits way harder

  26. Joe Banks

    30. Jan, 2011

    Hi I just took out my 12″ kicker cvrs out a sealed box running to a mono block 1500 watt Hifonics amp and replaced the sealed box with a ported box. Since the change i hardly have any bass. I have the subs running parallel. Are these speakers better in a sealed box or ported? And if ported how should I wire them to get better bass than in a sealed box? Thanks for any advice you can give me.

  27. Candy Aceveda

    04. Feb, 2011

    Simply wanna admit that this is handy , Thanks for taking your time to write this.

  28. Blake

    11. Feb, 2011

    Hi jefferson,

    Im working on an old system with 2 KFC-W3900′s

    They are curently in a verry large bandpass box CFT unknown.

    Manufacture reccomends 1.5cft each sub with a small ported enclosure..

    Everyone keeps telling me its too small and a larger 2.0 or more would be best.

    I really like to feel the bass more then anything.

    Whats my best course with these subs.

    Thanks!

  29. cory

    12. Feb, 2011

    I really like this site… I have two rf punch 1k watt. Only using one on a sony 1k amp using both channels because it seems to increase the drive.. the sub is in a little walmart box… I am deff for sure upgrading the box… ill give specs soon but I wanna make sure this thread is still active.. someone with knowledge dealing in subs and systems plz respond.. we can txt or w.e. with questions I have.. I am notin rush to do everything cause I want it done right but want it done by me.. just got a lot of small questions.

  30. Matt

    03. Jun, 2011

    i am so confused on where you got the 24 in your formula if someone could help me that would be Great!!!

  31. kevin

    22. Aug, 2011

    hi i got 3 subs…2 is q power 12s in a bandpass box 1400 watts for both and a rockford fosgate p1 punch in a sealed box and i got a pioneer 760 watt amp whats the dbs i would be lookin at?…and there in a 2004 chevy malibu…thanks alot

  32. Storm

    22. Oct, 2011

    Jefferson,

    I have 2 15” kicker solo barrack L5s in the back of a ’99 Jeep Grand Cherokee and a 6000 watt Lanzar Vector 2 channel amp and I was wondering what type of box I should build and how much air space I should have.

    Thanks, Storm

  33. Pirasanna

    02. Nov, 2011

    hey, i got 2 type x’s..12″..@ 4 ohms…im still having a hard time figuring the math. i got a 2003 hatchback mitsubishi eclipse…would you be able to tell me whats the perfect box for me? thanks

  34. Zach

    11. Nov, 2011

    I have a Kenwood kfc-w3012 and a Rockwood PA-2080 450 watt amp on a ported box. I dont know the specs on the box but its in a 99 durango

  35. Richie

    14. Nov, 2011

    Hey Jefferson, I have a 1997 Chevy Camaro that I have been trying to put a loud system in. I have to custom sealed box that goes into the well and stuffed it with polyfill. Ive had so many different woofers in there everything from L7s to P1s. My question is what two 12s would get me the loudest and how many watts could I run cleanly off my stock battery and alternator. I have 0 gauge wire. Any suggestion will help. Thanks.

  36. corey

    21. Nov, 2011

    hey jefferson my name is corey and i have four phenix gold r3 12′s with a sealed box, an apline 2000.d. amp a 1200 watt kenetic battery and 4 gau/ge wire. how if possible can i make my system any louder? its hitting 149 db but amp aint up that much do you think my speakers can handle or give me advice how to make it louder? thank you

  37. Paul

    27. Dec, 2011

    Hey Jefferson, i just bought a Kenwood kfc 3013 and a Kenwood 8105D. I am going to be putting this in a Chrysler cirrus and have a question before i build the box. Crutchfield and a few others say this sub is best in a sealed 1.25 cu ft box but i usually prefer ported. What would you recommend for this set up?

  38. johnny

    25. Jan, 2012

    i am gettin 4, T3 audio T400 12s4 400watts @ 4 ohmo. ok so what i need to know is what type of amp do i need and how many. what type of box. this is my first one so i dont know that much about how to match every thing up.

  39. amos

    08. Feb, 2012

    i have a sound storm (SSL) f3600d amp pushing 2 12′ pioneer premier ts-w3002d2 subwoofers in a ported box of about 2.5 cf in a geo metro hatchback what db would i get with that about

  40. amos

    09. Feb, 2012

    well the box is 3cubic feet and amp pushing out 1800 rms at mono block

  41. Devin

    13. Feb, 2012

    Hello, i have a power acoustik 15 inch mofo wired down to 1 ohm on a hifonics brutus 2000d amp so ill be putting about 1700 watts to it at 1 ohm, i think the sensitivity rating on the sub is 86. it will be in a competition spl enclosure with an areo port extending from the box tuned to 40 hertz. how many dbs do you think it will hit?

  42. cory fender

    11. Apr, 2012

    Hello im having troubl i have 3 12inch kicker comp subs and a punch 800 amp and a 2000 alpine amp in a sealed box in a suv what do i do to get the most out of it it just dont sound the way i think it should please help me out

  43. cory fender

    11. Apr, 2012

    hello could anyone tell me how to get the most out of 3 12inch subs in a seald box in a suv? it dont sound the way i think it should i want more bass the kind that take your breath away wene you sit in the car lol

  44. John

    20. Apr, 2012

    I have two Kicker comp 10s in a 1999 ford windstar van. I built a costom box, (and took my time at it, well built no leaks) to spec for the largest air space that they could handle (Portted box). They are on a 1000 watt max sony Xplode amp (only half way up). Is there anything else I can do for more dB from this set-up? It alredy shakes every mirror to the point that you cant see out of it.

  45. Aaron Duke

    06. Jul, 2012

    Hey Jefferson, i have 2 Kicker L5′s in a fairly large ported box being pushed by a 1000 watt mtx d class amp. Each sub can hold 600 rms, and they are connected with a pretty large gauge of wire. how many db’s can i get? ph, and im in a smallish SUV

  46. cristian garcia

    10. Oct, 2012

    i have 2 12″ Mmephis w/ a 600w Punch amp what do you think about those ?

  47. Clay

    10. Oct, 2012

    Hi i have 2 10 inch fosgate punchs (p-2′s) hooked up to a 1200 watt kenwood is that to much amp for two tens or what

  48. Brandon Pike

    16. Oct, 2012

    I have 4 12′s being pushed by a rockfordfosgate t10001bd at 1 ohm. Recently i went to a spl event and hit 140.4 db on the dash. I am throwing around the idea of adding 4 more 12′s making a total of 8. In a perfect world i would gain 3db. My question to you is if i get 4 more 12′s and a identical t10001bd, will i gain 3 db or 6 db based on the fact that i would be 2000 watts total instead of 1000w total? or am i just dreaming since every sub will be driven by 1000w? thank you

  49. By tryi

    01. Nov, 2012

    I have a 2000 corvette with 2 15′ kicker cvr subwoofers being pushed with 2 Kicker DX 1000.1 amplifiers. I also have an Alpine head unit. I just want to say that this thing is awesome!!!! (Can’t stay in the car!!!!!)

  50. rigo

    04. Nov, 2012

    hey i got 2 12″ alpine type r on a sealed box and a 1100 watt amp and the amp is also alpine what do u guys think about it should i get a ported box or bigger amp….. also its on a 1987 firebird

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