Official Power Sound Audio (PSA) Thread - Page 36 - Home Theater Forum and Systems -

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post #351 of 811 Old 02-03-14, 03:46 PM
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Re: Official Power Sound Audio (PSA) Thread

Saturn94 wrote: View Post
Good memory.

You're right, mixing the 16-46+ with the Triax did result in cancelations around the tuning point. It was encouraging that at least part of the spectrum did show improvement (above 20hz or so if my memory is correct). So my thinking is a sealed sub should give me the benefits above 20hz while not having the cancelation issues below 20hz.

Someone suggested a Seaton SubMersive would be a good match, but they have also gone up in price and would likely be more than I could spend. That brings me to the XS30. But I'm getting ahead of myself as it will be at least a year before I can consider going down that road . No biggie though, I'm thoroughly enjoying the Triax for now.
My thoughts also, I think a XS30 will compliment my Triax
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post #352 of 811 Old 02-08-14, 03:21 PM
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Re: Official Power Sound Audio (PSA) Thread

BTW, not sure if everyone has seen...

Reviewer Brent Butterworth wrote: “The bass was nothing less than brutal. When I played the 16-Hz low notes from the Organ Symphony, the XV15 whupped the other subs easily. The whole room pulsated, almost as if some sort of monster had plucked my home off the slab and begun shaking it like a toy.”

Also, go down that list and see how many of the winners are made right here in America..

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post #353 of 811 Old 02-08-14, 04:34 PM
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Re: Official Power Sound Audio (PSA) Thread

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!

Hopefully this explains my thought process a little when the discussion turns to subwoofer frequency response. Part 2 coming up..

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post #354 of 811 Old 02-08-14, 04:58 PM
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Re: Official Power Sound Audio (PSA) Thread

Quick part 2.

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.

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

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post #355 of 811 Old 02-08-14, 05:09 PM
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Re: Official Power Sound Audio (PSA) Thread

Part 3:

Before going on it is important to remember that a graph showing you maximum CEA-2010 output is *not* a graph showing you maximum output capabilities. The CEA-2010 data uses restrictive harmonic distortion limits. Take away these limits and subwoofers will score higher output numbers. Just how much higher depends on several variables. But all of this is beyond the scope of this quick write up so let's stay focused on the CEA-2010 burst numbers.

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.

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post #356 of 811 Old 02-09-14, 12:52 AM
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Thanks Tom! for the very detailed run down on a subject that seems to be argued hear and on many other threads.
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post #357 of 811 Old 02-09-14, 04:44 AM
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+1! Very good information Tom! Real world performance is what matters most. Testing is good to get an idea of how something will likely perform but it definitely does not tell the whole story.
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post #358 of 811 Old 02-09-14, 11:16 AM
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Re: Official Power Sound Audio (PSA) Thread

Great posts Tom. Thanks.
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post #359 of 811 Old 02-09-14, 01:06 PM
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Re: Official Power Sound Audio (PSA) Thread

Whoa...that was good information...I kind of understood some of that...but your explanation helps paint a much clearer portrait.

Like the others already said....thanks, Tom

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post #360 of 811 Old 02-09-14, 08:26 PM
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Re: Official Power Sound Audio (PSA) Thread

Great post Tom!!
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