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Official Craigsub rankings thread - Page 27  

post #781 of 6764
Quote:
Originally Posted by jakeman View Post

Laugh all you like, its indicative . Anyone can see they are amplitude graphs of certain movie scenes and not FR based on sweeps. Its been mentioned at least half a dozen times. There is no confusion to anyone following this thread and, while more technically accurate, renaming the graphs doesn't change anything. What we do have is a question posed regarding one subwoofer's seemingly abnormal behaviour during part of a scene. Its something worth following up on and the right person to do it is the guy who posed the question.

When something like that has bothered me enough I've done the analysis and presented alternate data and I expect the same here from Stan otherwise his posts serve no purpose but to disrupt the flow of this thread.

Exactly right and well said John.
post #782 of 6764
Okay, here is the first post where craigsub started posting the "peak hold" measurements for different subs - these scenes being from WotW. It's near the end of the page, and continues on subsequent pages. This is a good place to read more about what these graphs actually are all about.

http://av123forum.com/showthread.php...&pagenumber=60

If that link doesn't work, it's page 60 of this:
http://av123forum.com/showthread.php?threadid=15586

And remember, this is just one guy buying all these subs on his own, running tests in his spare time, calling friends over to do blind tests. All for the benefit of EVERYONE ELSE. Although I am sure he derives some sort of pleasure out of it, otherwise he wouldn't be doing it. I am grateful for all this and I am learning a lot, as I am sure others are as well. At the very least, it's interesting to follow.

So, thanks, craigsub. I hope you keep this up.

I don't know if I'll be able to do it in the scope you are, but I would love to have some friends over with their sub, run some sweeps and measurements, and compare subs. I have done it with some other great guys in the area, just listening to speakers and subs. But now I can run REW, etc.
post #783 of 6764
Quote:
Originally Posted by LowOrder View Post

As a designer of limiter circuitry, I have been exposed to a topology that can have this described behavior. The system was termed a "moving high-pass filter". It consisted of a 2nd order high-pass Sallen & Key with a Q significantly higher than 1. This setting provided bass boost to compensate for driver/box rolloff. Key resistive components are replaced with modulated impedances to allow dynamic filter retuning with a control voltage derived from input signal level. If the limiter ratios were recursive, its possible to reduce boost at a rate slightly greater than the increase in signal, if combined with overall compression at the same time. If the bass response at 20Hz is strictly excursion limited, then it is CORRECTLY TUNED to prevent any further output at that frequency, but also lets 45Hz climb to levels 6dB higher, since that results in the same excursion. As I see in CraigSub's graphs energy below 20Hz, it may be another form of EQ that is dynamically changed. Conversely, I suppose the scene may have timing that is fighting against the decay period of the limiter circuitry

I basically abandoned all forms of limiters that work on the threshold/attack/decay format. Instead, I apply frequency selective soft clipping, which is a cycle-per-cycle approach. It introduces harmonic distortion only on the peaks that need it, and causes zero effect on all bass away from peaks. Then it removes the harmonics with additional filtering, leaving a fixed level sine wave behind regardless of increasing signal input. By doing this processing before the crossover lowpass filter, or as a multi-band array followed by aligned band-pass filters, its operation is imperceptible except as a lack of shotgun-in-the chest impact at the peaking frequencies. Any other limiter type causes a general bass level decrease for some time after a peak(often as long as a second), and that ruins the body of bass output for the sake of peak control.

Please consider a limiter as a SAFETY DEVICE. I believe all products should have an LED light up to indicate any limiter action like pro gear does. To be actually serious about bass performance, full desired playback volume should occur below any threshold of limiting, driver distress, or amplifier clipping. If any of these errors are occuring, buy more subs...

heheh

Welcome! Who are you?
I had mentioned this a few times during phone conversations with audio equipment manufacturers, something similar to OBDII dignostics that are so common in modern day automobiles to register error codes. Strange analogy but makes sense. Viewing speakers like engines, it would be nice to have error codes stored in non-volatile memory. For me, this would have been invaluable if I had known if my sub was reaching limitations and some indicator of why. So yes, I am completely with you when you say all products should have at least an LED light indicating limiter actions.

About the moving high-pass filter, if I understand you right, what you are implying is that it moved to 45Hz due to dynamics at that point of time where the levels were measured? When pushed to limits, laws of physics obviously kick in and things start breaking loose (hooke's law, terminal velocity, nuclear effects etc etc).
I don't know what circuit is used in that sub, but if it is a loop like what you are referring to, I can see why this would happen. IMHO, there are too many variables in the real world where the measurments were done, predicting what could have happened is extremely hard.
-Jai
post #784 of 6764
Thanks for that post LowOrder as it presents a credible explanation for the observed difference in amplitude instead of specualtion or innuendo regarding Craig's measurement. If true your explanation points to a significant design flaw of the limiter implentation in the PB12-NSD.
post #785 of 6764
Quote:
Originally Posted by jakeman View Post

Thanks for that post LowOrder as it presents a credible explanation for the observed difference in amplitude instead of specualtion or innuendo regarding Craig's measurement. If true your explanation points to a significant design flaw of the limiter implentation in the PB12-NSD.

John ... Based on the experience with the PB12 ... I think the limiter does a great job. I mentioned this earlier, but thought re-stating this would be important. I REALLY pushed the PB12 to see how hard it could hit @ 20 Hz ... had I tried this with the VTF-2.3, I probably would have destroyed the driver.

The protection circuitry in the PB12 makes it totally ... for lack of a better term, "idiot proof". When you think about a relatively entry level sub ... bullet proof makes sense.

That being said ... kudos for following Loworder's post. It was extremely well written. And very ... smart ...
post #786 of 6764
Quote:
Originally Posted by jakeman View Post

Thanks for that post LowOrder as it presents a credible explanation for the observed difference in amplitude instead of specualtion or innuendo regarding Craig's measurement. If true your explanation points to a significant design flaw of the limiter implentation in the PB12-NSD.

Jakeman,
I got slapped over and over again for mentioning the word "design flaw" last time so watch out. I hope the forum will turn into a place where people can freely express what their opinions are without the fear of being flamed. I welcome your opinion. I only hope people won't get rude. I now have tuned myself not to take things personally. Challenging the status quo is a good virtue and I hope more people will accept it. While I openly acknowledge I am "fan" of SVS, your comments still don't bother me.
Take care,
-Jai
post #787 of 6764
Quote:
Originally Posted by craigsub View Post

John ... Based on the experience with the PB12 ... I think the limiter does a great job. I mentioned this earlier, but thought re-stating this would be important. I REALLY pushed the PB12 to see how hard it could hit @ 20 Hz ... had I tried this with the VTF-2.3, I probably would have destroyed the driver.

The protection circuitry in the PB12 makes it totally ... for lack of a better term, "idiot proof".

That being said ... kudos for following Loworder's post. It was extremely well written. And very ... smart ...

Couldn't agree more. Loworder, can you disclose who you are? Just curious, you sure are not a casual audio guy. I had to read your post 2 times before I understood what you said and there is logic behind it which I appreciate.
Craigsub,
Is the protection circuitry in the NSD the same as the PB12. While I don't completely buy your ratings (from your posts, I think you will respect my opinions), I do have a high degree of respect for you and what you contribute to this forum. Keep it up!
-Jai
post #788 of 6764
Quote:
Originally Posted by jmcomp124 View Post

Couldn't agree more. Loworder, can you disclose who you are? Just curious, you sure are not a casual audio guy. I had to read your post 2 times before I understood what you said and there is logic behind it which I appreciate.
Craigsub,
Is the protection circuitry in the NSD the same as the PB12. While I don't completely buy your ratings (from your posts, I think you will respect my opinions), I do have a high degree of respect for you and what you contribute to this forum. Keep it up!
-Jai

When you ask "Is the protection circuitry in the NSD the same as the PB12?" ... Do you mean the PB12-NSD vs. the PB12-Plus/2 ? If so ... I don't know if they are the same.

As for the ratings ... I am sure that, if we took 20 guys from here, we would get 20 different ratings for the subs ... ESPECIALLY using blind tests. I think there would be some consistency ... but also some variances in the point totals.
post #789 of 6764
craigsub,

You mentioned that at least for some of the test that led to the # ratings, you had some musician friends, etc. over, correct? Are the #scores and rankings based on the general consensus from the sessions? Or was that just part of it. I know you've been doing a lot of this over the last 3~ months or so.
post #790 of 6764
Quote:
Originally Posted by cyberbri View Post

craigsub,

You mentioned that at least for some of the test that led to the # ratings, you had some musician friends, etc. over, correct? Are the #scores and rankings based on the general consensus from the sessions? Or was that just part of it. I know you've been doing a lot of this over the last 3~ months or so.

Yes ... Some musicians .. my brother's lead engineer .. there are always several opinions in regards to the SQ of each sub.
post #791 of 6764
Quote:
Originally Posted by craigsub View Post

When you ask "Is the protection circuitry in the NSD the same as the PB12?" ... Do you mean the PB12-NSD vs. the PB12-Plus/2 ? If so ... I don't know if they are the same.

Yes, I meant the PB12-NSD vs the Plus/2.
That's ok. Maybe Tom or Ron will chip in.
Thanks,
-Jai
post #792 of 6764
Quote:
Originally Posted by bgillyjcu View Post

You are really starting to annoy me. I Seriously........LEAVE CRAIG ALONE, LEAVE THIS THREAD ALONE, and better yet........LEAVE AVS ALONE.
He is doing great things for everyone....Craig........do not waste your time posting to that jackass.......spend your time on something more important like your family, having a beer, testing subs......EVERYONE...PLEASE IGNORE SJMARCY NO MATTER WHAT HE WRITES....GOOD OR BAD...WHO CARES!

This seems like a possible violation of forum policy.

I read your post, and am saddened. Free speech and a sharing attitude can be good in a forum. For some reason I am reminded of Google cofounder Brin's recent comments about censorship. He now feels there censorship was not a good idea. Here is an interesting article about it should you want to know more:

http://business.guardian.co.uk/davos...999994,00.html

Reviewer Craigsub most assuredly did make 14.5-18.5 dB claims, others did note they understood this fact, and used it to justify their positions and thanked him. Obviously there is misinterpretation here, and I have certainly been hassled about the matter. Craigsub retested the device and reconfirmed his results. I have not checked to see if those posts are still here and in unedited form. Perhaps a disclaimer on these tests is needed so that matters are clearer to more members. Things like this, but not just this concern me in this murky series of tests and ratings which members use to evaluate their options.
post #793 of 6764
Quote:
Originally Posted by cyberbri View Post

I believe he pays for the subs out of his own pocket. You could do the same...

Sure I could do that. But if a reviewer claims a sub suddenly cuts it's output so massively when 3 more dB of input are added then this begs the question is the sub broken or not, design issue or not, do they all do this, etc. If it is broken then how can that be ascertained if I buy and test a different subwoofer? It seems to me that it would make more sense to test the one whose behavior was so greatly different than other tested devices. I am concerned when asking such things leads to efforts to ban someone like me, and a series of attacks across various forums besides this one. It sends the message that noone can discuss this matter and that hand claps are the only suitable responce. So in effect a sub that ran into a design issue, or broke, or a test issue seems to have uncovered a larger issue here. The fact that these tests/ratings cannot be discussed in an open manner without a person risking attacks. I received many PMs and emails about this matter confirming these concerns. For example if a reviewer finds himself banned at other forums (such as Craigsub) after testing a sub from a certain manufacturer...and then runs into various "issues" with subs from that manufacturer it presents concerns about conflicts of interest and motivations that harm credibility.
post #794 of 6764
Quote:
Originally Posted by jakeman View Post

Gentlemen. I think we should cut Sjmarcy some slack. I don't see anything disingenous in this comment and he is somewhat new to this forum and thread. Rather than asking for Craig's subs I suggest you source your own, borrow them or buy them and post the results. One thing for sure Craig's measurments are consistent, but if you think there is a defective sub in the lot or something you disagree with then provide another measurement. It sounds like you have the tools so measure some sweeps and make a real contribution. Perhaps you have identified an abnormality but without presenting alternate data its difficult to listen to you cry wolf.

Normally when such an unusual test result is found, the reviewer would look into the manner on their own. Since it is not normal, or desireable behavior. I noticed that when these reviews or tests are discussed, it is common for the person in my position to get attacked. It would be nice if that did not occur as it tends to eliminate the topic being discussed. Instead, a shoot the messenger tone develops which is not good for the credibility of these tests or this forum and it's members.
post #795 of 6764
Quote:
Originally Posted by jmcomp124 View Post

Jakeman,
I got slapped over and over again for mentioning the word "design flaw" last time so watch out. I hope the forum will turn into a place where people can freely express what their opinions are without the fear of being flamed. I welcome your opinion. I only hope people won't get rude. I now have tuned myself not to take things personally. Challenging the status quo is a good virtue and I hope more people will accept it. While I openly acknowledge I am "fan" of SVS, your comments still don't bother me.
Take care,
-Jai

Well said. If things like "howcum this happened?" are discussable then I think it is better for all concerned. If a sub suddenly nearly turns off in normal use this is not a good thing but is what this sub seems to have done if Craig's tests are accurate here. I'd like to find out without having to be attacked. I have seen the very unclear test methodology glossed over, and mentioned that the sub could be broken or of a crummy design. Moderators got involved. Lets find out what happened here instead of claiming that I did something or that some company has me posting here which is a pointed personal attack, etc.
post #796 of 6764
Quote:
Originally Posted by LowOrder View Post

As a designer of limiter circuitry, I have been exposed to a topology that can have this described behavior. The system was termed a "moving high-pass filter". It consisted of a 2nd order high-pass Sallen & Key with a Q significantly higher than 1. This setting provided bass boost to compensate for driver/box rolloff. Key resistive components are replaced with modulated impedances to allow dynamic filter retuning with a control voltage derived from input signal level. If the limiter ratios were recursive, its possible to reduce boost at a rate slightly greater than the increase in signal, if combined with overall compression at the same time. If the bass response at 20Hz is strictly excursion limited, then it is CORRECTLY TUNED to prevent any further output at that frequency, but also lets 45Hz climb to levels 6dB higher, since that results in the same excursion. As I see in CraigSub's graphs energy below 20Hz, it may be another form of EQ that is dynamically changed. Conversely, I suppose the scene may have timing that is fighting against the decay period of the limiter circuitry
I basically abandoned all forms of limiters that work on the threshold/attack/decay format. Instead, I apply frequency selective soft clipping, which is a cycle-per-cycle approach. It introduces harmonic distortion only on the peaks that need it, and causes zero effect on all bass away from peaks. Then it removes the harmonics with additional filtering, leaving a fixed level sine wave behind regardless of increasing signal input. By doing this processing before the crossover lowpass filter, or as a multi-band array followed by aligned band-pass filters, its operation is imperceptible except as a lack of shotgun-in-the chest impact at the peaking frequencies. Any other limiter type causes a general bass level decrease for some time after a peak(often as long as a second), and that ruins the body of bass output for the sake of peak control. Please consider a limiter as a SAFETY DEVICE. I believe all products should have an LED light up to indicate any limiter action like pro gear does. To be actually serious about bass performance, full desired playback volume should occur below any threshold of limiting, driver distress, or amplifier clipping. If any of these errors are occuring, buy more subs... heheh

First of all, welcome. Second of all if this is occurring here...it would be great to find out.
post #797 of 6764
Quote:
Originally Posted by cyberbri View Post

craigsub, You mentioned that at least for some of the test that led to the # ratings, you had some musician friends, etc. over, correct? Are the #scores and rankings based on the general consensus from the sessions? Or was that just part of it. I know you've been doing a lot of this over the last 3~ months or so.

It warms my heart to see that this sort of thing is coming up, and hopefully without an attack on you. I have asked for more information, the blind test data, test methodology and was either ignored or attacked for the most part.

Can the test methodology and blind test procedures be disclosed in a clear manner and made available to interested readers? I have asked repeatedly. I think it would help clarify things.
post #798 of 6764
Quote:
Originally Posted by craigsub View Post

I am sure that, if we took 20 guys from here, we would get 20 different ratings for the subs ... ESPECIALLY using blind tests. I think there would be some consistency ... but also some variances in the point totals.

I don't agree. I have been in blind tests, designed them, run them. When done right, the results are not a free for all at all.
post #799 of 6764
Quote:
Originally Posted by cyberbri View Post

Okay, here is the first post where craigsub started posting the "peak hold" measurements for different subs - these scenes being from WotW. It's near the end of the page, and continues on subsequent pages. This is a good place to read more about what these graphs actually are all about.

http://av123forum.com/showthread.php...&pagenumber=60

If that link doesn't work, it's page 60 of this:
http://av123forum.com/showthread.php?threadid=15586

And remember, this is just one guy buying all these subs on his own, running tests in his spare time, calling friends over to do blind tests. All for the benefit of EVERYONE ELSE. Although I am sure he derives some sort of pleasure out of it, otherwise he wouldn't be doing it. I am grateful for all this and I am learning a lot, as I am sure others are as well. At the very least, it's interesting to follow.

So, thanks, craigsub. I hope you keep this up.

I don't know if I'll be able to do it in the scope you are, but I would love to have some friends over with their sub, run some sweeps and measurements, and compare subs. I have done it with some other great guys in the area, just listening to speakers and subs. But now I can run REW, etc.

New27

Could you edit the first post in this thread to include these links?

This would help everybody, especially those joining late, to understand what Craigsub is doing.
post #800 of 6764
Quote:
Originally Posted by sjmarcy View Post

This seems like a possible violation of forum policy.

I read your post, and am saddened. Free speech and a sharing attitude can be good in a forum. For some reason I am reminded of Google cofounder Brin's recent comments about censorship. He now feels there censorship was not a good idea. Here is an interesting article about it should you want to know more:

http://business.guardian.co.uk/davos...999994,00.html

Reviewer Craigsub most assuredly did make 14.5-18.5 dB claims, others did note they understood this fact, and used it to justify their positions and thanked him. Obviously there is misinterpretation here, and I have certainly been hassled about the matter. Craigsub retested the device and reconfirmed his results. I have not checked to see if those posts are still here and in unedited form. Perhaps a disclaimer on these tests is needed so that matters are clearer to more members. Things like this, but not just this concern me in this murky series of tests and ratings which members use to evaluate their options.


Mr. Marcy, please point out where I made the proclamation that the Hsu would out deliver the SVS @ 45 Hz.

If you can find this statement, it would be helpful.
post #801 of 6764
Quote:
Originally Posted by sjmarcy View Post

I don't agree. I have been in blind tests, designed them, run them. When done right, the results are not a free for all at all.

You are one of thse guys who just cannot help himself. I never said anything about a free for all.
post #802 of 6764
Quote:
Originally Posted by sjmarcy View Post

I don't agree. I have been in blind tests, designed them, run
them. When done right, the results are not a free for all at all.

You would still get some variation in scores since to me these are based on subjective experiences. It is like like me tasting a wine yesterday that was given a Wine Spectator score of 90, but I didn't care for the wine at all.

I supposed if people were trained in how to score their subjective impressions, perhaps the variation in scores would decrease, but you still see variation between these scores.

With that said, Craig did some blind listening tests between the EP500 and Ultra a year ago. Though variable, the 4-5 reviewers' scores were reasonably close to each other.

FWIW, I wouldn't call his listening tests a "free for all".
post #803 of 6764
Quote:
Originally Posted by sjmarcy View Post

Well said. If things like "howcum this happened?" .


How Old are you???? Who in their adult mind would spell the words how come as howcum.

There is no way that an intelligent ADULT can misspell the word COME for CUM....

I'm seriously doubting any thread of intelligence on your end, rather, just the need to spark doubt on things and stir up problems.

If you don't like my posts....then please leave!
post #804 of 6764
The PB12-NSD amp has a fixed high pass filter at ~18 Hz. It also has peak limiters which have adjustable parameters for attack/sustain duration and continuous/peak power levels. Craig is correct - the high pass and the limiters in this model have been designed to make the subwoofer just about bullet-proof, even when deliberately over-driven.

Regarding the 22 Hz "the cold" scene in The Haunting DTS, 100-101 dB on the RS meter at the listening position is about 106 dB actual sound pressure. This meter is equipped with a C-weighted filter which causes it to read low in the deep bass ranges. The C-weighted correction factor at 22 Hz is about 5 dB.

Also, running the subwoofer 5 dB hot on the RS meter (75 dB speakers, 80 dB sub) actually means the sub is running about 7 dB hot. While the spectral content of subwoofer calibration tones certainly varies with the AVR/source, they are generally centered in the 40-50 Hz region. So the RS meter reads about 1.5-2.0 dB low on the typical subwoofer test tone.

Running the subwoofer 6-7 dB hot is fine (everyone has different tastes in bass), but realize that a doubling of the subwoofer results in the 6 dB increase in headroom. So you're definitely a candidate for duals.

The closer the user pushes to Dolby Reference Level, the more we recommend running the subwoofer calibrated "flat" (i.e., even with the speakers) to prevent subwoofer overload and/or audible artifacts like port chuffing. That means about 73-74 dB on the RS meter if the speakers are calibrated to 75 dB.
post #805 of 6764
Quote:
Originally Posted by sjmarcy View Post

Normally when such an unusual test result is found, the reviewer would look into the manner on their own. Since it is not normal, or desireable behavior. I noticed that when these reviews or tests are discussed, it is common for the person in my position to get attacked. It would be nice if that did not occur as it tends to eliminate the topic being discussed. Instead, a shoot the messenger tone develops which is not good for the credibility of these tests or this forum and it's members.

I've been in similar positions and attribute it to the sometimes rough and tumble culture at this forum. People get over it soon enough and move on to the next discussion thread though some egos do get bruised easily. I appreciate you don't have a recent history here and your early posts clearly showed a good knowledge of the subject matter but the tone of your statements invited the attacks. Yes a new poster with a critical message sometimes gets shot, so you have to have good reasons and a defensible position when waving a red flag. Just crying wolf doesn't cut it here. Speaking for myself its now history and no big deal and I welcome your comments. However the bar is higher at this forum than what you are suggesting.

Yes the reviewer should double check an unusual test result, which Craig did, but the onus is also on the poster to produce other data or evidence if you continue to be dissatisfied. Indirectly your persistence may have prompted that excellent post by LowOrder which has linked the suspicious results to an overaggressive limiter. Under these circumstances, if you are still not satisfied get the SVS sub and test it yourself especially its limiter.

In that regard I agree that Craig's testing comparisons would not make it in a scientific journal however no one here expects that standard. More importantly, the man is honest and experienced with many subs which is worth much more to many people here including myself. Please keep that in mind as you comment on any other problems and the guns will be put back in the rack.
post #806 of 6764
Quote:
Originally Posted by Ed Mullen View Post

The PB12-NSD amp has a fixed high pass filter at ~18 Hz. It also has peak limiters which have adjustable parameters for attack/sustain duration and continuous/peak power levels. Craig is correct - the high pass and the limiters in this model have been designed to make the subwoofer just about bullet-proof, even when deliberately over-driven.

Regarding the 22 Hz "the cold" scene in The Haunting DTS, 100-101 dB on the RS meter at the listening position is about 106 dB actual sound pressure. This meter is equipped with a C-weighted filter which causes it to read low in the deep bass ranges. The C-weighted correction factor at 22 Hz is about 5 dB.

Also, running the subwoofer 5 dB hot on the RS meter (75 dB speakers, 80 dB sub) actually means the sub is running about 7 dB hot. While the spectral content of subwoofer calibration tones certainly varies with the AVR/source, they are generally centered in the 40-50 Hz region. So the RS meter reads about 1.5-2.0 dB low on the typical subwoofer test tone.

Running the subwoofer 6-7 dB hot is fine (everyone has different tastes in bass), but realize that a doubling of the subwoofer results in the 6 dB increase in headroom. So you're definitely a candidate for duals.

The closer the user pushes to Dolby Reference Level, the more we recommend running the subwoofer calibrated "flat" (i.e., even with the speakers) to prevent subwoofer overload and/or audible artifacts like port chuffing. That means about 73-74 dB on the RS meter if the speakers are calibrated to 75 dB.


Ed you are so knowledgeable! Knowing this I'll back the sub off about 3db. I obviously want to maximize performance across the Frequency range... Thanks
post #807 of 6764
Nice post Ed!

Thanks for pointing out that the RS meter needs a compensation curve overlayed on its results, especially for the lowest accepted octave 20Hz - 40Hz. When developing products, I perform near-field testing using LMS, under 1" from the cone, excursion allowing. This is followed up with the THX-mandated 2meter ground-plane measurement, with the mic on the concrete floor facing the sub, in an open-plan manufacturing facility. The walls are all over 50ft away! Even so, care is given to locate the station away from dead center. As this isn't likely available to in situ home reviewers, more insight is now available regarding RS results.

I have access to the Phonic PAA3 and recommend it as a step-up from the basic functionality of the RS meter. One feature I like is the jog shuttle that lets you highlight a specific frequency for a digital decibel display. There are several response times to choose from, so RTA and average measurements can easily be obtained.

No I don't work for Phonic, although a company I contract for sells them. I do think its a more powerful and flexible tool as a logical next increment in testing gear.

post #808 of 6764
Quote:
Originally Posted by jakeman View Post

Thanks for that post LowOrder as it presents a credible explanation for the observed difference in amplitude instead of specualtion or innuendo regarding Craig's measurement. If true your explanation points to a significant design flaw of the limiter implentation in the PB12-NSD.

I suggest caution in concluding that any one type of limiter execution is a design flaw. At best they are design choices akin to how big a power amp and how large an enclosure can be used in a given design. Even more interesting is that one of Craig's favorite subs used sliding high pass limiting. Different limiter implementations have different effects depending on the particular system and what they are protecting the system from doing.

I see nothing *wrong* in the behavior observed and questioned in the PB12-NSD. The observation is very much as Craig noted, where the other subs hit some wall before a limiter can get aggressive enough to compress peaks like this. The PB12-NSD was bullet-proof enough to allow Craig to keep pushing to see what was possible down low. Bullet-proof or not, as Ed and others imply, this isn't a region of operation you want be observing often.

While it adds to the measurements taken quite a bit, the peak hold graphs would likely give us much more insight if 3 more measurements were added to the set. Ideally seeing a measurement with the level -5, -10, and -20 from maximum would give much more insight as to the behavior of the subwoofers, and give us a insight on the limiting behavior. Of course doing so multiplies the testing required by a factor of 4!
post #809 of 6764
Quote:
Originally Posted by Mark Seaton View Post


I suggest caution in concluding that any one type of limiter execution is a design flaw. At best they are design choices akin to how big a power amp and how large an enclosure can be used in a given design. Even more interesting is that one of Craig's favorite subs used sliding high pass limiting. Different limiter implementations have different effects depending on the particular system and what they are protecting the system from doing.

I see nothing *wrong* in the behavior observed and questioned in the PB12-NSD.

I second Mark's quote here. A design choice is not a design flaw.
I call something a design flaw when it does not deliver what it was intended and designed for. When operating within spec, if the product does not deliver as claimed and if there was no manufacturing defect, then in my mind, it is ok to call it a design flaw. I had reason to believe that I was operating within spec and to my knowledge there was no defect and I tried to address every possible area of potential defect but I had limited visibility and access into the product unlike the manufacturer who has full visibility. So now it is going back to the designer's hands.
Also, about titling the chart as Mark suggested is not a bad idea at all. It is a constructive comment which if taken and followed through will avoid confusion. I knew exactly what the charts were the first time I looked at them, but there are few who do get confused. Name your charts, name the axis with the correct names. Remove things which cause confusion. Simple guidelines which if easy to do in the software should be done.
As I indicated earlier, just by looking at these charts coming to conclusions is not right in my opinion. We need more data or tests if possible.
-Jai
post #810 of 6764
Quote:


I'm seriously doubting any thread of intelligence on your end, rather, just the need to spark doubt on things and stir up problems.

IMHO, I welcome any counterpoint. Without knowing the limitations of any experiment or study, it is difficult to assess the validity of any conclusions. What I have problems with is the tone that some people take when they make criticisms; it almost always seems to take a personal tone at this forum. What people don't seem to realize is that is that Craig takes his own time and money to these tests. Though he spends a lot of time on these tests, this is not his full time job (plus he has a family). We can scream until we're blue in the face of how he should change he can make his subwoofer tests "better", but it gets to the point where these changes are not feasible.

No study is perfect. Every study has limitations. But I think it would be ignorant to ingore any conclusions completely because a study has limitations. There is always something to take away. I think Craig said it best one of his previous posts, his listening tests are not meant to be the bible, but a guide. This is a guide that no one else has attempted to create. His tests have value.

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How Old are you???? Who in their adult mind would spell the words how come as howcum.

There is no way that an intelligent ADULT can misspell the word COME for CUM....

I've been known to misspell words and make grammatical errors when I write my papers... So bad, that I have pressed the edit button 4 times to write this post. Though I'm not the brightest bulb in the shed, I don't think it is a fair indication of my intelligence.
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