Subwoofer Tests - Fall 2007 - Page 10 - Home Theater Forum and Systems - HomeTheaterShack.com
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post #91 of 475 Old 10-12-07, 04:41 PM Thread Starter
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Re: Subwoofer Tests - Fall 2007

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WillyD wrote: View Post
And there are a few differences between the tests in the fall and the ones in the spring. Fall, Ilkka used the CE4000 all around. Superior amp, as you know, the 2000 could've definitely used a more powerful amp in the spring. There is at least a 1000W difference between the CE4000 and the t.amp TA2400 MK-X used with the TC-2k. Something tells me that extra 1000W would bump up the TC-2000s CEA-2010 clean output results from the spring just a tad.
Around 1 - 1.5 dB more as 2400W vs. 3600W should be. Though it should be noted that not all drivers can take 3600W, even peak.

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I'll still wait and see the full set of results. The CEA-2010 table isn't enough by itself for me to completely judge a sub. Its neat, but the individual threads tell the real and true story.
Spot on, Willd.
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post #92 of 475 Old 10-12-07, 04:44 PM Thread Starter
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Re: Subwoofer Tests - Fall 2007

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bsoko2 wrote: View Post
Ilkka, is there any way to test the HSU 3.3 Turbo with the HSU MBM-12 together? This is what the MBM-12 was made for, use with the HO or 3.3 Turbo. I would be interesting to see how they would rank in the pack as a single unit.

Bill
I don't have them anymore so that's not possible. Nor it would give us any new data. You can simply add their SPLs together to see how they would do as a pair. Of course it also depends on what kind of crossover configuration one is using with them.
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post #93 of 475 Old 10-12-07, 07:22 PM
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Re: Subwoofer Tests - Fall 2007

Hi Ilkka,

You didn't happen to measure the amplifier output voltage during the distortion test sweeps, did you? While you are already doing a massive amount of work, this would help settle the debate about how much power is required to really push these DIY sub drivers tot their CEA-2010 distortion limits etc.

As you mentioned, most subs aren't going to do much with anything with that 1.76 dB of gain (going from 2400 watts to 3600 watts).

Wild,

It's not like you need 7200 watts of power to run a pair of 15" subs to their limits. While I haven't read everything in detail, I think Ilkka used this much power so that clipping etc. was simply not a factor.
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post #94 of 475 Old 10-12-07, 07:30 PM
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Re: Subwoofer Tests - Fall 2007

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You didn't happen to measure the amplifier output voltage during the distortion test sweeps, did you?

Good Q. Another reason I am critical of not Ilkka, but comparing the spring DIY results to the Fall. I trust the CE-4000 map more than I trust the t-amp, if you know what I mean.

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As you mentioned, most subs aren't going to do much with anything with that 1.76 dB of gain (going from 2400 watts to 3600 watts).
That is, if the difference was really 2400w to 3600W.



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Wild,

It's not like you need 7200 watts of power to run a pair of 15" subs to their limits. While I haven't read everything in detail, I think Ilkka used this much power so that clipping etc. was simply not a factor.
Absolutely, but the amount of power available would most certainly make a difference. You even bring up clipping, which was present when the TC-2000 was tested. I am just calling it like I see it. Its not fair to completely compare the spring 2K results to the Fall SDX results and declare a "winner". And even if one wants to, wait for the full results, and look at the whole picture (as in, not just 25Hz+ performance, but <25Hz performance...you know, where subs are supposed to excel.)

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The CEA-2010 standard defines a new way for measuring and determining the clean maximum output level for a subwoofer. The signal used is a 6.5 cycle long sine burst which allows a safe measurement of the maximum output level. The max SPL is limited by the stepped distortion threshold (allows less distortion for higher harmonics) or the limitations/limiters of the subwoofer itself, which ever is reached first. The standard defines the max SPL normalized to 1 meter distance (half-space) and peak value of the sine burst, but I use the more familiar 2 meter distance and the RMS value of the sine burst. That way these figures are more comparable to the results measured by using the more common sine wave sweep/tone method.
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post #95 of 475 Old 10-12-07, 10:15 PM
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Re: Subwoofer Tests - Fall 2007

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Willy wrote:
Its the <25Hz performance that concerns me with the SDX
Correct, it's not as good as the TC drivers in low end efficiency, but using it in a LLT would bring up the low end output. The TC2k quasi LLT was cleaner from tuning to 35hz than it was above 35hz due to the port output, so if you start with a driver that trades a bit of cleanliness down low to gain it up top, you should end up with more consistent, low distortion.

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And since when have you or anyone else cared so much about >25Hz performance from a sub?
Umm, I do like to hear bass in addition to feeling it . The majority of the output of the sub will come from >25hz. <25hz is definitely very significant nowadays, but you gotta have your ducks in a row and have the frequencies we are more sensitive to clean first.

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And there are a few differences between the tests in the fall and the ones in the spring. Fall, Ilkka used the CE4000 all around. Superior amp, as you know, the 2000 could've definitely used a more powerful amp in the spring. There is at least a 1000W difference between the CE4000 and the t.amp TA2400 MK-X used with the TC-2k. Something tells me that extra 1000W would bump up the TC-2000s CEA-2010 clean output results from the spring just a tad.
For sweeps, I would definitely agree. For 6 cycle bursts like were used (I believe?) for the CEA testing, I'm not so sure. Ilkka - was power the limiting factor for the TC2k CEA test above 25hz, or was it distortion?

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The CEA-2010 table isn't enough by itself for me to completely judge a sub
Quote:
I would definitely wait for the full results before jumping into conclusions.
Absolutely - we have to talk about something though. I'm neither completely judging a sub nor jumping to any conclusions, I'm simply making observations based on the data presented.

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Ricci wrote:
Also how is it that the premium is that BIG? 2 SDX's is about $600 and keep in mind that you need 2 CE4000's at $600 a pop used, (that is actually quite the deal there), that's roughly $1.8k
I disagree. You may need two such amps to extract the bulk of the performance from a LMS 18, but you definitely don't need that much to get the bulk of performance from a SDX. A pair of EP2500s would do it.

Quote:
Ilkka wrote:
Distortion and enclosure size wise the LMS is much better.
From sweeps or from bursts? Isn't burst testing more representative of real world material reproduction?


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post #96 of 475 Old 10-12-07, 10:46 PM
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Re: Subwoofer Tests - Fall 2007

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Correct, it's not as good as the TC drivers in low end efficiency, but using it in a LLT would bring up the low end output. The TC2k quasi LLT was cleaner from tuning to 35hz than it was above 35hz due to the port output, so if you start with a driver that trades a bit of cleanliness down low to gain it up top, you should end up with more consistent, low distortion.
Not as good in low end efficiency? How about not as good in low end distortion as well, which I suspect. Yeah, the LLT would definitely help. And we can't yet assume the SDX is cleaner up top. With the much more powerful amp, which Ilkka says might would account for 1 to 1.5dB difference in output, the SDX has just 1.7dB more output at 80Hz than the TC-2K.

If the full results from from Ilkka show it, more specifically the harmonic distortion by component figure, then so be it.


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Umm, I do like to hear bass in addition to feeling it . The majority of the output of the sub will come from >25hz. <25hz is definitely very significant nowadays, but you gotta have your ducks in a row and have the frequencies we are more sensitive to clean first.
Sure, but my point is, getting clean >25Hz output has never been the issue. If one truly wanted that, they could go with a load of high efficiency 18" pro drivers like B&C or BMS and port them to 25Hz and give them a bunch of power. That'd obliterate any of these subs in >25hz performance.

And are you suggesting that the TC-2K isn't clean in the frequencies we are more sensitive to? It still put out 114dB from 2m @ 50Hz. I'd say thats pretty significant "clean output", even with the problems Ilkka said the drivers had.


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For sweeps, I would definitely agree. For 6 cycle bursts like were used (I believe?) for the CEA testing, I'm not so sure. Ilkka - was power the limiting factor for the TC2k CEA test above 25hz, or was it distortion?
Actually, I would say its the other way around. You mentioned compression, yet compression much sooner rear its ugly head with sweeps than it would with bursts. Maybe I am missing somehing...but that sure seems to be the case. For instance, compare the LLT TC-2K's maximum output level done with the 30 second linear sine sweep and compare it to the CEA-2010 max output figures.

linear sine sweep - ~112.3dB @ 50Hz
6.5 cycle long sine burst- ~ 114.8dB @ 50hz

Quote:
Absolutely - we have to talk about something though. I'm neither completely judging a sub nor jumping to any conclusions, I'm simply making observations based on the data presented.
Well, to me it certainly sounded like you were jumping to conclusions and not considering all the facts and the ones yet presented. I am not trying to put down anyone or anything, but one must look at the entire picture.

Quote:
I'm not so sure. Ilkka - was power the limiting factor for the TC2k CEA test above 25hz, or was it distortion?
Thats a good Q. On a somewhat unrelated note, I do remember this post from Ilkka in the spring: http://www.hometheatershack.com/foru...87-post34.html

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One interesting note. The large TC-2000 15" based sonosub was clipping its ~2000W amp at 40 Hz and above.
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post #97 of 475 Old 10-12-07, 11:26 PM
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Re: Subwoofer Tests - Fall 2007

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Willy wrote:
Sure, but my point is, getting clean >25Hz output has never been the issue
I agree, but by using these drivers in a LLT configuration, clean output below 25hz to tuning isn't much of an issue either. So which becomes the remaining bottleneck as output increases - the top end or low end? Sensitivity is higher in higher frequencies, so IF one were to start demanding greater than reference levels, the top end would be the bottleneck for a LLT in my eyes, whereas the low end would be the bottleneck for a sealed sub using the same driver well before approaching reference levels. Taking overall performance into account, based on this data - without jumping to conclusions - I would imagine a SDX LLT would be slightly more well rounded than a TC2k, and two SDX LLTs would be slightly more well rounded than the LMS PR'd sub. None of this is passionate debate, just observations.

Quote:
And are you suggesting that the TC-2K isn't clean in the frequencies we are more sensitive to? It still put out 114dB from 2m @ 50Hz. I'd say thats pretty significant "clean output", even with the problems Ilkka said the drivers had.
Absolutely, well more capability than most adventurous enthusiasts would ever care to put to use. I'm definitely not trying to say it's lacking, merely that the SDX has a slight advantage in that range. If I felt the TC2k was lacking, I wouldn't recommend it.

Quote:
Actually, I would say its the other way around. You mentioned compression, yet compression much sooner rear its ugly head with sweeps than it would with bursts. Maybe I am missing somehing...but that sure seems to be the case. For instance, compare the LLT TC-2K's maximum output level done with the 30 second linear sine sweep and compare it to the CEA-2010 max output figures.
Quote:
Thats a good Q. On a somewhat unrelated note, I do remember this post from Ilkka in the spring
I know the amp clipped during the sweep testing, but I don't believe it clipped during the burst testing. If that's the case, then more power wouldn't necessarily add much to the burst test.


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post #98 of 475 Old 10-13-07, 12:14 AM
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Re: Subwoofer Tests - Fall 2007

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Ilkka wrote: View Post
I have kept you all under the radar thus far, but I have just completed my fall 2007 subwoofer test session. These are the subwoofers (and one speaker) I tested today. Results and pictures will follow.
Ilkka,
Simplified this post. For the ultra-low/low bass representation with a single number, IMHO, the CEA2010 is using too simplistic an approach by going with Arithmetic means. I suggest going with weighted arithmetic means or simply not using a single number at all. The weights need to be carefully chosen.
-Jai

Last edited by jmcomp124; 10-13-07 at 10:18 AM.
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post #99 of 475 Old 10-13-07, 12:32 AM
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Re: Subwoofer Tests - Fall 2007

For the motivated reader..

http://en.wikipedia.org/wiki/Harmonic_mean
http://en.wikipedia.org/wiki/Weighted_arithmetic_mean
http://en.wikipedia.org/wiki/Geometric_mean

Last edited by jmcomp124; 10-13-07 at 10:19 AM.
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post #100 of 475 Old 10-13-07, 02:02 AM
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Re: Subwoofer Tests - Fall 2007

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I know the amp clipped during the sweep testing, but I don't believe it clipped during the burst testing. If that's the case, then more power wouldn't necessarily add much to the burst test.
Why don't you believe it did. Just have a lot of faith I guess? Seems to me that it would be a more significant leap of faith to believe the differences in amplifiers wouldn't have affected the results. Even if the amp hadn't clipped or limited the 2K in the burst testing (and we might never know), the differences in upper end efficiency are so relatively small. We're talking about a low bass avg difference of 1.1dB.

And oddly enough, the CEA-2010 figures for the SDX-15 are quite close (in the higher frequencies) to the simulated output in Unibox. For instance...

Unibox: SDX-15 in 100liters with 3600W= 117.1dB @ 63Hz
CEA-2010: "....................................." = 116.1dB @ 63Hz

A whopping 1dB difference. And what about the TC-2K Quasi-LLT?

Unibox: TC-2K in 270liters tuned to 16.5Hz with 2400W = 114.7dB @ 63Hz
CEA-2010: "..........................................................." = 114.4dB @ 63Hz

.3dB difference. Interesting.

At any rate, what I'd like to see is the Max output level and power compression graphs for the subs. Those will be just a tad more informative....
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