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Discussion Starter · #1 ·
I compared my current 15 RE SRx @ 2cuft sealed (I believe that's what my box is now).

Also compared, MM1540 sealed, MM1540 ported, MM1240 sealed, MM1240 ported.

WinISD is showing me that a 2cu ft box @ 26hz with the MM1240 is by far my best option.

It gives me a net gain of 10db @ 30hz over the 15 sealed @ 2cu ft, and a 15db gain at 30hz over my current setup. I am dumbfounded.

Even at 60hz the difference is 8db or so.

Is this right? If so I am making a new box and buying a new subwoofer immediately.

P.S the Polk lists on its website that its Xmax is 25mm, which is abnormally high for this budget of subwoofer. Do you think that is incorrect? My SRx is only 18mm...
 

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The polk data is suspect. Using WinISD Pro I can't get it to match. Plus hard to believe a 15 is THAT outperformed by a 12.

I suggest your current sub in a ported enclosure. Tuning in the 30-35 hertz range is going to provide ridiculous lows in a car. using a SSF to control excursion will allow greater mechanical power handling but it's the thermal handling that would concern me. If you listen to music other than ultra tone heavy (rap/hip hop/house) you can get around that. But if not be careful.

Also going ported in the 30-35 hertz range will require a good midbass to give you adequate punch.
 

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Discussion Starter · #4 ·
I am not specifically looking for output, rather efficiency. I don't listen to any rap, hip hop, etc at all. Rock, acoustic, metal, vocal, more along those lines.

My SRx now is getting 600 RMS, so twice what it is rated, and I find it lags behind my front stage which is getting about 120-130, or at least my lights dim very badly (near max volume). I previously had the same sub in a 3 cu ft box at 32hz, and it was very boomy.

Maybe I will try modelling a 12" JBL when I get home, ported @ 2 cu ft.

In the end I want the flattest response possible. The gains from higher freq tuning do not interest me whatsoever.
 

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Trust me winisd sucks sometimes, you can not predict gain, plus some subs do not work well with the program...

Many other free programs .... Look around :D
 

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Unibox is another great one.

AKABAK is amazing. But there is a steep learning curve.

Hornresp is also another free one. again a learning curve.

I have not had issues with WinISD pro. It's not bad for a free piece of software. User friendly, fairly accurate. It's good to get a ballpark idea of what your enclosure will do.

The issues I have had when a company posts specs that are.... slightly inflated ;). Plus a lot do not post MMS or CMS data. a lot of them don't post Le data as well.
 

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Discussion Starter · #8 ·
I just looked, and saw the IDMax 12 has 93db sensitivity, with 25mm xmax. How is the sub that efficient, and have that much excursion? I think I am going to save for one of those, since I will probably never need to buy a sub again after that. I mean, it will essentially be a HUGE increase in output (ported) vs my now sealed RE SRx 15 (which imo does not sound great, however my tuning is probably terrible).
 

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I just looked, and saw the IDMax 12 has 93db sensitivity, with 25mm xmax. How is the sub that efficient, and have that much excursion? I think I am going to save for one of those, since I will probably never need to buy a sub again after that. I mean, it will essentially be a HUGE increase in output (ported) vs my now sealed RE SRx 15 (which imo does not sound great, however my tuning is probably terrible).
Using sensitivity to compare subs is useless... If your sub is really sensitive, it will require a bigger box - Iron's law @ its best
Sensitivity is a calculated number and won't tell you how a subwoofer would respond with XXX watts.

Kelvin
 

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Using sensitivity to compare subs is useless... If your sub is really sensitive, it will require a bigger box - ohm's law @ its best
Sensitivity is a calculated number and won't tell you how a subwoofer would respond with XXX watts.

Kelvin
not that I am saying you are wrong. but what is the point of an effcient sub if it doesnt actualy give you more output per watt? if what you are saying is true, then a 70dB sub should be as good as 90?
 

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Also remember that sensitivity is based on a 1k frequency. Which as pointed out is useless for bass frequencies. I believe there is an article somewhere (can't remember site) that tried several different woofers of various "posted" efficiencies. In the low end, the less efficient were "more efficient" down low.

Also the enclosure type is going to have a huge impact on output.
 

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not that I am saying you are wrong. but what is the point of an effcient sub if it doesnt actualy give you more output per watt? if what you are saying is true, then a 70dB sub should be as good as 90?

So many factors when building boxes. smaller boxes take much more power, so the subs can take more than rated but you usually have a spike in the response, larger boxes take less power but more flat response and less output.


if a sub has a higher sensitivity than it takes less power to get it moving.
 

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not that I am saying you are wrong. but what is the point of an effcient sub if it doesnt actualy give you more output per watt? if what you are saying is true, then a 70dB sub should be as good as 90?
Here's how you calculate sensitivity: http://www.diymobileaudio.com/forum/236-post1.html
Try to create an Excel sheet and enter the parameters for some industry known woofers and subwoofers... You'd be surprise @ their real number ;)
Also, the above ^ calculated number is pretty much spot on with the one taken @ 1kHz - useless for subwoofers

Now, here's a good thread comparing 2 subs with a different sensitivity number: Sensitivity Spec in Car Audio : Hoffmans Iron Law Discussion - Car Audio Classifieds
Yes, the sensitive subwoofer can play louder with less power but in the same size box as the other one, it will have no lows... Iron's Law @ its best...
Also sensitivity does not really mean efficiency :eek:

Kelvin
 

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ok, I will go look at that stuff.


I will say, I know it is industry standard, but maybe they should test speakers for sensitivity in thier actual range. this would be like comparing cars by thier 0-150MPH test. only a handfull would even make it.
 

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Interesting....I wonder why reputable companies tout the number then.

I'll have to read those discussions in their entirety to comment some more, I wish an actual manufacturer would chime in.
 

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Discussion Starter · #16 ·
Want to update this. I bought a new IDMAX 12 D2. It's sensitivity is 93 db between 50-150hz (which is the most important area, as you said - a great sub) and 88.1 db throughout its entire range.

2" of total excursion, I am so excited. Won't be getting it for a few days.

I am thinking 2.5 cu ft @ 26hz.
 

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Want to update this. I bought a new IDMAX 12 D2. It's sensitivity is 93 db between 50-150hz (which is the most important area, as you said - a great sub) and 88.1 db throughout its entire range.

2" of total excursion, I am so excited. Won't be getting it for a few days.

I am thinking 2.5 cu ft @ 26hz.
Do not tune this low! For the type of music you listen to you'll be much happer with a 35 to even 40hz tune and chop the low end off with your SSF. I have trial and errored time and time again getting a system to play technical music right and found that a higher tuned vented cabinet does wonders.
 

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Using sensitivity to compare subs is useless... If your sub is really sensitive, it will require a bigger box - Iron's law @ its best
Sensitivity is a calculated number and won't tell you how a subwoofer would respond with XXX watts.

Kelvin
x2....*Efficiency is not an accurate indicator of a subwoofer’s output capability and should not be used as a comparison to other subwoofers to determine which one is “louder”!
 

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Discussion Starter · #20 ·
Do not tune this low! For the type of music you listen to you'll be much happer with a 35 to even 40hz tune and chop the low end off with your SSF. I have trial and errored time and time again getting a system to play technical music right and found that a higher tuned vented cabinet does wonders.
What? Why would I want a response curve that looks like a mountain? That will be difficult to tune out, I don't think it is worth it. Explain why I want such a bump in response between 40 and 50hz?
 
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