When will doubling the power really add 3dB?

[SPL140.2 5,000+ posts]

So would you rec 1 12" sealed in my hatch? (Jeep GC)

I recommended that for HIS setup //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif honestly i wouldnt recommend any sealed enclosure im not into sq lol

 

[SPL140.2 5,000+ posts]

If you were to compare 1 sub at 800w vs. 2 subs at 400w each, you will get close to a 3db increase in output with the 2 sub setup. Remember, doubling power gets you 3db increase. Doubling cone area (and of course adding same power to the 2nd sub) results in a 6db increase. This results in twice the displacement. It takes 4 times the power to double excursion (or displacement), so if you wanted a 6db increase in output with one sub, you would need to quadruple the power (assuming no losses from power compression).

hmmnn not in my tests,

1 sub



2 subs



1 sub had the same amount of power as the test with 2 subs splitting the power //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif it did gain some but not as much as your speaking of. BTW, didnt reach the power compression yet, yet to find it lol maybe within the next week or so //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[dipitydoo 10+ year member]

Under ideal conditions, it should be 3db gain. At that spl level, there are factors that may be contributing to the reduction in gain, such as cabin leakage. At a certain point, it becomes more difficult to get incremental gains in spl.

 

[SPL140.2 5,000+ posts]

Under ideal conditions, it should be 3db gain. At that spl level, there are factors that may be contributing to the reduction in gain, such as cabin leakage. At a certain point, it becomes more difficult to get incremental gains in spl.

even at moderate power levels the 1 sub are just as loud to the ear as both running, get em on the meter and its a slight difference //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[jeremiah 10+ year member]

so if your sub is at 1/2 excursion by tripling the power you should See a big gain in SPL right?

 

[newusername 10+ year member]

When I have no idea or have nothing to contribute, I just hit refresh. Cotjones has to cause a scene and scew up an otherwise useful thread.
What I want to know is how you can install to control DC Re, BL, and Cms (the factors in power compression)

I think before I can begin to "control" it, I must 1st learn how these characteristics work together (or not), and to ensure one does to reverse the other. (Such as building to make BL more linear makes DC Re increase)

Haev a look around SSA. I'm fairly sure that I've covered it in some respects, either in an entire thread or piece-meal through a few different posts. I'll try and summarize quickly here...

Cms: Progressive spiders. This is one of the easier ones to solve (within reason) by carefully designing the spider geometry and positioning. The surround has a little bit to do with this, but the spider is the predominant factor here. However, over huge stroke (like 40-50mm plus), it becomes a little more challenging. Remember, it's just a treated piece of cloth.

BL: Utilization of linear BL gap treatments can easily solve this. Of course, treatments like LMT, for example, require substantially longer voice coils due to the increased number of windings, which causes an increase in DC resistance, but that factor is not really power compression, perse.

Thermal: This is a challenging one to overcome. It doesn't take long to double DC Re, which doubles Qes, which doubles Qts...I think you see the pattern here. This can be limited by utilization of larger voice coils (both in diameter and length, but more importantly, in surface area), various cooling treatments in the motor (see DD or Fi), or by using different materials.

With all of them, it takes careful planning to steer clear. However, if you can stay away from Cms and BL power compression, you're in great shape. They are the big contributors to distortion (BL ~60% and Cms ~30%) and are very dynamic and immediate in nature. Whereas thermal power compression begins maybe 10-15 seconds into play and can remain fairly constant at a given power input, BL and Cms compression occur on every single stroke. So if you play a 50 Hz note (50 cycles with movement in the forward and rearward direction), you encounter BL and Cms compression 100 times in one second! Obviously overcoming these two are the most critical components of the three.

 

[audioholic 5,000+ posts]

At least CotJones is trying to learn, and admitting when he realizes he is wrong. He's alot better than when he first came here. Cut the guy some slack gentlemen.

 

[SPL140.2 5,000+ posts]

so if your sub is at 1/2 excursion by tripling the power you should See a big gain in SPL right?

depends upon the subs and vehicle..... a sub with tons of excursion doesnt always mean its gonna be louder.

 

[cotjones 10+ year member]

At least CotJones is trying to learn, and admitting when he realizes he is wrong. He's alot better than when he first came here. Cut the guy some slack gentlemen.

hey thanks! really decent of you!//content.invisioncic.com/y282845/emoticons/thumbsupwink.gif.129404938effda6ad9cca39e7f4b58a3.gif

 

[phantom240 5,000+ posts]

At least CotJones is trying to learn, and admitting when he realizes he is wrong. He's alot better than when he first came here. Cut the guy some slack gentlemen.

Indeed. But instead of stating his previous posts as facts, he should have asked them in question form. That way the more experienced members who know whether what he asked was correct or not can tell him so.

But eh, he's not being blatantly stupid like he used to. So w00t for that.

 

[ghart999 10+ year member]

Great thread all. Appreciate the input. I think I will add the extra 1000 watts and see if the diff is worth it. If not, I will sell the amp.

 

[cotjones 10+ year member]

Indeed. But instead of stating his previous posts as facts, he should have asked them in question form. That way the more experienced members who know whether what he asked was correct or not can tell him so.
But eh, he's not being blatantly stupid like he used to. So w00t for that.

i wouldn't present them as facts except i thought they were and i was mistaken...

i got on this forum with knowledge (even if it was incorrect) which i believed to be true...

but i am only learning, its kinda like... what i know is what i believe till i'm proven wrong...

i am learning pretty fast because of it too...

i'd wager that i've learned alot more in the last month than alot of people do in a year.

the down side is when the incorrect knowledge i have is so rediculous i look stupid till i know better...

but i am not the same CA idiot i was when i first got on here, as alot of people on here try to think

 

[casper97ta 10+ year member]

i wouldn't present them as facts except i thought they were and i was mistaken...
i got on this forum with knowledge (even if it was incorrect) which i believed to be true...

but i am only learning, its kinda like... what i know is what i believe till i'm proven wrong...

i am learning pretty fast because of it too...

i'd wager that i've learned alot more in the last month than alot of people do in a year.

the down side is when the incorrect knowledge i have is so rediculous i look stupid till i know better...

but i am not the same CA idiot i was when i first got on here, as alot of people on here try to think

X10000 on this. ^^^. I think you've come a long way and have actually proven that in the last month or so. Thats what this forum is supposed to be for. And just for that, I think I'll take my Cotjones sig quote out.//content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif . Good luck with the new setup.

 

[sku 10+ year member]

I don't know if it's been mentioned but frequency is a factor as well.

Excursion increases 2 or 4 times for every halving of the octave? Can't remember exactly...i.e. maintaining the same db level at 40 hz vs. 80 hz will require more excursion...

So depending on the frequency and if you're already near the limits of the sub...adding more power may or may not gain...

Do you have a friend with a big amp? You can easily run a test before spending money on more power..