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Discussion Starter #1
Hello,
i've been modeling in winisd this driver in this unstandard enclosure. I've used Linkwitz transform from F0 47,25 Q0 1,06 to Fp 35 Qp 0,707 and the curve looks ok, also does SPL. I can get simmilar SPL curve results from this box with vented 12"drivers, which have quite high air vent speed at max volume, also transient response. Theoretically Ultimax 15 should sound better as it is closed box, which many consider more musical somehow.

My question is, if there are going to be any other factors to consider on sound quality. Will the 15" squeezed in such small enclosure and equalized sound in some way worse than driver that is made for smaller enclosure ? (matching spl level and curve, or lets say sinewave ), i mean if there can be some dissortion, bass flappyness or something i don't see on winisd model.
 

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You are limiting the subs potential from 40 Hz down by squeezing it into such a small box.

I don't know the exact x-max for the UM 15 so take these numbers with a grain of salt, but you will need about 1700w to hit 22mm with a sine wave. So figure at least twice that with program content.

My experience with undersized enclosures is that they sound bad, but eq will help even out the sound though you still leave a lot of performance untapped. Bottom line, it's the wrong sub for a box that size.
 

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Discussion Starter #5
You are limiting the subs potential from 40 Hz down by squeezing it into such a small box.

I don't know the exact x-max for the UM 15 so take these numbers with a grain of salt, but you will need about 1700w to hit 22mm with a sine wave. So figure at least twice that with program content.

My experience with undersized enclosures is that they sound bad, but eq will help even out the sound though you still leave a lot of performance untapped. Bottom line, it's the wrong sub for a box that size.
They sound bad how? just by not being able to play low end well? OR there is another factor? As i mentioned i added Linkwitz transform to qts 0,707 so it should play ok in this point of view. Yes in column amplifier apparent load, it goes to 1200w+ to get to cone excursion at around 20hz, would that by ok for Um-15 as it is rated 800rms-1600 peak? (not sinewave but normal content, prob movies only)

I am quite sattisfied with numbers i see in winisd, i am just concerned if there aren't any other dimensions of sound i don't see there

I chose ultimax, as i cannot get higher spl @ 20hz (the difference becomes even more apparent in higher frequencies)from other drivers, HO doesn't come even close, as it simply has only 12 vs 19 mm of excursion, neither does um-12.

If you could advice other driver that could do better than um-15, I would be thankful.
 

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They sound bad how?
It makes a peak in the upper end of response with a neutered bottom end. The result is harsh and unnatural IME. Like I said, you could correct with eq but that's the wrong approach. You end up using a lot more power which creates more heat and more compression. The right approach is to design the box to work with the driver and room so that you don't need any, or at least minimal eq.

Re: Recommend a driver? I guess I would be looking at 12's if 2 cu ft is all you can make fit. Otherwise you need a 15 with lots of motor to work in than small of a box. LMS R 15 comes to mind. Or the HO 15.

I chose ultimax, as i cannot get higher spl @ 20hz (the difference becomes even more apparent in higher frequencies)from other drivers, HO doesn't come even close, as it simply has only 12 vs 19 mm of excursion
HO 15 won't run out of excursion in 2 cu ft. You'll cook it first. It is the better choice.
 

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Alpine SWR-15 or SWS-15 comes to my mind, car subs designed for a small box. I haven't modeled either one so it may or may not work...
 

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Discussion Starter #8
I just tried modeling alpine and it does quite well
SPl vise i can get something like this (all in 50l), ultimax and alpine have linkwitz transform so they play lower, seas is 10" vented tuned to 22, just for comparison, as i think it's quite fine choice


http://postimg.org/image/66xwm165f

The max spl in previous picture is by setting singnal power, so max excursion of drivers goes a little below their respective xmax (550 ultimax, 400 alpine, 250 seas)


http://postimg.org/image/jvcq5hoed

More problematic thing might be the amplifier apparent load:


http://postimg.org/image/l7z8d5bw9

where alpine is quite fine, within its paper limit (250rms), ultimax needs 1100w+ on lower fs to get to its xmax - spl projected on first picture. Is that ok to push driver by content - not sinewave occasionally this way? I mean what % of time you get 15-25hz signal? Ultimax is 800rms-1600peak on paper

Ho15 simply cannot play that low/loud in small box, so as with the others linkwitz needed to be applied, and after that, it could took only 180w to get to excursion, and final spl wasnt competetive to other drivers. I can get similar spl with vented 12" (closed 12" didn't get even close), but they had higher vent speeds, and in general all the problems of vented box. But still i am wondering if the max spl difference is worth the fuzz, over blue line - vented seas, where no eq is needed and no highpower amp.
 

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Are you willing to put a HPF on so that movie LFE doesn't fry the driver? What amp will you use that will push enough power? Note that power compression might keep you from realizing all the modeled performance when pushing a lot of power into the driver. That said, it could work.
 

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Ho15 simply cannot play that low/loud in small box, so as with the others linkwitz needed to be applied, and after that, it could took only 180w to get to excursion, and final spl wasnt competetive to other drivers.
I'm not sure where you are getting this. The Linkwitz Transform you are applying isn't free low end. You are eating up 3+ db of headroom to flatten out the UM with eq. That means twice the power, twice the heat etc. WinISD doesn't seem to show this correctly in the cone excursion plot.

The HO does not hit xmax with 180w in 2 cu ft. It starts getting into excursion limits with 800w in the single digits. Again, that's sine waves. With program content you will cook it before you bottom it out.

Look at only the performance of the 2 subs in box (SPL chart) and you will see that the HO has more output per watt below 20Hz and smoother response above 20Hz in 2 cu ft. Max SPL & Max Power show that they are both thermally limited above 10Hz in that enclosure.
 

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in a heavy stuffed cab, the um15 should be ok at 3 cubic feet.


800 watts gets it up to around xmax.


there is a lot of misunderstanding with respect to reading the va power graph. it's not just the power on that graph that matters, it is also the voltage capability of the amplifier. with too much linkwitz transform, the problem may end up being amp clipping more than anything else.


with a single sub, it would be much wiser to simply add a parametric eq (something like f=27hz, q=1.6, gain=+3db). that way you will get a little boost in the 20's, but it won't be overdriving the sub or the amp in the single digits (which for a single 15" sub is a bad idea).
 

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Discussion Starter #12
Thanks for all answers.
Maybe i am doing it wrong, but i somehow try to maximize output around 20hz, compromising of linkwitz and power so driver wont go over xmax, as show in my previous post with pictures. Now added HO, max SPL:

http://postimg.org/image/m3njktdjd/

There is HO with LT and without, you can read from pictures whats what.

http://postimg.org/image/d74hs1iv7/

Ultimax is quite below its xmax, apline is also a little below, HO gets to its xmax as you can see in the picture by 280w with LT (120 was with LT set lower) and 550 without LT,

Amp load:

http://postimg.org/image/oib56msf7/

Ultimax gets over its paper value (800rms) only in 25hz and lower, other speakers are fine within their range.

Question is:
1.- How can i know if amp will be clipping or not? (I dont have amp yet, but im thinking inuke 1000 or 3000 dsp)
2.- Ultimax has paper value 800rms, 1600 peak, does that mean it can handle 1200 short term? I mean movies and stuff? Cause this only driver in these circumstances isn't limited by cone excursion but W.
3.- From this it seems alpine swr-1522 looks like a winner or am i wrong?
4.- If someone can do better simulation, i would be glad. (in that price range)(i can do similar or even slightly better with vented 12" like titanic, alpine swr12 and others with tuning to ~22hz, which is bringing the problem with BR being too long, or air velocity getting over 30-40, and transient response also quite high)

If my thinking is in any way wrong, please correct me, i'm just learning from you guys:)
 

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From the charts your showing I would pick between the Ultimax and the Alpine based on price. Build the box as big as you can, and or stuff it as full as reasonable. Then do a second. Get an Inuke6000DSP and run both, tuning DSP should accomplish much the same outcome as the linkwitz. I dont think I would worry about blowing your drivers unless you were purposely trying, however I suspect the alpine would be a little more robust as its rated 1000 watt/rms 3000 peak. What your building may not be totally optimal, but used within its limits will still pound.
 

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Discussion Starter #14
I can get ultimax and alpine around the same price, but i will definitely won't be able to build both (as i am already doing stupid compromises about the size). What i am trying to do is to get the most of 2cuft size, and based on what i came up so far, i think alpine is the best as ultimax needs power exceeding its paper rms to get to the same spl level.
I've been reading about Linkwitz transform vf PEQ,DEQ etc and what it does that inuke cant is it can also modify qts of a box+driver, it is a parametric equalizer + shelving filter + idk stuff i don't understand:p, but basic dsp doesn't have that function (but minidsp does, so maybe thats something to think about, as i would like to have some modifying options, as i don't know what kind of sound i prefer), so i will probably make LT circuit into the sub as default(with possibility to turn on off), and equalize the rest.
 

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If your goal is alot of 20hz output with 2 cubic feet, one of the HST subs from stereo integrity might work. They are more expensive but offer the type of specs needed for low end extension in small boxes. If you're budget allows for them, they would be worth modeling. There is an 11, 12, 15, and 18. The 15 isn't listed on the site but rumor says that it is available (although without specs to model).

HST-12
http://stereointegrity.com/product/hst12-12-subwoofer/
 

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Discussion Starter #16
It is not my goal, just a benchmark a little. Unfortunately HTS would cost me atleast double of the previous ones with shipping and taxes to eu
 
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