Determining Ported Tuning Frequency (Eminence Lab 15 Ebay) - AVS Forum
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post #1 of 29 Old 08-03-2014, 02:32 PM - Thread Starter
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Determining Ported Tuning Frequency (Eminence Lab 15 Ebay)

I'm having a hard time finding a description via Google search on how a tuning frequency is selected in a ported subwoofer. From what I think I learned, the tuning frequency should be set slightly lower than the Fs of the speaker. If that's a correct assumption, what does "slightly" mean? Or more specifically, how can you tell when you have the tuning frequency in a good spot? That's what I'm struggling with.


I'm working in WinIsd trying to model the Eminence 4ohm woofers that were posted on here earlier with a Fs of 34.4. I see notnyt modeled a 35hz tune, which would sync with what I wrote above. So is it as simple as that? Or are there other qualitative factors you look at when picking a tune? Thanks!
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post #2 of 29 Old 08-03-2014, 02:34 PM
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I believe notnyt said 30hz for lowest tuning of that driver.
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post #3 of 29 Old 08-03-2014, 03:38 PM
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There are a number of standard alignments: maximally flat or QB4 is the textbook example. However there are others, such as SBB4, QB5, sixth order, LLT etc. It depends what you're trying to achieve and whether you're willing to use external filters to finalise the response.
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post #4 of 29 Old 08-03-2014, 03:47 PM
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I'm tuning 27 hz. You lose like 1-2 dB from 30-35 hz around but get the extra couple hz extension. Mines going in a fairly big box though (2 drivers in 2x2x4)
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post #5 of 29 Old 08-03-2014, 05:27 PM - Thread Starter
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Appreciate the input so far! I'll try to frame up what I'm struggling with, using my Winisd results. When I look at them, I'm arriving at a different conclusion than what I'd expect. And that's where I think I must need help interpreting the results, because I'd be tempted to do a 25hz tune given what I think I'm seeing. This is my first time doing a ground up model, so I suspect I simply need a bit of schooling...


I have three scenarios for tunes: 35 (blue), 30 (red), and 25 (green). All assume a 3.5 cuft box, and will be powered by an inuke3000dsp. So I plugged 680 watts for power. I have a highpass filter of 28, 27, and 25 for the 35, 30, and 25 tunes respectively. The 25hz tune does give up 2db between 35-50, but is the clear winner below 30hz. It sure seems like 25-30 would be the range to set a tune, but I don't know if I'm interpreting things right. I'm an analytical guy, so love to know the "why" behind a design. I also recognize there's a little "voodoo" here in picking a design as well, which I don't have any of....
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post #6 of 29 Old 08-03-2014, 05:28 PM
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Quote:
Originally Posted by chalugadp View Post
I believe notnyt said 30hz for lowest tuning of that driver.
fs of driver is 34hz, you can tune to wherever you want, you just have to adjust box size. It will struggle around 20hz and below. This is max spl for 21hz at 10 cubes, and 34hz at 6 cubes, both highpassed.

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Last edited by notnyt; 08-03-2014 at 05:35 PM.
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post #7 of 29 Old 08-03-2014, 05:33 PM
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And here it is with 800w for 34hz tune, ad 400w for 21hz tune. Each of these peak excursion at xmax.



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post #8 of 29 Old 08-03-2014, 05:34 PM
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Quote:
Originally Posted by G-Money1572 View Post
Appreciate the input so far! I'll try to frame up what I'm struggling with, using my Winisd results. When I look at them, I'm arriving at a different conclusion than what I'd expect. And that's where I think I must need help interpreting the results, because I'd be tempted to do a 25hz tune given what I think I'm seeing. This is my first time doing a ground up model, so I suspect I simply need a bit of schooling...


I have three scenarios for tunes: 35 (blue), 30 (red), and 25 (green). All assume a 3.5 cuft box, and will be powered by an inuke3000dsp. So I plugged 680 watts for power. I have a highpass filter of 28, 27, and 25 for the 35, 30, and 25 tunes respectively. The 25hz tune does give up 2db between 35-50, but is the clear winner below 30hz. It sure seems like 25-30 would be the range to set a tune, but I don't know if I'm interpreting things right. I'm an analytical guy, so love to know the "why" behind a design. I also recognize there's a little "voodoo" here in picking a design as well, which I don't have any of....
3.5 cubic feet is too small.
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post #9 of 29 Old 08-03-2014, 06:21 PM - Thread Starter
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Quote:
Originally Posted by notnyt View Post
3.5 cubic feet is too small.
I'm guessing that's one of the reasons my spl is quite a bit lower than yours? I can go a bit larger, maybe 4-5 cuft. But that's it. Maybe I should be considering a different driver than, or maybe I just need to keep my expectations lower? I was trying to work off chaluga's mini cube concept.
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post #10 of 29 Old 08-03-2014, 06:22 PM
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As 'not mentioned....the tuning frequency can be different from the fs of the driver AND by a wide margin. Just model until you get the response that you want knowing that lower tuning requires more excursion and is less sensitive higher up.

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post #11 of 29 Old 08-03-2014, 06:23 PM
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Quote:
Originally Posted by G-Money1572 View Post
I'm guessing that's one of the reasons my spl is quite a bit lower than yours? I can go a bit larger, maybe 4-5 cuft. But that's it. Maybe I should be considering a different driver than, or maybe I just need to keep my expectations lower? I was trying to work off chaluga's mini cube concept.
Ported enclosures require more space as they get larger. This driver is not a good match for a low tuned ported enclosure. Not sure what you were hoping for.
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post #12 of 29 Old 08-03-2014, 06:53 PM - Thread Starter
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I guess I was a bit drawn in by the marketing spin on it, which was described on more than one site as a "subwoofer suited for small vented boxes". But I also see Parts Express saying it's for medium to large vented enclosures. The reality is, a ported 3.5 cube box doesn't perform much better at all than just putting it into a sealed box. When I model it, I can definitely see the performance improve when I take the box size up into the 6's.


As much as I like a good deal, I should probably just call this one DOA. I could throw it into a sealed box, but I'd probably be better off spending a few more $$ and getting a HO/SI 15" driver.
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post #13 of 29 Old 08-03-2014, 07:03 PM
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Quote:
Originally Posted by G-Money1572 View Post
I guess I was a bit drawn in by the marketing spin on it, which was described on more than one site as a "subwoofer suited for small vented boxes". But I also see Parts Express saying it's for medium to large vented enclosures. The reality is, a ported 3.5 cube box doesn't perform much better at all than just putting it into a sealed box. When I model it, I can definitely see the performance improve when I take the box size up into the 6's.


As much as I like a good deal, I should probably just call this one DOA. I could throw it into a sealed box, but I'd probably be better off spending a few more $$ and getting a HO/SI 15" driver.
That's not true if you have the right driver in the small ported box. I consider an improvement of 4-5 db's from 18-40hz significant .
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post #14 of 29 Old 08-03-2014, 07:54 PM - Thread Starter
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Quote:
Originally Posted by chalugadp View Post
That's not true if you have the right driver in the small ported box. I consider an improvement of 4-5 db's from 18-40hz significant .
I agree. I should have said this driver in a small ported box. I like the small ported box concept. What I haven't done is graphed this driver vs the HO 15 in your micro cube. I know you did on the first page of the other thread, but I suspect that might have changed with the different Fs parameters? I'll try that tomorrow night. Away from my desktop computer for the evening.
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post #15 of 29 Old 08-03-2014, 07:58 PM
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Quote:
Originally Posted by G-Money1572 View Post
I guess I was a bit drawn in by the marketing spin on it, which was described on more than one site as a "subwoofer suited for small vented boxes".
Said sites don't have their ad copy written by engineers.
It's a driver that will work in a small vented enclosures, as small as 2 cu ft, but only from the standpoint that response won't have a major midbass hump. It won't go very low.
LAB series drivers are specifically designed for use in pro-sound horns, and so employed they work very well. It's the very same specs that make them well suited for pro-sound horns that render them less than optimal in other alignments.

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post #16 of 29 Old 08-03-2014, 07:58 PM
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Quote:
Originally Posted by G-Money1572 View Post
I agree. I should have said this driver in a small ported box. I like the small ported box concept. What I haven't done is graphed this driver vs the HO 15 in your micro cube. I know you did on the first page of the other thread, but I suspect that might have changed with the different Fs parameters? I'll try that tomorrow night. Away from my desktop computer for the evening.
I looked seriously at the eBay buy but the higher fs in a small box not a good match. Here's the original lab15 vs ho

Blue lab15 and red Dayton.
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post #17 of 29 Old 08-03-2014, 08:57 PM
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Quote:
Originally Posted by G-Money1572 View Post
I guess I was a bit drawn in by the marketing spin on it, which was described on more than one site as a "subwoofer suited for small vented boxes". But I also see Parts Express saying it's for medium to large vented enclosures. The reality is, a ported 3.5 cube box doesn't perform much better at all than just putting it into a sealed box. When I model it, I can definitely see the performance improve when I take the box size up into the 6's.


As much as I like a good deal, I should probably just call this one DOA. I could throw it into a sealed box, but I'd probably be better off spending a few more $$ and getting a HO/SI 15" driver.
The lab 15 is suited for a small(ish) vented box. However it may not be the best choice if you want a super low tuning. IMO it is not true that a ported box doesent perform better than a sealed box. In a 4 cu ft its about 8db+ louder than if it was sealed. Thats a lot...

Here it is with a 6" port and a 3rd order Butterworth highpass.

VB Response lab15.gif

EDIT: This is the -standard- Lab 15.

Last edited by splotten; 08-04-2014 at 11:25 AM.
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post #18 of 29 Old 08-03-2014, 09:10 PM
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Here is the 15" HO from Dayton in the same box as above.

VB Response 15HO.gif

They look very close to my eye.
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post #19 of 29 Old 08-04-2014, 07:38 AM
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Quote:
Originally Posted by splotten View Post
Here is the 15" HO from Dayton in the same box as above.

Attachment 195785

They look very close to my eye.
Are you modeling the standard 6ohm lab15 or the 4ohm ebay lab15?
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post #20 of 29 Old 08-04-2014, 11:25 AM
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Quote:
Originally Posted by notnyt View Post
Are you modeling the standard 6ohm lab15 or the 4ohm ebay lab15?
The standard Lab 15. I wasn't aware that the "Ebay Lab 15" is different. Didn't even cross my mind. Sorry if its causing confusion.
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post #21 of 29 Old 08-04-2014, 11:25 AM
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Quote:
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The standard Lab 15. I wasn't aware that the "Ebay Lab 15" is different. Didn't even cross my mind. Sorry if its causing confusion.
Very different. See the eminence thread in here. fs is 34hz.
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post #22 of 29 Old 08-04-2014, 11:42 AM
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I see. It really is much different. Looks like it needs a much bigger box.

Heres a quick Stab at it with TS form #19 :

VB Response lab15 Special 4Ohm.gif

CB Response lab15 Special 4Ohm. Sealed.gif
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post #23 of 29 Old 08-04-2014, 12:13 PM
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Quote:
Originally Posted by splotten View Post
I see. It really is much different. Looks like it needs a much bigger box.

Heres a quick Stab at it with TS form #19 :
Some of the user entered specs there are wrong, but the ts specs look accurate. I received updated specs and posted here:

Eminence driver sale
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post #24 of 29 Old 08-04-2014, 01:31 PM
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OK. It doesent seem to make any real difference. Same box and filter as before:

VB Response lab15 Special 4Ohm.gif

CB Response lab15 Special 4Ohm. Sealed.gif
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post #25 of 29 Old 08-05-2014, 07:16 AM
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I can get as much as 3.8 cu ft out of my available space. I might be better off with ported, even though more space would be ideal. There would still be an advantage over sealed with that space.
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post #26 of 29 Old 08-05-2014, 11:50 AM
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Oops, make that 2.8 cubes max for the LAB
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post #27 of 29 Old 08-05-2014, 11:55 AM
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Oops, make that 2.8 cubes max for the LAB
that's small
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post #28 of 29 Old 08-05-2014, 12:22 PM
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Yeah, it is. I squeezed another .3 to make room for 3.1 cubes. I might try a 4" x 9.6" port out the back or two 16" ports vented underneath and see if I get chuffing. Wood is cheap.
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post #29 of 29 Old 08-10-2014, 06:45 PM
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The enclosures I am considering are 4.3 cubes tuned at 27Hz (a pair of 4" ports, 18" long On 500w it is showing 117db and xmax is hit at 22Hz (no filter). I have also modeled it in a Uframe. It is limited to about 100db in that scenario. That may be sufficient though for my admittedly very small room.
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