Steve81

Steve81

Audioholics Five-0
"Also, contrary to the bogus claims by this individual--- there is *no* evidence showing that having max output capabilities as even as possible across the operating bandwidth offers any audible benefit. In fact, the opposite is true."

Here he seems to argue linearity does not matter, and that disproportionate upper bass is preferred. I doubt very much that anyone in the industry would agree, including Ricci and Seaton. If there is ANYONE reading this who prefers that kind of frequency response to a neutral response (aside from the guy selling the subs where that response is built-in), please speak up, as this line of argument needs all the support it can get.
Funny enough we've had this conversation before, but you were on the other side of the argument :p

Anyway, there is just no point in eliminating headroom for the sake of a flat FR, no one is using these things in an anechoic chamber.
Of course, I'm curious: take the case of the Epik Empire and the LFM-1EX. From 50Hz on up, the Empire has a big output advantage. Epik's issues aside, would you qualify the Empire as being significantly better than the LFM? I'd personally say that unless you've got a small room to boost the low end of the Empire, all that excess output is mostly for naught, but YMMV.
Everything else being equal, yes, a sub with more output above 50 hz is going to be better. If you can get it, there is no reason not to have it. For starters, if you have dips above 50 hz, you have more room to EQ the response down to flat without losing output for the entire subwoofer frequency range. Secondly, there is nothing wrong with having extra headroom in a certain range; it may not play flat when brought to its limits, but the extra dynamics in that range will still be truer to the dynamics of the recording than a sub that just can not cross that output line at any frequency. Third, there is a lot more bass material above 50 hz than below in most movie and music recordings, so if you can have extra headroom there, that is the region where you want it.
And of course as I said a couple posts ago:
I prefer to view this another way: realistically, you're not likely to need 136dB of output at 63-100Hz, but such output capability is indicative of the S3000i's efficiency through this range. In other words, while the sub may never be asked to deliver full power at 63-100Hz, what content it does get up in that range is simply shrugged off, leaving more resources for deep bass.
 
S

shadyJ

Speaker of the House
Staff member
I am not saying upper bass headroom is a bad thing at all. I am saying its not worth trading for lower bass beyond a flat response. After all, what would you rather have, an flat maximum output response from 20 Hz to 100 Hz, or a response more tilted toward upper bass with less lower bass? That is called compression, and it used to be considered a bad thing until just now where Tom says it's a good thing.
 
Steve81

Steve81

Audioholics Five-0
After all, what would you rather have, an flat maximum output response from 20 Hz to 100 Hz, or a response more tilted toward upper bass with less lower bass?.
Depends on the room in question. In my space, an anechoic response with a tilt towards the upper bass yields a flatter in room response. That was a big reason I swapped out the PB13 for the FW18.0, and I haven't looked back at all in spite of sacrificing a few dB around port tune.

As far as compression goes, I don't think anyone is really suggesting buyers should try to push the S3000i (or any other sub) beyond its limits down low and run into heavy compression / distortion. What I do suggest is that with real world content (as opposed to 20hz sine waves) you're likely to find the limits a lot more quickly with a sub like the PB13, which seems to be borne out when compared with the SubM (or my Funk).
 
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Tom V.

Audioholic
Hi Steve,

There was some discussion on this topic a while back that included Josh Ricci and Mark Seaton.

http://www.avsforum.com/forum/113-subwoofers-bass-transducers/1425179-subwoofer-recommendation-pricepoint-thread-2.html

Post 46 (Josh Ricci) Post 50 (Mark Seaton).

You can see they share the same POV as I do. More headroom is *never* a bad thing...contrary to the anti-tom parade of one..;)


Also,

Couple of comments regarding the term "linear" in regards to subwoofer capabilities---particularly in regards to maximum output capabilities.

I want to address the frequency response of a subwoofer first as (imo) this IS an important indicator of the bass quality that one can expect from a subwoofer. With a frequency response graph a "linear" (or a straight)line can have some importance although there are still variables that need to be considered. The misunderstanding in some comments seems to be rooted in folks assuming the same importance of a "straight line" should apply to other measurement graphs as well. In other words....the mantra is "straighter is always better"....and this is simply *not* the case.

Let me break down some of the factors I consider important in regards to frequency response of a home audio subwoofer first and then I will circle back to the max output stuff.


a)First area would be the "mid and upper" frequency range...let's use 40hz to 120hz as an example. The goal here is relatively flat response across the entire range. Something like +/- 1dB is great but it can certainly be argued that there is no real advantage between +/- 1dB and +/- 2dB in this context as the room effects will always "overwhelm" this portion of the frequency range anyway. Also, I feel it is very important to have a frequency response that extends above the intended crossover point. If you see a frequency response that drops say....6-8dB by 100hz or so....that will affect the sound quality.

b) The second area is the deepest frequency operating range of the product.. With a quality subwoofer this will be in the 10-40hz range. In this frequency range you can have very different design goals depending on the manufacturer. While it is true that the overwhelming majority of music bass is recorded in higher frequencies, the shape of the frequency response in this "deep bass" range can be very important in regards to sound quality as well. The shape of the frequency response in this range will largely determine the subwoofer's "group delay", "impulse response", and "stored ringing" performance. These three metrics(combined with the frequency response data) can go a long way in predicting the overall sound quality of a subwoofer. Another important consideration when shaping the deep bass frequency response is room gain----also referred to as "pressure vessel gain". Below a certain frequency the room will no longer be able to support full sound wave length development. When this occurs the room begins to become "pressurized". The further you drop in frequency the more the pressure builds---the more the pressure builds the more of a volume boost the subwoofer will get. The size of the room, openings into other areas of the home, even the construction used will all influence the amount of "pressure vessel effect" one will experience. You can see this phenomenon in action with the reviewers and customer posting their in room frequency response of our products----particularly the XS15 and XS30 Power X subwoofers. The XS15, for example, begins a carefully shaped frequency roll off around 38hz(when measured quasi anechoic - aka "ground plane"). But when placed in a small to medium room environment the XS15 often measures relatively flat down to the 10hz range!

Why the CEA-2010 burst method is the most accurately way to gauge the maximum "clean" output capabilities of a subwoofer. I will quickly address some of the misinformation I have seen posted.

First I have seen comments that CEA-2010 is over lenient of harmonic distortion.

Not true. The CEA-2010 protocol has been developed based on extensive research into the audibility of harmonics in the typical subwoofer operating range. This research includes controlled listening tests with and without masking content. Any members of the AES will be able to find multiple white papers on the subject.

Second, I have seen comments that something like a long continuous sweep(or worse, a steady state signal like a sine wave) would be better indicators of a subwoofer's performance capabilities.

Again, not true. The tone bursts used in the CEA-2010 measurement process were *specifically* designed (By Don Keele!) to simulate the transient nature of music/film source material. If you are worried about winning a test tone war in a parking lot....okay, a sine wave will "load" the subwoofer much differently. But we have no/little concern with this at Power Sound Audio. Our only concern is how our product will sound with real world source material---music, home theater, etc.

There's a little reading about this subject here

http://www.diy-audio.narod.ru/litr/K..._EIA-426-B.PDF

http://www.synaudcon.com/site/articl...st-test-track/

The frequency response of a subwoofer is very different from the maximum output capabilities of a subwoofer. I have seen comments implying that it is more "accurate" if the subwoofer has all of its output capped at approximately the same SPL versus a subwoofer that does not. This is actually backwards assuming the latter has the same/higher output capabilities at all/most of the tested frequencies.

Let's look at two generic examples using the CEA-2010 industry standard measurement protocol.. Subwoofer *A* has a maximum output capability of 105dB at all measured frequencies----20,25,31,40,50,63hz. Subwoofer *B* has maximum output capabilities of 105dB at 20hz, 106dB at 25hz, 107dB at 31hz, and 110dB at 40hz, 50hz, and 63hz. Now, before we go further it is important to remember that at 105dB, subwoofer *B* will very likely maintain all of its inherent frequency response "linearity". So if the source material only requires 105dB of output....both subwoofers will sound very much alike. This assumes all other performance characteristics(group delay, impulse response, stored ringing, overall frequency response,etc) of the two example subwoofer are very similar too of course. For this example, let's assume these variables are all similar though so we can focus on one variable at a time.


Now, what if the source material requires the subwoofer to reproduce bass louder than 105dB at the seating position? What about 110dB? Well, subwoofer *A* will not provide ANY of this additional material that you are intended to hear and feel. All of the dyanmic headroom is "squashed" and the audio presentation will suffer accordingly. On the other hand, subwoofer *B* WILL provide all of this material in the 40hz and up range AND a good portion of it in the 25-40hz range. Will you experience all of the intended bass effects at the 110dB level from subwoofer B? No. But you will experience significantly more content that you are absolutely intended to hear/feel. The whole idea with audio reproduction is for the system to have the ability to reproduce AS MUCH of source material as possible.

The root of the misunderstanding in these cases seems to be folks assuming you can use a "maximum output graph" as an indicator of something other than...well....maximum output. You can *not* accurately determine anything from the maximum output graph except maximum output. This would be like looking at a frequency response graph and attempting to determine maximum output capabilities. Two VERY different graphs, each serving a singular purpose.

Jim and I have been comparing the above scenario in varying degrees in over a decade's worth of listening sessions and I can say, without any doubt, subwoofer *B* will always provide a much more dynamic, realistic presentation for both music and film material. I believe the feedback from other audio enthusiasts who have compared these "types" of subwoofers affirms this point of view as well.


Sorry for the long post(much of it I copy/pasted from my past thoughts).

Tom V.
Power Sound Audio
 
djreef

djreef

Audioholic Chief
...and this is why ID works so well. You really don't know how things are going to work until you get them in your specific home/studio environment. 30 day return policies rock!

DJ
 
S

shadyJ

Speaker of the House
Staff member
Hi Tom,

I am afraid I am going to have to disagree on a few of your points, one of which is that CEA is not too lenient in distortion levels. CEA-2010 testing has value, but that value is limited when a measurement as poor as over 34% THD makes a passing grade. This is especially true in the sub's band, 80 Hz and below, where the equal loudness curve veers sharply upward as the frequencies decline. It doesn't take much harmonic distortion to overwhelm the fundamental in deep bass, even just second order harmonic distortion. While I certainly don't have Don Keele's expertise, anyone with a tone generator can see for themselves which is more easily heard, a 20 Hz tone or a 40 Hz tone which is 10 dB lower. I would prefer a grading scale in CEA, in which a just barely passing score gets a D, and an extremely clean passing score would get an A. Also I think the equal loudness contour should be factored into the passing measurements, which it presently is not.

It's a bit odd that you are such an advocate of CEA testing when it was brought to my attention recently that you only very loosely adhere to its proscribed methodology. Per this post, CEA isn't normally supposed to be done indoors. I assume you were using a correction formula to make indoor measurements comparable to outdoor measurements? Even if you obtained similar results, one would hope for a more solid footing in measurements before you go on to compare your own results favorably to other products' measurements which were tested with a more rigorous adherence to CEA-2010 protocol, especially in light of the confusion your contradictory results ended up creating.

Furthermore, you state that you have updated your measurements with some outdoors testing, in a post dated 3/13. In Ohio? Any day in Ohio up to that point would have been much too cold to be within CEA parameters, as the denser air would be an advantageous condition for SPL tests vs humid, warm weather. CEA specifies testing be done within 62.6° to 80.6° F and 30% to 80% relative humidity, conditions not met in the timeframe you discuss, at least in your part of the world. Did you drive over to California to do your testing? Or did you just gloss over the permitted weather conditions for CEA testing, knowing that if anything that atmosphere will give your tests results a nice little boost. Seeing how your own CEA testing is plainly illegitimate, will you be sending samples of your product out for third party verification, ie Josh Ricci? Or is that not in your plans, and we should just accept the fiction that is your measurement results as comparable to other testers who take the protocol more seriously?
 
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Tom V.

Audioholic
1) You are missing the point entirely. CEA-2010 is an industry accepted protocol to measure distortions versus output and determine the audibility of those distortions with REAL WORLD SOURCE MATERIAL. Music and film. Introducing the concept of a test tone with no masking material has *zero* relevance to the topic.

2) We've performed/posted more CEA-2010 measurements than every other ID OEM combined. The CEA-2010 protocol outlines very specific details when measuring INSIDE or OUTSIDE. CEA-2010 has specific steps to follow when measuring inside or outside. We measure our products following these instructions.




3)

a)We OFTEN measure outside anything from mid 40s and up. The KEY is the wind and the sun. We measure on blacktop so if the sun is out....mid 40s are really pretty comfortable. If the wind is <10mph that helps with the comfort level too as well as lowering the "noise floor" of the environment.

We even measured in the rain one day. Two Umbrellas---One over the measurement rig and one over the DUT. OMG wait----CEA-2010 didn't specify measuring in the rain when necessary---off with Tom's head!

b) We have measured in temps from the upper 30s into the 90s. We have more documented measurement data on hand then you could possibly imagine. And we have measured the exact same subs in every conceivable weather condition. So we know *exactly* how measurements will be effected due to a temperature variance. the data doesn't change much. From 50 degrees and sunny to 80 degrees and sunny...you're looking at about 0.25-0.75dB(varies with other weather conditions).

Anyone following along, please feel free to email Josh Ricci and ask him about the relevance of measuring at 50-60 degrees(sunny on blacktop at 45-50f) versus 60-65 degree ambient temps. After he gets down laughing he'll probably ask...."let me guess, shaydj is after TV again?"..:)

Tom V.
Power Sound Audio
 
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S

shadyJ

Speaker of the House
Staff member
Anyone following along, please feel free to email Josh Ricci and ask him about the relevance of measuring at 50-60 degrees(sunny on blacktop at 45-50f) versus 60-65 degree ambient temps. After he gets down laughing he'll probably ask...."let me guess, shaydj is after TV again?"..:)
And after you finish asking Josh about that, also ask him what he thinks about the method in which Tom is using CEA measurements to sell his products. Oh wait, you don't have to, because he has already addressed that here. And if indoor measurements are such a reliable way to produce CEA data, why the discrepancy which was the cause of confusion that forced you to admit you were testing indoors in the first place? One would hope you would have better consistency when you go on to compare the CEA measurements of other products unfavorably to yours.

As for test tones vs real world material, there certainly is a difference, but in either one having the output consisting of over 1/3 THD is very poor. One would hope for greater fidelity, but then again when you use (or more properly stated, 'misuse') CEA measurements as a primary marketing tool, it certainly pays to have as much latitude and room for ambiguity as you can get.

One more thing you did not address, if your range of weather conditions result in such a small margin of performance, your tests results should be easily reproducible by a third party, ie Josh Ricci. Do you or don't you have any plans to have your internal test results confirmed by anyone else? As it is, I have no trust in the figures you report.
 
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Tom V.

Audioholic
1)I've already stated we much prefer to measure outside. But when you have the amount of data we do on dozens of products measured outside it isn't complicated to do a series of transfer functions to ensure an indoor measurement is accurate. CEA-2010 explains this and approves of it as well. Sorry you don't approve. Stop in some time and Jim and I can show you how indoor measurements can be *very* accurate with enough experience and the correct methods. Also, perhaps I should explain, by "indoors" we're talking about a warehouse that is 100ftx30ftx20ft(high). Now, consider the length of the burst(6.5ms). Its really not as hard as you think to get accurate, repeatable data-sets.

2)CEA-2010 isn't a marketing tool. CEA-2010 is an industry standard for measuring subwoofer headroom. We provide that information to our customers who are interested in it. Sorry you feel that is a poor idea.

3)The primary consideration with regards to temps outside is the microphone element. Any professional microphone is going to be fine well below 45 degrees. . CEA-2010 protocol suggesting a minimum temp around 60 degrees is very likely trying to protect against circuit board condensation/PC failures. That is a risk of course.

4)Josh has already measured 3 of our products(which is more than ANY other ID company except svs!) with all of his data-sets being extremely close/identical to our posted data-sets. We do have plans to have all of the new ICE powered products measured once we're able to ensure stable inventory for each model. As of now, the S1500 is still back ordered several weeks, we JUST got caught up with V1500 orders(2 days ago?) and they will likely be "out of stock" again soon. And we have very low stock on the S3000i. I guarantee we'll be out of stock on these for weeks. We've already turned down approximately half a dozen review requests because a couple of our key suppliers simply cannot keep up with demand. We are doing our best to remedy this asap.


Tom V.
Power Sound Audio
 
S

shadyJ

Speaker of the House
Staff member
Second, I have seen comments that something like a long continuous sweep(or worse, a steady state signal like a sine wave) would be better indicators of a subwoofer's performance capabilities.

Again, not true. The tone bursts used in the CEA-2010 measurement process were *specifically* designed (By Don Keele!) to simulate the transient nature of music/film source material. If you are worried about winning a test tone war in a parking lot....okay, a sine wave will "load" the subwoofer much differently. But we have no/little concern with this at Power Sound Audio. Our only concern is how our product will sound with real world source material---music, home theater, etc.

There's a little reading about this subject here

http://www.diy-audio.narod.ru/litr/K..._EIA-426-B.PDF

http://www.synaudcon.com/site/articl...st-test-track/
One more thing I wanted to address was this point. I wouldn't claim that burst performance is less important than continuous sweeps, however the sub's long term behavior is an important facet of its performance and shouldn't be discounted so readily, unless all you listen to is kick drums, gunshots, and explosions (so, the typical PSA customer). There is a lot of music and even some movies with continuous bass which resembles a long term sweep more than a short term burst, and long term sweeps are more relevant with respect to how the subwoofer handles those situations than burst tests. A particularly relevant example currently is the Interstellar OST, with its continuous deep bass notes, like so:

A sub which has a big difference in long term output vs burst tests will have problems accurately playing back material like this. Such a sub would end up playing back the note substantially quieter then how the note is started, in effect being unable to accurately sustain the sound. Some subwoofers compress long term output more than others, and for those of us who listen to music that contain this sort of bass (some organ music and a variety of electronic music), its worth comparing the difference between the two metrics. Burst testing is not the only metric that matters.
 
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Tom V.

Audioholic
Someone just came into chat asking what a "transfer function" means.

Here is a quick example before I call it a day(I know, HALF a work day?)

Let's say we have a subwoofer that measures 100dB per CEA guidelines at every test frequency from 16hz to 100hz when measured outside at 2 meters.

When we bring it into our 100x30x20 warehouse we measure 102dB at 16,25,31,40,50hz and 100dB at 63,80,100hz.

The transfer function here would be to subtract 2dB from 16-50hz to minimize any differences between the outdoor test and an indoor test.

We checked about 10 different subs(ported and sealed) in various orientations (driver firing up, down, sideways). Averaged the differences(which were all minor) and the result was a transfer function that has proven to be nearly identical to the outside measurements we have taken in the last month.

Its really an easy process if you have the amount of data we do on file(and a very large room environment).

And yes, out of the MILLION(?) bassy scenes in thousands and thousands of DVDs/BLU RAYS....you WILL be able to find a few examples that resemble a sweep. But the way these scenes "load" a subwoofer will still be different than a steady state test tone.

As always, we encourage everyone to listen for themselves. That is why we offer the 30 day trial period with free shipping both ways. Grab the XS15se at $749, give it a whirl, let me know what other sub at/near its price point sounds better to you...;)

Tom V.
Power Sound Audio
 
S

shadyJ

Speaker of the House
Staff member
1)I've already stated we much prefer to measure outside. But when you have the amount of data we do on dozens of products measured outside it isn't complicated to do a series of transfer functions to ensure an indoor measurement is accurate. CEA-2010 explains this and approves of it as well. Sorry you don't approve. Stop in some time and Jim and I can show you how indoor measurements can be *very* accurate with enough experience and the correct methods. Also, perhaps I should explain, by "indoors" we're talking about a warehouse that is 100ftx30ftx20ft(high). Now, consider the length of the burst(6.5ms). Its really not as hard as you think to get accurate, repeatable data-sets.

2)CEA-2010 isn't a marketing tool. CEA-2010 is an industry standard for measuring subwoofer headroom. We provide that information to our customers who are interested in it. Sorry you feel that is a poor idea.

3)The primary consideration with regards to temps outside is the microphone element. Any professional microphone is going to be fine well below 45 degrees. . CEA-2010 protocol suggesting a minimum temp around 60 degrees is very likely trying to protect against circuit board condensation/PC failures. That is a risk of course.

4)Josh has already measured 3 of our products(which is more than ANY other ID company except svs!) with all of his data-sets being extremely close/identical to our posted data-sets. We do have plans to have all of the new ICE powered products measured once we're able to ensure stable inventory for each model. As of now, the S1500 is still back ordered several weeks, we JUST got caught up with V1500 orders(2 days ago?) and they will likely be "out of stock" again soon. And we have very low stock on the S3000i. I guarantee we'll be out of stock on these for weeks. We've already turned down approximately half a dozen review requests because a couple of our key suppliers simply cannot keep up with demand. We are doing our best to remedy this asap.


Tom V.
Power Sound Audio

Points 1 and 2 don't really address the issue that you have already run into problems with your use of CEA data. Those undermine your fourth point, the matter with having your results confirmed by an independent tester. Until you restrict your comparison charts to a single (preferably third party) data set, it is essentially misleading.
 
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billy p

billy p

Audioholic Ninja
Man this ShadyJ fella is really full of it. Just runs his mouth with a lot of circular reasoning and straw man nonsense.

Just google his name and PSA. Wow.
No point getting yourself in hot water over this guy...I used similar comments over at AVS and received a insulting other members warning. Maybe that's why he has taken things on such a personal level as others have mocked him. He's really not worth anyone's time...he's a legend in his own mind.
 
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ATLAudio

ATLAudio

Senior Audioholic
No point getting yourself in hot water over this guy...I used similar comments over at AVS and received a insulting other members warning. Maybe that's why he has taken things on such a personal level as others have mocked him. He's really not worth anyone's time...he's a legend in his own mind.
You're right, but I just get fired up over someone who's is just obviously on a mission to trash one manufacturer. It truly spoils the environment for those who are seeking the best information. Someone who has enormous bias to account for and who is on an easily documented mission, simply should NOT be allowed to continue. Or that's my opinion at least.

AH should see it for what it is, and WARN HIM. it's his kind of posting which makes a toxic environment, and AH should address that.
 
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KEW

KEW

Audioholic Overlord
I suspect he got such a warning. You'll note that his last post was edited by a moderator.

Tom V.,
I applaud you for your patience and thanks for the information you have presented. I know if you let his statements stand unanswered many will believe they have validity. It doesn't seem fair that you need to spend your Easter defending your company from this type of malice, but thank you. Those of us who know him to have made false statements in the past would feel obliged to refute him so newbies would not be misled, but you do it much better.
 
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S

shadyJ

Speaker of the House
Staff member
Those of us who know him to have made false statements in the past would feel obliged to refute him so newbies would not be misled, but you do it much better.
Please point to a false statement of mine. Just one. If you can't accomplish that much, where does that leave you and the accusation of levying false statements?
 
KEW

KEW

Audioholic Overlord
Please point to a false statement of mine. Just one. If you can't accomplish that much, where does that leave you and the accusation of levying false statements?
In post #27 of the thread linked below, you state that no measurements exist to indicate sealed mode offers better articulation and clarity than ported mode. This was in the context of whether Myriad1973 should use his HSU VTF2 in ported or "sealed" mode.

http://forums.audioholics.com/forums/threads/i-need-help-choosing-a-new-sub.93718/page-2#post-1075641

That is a false statement. Data-bass measurements clearly show the improved impulse response of the VTF15 in sealed mode over ported mode. I posted these graphs in post #28 of said thread or you can find them via the link below.

http://www.data-bass.com/data?page=system&id=100
 
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shadyJ

Speaker of the House
Staff member
The mods have already done this- on this thread. It's been done routinely on AVS.

This statement should help prove everyone's point.
The mods did not alter my post to correct misinformation. They only removed a jab to make it a bit more civil. The mods at AVS have never altered any of my posts. If there is a problem with anyone's posts at AVS, those posts are simply removed. Out of over 7000 posts at AVS from posting since 2009, I have had a grand total of 4 posts removed, and none of them were removed for spreading false information. As for being wrong, I am wrong about a lot of things very frequently, however I haven't made any deliberately misleading statements as KEW stated, a statement which he is unable to back up with any evidence.
 
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Alex2507

Alex2507

Audioholic Slumlord
You just have to ignore this guy. It works surprisingly well with the new forum set up. Try it. Your experience will get better. Promise.
 
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shadyJ

Speaker of the House
Staff member
In post #27 of the thread linked below, you state that no measurements exist to indicate sealed mode offers better articulation and clarity than ported mode. This was in the context of whether Myriad1973 should use his HSU VTF2 in ported or "sealed" mode.

http://forums.audioholics.com/forums/threads/i-need-help-choosing-a-new-sub.93718/page-2#post-1075641

That is a false statement. Data-bass measurements clearly show the improved impulse response of the VTF15 in sealed mode over ported mode. I posted these graphs in post #28 of said thread or you can find them via the link below.

http://www.data-bass.com/data?page=system&id=100
Lol, I am not so sure the measurements of the Hsu prove your point, because the differences are so slight and very unlikely to be audible. If I were you, I would have used the PB13 Ultra as evidence to that effect, as the impulse response is far more improved going from ported to sealed. That said, articulation and clarity are subjective terms, and I probably should not have used the word measurements when a better way to gauge articulation and clarity would be something like a blind test. Anyway, since there are no studies that I know of where anyone is able to differentiate between a sealed and ported subs when all other things are equal, I would say my point stands, although it is perhaps badly stated.
 
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