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post #661 of 682 Old 03-31-2008, 04:28 PM
 
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Originally Posted by Thomas-W View Post

Everyone knows a good Pastrami sandwich is far more important than any subwoofer...

I makes no claims to have invented anything with regard to IB subs. People were putting Altec 15"s in-wall during the 1950's. AFAIK the first manifold IB sub was created by Tom Nousaine in the mid 1990's.

Dan Wiggins, David Hyre, Tom Nousaine, and various members of the Bass-list were the resources I used for designing my first IB. The IB forum is simply an extension of the conversations with the people who assisted me; combined with my 9yrs of hands-on experience, plus feedback from the several hundred people who've built IB subs and posted about them.

No, you never suggested you invented anything. You have, however, been a terrific resource for those who have the right circumstance for building an IB.

That was a compliment, by the way.
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post #662 of 682 Old 03-31-2008, 04:29 PM
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Originally Posted by SteveCallas View Post

Sure, but a LLT is still a ported subwoofer. It's just a large and low tuned one. An IB is still a sealed subwoofer, just a large one that tends to use an adjacent space as the enclosure.

Nope an IB sub is a ELLTSBWNHRC.....

Extremely-Large-Low-Tuned-Sealed-Box-With-No-Helmholtz-Resonance-Colorations
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post #663 of 682 Old 03-31-2008, 04:30 PM
 
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Originally Posted by Thomas-W View Post

Nope an IB sub is a ELLTSBWNHRC.....

Extremely-Large-Low-Tuned-Sealed-Box-With-No-Helmholtz-Resonance-Colorations

Classic. JUST classic.
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post #664 of 682 Old 03-31-2008, 05:17 PM
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The rambling arguments are all stemming from a lack of clarity in what people are asserting.

You have an uncanny ability to sum an entire thread, perhaps an entire forum, in a sentence.

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post #665 of 682 Old 03-31-2008, 05:33 PM
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I hate all this attention that we give to parameters like the Qtc, vas and fs, what really matters is frequency response of the system. Heres something fun to do, try modeling an AE IB15 for an IB with Qtc of 0.7 and have a look at the corresponding fr, its dead flat to 20Hz, when do you ever see a sealed system, especially one with a qtc of 0.7 get a flat anechoic response to 20Hz? No other driver that I have seen does that, you don't need an LT circuit to get the most from your low end even in anechoic rooms. When you really look at just how various drivers actually perform in their alignments you start to realize just how useless of a parameter the Q of the system is when you just look at it by itself. You simply cannot generalize them, some drivers will sound boomy with a Q of well below 0.5, others can have ruler flat response with a Q of 0.7. A high Q is anything but a sound way to prevent over excursion down low and a low is anything but a sure way to get a subs frequency response flat to lower frequencies, even if it does have a fairly low fs.

Qts (I assume you mean this parameter instead of Qtc), Vas and Fs are the parameters you need to model a sealed sub. Modeling the AE IB15 in any size sealed box without entering Vas will net you a .7 system Q, which is 'optimally flat'. Enter the HUGE Vas and the response changes accordingly.

To get a low Fs (16Hz), you add mass and/or raise compliance, which raises Qts (.7) and Vas (12,000 cubic feet) and lowers 1W/1M (86.0dB). This driver will be optimally flat to a very low F3 in a HUGE box, thus its obvious design for IB. The compliance of this driver must be so high it will bottom if you breathe on it. I'd be interested to know if any IB builders who used this driver have had that problem. These are the only T/S I see on the AE site, and they just don't seem right at first glance to me.

Thomas' point is that a box will raise system Q and Fb proportional to the size of the box vs the driver's parameters. This will change the FR and, therefore, sonic signature. Call it box coloration or whatever. Not only can you generalize, you can take it to the bank.

I must be misunderstanding your point about a .5 system Q sounding boomy? You must mean using a driver that has a Qts below .5 can possibly sound boomy, but just before that you mention the Q of a system being a useless parameter?

In any case, Qts, Vas and Fs are anything but useless parameters in an IB or any other sealed application.

Bosso
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post #666 of 682 Old 03-31-2008, 06:02 PM
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Originally Posted by bossobass View Post

Thomas' point is that a box will raise system Q and Fb proportional to the size of the box vs the driver's parameters. This will change the FR and, therefore, sonic signature. Call it box coloration or whatever. Not only can you generalize, you can take it to the bank.
In any case, Qts, Vas and Fs are anything but useless parameters in an IB or any other sealed application.

Bosso

I was just about to type up my reply to that post, now there's no need....

Thanks....

There are several dozen second generation AE-IB 15"s installed. No one is reporting issues with bottoming. Let me check to see if there's a typo or something..
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post #667 of 682 Old 03-31-2008, 07:06 PM
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The important detail is that the affect of the listening room at low frequencies is also largely minimum phase, where boosting or attenuating frequency ranges at the listening position show mostly the same phase changes we would see if we matched this response outdoors with PEQ

Quote:
Well you know me Mark, I'm going to want to see measurements - not because I don't believe you, just because I like to see things with my own eyes. I'll see if Ilkka is up for any in-room measurements with his monster LMS subwoofer.

See the attached graph of in-room FR, non-equalized and equalized with the corresponding GD graph. Since GD is computed as a derivative of phase with respect to frequency...

Bosso
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post #668 of 682 Old 04-01-2008, 01:19 AM
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Originally Posted by bossobass View Post

Qts (I assume you mean this parameter instead of Qtc), Vas and Fs are the parameters you need to model a sealed sub. Modeling the AE IB15 in any size sealed box without entering Vas will net you a .7 system Q, which is 'optimally flat'. Enter the HUGE Vas and the response changes accordingly.

To get a low Fs (16Hz), you add mass and/or raise compliance, which raises Qts (.7) and Vas (12,000 cubic feet) and lowers 1W/1M (86.0dB). This driver will be optimally flat to a very low F3 in a HUGE box, thus its obvious design for IB. The compliance of this driver must be so high it will bottom if you breathe on it. I'd be interested to know if any IB builders who used this driver have had that problem. These are the only T/S I see on the AE site, and they just don't seem right at first glance to me.

Thomas' point is that a box will raise system Q and Fb proportional to the size of the box vs the driver's parameters. This will change the FR and, therefore, sonic signature. Call it box coloration or whatever. Not only can you generalize, you can take it to the bank.

I must be misunderstanding your point about a .5 system Q sounding boomy? You must mean using a driver that has a Qts below .5 can possibly sound boomy, but just before that you mention the Q of a system being a useless parameter?

In any case, Qts, Vas and Fs are anything but useless parameters in an IB or any other sealed application.

Bosso

I'm not really seeing what new information you are bringing to the table, maybe we got our lines crossed, there wasn't anything there that I don't agree with. My point about the 0.5 Q system being boomy is that often times people associate boominess with a driver that has too steep of a rolloff resulting in "one note" bass. If you look at the TC5200, it rolls off from the get go and is down a lot more at 20Hz in an IB alignment than a AE IB15, even though the IB15 has a Qts of ~0.7 and the TC5200 has a Qts of ~.16. I was not trying to say that they were useless parameters, but rather that they can be misleading when looking at any one or even two of them, they combine to form the overall system response. I can have two subs with the same Qtc (from the box) and fsc and still have VASTLY different frequency responses. When someone comes on here with complaints of a boomy sealed sub, we first look at the Q of the box, then we try to find a suitable LT filter to correct the issue, typically, a Q of 0.5 is considered ideal for an HT sub and 0.7 is nice for a music sub. However, if the frequency response is the problem just looking at the Q parameter is a very vague way of calculating the fr of the system as the rolloff's take place at different frequencies, and WHERE the rolloff starts, is often times just as important if not moreso than how steep it is.

I understand Thomas's point about the size of the box changing the qtc and fsc of the system, MY point was that there is no magic number at which it ceases to affect in any meaningful way, of course, 25x vas looks nice with pretty much any driver, but as I said, the qtc still does not = the qts of the driver at that point and even with boxes much smaller, it often times does not raise the qtc of the system very much. Thomas knows this, I was trying to address the issue before we start getting people quoting it as law around here without really understanding what is going on. Thomas is a rather esteemed member and people take a serious look at the things that he says.
I have found that if you don't clarify something, you will have to correct it a lot before the truth of the matter can be elevated once again, if you discuss it right away, it tends to keep those mentalities from forming. One thought that I have seen on here is that the system Q is an accurate way of judging the fr of a system, when in fact, it is not (even if you factor in the fsc as well). The Q tells the slope of the roll off, it does not tell where it will occur, or what the fr will do above that roll off. A driver can have a very high Q (0.9) and still be down less at 20Hz than a sub with a Q of less than 0.5 even though the roll off is much shollower with the system with the Q of 0.5.

About those parameters on Johns site, if anyone knows how to make a loose suspension, its him, I have a pair of his PR's and they wave back and forth if you move them, I certainly believe they are accurate, they are loose and have plenty of stopping power at the suspension limits. If you notice, his drivers have more overexcursion protection than Ficar's IB drivers, maybe this is why, it looks like ficars drivers have a firmer suspension as the fs is quite a bit higher on them. IMO of all the new IB drivers, John's have me most excited, I can't wait to try kevin's as well though, IB drivers with XBL!
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post #669 of 682 Old 04-01-2008, 07:19 AM
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Originally Posted by SteveCallas View Post

Well you know me Mark, I'm going to want to see measurements - not because I don't believe you, just because I like to see things with my own eyes. I'll see if Ilkka is up for any in-room measurements with his monster LMS subwoofer.

You mean like the measurements contained in the Harman white papers I directed you to research? The homework is for you to do, I've done mine. I have many more interesting investigations to waste time on.

Note I'm not saying that EQ is the preferred fix for in-room subwoofer response. Subwoofer location and if possible, acoustic control devices are the first line of attack. The point is just that EQ has been proven many times over to be beneficial at low frequencies in the ways I have described. The other point is that we really don't need fancy filtering. Determining what you want the EQ to do is a bigger factor, and why we have so many spins on "auto EQ" efforts in the market.

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post #670 of 682 Old 04-01-2008, 07:27 AM
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Originally Posted by Thomas-W View Post

Give me a little bit of time to get a measurement setup in place, and I'll run most of the tests people want.

I can't however post max SPL/distortion for my big IB, since it's positioned ~8' from a 60 sq ft picture window...

Any thoughts on Praxis vs something like Smith & Larson Woofer Tester Pro/Speaker Tester? Approx $1k is my threshold of pain for this investment

http://www.woofertester.com/wtproproduct.htm

Hi Thomas,

I have only just started playing with Praxis, as I've grown quite comfortable in getting the info I want from my TEF, although I wouldn't recommend a TEF to most. I have heard some very good first impressions of the new "woofer tester" where it's obviously a monumental step beyond the first two. I've heard it takes measurements very quickly and appears to require a bit less cobbling of measurement connections than Praxis. I believe Praxis offers a bit more capability for more detailed measurements, but the utility of those extra capabilities could easily be questioned for even the most hard-core hobbyist.

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post #671 of 682 Old 04-01-2008, 09:04 AM
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I think part of the problem here is mostly one of terminology.

Quote:


However, if the frequency response is the problem just looking at the Q parameter is a very vague way of calculating the fr of the system as the rolloff's take place at different frequencies, and WHERE the rolloff starts, is often times just as important if not moreso than how steep it is.

Quote:


One thought that I have seen on here is that the system Q is an accurate way of judging the fr of a system, when in fact, it is not (even if you factor in the fsc as well).

I think you mean extension (F3) when you say FR.

In any case, what you're saying is simply not true. If the system Q and Fsc are the same, so is the FR, going down in frequency.

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A driver can have a very high Q (0.9) and still be down less at 20Hz than a sub with a Q of less than 0.5 even though the roll off is much shollower with the system with the Q of 0.5.

Not when you factor in Fs, strictly speaking in an IB application, which I think you are. Driver Fs and Qts will dictate FR and extension in an IB. You can't have a driver with a Qts of .9 that is 'down less at 20Hz' than a driver with a Qts of .5 in an IB if the Fs of the higher Q driver is higher than than Fs of the lower Q driver.

I see now what you're trying to say, but in an IB the Qts of the driver is the system Q, so a high Qts driver isn't desirable. You're basically describing the knee of the FR. In an IB the higher Q driver will have higher output at the knee and therefore extend lower before it rolls off, but that will mean higher excursion and a noticeable boost in the BW of the knee. It could (and most likely would) be EQ'd to the desired system Q.

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I can have two subs with the same Qtc (from the box) and fsc and still have VASTLY different frequency responses.

To repeat, if Fsc and Qtc are the same, FR is the same, going down in frequency. I don't see how that isn't obvious.

You can just divide Fs by Qts to get a quick idea which driver will have the lowest F3 and the driver Qts will be the system Q, which shows there is a relationship between the 2...like Thomas has said many times.

Bosso
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post #672 of 682 Old 04-01-2008, 09:41 AM
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Once again Bosso saves the day.....

And in conclusion.......

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Originally Posted by armystud0911 View Post

typically, a Q of 0.5 is considered ideal for an HT sub and 0.7 is nice for a music sub.

Most people I know consider low a Qtc, 0.6 or less the best for music, and a higher Qtc, 0.7 and above to be best for HT.

So you and I live in very different worlds.....

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Originally Posted by Mark Seaton View Post

I believe Praxis offers a bit more capability for more detailed measurements, but the utility of those extra capabilities could easily be questioned for even the most hard-core hobbyist

Thanks for the feedback...
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post #673 of 682 Old 04-01-2008, 04:04 PM
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Originally Posted by bosso View Post

See the attached graph of in-room FR, non-equalized and equalized with the corresponding GD graph

Thanks. So why then do I see an increase in group delay in both WinISD and real life when EQ boosting is applied down low to a sealed subwoofer?

Velo DD18 Group Delay with low end boost
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post #674 of 682 Old 04-01-2008, 04:08 PM
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Originally Posted by SteveCallas View Post

Thanks. So why then do I see an increase in group delay in both WinISD and real life when EQ boosting is applied down low to a sealed subwoofer?

Velo DD18 Group Delay with low end boost

Because they're not using linear phase FIR filtering
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post #675 of 682 Old 04-01-2008, 04:18 PM
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Originally Posted by SteveCallas View Post

Thanks. So why then do I see an increase in group delay in both WinISD and real life when EQ boosting is applied down low to a sealed subwoofer?

Velo DD18 Group Delay with low end boost

You are confusing two separate issues. One is what is going on with the affect of the room acoustics, and the other is the inherent time behavior of an acoustically small direct radiator of a given bandwidth and cut-off slope. By the nature of how subwoofers and filters work, as you push the corner of a given alignment (roll off shape) lower, group delay near the corner will increase. Note that at low frequencies, a 12dB/oct roll off shows constant group delay.

Separate from the above operational realities, remember that how you EQ a sealed subwoofer matters greatly. Applying a parametric boost down around or below the corner is nothing like the effect of an L/T or appropriate shelving+PEQ. If you expand the frequency range you will see significant differences in both the frequency response and phase response.

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post #676 of 682 Old 04-01-2008, 05:04 PM
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Originally Posted by bossobass View Post

I think part of the problem here is mostly one of terminology.





I think you mean extension (F3) when you say FR.

In any case, what you're saying is simply not true. If the system Q and Fsc are the same, so is the FR, going down in frequency.



Not when you factor in Fs, strictly speaking in an IB application, which I think you are. Driver Fs and Qts will dictate FR and extension in an IB. You can't have a driver with a Qts of .9 that is 'down less at 20Hz' than a driver with a Qts of .5 in an IB if the Fs of the higher Q driver is higher than than Fs of the lower Q driver.

I see now what you're trying to say, but in an IB the Qts of the driver is the system Q, so a high Qts driver isn't desirable. You're basically describing the knee of the FR. In an IB the higher Q driver will have higher output at the knee and therefore extend lower before it rolls off, but that will mean higher excursion and a noticeable boost in the BW of the knee. It could (and most likely would) be EQ'd to the desired system Q.



To repeat, if Fsc and Qtc are the same, FR is the same, going down in frequency. I don't see how that isn't obvious.

You can just divide Fs by Qts to get a quick idea which driver will have the lowest F3 and the driver Qts will be the system Q, which shows there is a relationship between the 2...like Thomas has said many times.

Bosso

Thats not quite what I am seeing, yes that is the proper way to calculate the F3, however, the actual frequency response, calls for different things in different situations and just looking at the Q is (at least IMO, a poor way of doing this), I hate posting graphs, but lets have a look at the transfer function magnitude of a TC5200 and a Soundsplinter RL-s15, these are the highest and lowest Q drivers that I know of so the effect I going for should be apparent. The RL-s15 has a Q of 0.932 and the TC5200 has a Q of 0.151, not only does the TC sounds driver have a far lower Q, but it also has a much lower fs (and hence fsc) than the soundsplinter, but it is still over 3dB ahead at 10Hz and is substantially higher through the entire frequency spectrom.

The steady graph downward is the TC5200 and the one with hump is the RL-s15. Yes you can readily see the difference in slope here, the effect of the low Q of the TC5200 in its IB situation is apparent as it does take over output wise at 6Hz and below. However, wouldn't you expect a driver with a lower Q and fsc to have more output through much of the band?

Have a look here



Both drivers are in massive enclosures, I think 1000 cubic feet, so its very much an IB situation. The fsc of the TC5200 is 18.91Hz and the fsc of the RS-s15 is 25.5Hz. The output for the RL-s15 is 9dB higher than that of the TC5200 at 20Hz.


Edit*** this is the statement that I have the problem with
Quote:


Not when you factor in Fs, strictly speaking in an IB application, which I think you are. Driver Fs and Qts will dictate FR and extension in an IB. You can't have a driver with a Qts of .9 that is 'down less at 20Hz' than a driver with a Qts of .5 in an IB if the Fs of the higher Q driver is higher than than Fs of the lower Q driver.

As you can see, the substantially higher Q and higher Fs driver has MUCH lower F3 than the lower Q lower fs driver when both are in an IB. The math supports this, the F3 on the TC5200 is 117Hz, and on the RL-s15 its at about 26Hz, now if you put the TC5200 in a much smaller box, say 0.3 cubic feet, you get a similar Qtc to the RL-s enclosure, the higher Q lowers the F3 to 99Hz and the TC5200 is now down substantially at all frequencies. This is just an example of how a high Q system can actually work to great effect imo, the RL-s can be put in a box thats 10 cubic feet or less and have an Fsc of 30Hz and simply run at max excursion the whole way down to 1Hz.
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post #677 of 682 Old 04-02-2008, 09:05 AM
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Edit*** this is the statement that I have the problem with
Quote:
Not when you factor in Fs, strictly speaking in an IB application, which I think you are. Driver Fs and Qts will dictate FR and extension in an IB. You can't have a driver with a Qts of .9 that is 'down less at 20Hz' than a driver with a Qts of .5 in an IB if the Fs of the higher Q driver is higher than than Fs of the lower Q driver.

As you can see, the substantially higher Q and higher Fs driver has MUCH lower F3 than the lower Q lower fs driver when both are in an IB. The math supports this, the F3 on the TC5200 is 117Hz, and on the RL-s15 its at about 26Hz, now if you put the TC5200 in a much smaller box, say 0.3 cubic feet, you get a similar Qtc to the RL-s enclosure, the higher Q lowers the F3 to 99Hz and the TC5200 is now down substantially at all frequencies. This is just an example of how a high Q system can actually work to great effect imo, the RL-s can be put in a box thats 10 cubic feet or less and have an Fsc of 30Hz and simply run at max excursion the whole way down to 1Hz.

Notice the bold part (since no one would consider a driver with a 0.2 Qts for an IB application).

Divide Fs by Qts:

Fs (18.91) divided by Qts (0.151) equals 125.23
Fs (25.50) divided by Qts (0.932) equals 27.36

In fact, in an IB, you might find this math to be more accurate than your model in a real world model.

Quote:


Both drivers are in massive enclosures, I think 1000 cubic feet, so its very much an IB situation. The fsc of the TC5200 is 18.91Hz and the fsc of the RS-s15 is 25.5Hz. The output for the RL-s15 is 9dB higher than that of the TC5200 at 20Hz.

Please apply an equal amount of power to both drivers in your example and post the graph.

Bosso
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post #678 of 682 Old 04-02-2008, 09:20 AM
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Originally Posted by armystud0911 View Post

The steady graph downward is the TC5200 and the one with hump is the RL-s15. Yes you can readily see the difference in slope here, the effect of the low Q of the TC5200 in its IB situation is apparent as it does take over output wise at 6Hz and below. However, wouldn't you expect a driver with a lower Q and fsc to have more output through much of the band?

Nope. Welcome to the realization that more motor or a higher sensitivity driver ain't always mo-better.

Bosso is correct though. Appart from upper frequency effects like inductance, the frequency response of a 2nd order LF system (sealed/IB/whatever you want to call it) is defined by the system Q and resonant frequency. With only one parameter you know very little about the system's frequency response.

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post #679 of 682 Old 04-02-2008, 01:47 PM
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Originally Posted by bossobass View Post



Please apply an equal amount of power to both drivers in your example and post the graph.

Bosso

Now your trying to see how sensitivity plays into this bosso, I was referring to frequency response, not what happens at a given power input.

Here I'll post the graph of the 15" TC5200, the 18" one still has less output at 20Hz, but things look different because you can't see the effects of its excursion as well since its cone is so much bigger. The 15" model has an fsc of 21Hz while the RL-s15 has an fsc of 25.5Hz, heres how they look in a 1000 cubic foot box being pushed to near max output with 1500 watts of input power. I have factored in the inductance, but the RL-s15 still has a hump without it, its just smaller. Here I'll extend my results down to 5Hz so we can see that yes, the TC5200's slow rolloff causes it to take over again, at 20Hz though, the results are quite apparent. Furthermore, the effects of inductance in a system can cause the frequency responses to behave quite differently where the fsc and qtc are the same.



Here I'll go back to what I said earlier, about a driver with a Q of 0.5 being down more at 20Hz than the one with a Q of 0.9 with similar or even lower fs's in an IB system (so of course the fs will nearly equal the fsc). its hard to find any drivers that fit this bill exactly, but I'll choose the ficar Q15, it yields a Q of 0.508 in an IB but its natural qts is 0.493, anyway, its right around 0.5, also, its fs is 24.9Hz, a tad lower than the RL-s15 with its fs of 25.5Hz.



Now, the RL-s15 still has a lower F3 (naturally, the math still supports that) and its down 6dB at 20Hz, whereas the ficar is down 10dB at 20Hz. Once again, you can see that the more gradual slope of the Q15 causes it to take over down low, around 8Hz. (I am not saying this to inform you bosso, but to show what I understand).

Actually, the math supports the models in winisd perfectly, how do you think it calculates its F3? From what I can see the math is by no means "more accurate" at least, unless you are referring to the discrepancy that I had with ThomasW saying that at 25x vas, fs = fsc and qts = qtc which from the how it looks to me, it still can need more volume than that to drop more and with less volume, it may not change significantly, still I had no problem with the generalized statement as I said earlier, pretty much any driver will look good at 25x vas for IB.


Quote:


Welcome to the realization that more motor or a higher sensitivity driver ain't always mo-better.

Actually I noticed this a long time ago, all this talk of Q kinda brought it to the surface. There was a time that I was interested in trying out an RL-s15 a little over a year ago, and that is where my true journey into the Q began.
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post #680 of 682 Old 04-03-2008, 05:53 PM
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Originally Posted by Mark View Post

By the nature of how subwoofers and filters work, as you push the corner of a given alignment (roll off shape) lower, group delay near the corner will increase.

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Applying a parametric boost down around or below the corner is nothing like the effect of an L/T or appropriate shelving+PEQ. If you expand the frequency range you will see significant differences in both the frequency response and phase response.

Ok, so I should have said low end boosting as opposed to fixing peaks and nulls.
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post #681 of 682 Old 04-05-2008, 12:42 PM
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Originally Posted by SteveCallas View Post

Thanks. So why then do I see an increase in group delay in both WinISD and real life when EQ boosting is applied down low to a sealed subwoofer?

Velo DD18 Group Delay with low end boost

From SL:

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I am not certain what happens in the range below 100 Hz and I have strong suspicions that this is the region where delay distortion is audible. It is also the region where delay really accumulates via vented and bandpass woofers, and the great numbers of dc blocking capacitors in the signal chain from microphone to speaker terminal.

See the attached chart. GD is frequency relative and alignment relative. All of the subs are 'tuned' to 20Hz, either by ports, PRs or EQ.

Note the lowest GD and change going down from 30-20Hz is in the sub that has no EQ boost, but that it's exactly the same in the Velo DD-15, which uses EQ boost. Both are lower, with less change than the ported/PR subs, which are influenced by the port/PR.

Bosso
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post #682 of 682 Old 08-16-2008, 10:15 PM
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Originally Posted by penngray View Post

I honestly dont think anyone is going to build a sub $$$ vs $$$ better then what I see with that AV123 sub right now. I cant really chart it better with my TC2000K 15" drivers, which are probably some of the best drivers that exist out there.


Where did you come across the T/S params for the driver to model?
Do you still have them?
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