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post #451 of 479 Old 05-25-2011, 05:59 AM
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Quote:
Originally Posted by mphfrom77 View Post

With all this talk in other threads lately about how we really can't judge subs based on the manufacturers claims and in room results, I think it is sad that Ricci has only had one company send him a sub for testing. (Rythmik possibly sent one in...I really don't know.) Maybe they are waiting for his next round of results to come back...idk.

Companies went through the process with Illka and its not always a smart business decision to do it. DIY subs tend to overshadown commercial offerings. Anyone that owns a business understands that its not an intelligent move to place your product up against superior products. The goal of any company is to successfully market their product in a way that maximizes its value and minimizes its flaws.

3rd party measurements tend to maximize the flaws


Saying that Im still excited about the 2nd round of testing results. I want to see how bad/how good that BIC sub is relative to its price point.

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post #452 of 479 Old 05-25-2011, 07:17 AM
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It's not that the outdoor GP regimen is the be-all, end-all of subwoofer performance comparison data. In fact, no one has really ever devised a system for translating the data into real world actual use of a subwoofer.

So far, it's been: "Loud good, harmonic distortion bad".

The CEA numbers are considerably higher than the old 10% THD limited sine wave numbers, so "loud good" gets bumped up a notch and THD gets bumped down a notch and not much else has happened.

IMO, Keith Yates had the real deal. He included SL's shaped tone bursts long before CEA. He actually used his ears to determine the maximums. He also is the only guy ever to include SpectraLab graphs to compare the actual content to the subs reproduction of that content, which is the closest test to real world there is.

Unfortunately, even though it's one of the simplest test to conduct, since all of the digital graphs can be done indoors at one's leisure and stored for future use, no one has followed Yates' lead with SL.

AND... when it comes to moving any testing into an actual room, the experts hit a concrete wall of superstition and morbid fear. OMG, the ROOM!!!, It can't be done!! It's a mystery that no one can ever solve!! It has SWAMPS and MODES and NODES and every one is DIFFERENT!!!

Pity... so close, yet so far away. The next gen is just not interested in taking the baton and running. Josh seems to be on his own. So, wait it is and don't hold your breath waiting for the guys with the wild and crazy performance claims 'cause they're NEVER gonna send Josh a sub.

Bosso
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post #453 of 479 Old 05-25-2011, 07:45 AM - Thread Starter
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Completely agree about manufacturers never sending something to test. Who would want to have a lambo against a "tuned" buick that costs a tenth of the cost and find out the buick wins? Yes there will still be people lined up for the lambo just because of the name and reputation, but how many customers will they lose when the buick beats it? Sketchy subject for manufacturers.

The outdoor vs indoor testing...the way I see the testing for outdoor is plain and simple, it keeps the playing field even. It shows the sub for what it is and no adding or skewing the sound or performance. You're not having a quarter mile race with a kia and a porsche where the porsche is on a frozen lake and the kia is on the bank.
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post #454 of 479 Old 05-25-2011, 08:22 AM
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I've got to be honest here... In the last couple of months I have started to think "What have I gotten myself into?". It is so much work. Unless you have done something like this you will never know. Most of the time all you will get back is a little respect from some, the data itself and a healthy dose of bickering over the data or how it was taken. I've thought about giving it up already a couple of times. That's not really an option either I have too much invested. The positive thing is that I should get to a point where things are easier and quicker and routine. I have a very large hump to get over first though. I should be getting close.

As far as manufacturers sending subs in...The ones who are confident that they have a solid, competently designed unit might go for it. Others will not. I bought 3 of the subs tested last round mostly out of pocket. I have managed to sell all 3 but I still took a significant loss on the deal overall. I figure it is a necessary cost to get things started up.

I did happen to do some tests that will turn into an article about room gain and subs with multiple radiating surfaces. I put quite a bit of effort into testing the Empire versus other single side radiating subs both outdoors and in room in order to give the dual opposed Empire a fair shake in the tests. This was kicked off after being sent an email from Epik concerned about the tests. Should be interesting.

There is a bunch of other things in the pipeline. There should be a generous amount of testing and retesting in the next 3 months. Mostly diy type stuff.

Don sent me a generator that produces 3 of his shaped bursts spaced at 1/3rd octave intervals simultaneously. It is a broad band signal that represents a complex wide range bass signal pretty well. I am planning to incorporate it in some way probably involving SL. Any other ideas for how best to use SL for quick tests comparing input signal and sub output waveform in an outdoor setting? Bosso? I am not going to test every sub indoors and then outdoors it is too time consuming and rather difficult with some of the bigger subs. I would be more interested in testing different rooms themselves with a known subwoofer, measurement rig and drive level.
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post #455 of 479 Old 05-25-2011, 01:02 PM
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Quote:
Originally Posted by bossobass View Post

AND... when it comes to moving any testing into an actual room, the experts hit a concrete wall of superstition and morbid fear. OMG, the ROOM!!!, It can't be done!! It's a mystery that no one can ever solve!! It has SWAMPS and MODES and NODES and every one is DIFFERENT!!!"

Not sure what your point is.

As you know, every room is different and test results from different rooms can vary by a huge amount.

What then are you suggesting, if anything?

Noah
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post #456 of 479 Old 05-25-2011, 01:04 PM
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Yes.

My idea is to come to a consensus of where room gain starts and what the average dB/octave increase is. We already have plenty of sources and articles on the subject, as well as members posted in-room vs close mic graphs and their willingness to participate in gathering further data on the subject.

Once the consensus is reached, we can vote on some movie scenes that would represent a well rounded collection of average and extreme effects.

Once you have the scenes, a consensus for SpecLab settings can be arrived at and the scenes can be graphed and stored at your leisure (I, for one, would be happy to contribute the that part of the effort).

My idea is to take Yates' SL tests one step further by applying a mic cal derived from the consensus average room gain transfer function, mic the scenes as rendered by each sub with the mic cal file engaged.

This would simulate the subs performance in the average room with a smoothed in-room response at the LP. and, a 1M mic distance will roughly offset typical boundary gain at typical listening distance of 3-4M.

This is a good compromise between the lack of any room gain effects in Yates' version and the problems encountered in deciding on a room and how to deal with other room effects.

Just my 2 cents. I do these SL direct vs mic'd sub comparos for every sub I build and with every movie I watch. I find them to be the most revealing and analytical test there is.

Bosso
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post #457 of 479 Old 05-25-2011, 04:07 PM
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Quote:
Originally Posted by bossobass View Post

In fact, no one has really ever devised a system for translating the data into real world actual use of a subwoofer.

No one? I've seen plenty of literature on the subject with good correlation to real world results.

Quote:
Originally Posted by bossobass View Post

So far, it's been: "Loud good, harmonic distortion bad".

For who? I most certainly don't read these measurements in that manner at all...

Quote:
Originally Posted by bossobass View Post

IMO, Keith Yates had the real deal. He included SL's shaped tone bursts long before CEA. He actually used his ears to determine the maximums. He also is the only guy ever to include SpectraLab graphs to compare the actual content to the subs reproduction of that content, which is the closest test to real world there is.

Right, because using ears is far more repeatable and without bias...

For what it's worth, the output from spectralab is almost completely useless. I would highly recommend learning how to interpret other methods of measuring performance as they offer far greater levels of precision and repeatability.

Quote:
Originally Posted by bossobass View Post

AND... when it comes to moving any testing into an actual room, the experts hit a concrete wall of superstition and morbid fear. OMG, the ROOM!!!, It can't be done!! It's a mystery that no one can ever solve!! It has SWAMPS and MODES and NODES and every one is DIFFERENT!!!

Which "experts" are you referring to, and what specifically was said?

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post #458 of 479 Old 05-25-2011, 04:12 PM
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Originally Posted by MBentz View Post

No one? I've seen plenty of literature on the subject with good correlation to real world results.


For who? I most certainly don't read these measurements in that manner at all...


Right, because using ears is far more repeatable and without bias...

For what it's worth, the output from spectralab is almost completely useless. I would highly recommend learning how to interpret other methods of measuring performance as they offer far greater levels of precision and repeatability.



Which "experts" are you referring to, and what specifically was said?

Everyone knows you're exempt because you're special.

Bosso
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post #459 of 479 Old 05-25-2011, 08:39 PM
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Quote:
Originally Posted by Ricci View Post

I've got to be honest here... In the last couple of months I have started to think "What have I gotten myself into?". It is so much work. Unless you have done something like this you will never know. Most of the time all you will get back is a little respect from some, the data itself and a healthy dose of bickering over the data or how it was taken. I've thought about giving it up already a couple of times. That's not really an option either I have too much invested. The positive thing is that I should get to a point where things are easier and quicker and routine. I have a very large hump to get over first though. I should be getting close.

As far as manufacturers sending subs in...The ones who are confident that they have a solid, competently designed unit might go for it. Others will not. I bought 3 of the subs tested last round mostly out of pocket. I have managed to sell all 3 but I still took a significant loss on the deal overall. I figure it is a necessary cost to get things started up.

I did happen to do some tests that will turn into an article about room gain and subs with multiple radiating surfaces. I put quite a bit of effort into testing the Empire versus other single side radiating subs both outdoors and in room in order to give the dual opposed Empire a fair shake in the tests. This was kicked off after being sent an email from Epik concerned about the tests. Should be interesting.

There is a bunch of other things in the pipeline. There should be a generous amount of testing and retesting in the next 3 months. Mostly diy type stuff.

Don sent me a generator that produces 3 of his shaped bursts spaced at 1/3rd octave intervals simultaneously. It is a broad band signal that represents a complex wide range bass signal pretty well. I am planning to incorporate it in some way probably involving SL. Any other ideas for how best to use SL for quick tests comparing input signal and sub output waveform in an outdoor setting? Bosso? I am not going to test every sub indoors and then outdoors it is too time consuming and rather difficult with some of the bigger subs. I would be more interested in testing different rooms themselves with a known subwoofer, measurement rig and drive level.

FWIW, I think there are two kinds of measurements: one where you use quantifiable metrics to isolate and fix problems, and the other where you try to quantify absolute performance.

Trying to quantify absolutes like you're talking about is a very tall order. At work, we could easily spend a week making the measurements that will end up in marketing material, but it may only take a minute or two to drive the design.

I've been thinking about your databass and was wondering if it might be less work if you just try to compare various design choices, rather than actual finished product. For example, you could use an infinite baffle configuration with quick clamps to get the non-linearity of the driver separate from the enclosure and alignment. Anyone that understands how the cabinet alignment works would be able to make the appropriate design choices and then the resultant performance is merely academic to quantify. Likewise, you could pick a driver to use to quantify the behavior of different sized ports, passive radiators or even cabinet dimensions. The nice thing about audio is everything scales with wavelength so it's not hard to predict how things will behave - even with a dramatically different application.

Anyways, just thinking out loud...I'd hate to see you get burnt out after getting this far.

Btw, I wanted to thank you for your work as I've already made good use of some of your data.

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post #460 of 479 Old 05-25-2011, 08:41 PM
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Originally Posted by bossobass View Post

Everyone knows you're exempt because you're special.

Bosso

Let's not be jealous now...

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post #461 of 479 Old 05-25-2011, 08:45 PM
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One other question for you Ricci, any chance of adding a column to the systems page that lists the total enclosure volume? Might be interesting to create a metric of performance vs size, or maybe even performance vs price...

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post #462 of 479 Old 05-25-2011, 11:07 PM
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"any chance of adding a column to the systems page that lists the total enclosure volume? "

that should be pretty easy if the external dimensions are part of the data-bass.

if the data hasn't been collected, sol.

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post #463 of 479 Old 05-26-2011, 06:16 AM
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For what it's worth, the output from spectralab is almost completely useless. I would highly recommend learning how to interpret other methods of measuring performance as they offer far greater levels of precision and repeatability.

Your posts smack of an ego with a personal problem, but unfortunately lack anything of pertinent value.

So far I have:

1) ACO Pacific's system noise follows an A weighted curve.

2) Everything below 30 Hz in my measurements is useless.

3) The Tukey window causes a 20 dB error in my graphs.

4) SpectrumLab is useless.

BTW, have you asked Josh what measurement hardware he's using? If the ACO Pacific hardware is off by 20dB or more, why aren't you offering your tutorial to him?

FWIW, the RS meter is far from a precision instrument for measuring the dBSPL of a tone at a particular location in room, but it's very accurate for comparing the difference in dBSPL between 2 sources at that same location.

To date, Keith Yates has turned in the best eval of HT subwoofers on record.

And you? I'm still waiting for these precision results you keep suggesting.

Bosso
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post #464 of 479 Old 05-26-2011, 09:24 AM
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I see that things are progressing as normal around here...

Anyway I actually did have a graph set-up that had the subs external volume and weight. It would've had the smallest and lightest sub and the largest and heaviest sub for comparison to the DUT. Kyle didn't incorporate it though. DAMN YOU KYLE!!! Seriously though it was sort of clunky. Incorporating some sort of size / weight metric has been a goal from the beginning. We all know it is far easier to get big bass from a refrigerator than a microwave. We are listing the dimensions, weight and external size already but it is on the system overview page. I will talk with Kyle and see what we can do about perhaps getting it in the charts.

From talking with a few sub manufacturers and reading some of the discussions going on lately it appears that quite a few out fits are tweaking their offerings simply in an effort to get higher CEA2010 burst numbers. Remember the official cea2010 test is 6 center freq's between only 20 and 63hz barely an octave and a half. This is a negative side effect of having a standard test. In one way it is good in that it does tend toward engineering the subs to have higher headroom in this range which is the majority of the bass content IMHO. However at what point are some sacrifices made in other areas just to do well in this test? This is part of the reason that I am extending the burst testing to cover a much wider range from 10-125hz using 12 center freq's, which is nearly 3.5 octaves and a much bigger chunk of the LFE bandwidth. It is much more difficult to make a sub that gives a good showing over that entire range. Granted that most subs will have no output to speak of below 16hz at 2m gp but those that do will be that much more impressive for doing so. Also I have heard it said that there is no reason to test past 63hz as the subs will inevitably be amp limited. This is true, but isn't it still of interest to know what the amplifier and speaker combo is capable of past there? The bass range does not end at 63hz. The LFE channel extends up to 120hz and the 63-125hz octave is one of the richest and heavily concentrated in music. Not all subs have a linear frequency, impedance or power response by any means either.
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post #465 of 479 Old 05-26-2011, 09:39 AM
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Ricci,

Maybe a basic question but why would a sub be amp limited past 63HZ? Thanks.

James
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post #466 of 479 Old 05-26-2011, 11:00 AM
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Actually its usually more like 50hz on up...

The higher bass frequencies don't require as much excursion. The amps don't typically has the huge amount of voltage required to mechanically over drive the driver at those frequencies. The bursts are very short duration so there is no chance of overheating the voice coil either.
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post #467 of 479 Old 05-26-2011, 11:02 AM
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Thank you.

James
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post #468 of 479 Old 05-26-2011, 11:18 AM
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Quote:
Originally Posted by bossobass View Post
So far I have:

1) ACO Pacific's system noise follows an A weighted curve.

2) Everything below 30 Hz in my measurements is useless.

3) The Tukey window causes a 20 dB error in my graphs.

4) SpectrumLab is useless.
Well the only one you got right is how useless SpectrumLab is...

Quote:
Originally Posted by bossobass View Post
BTW, have you asked Josh what measurement hardware he's using? If the ACO Pacific hardware is off by 20dB or more, why aren't you offering your tutorial to him?
He's not drawing insane conclusions, and is actually setting things up properly, and completely quantifying his measurement method.

He's also not posting pretty flat lines, nor pushing "progress" by misleading people in ways that result in damaged systems.

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post #469 of 479 Old 05-26-2011, 12:54 PM
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Originally Posted by MBentz View Post
Well the only one you got right is how useless SpectrumLab is...


He's not drawing insane conclusions, and is actually setting things up properly, and completely quantifying his measurement method.

He's also not posting pretty flat lines, nor pushing "progress" by misleading people in ways that result in damaged systems.
Baloney.

You mean to say that he's using better hardware than ACO Pacific and uses the Blackman-Harris window?

If you prefer to dodge the questions, say so.

I've been pushing that "progress" since 25 Hz was the bottom, according to guys like yourself, who know everything but post nothing.

Instead of hijacking threads, start a thread about your superior suggestions, test methods and hardware vs Bosso's insane ideas and damaging advice.

We can keep this up as long as you care to. You have no credibility with me, and you've had all the passes you're gonna get.

Bosso
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post #470 of 479 Old 05-29-2011, 05:42 PM
 
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Bosso, do you know if SpecLab is capable of, or the author could easily add capability to do subtraction of sweeps?

I'm thinking if you run a waterfall of your actual in-room output (as you do, or outdoor GP output with added average room gain curve), subtract it from the reference waterfall for a given scene (derived from digital, perhaps within an "audible match" window, say +/-3dB or less) you could plot a waterfall of the differences in varying intensity to know where your in-room response differs from reference and also possibly calculate a percentage accuracy to reference.

I'm envisioning a catalog of results from DIY designs and commercial subs with waterfalls showing their variance from reference reproduction for the most demanding film bass scenes along with a calculated score for accuracy.

Perhaps three classes created for a 3-120Hz accuracy, 12-120Hz and 24-120Hz scores.
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post #471 of 479 Old 05-29-2011, 07:03 PM
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Quote:
Originally Posted by bossobass View Post

Baloney.

You mean to say that he's using better hardware than ACO Pacific and uses the Blackman-Harris window?

If you prefer to dodge the questions, say so.

I've been pushing that "progress" since 25 Hz was the bottom, according to guys like yourself, who know everything but post nothing.

Instead of hijacking threads, start a thread about your superior suggestions, test methods and hardware vs Bosso's insane ideas and damaging advice.

We can keep this up as long as you care to. You have no credibility with me, and you've had all the passes you're gonna get.

Bosso

I'm with you on this. What do you expect when dealing with armchair experts though?
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post #472 of 479 Old 06-25-2011, 08:50 AM
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Josh,

Thanks so much for creating real data!

One other new thing - please stop groaning, everyone! - that I think may be of benefit, brought on by Brian's idiotic comment in the Rythmik testing thread that his sub - a 15" driver with a 2" voicecoil - had no power compression because of its servo, is to take measurements of broadband power compression. Something along the lines of the graph in this old JBL Tech Note, at 5. Though perhaps with a different bandwidth (say, 30-120Hz) of noise, and maybe a constant voltage rather than power (if only because that seems intuitively easier to measure).

The power compression graph format you inherited from Illka and the TalkBass stuff does not show anything about broadband power compression, and can lead to people being misled by statements such as Brian's.

Perhaps you already have such data but haven't displayed it thusly?

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post #473 of 479 Old 06-25-2011, 09:41 AM
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Brian's driver is a 3" coil. That was a typo on my part corrected a couple days ago. His servo system does inherently seem to correct for compression while the amplifier has enough power to do so. I don't think that a broad bandwidth signal would change this behavior.

I am not sure that a test like you propose would show much difference. I would still expect the individual subwoofer compression performance to be the same relative to another. The test as is already identifies what frequency ranges are most prone to compression for each sub also.

What I have wanted to do for awhile is a short term wide bandwidth signal, dynamic tracking test which Don Keele already has conveniently already developed a perfect signal for. I just need to devise the way to capture and present it.
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post #474 of 479 Old 06-25-2011, 10:41 AM
 
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Josh, Do you have any idea when the last tests results will be posted on your site?
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post #475 of 479 Old 06-25-2011, 11:21 AM
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At this point I don't Mike. If you want me to I can post your test in the subwoofer forum here.
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post #476 of 479 Old 06-25-2011, 11:56 AM
 
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At this point I don't Mike. If you want me to I can post your test in the subwoofer forum here.

Sure, if it is not too much trouble.
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post #477 of 479 Old 06-25-2011, 08:44 PM - Thread Starter
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Hey Mike,

Did you send josh a sub? The maelstrom? Give me a call some afternoon when you get a chance. I gotta get you down here to check out what I got going now.
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post #478 of 479 Old 06-26-2011, 02:24 PM
 
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Originally Posted by brandonnash View Post

Hey Mike,

Did you send josh a sub? The maelstrom? Give me a call some afternoon when you get a chance. I gotta get you down here to check out what I got going now.

Josh said he had a 18" Mal-x coming from some one else. I loaned him my ED A7S-450. Josh was wanting some commercial subs to compare to DIY subs.

Yes, I would like to come down and see what you have going on. Send me a PM, filling me in. My latest project was building a HTPC. I added it to the system a month ago. Building it was easier than I expected. Got my brother to help with the software. Talk about cool, having all of your movies displayed and readily available is great. I added dual TV tuners to it last week. Now I have full dual tuner DVR capability for recording SD and HDTV (clear QAM), while only paying the cable company for basic cable service.

My home phone number has changed. I now use VOIP (voice over internet protocol).
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post #479 of 479 Old 06-26-2011, 08:27 PM
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Quote:
Originally Posted by DS-21 View Post

...idiotic comment in the Rythmik testing thread that his sub - a 15" driver with a 2" voicecoil - had no power compression because of its servo...

Quote:
Originally Posted by Ricci View Post

... His servo system does inherently seem to correct for compression while the amplifier has enough power to do so.

If the sensor measures a mechanical parameter (acceleration, velocity, or position) as opposed to electrical, then the error signal would demand more power from the amp to counteract compression.

Noah
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