1. ## Why is it so hard to get loud?

If you have one sub that does 135 on a meter and you add a second sub in the same identical setup why wont you hit 270db? (Even though I know it is physically impossible.) But hopefully you guys will get what i mean by that. What factors come into play when trying to gain a couple of DB's on the meter at a time over 145.XX....Just wondering what peoples opinions are.

2. ## Re: Why is it so hard to get loud?

Well, there are a lot of factors involved, nearly every single factor to be exact. You have limitations that are one of the major factors. The others would be driver excursion, power handling, and surface area. The average gain in dB you will recieve nominally from an added enclosure is around 3-5dB. Why is this? To simplify it as much as I can, the compression has a lot to do with it as well as coupling the subs to the box using compression ratios, though some say ratios do not exist....they do. Simply by matching the drivers ability to reproduce the output using an enclosure, the physical compression ratio between one enclosure and another the same size added is closer to 1:1 than you think. And since compression/expansion of the drivers cone creates pressure, if the ratio was less than 1:1 for box to drivers acoustical compression volume, then output normally increases, but this is limited by physical factors mentioned above, not to mention the ability to create backpressure if the design allows it to happen.

Now, going back to the actual question, why is it so hard....is because of electrical/acoustical relation to sound pressure and power. Due to Ohms law, the factors of resistance, current, and voltage are limited to the circuit they are connected to. And it is all about matching the impedance of the subs to the amplifier that gives you the easiest and cheapest way to increase output. But on average, again due to Ohms Law and factors of power in relation to electrical current, you have to nearly double the amount of power to create that same 3dB increase as adding another enclosure. not to mention if the drivers sensitivity is low, the output will suffer. So, matching sub configuration impedance, finding drivers with high sensitivity, high power ratings, and great amount of linear excursion, you will get good results, but limited still by the power factor.
Take this for example: You have a driver that is rated at 90dB sensitivity. The enclosure will add the efficiency and acoustical means of gaining output to that 90dB. And that is based on the designs ability to couple the impedance, control the driver, and placement, and well many many things, but lets take a single frequency, like a burst for example (trying my hardest to keep it simple...it gets very very complicated normally), and feed it power. Now using Ohms law, You figure for lets say its 4 ohms resistance, and you have measured a voltage of 28V, and lets say that is the most your amp will put out as is. So, taking 28V, and resistance, you can figure for power. P=V^2/R. So, 28*28, then divide by 4. You get 196 watts. And to keep it REALLY simple, I will not show the calculations to figure for dB output, lol. But lets say it was measured at 110dB. Now, the dB increase from 90dB to 110dB is 20dB. That is a great increase. Now, to get 113dB (nominally), you would need around 392Watts of power (twice of the 28V power). But voltage does not increase at the same rate as power. But continuing with this, Lets say you want to try to get to 140dB with this particular design. Now, figuring for how many times it takes using 3dB increases, we can figure for power requirements. So, from 113dB to 140dB is alittle less than 10X the 3dB increases. So, we were at 392 watts, now for another 3dB, you need twice the power (I hope you see already where this is going). So, take 392 watts, double it 9 X. You will get more than 200K Watts! Now, the question is not can you get that much power, but can you utilize it with the drivers power level ratings and excursion limitations( that would be a no by the way)? That is why it is so hard to acomplish because the higher the dB levels increase, the more power it will take in relation to the 2X increase in power. So, to get 160dB from this, you will need way over 25M watts of power. Wow right?
So, what we do in order to balance this, is design around efficiency and coupling to get as much dB out of it at 2.83V as possbile before any more power is added. Then you can figure for everything else until one factor is fully limited.

3. ## Re: Why is it so hard to get loud?

i was going to reply to this... but after mobile's reply... i kinda feel like i'm on old school... debating will ferrel... "i have no rebuttal, that was, uh... perfect" haha

4. ## Re: Why is it so hard to get loud?

It's not hard to get loud if you have \$\$\$

5. ## Re: Why is it so hard to get loud?

To simplify it: physics come into play. Its like asking, if I can lift 100 lbs with one arm.. why cant I lift 300 with both? Thats oversimplification, but it gets the idea across.
But say you add straps or youve had some caffeine, you may be able to do that 150 per arm.. thats where enclosure, vehicle, etc come into play

6. ## Re: Why is it so hard to get loud?

alright well mobile knocked this one into Steven hawkins front yard and surreal was talking weight lifting lol just playing surreal..

Sound Decibels aren't 1 is 1 and 2 is 2 times whatever made 1.. its not that simple.. every 3 dbs is a doubling of sound if I remember correctly.. been a while since I looked at it.. In a PERFECT world doubling power and cone area.. Basically doubling your current setup would gain you 3 dbs.. Now then that is in a perfect world where all variables lined up perfectly..

7. ## Re: Why is it so hard to get loud?

Last time I checked it really hard to achieve silence too. Lol. Or maybe I just need a luxury car

8. ## Re: Why is it so hard to get loud?

A lot of time and money. Headaches. More money. Build. Rebuild. Test. And more testing More rebuilding. More testing. And so on. It never ends

9. ## Re: Why is it so hard to get loud?

Originally Posted by mylows10
Slot of time money. Headaches. More money. Build. Rebuild. Test. And more testing More rebuilding. More testing. And so on
this..
the initial getting loud is simple.. its once you find your vehicles POVR(point of vanishing returns) where it gets expensive and takes a while.. Throwing in the biggest box/sub power you can is the easy part.. its the getting louder than that, that takes a while.. you may fit 9 cubes and 2 15s and get 150.. but it might be 4 cubes and 2 12s off more power that is what gets louder.. its all testing

11. ## Re: Why is it so hard to get loud?

I haz major headache from this...

12. ## Re: Why is it so hard to get loud?

Its not that hard to get louder, lots more money sure. I went from a 135db @36hz with 4 12's in a sealed 6cft with almost 5k watts to a 153.6db at 36hz with 4 15's ported at 20cft and 10k watts. Basically double and gained way more than 3db. There are other factors that apply but not really relevant.
Also I'm no expert on this matter, just stating my experience with what I did.
Russ

13. ## Re: Why is it so hard to get loud?

Originally Posted by manyhobbies
Its not that hard to get louder, lots more money sure. I went from a 135db @36hz with 4 12's in a sealed 6cft with almost 5k watts to a 153.6db at 36hz with 4 15's ported at 20cft and 10k watts. Basically double and gained way more than 3db. There are other factors that apply but not really relevant.
Also I'm no expert on this matter, just stating my experience with what I did.
Russ
That's a really low number. No offence meant just, wow. I hit 138.9 db a while back with 2 12's in a .8 cu ft sealed box (per chamber) with ~600 Wrms.

You probably had some enclosure design errors in first build along with other problems. Typically if you had all same equipment and add another of same amp you can gain ~3db. If you had a setup with 1 15 and add another 15 you can see ~3db. Take that same setup that you just gained 3db with and add another 2 15's to that same setup you can see another ~3db. This is very generally speaking. The 3db increase can be accurate based of how you go about adding the equipment to the occasion. So you can 3db gains in cases and not see 3db in other cases depends how you go about your next setup versus the previous and etc.

This was that setup in the Firebird..

14. ## Re: Why is it so hard to get loud?

I'm not reading these long post so it may be a repost but...
3db (the increase of adding double the power or double the piston) is twice the acoustical energy. For the human ear to perceive it as twice as loud you need 10 decibels. The reason you do not get a 100% 3db increase is all down to your cabin.

15. ## Re: Why is it so hard to get loud?

Originally Posted by wenn_du_weinst
I'm not reading these long post so it may be a repost but...
3db (the increase of adding double the power or double the piston) is twice the acoustical energy. For the human ear to perceive it as twice as loud you need 10 decibels. The reason you do not get a 100% 3db increase is all down to your cabin.
I forgot to mention that..

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