# Subwoofer Tests - Spring 2006



## Ilkka (Jun 8, 2006)

http://www.hometheatershack.com/forums/subwoofer-tests-archived/

The results are posted. :yes:


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## bobgpsr (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Bump.

Nice work Ilkka :thankyou: 

This deserves a sticky for awhile. :T 

Bob


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## russ.will (May 10, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Oh er! I'm going to get through some cups of tea reading this one.

Thanks Ilkka

Russell


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## Mark Seaton (Jun 22, 2006)

*Re: Another Face Off Thread*

I want to give Illka proper credit for what I'm certain was a MAJOR undertaking. There is LOTS of very interesting data there. Definitely more information I'll add to my online "library."


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## Ilkka (Jun 8, 2006)

*Re: Another Face Off Thread*



Mark Seaton said:


> I want to give Illka proper credit for what I'm certain was a MAJOR undertaking. There is LOTS of very interesting data there. Definitely more information I'll add to my online "library."


Thanks Mark! I value your opinions/thoughts very much. If you have any suggestions or development ideas, I'm all ears. Hopefully we will see a certain dual 15" sub in our next session. :yes: 

And yes, it was a major undertaking. The measurements itself didn't take more than two ~8 hour days, but sorting out the data the next 5 weeks. :blink:


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## Mark Seaton (Jun 22, 2006)

*Re: Another Face Off Thread*

The one suggestion for future testing might be to keep one subwoofer around as a constant to highlight any un-expected changes from test to test. It gives you a measuring stick by which to compare other tests or show where we should be cautious in comparing.

I also find the results with the multi-tone tests rather interesting. I will need some more time to read more carefully and digest all of the information, but one the spectral contamination tests do actually paint some pictures of measurable differences. The complication lies more in interpretation and what those measurements actually mean. I suspect as we have more samplings, trends will start to become more clear. An intresting example comparison is the 90 & 95dB measurements from the SVS PB12-Plus/2 in 20Hz with the 12.1 driver vs. the 12.3 driver. The spectral contamination tests do correlate to the fact that this same box design uses drivers having somewhat different characteristics.


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## JCD (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

First off, thanks for doing all that work. I'm sure you're getting a lot of love thrown at you right now, but as one who's done similar (work related/non-AV) projects in the past, I know what a huge undertaking this can be. So here's some more 'love' -- Great work. :T 

I've skimmed the results -- seriously reading and anylyzing the results will have to wait until later -- and noted that you left a post for your comments on the test of each sub. When do you think you might post those? I'd follow the rest of the conversations, but, well, I don't speak Finnish.

JCD


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## bobgpsr (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Well Ilkka I do have a question. What happened to reverse sweeps? Do these test results just use the TrueRTA built-in (increasing freq) quick sweep for max SPL tests?

Bob


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



bobgpsr said:


> Well Ilkka I do have a question. What happened to reverse sweeps? Do these test results just use the TrueRTA built-in (increasing freq) quick sweep for max SPL tests?
> 
> Bob





> Max output level and power compression
> 
> Maximum long term output level was measured using a 30 second sine sweep from 100 Hz to 10 Hz. First sweep was level matched at 90 dB at 50 Hz. Drive level was rised by 5 dB after each sweep. There was around 20 s delay between each sweep. Sweeps were taken up to the point where the output level stopped rising anymore (5 dB or more of compression). I also tried 2 dB as the last step, but usually it didn’t help. This is a very demanding test and the results should not be compared to other tests with faster sweeps etc. Power compression graph is showing the relative compression to the 90 dB sweep.


Reverse sweeps are exactly what I used also this time. I also did Quick Sweep, but its results weren't that much higher. I need to work something else for peak output tests.


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## Mark Seaton (Jun 22, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Ilkka,

By far the most appropriate way to do peak output tests is with the 1/3rd octave tone-bursts that Don Keele and Sigfried Linkwitz first put to use years ago. There is plenty of information on the web about the signals, but they are basically an enveloped sine wave of various filter types, typically 5-6 cycles long. I believe this is also what the new CEA testing is adopting for its stimulus. So far as actual limits, I would say both the limits defined by the CEA and simple audible thresholds would be quite useful. With these tones it is very easy to hear the onset of distortion and any resultant noises. If you look at the process Keith Yates used, he wrote down various observations (what he heard) alongside the numerical data.

To clarify about the reverse sweep signal, I am assuming it was a reverse log-sweep? The measurements appear to track what others have measured, but I am guessing you did loopback tests to confirm TrueRTA was reading the signal as flat, correct? I'm more asking to clarify for anyone reading along.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Mark Seaton said:


> Ilkka,
> 
> By far the most appropriate way to do peak output tests is with the 1/3rd octave tone-bursts that Don Keele and Sigfried Linkwitz first put to use years ago. There is plenty of information on the web about the signals, but they are basically an enveloped sine wave of various filter types, typically 5-6 cycles long. I believe this is also what the new CEA testing is adopting for its stimulus. So far as actual limits, I would say both the limits defined by the CEA and simple audible thresholds would be quite useful. With these tones it is very easy to hear the onset of distortion and any resultant noises. If you look at the process Keith Yates used, he wrote down various observations (what he heard) alongside the numerical data.


Yes, this would probably be the best option, but it's PITA to measure. I mean it takes a lot more time than a 30 second sweep. It also requires much more attention since you have to carefully listen at the subs. If I could measure only a few subs in a day...but 27 in two days? 



> To clarify about the reverse sweep signal, I am assuming it was a reverse log-sweep? The measurements appear to track what others have measured, but I am guessing you did loopback tests to confirm TrueRTA was reading the signal as flat, correct? I'm more asking to clarify for anyone reading along.


It was a reverse linear sweep. Log-sweep didn't work with the THD plotting, that's why linear. And of course I looped it, that's essential with TrueRTA. And actually it needs a trick or two to even get it flat.

And I believe my absolute SPL was pretty accurate too. If you look at the Genelec 7073A results, it scored ~106 dB at 20 Hz with ~2 dB of compression, exactly the same what Yates and AV Talk measured.


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## bobgpsr (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> Maximum long term output level was measured using a 30 second sine sweep from *100 Hz to 10 Hz*.
> ...
> Reverse sweeps are exactly what I used also this time. I also did Quick Sweep, but its results weren't that much higher. I need to work something else for peak output tests.


I do not know why I did not read reverse sweep from the *100 Hz to 10 Hz* text. :blush: 

But the tone burst and log vs linear discussion that ensued between you and Mark made my dumb question worthwhile. The idea to push the sub starting at its more efficient frequency response area first before the lower freqs where more voice coil heating occurs seems to me to be a good way to characterize a sub's true capabilities. Did not AV Talk also change to this general idea for their most recent tests?

Using tone bursts ("enveloped sine wave of various filter types, typically 5-6 cycles long") like Mark describes sounds like it would require a much more involved test setup. A remote controlled PC or IEEE-488 controlled waveform generator working with the measuring PC?

Bob


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## Mark Seaton (Jun 22, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> Yes, this would probably be the best option, but it's PITA to measure. I mean it takes a lot more time than a 30 second sweep. It also requires much more attention since you have to carefully listen at the subs. If I could measure only a few subs in a day...but 27 in two days?


At least someone can appreciate what Keith Yates went through in his Way Down Deep report. Now remember that there were 2x that many subs since he also did a similar style report for Home Theater Magazine. Of course Keith's measurements were from 5 sets of measurements for each subwoofer on different days. Oh, and he did extensive listening tests as well! I remember him grumbling a lot and mentioning something about a perfect job for a college intern. 

I would think that someone would be able to write script that could look for a distortion threshold such as described by either the CEA standard or a 12dB/octave approximation of it. The system could then step through ISO center frequencies noting the highest level achieved and capture the spectrum.



Ilkka said:


> It was a reverse linear sweep. Log-sweep didn't work with the THD plotting, that's why linear. And of course I looped it, that's essential with TrueRTA. And actually it needs a trick or two to even get it flat.


The TEF measurements Keith Yates and I use are in fact a linear sweept that can be set to sweep either direction. For subwoofers it is usually better to start high and sweep low. We should remember there are slight differences that will impact compression somewhat so far as how much time of the sweep is spent over various frequency ranges. I would expect that the shaping of the magnitude you had to do actually balances this out closer to that of a log-sweep for the TrueRTA to read flat. 

Now that I look at the data again, I am curious what process you are using to measure THD? FYI, if you haven't checked out WinMLS before, I think it might be a good program for you to experiment with as well. Lars Morset, the creator of the program, is a *very* sharp guy. If you contact him he might also have some useful suggestions towards streamlining such a measurement process.



Ilkka said:


> And I believe my absolute SPL was pretty accurate too. If you look at the Genelec 7073A results, it scored ~106 dB at 20 Hz with ~2 dB of compression, exactly the same what Yates and AV Talk measured.


Indeed, the data looks to largely follow the sort of performance I would expect from the various devices tested. Again, I can appreciate how much a PITA such an undertaking is. Great Job.


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## Jack Gilvey (May 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Looks like any reference to this work over on another forum has been nuked...typical. I nominate this forum as the place for learned discussion since the mods will actually grasp what's being discussed.



> I would think that someone would be able to write script that could look for a distortion threshold such as described by either the CEA standard or a 12dB/octave approximation of it.


 I nominate Illka.

Edit...one thread is still there...for now.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Jack Gilvey said:


> Looks like any reference to this work over on another forum has been nuked...typical. I nominate this forum as the place for learned discussion since the mods will actually grasp what's being discussed.
> 
> 
> I nominate Illka.
> ...


Yeah, my second visit to AVS was pretty short... Now my both nicks are banned for forever. :rolleyesno:

Also www.avforums.com deleted my thread, since they don't allow linking to another forum.


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## russ.will (May 10, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Hi Ilkka,

I think you'll find that the heavy SVS following on AVF were quite satisfied with the results - apart from the PB10 owners that is. I think it had been built up on the forum to be the only sub at it's price point. Beside that, I believe they have nothing but utter respect for your endeavours.

Russell


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## Sthrndream (Apr 21, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Hi Ilkka,

I think you'll find most forums frown upon "linking" to other competing forums. You may get away with it more in the states because they(forum owners) probably won't consider a finnish forum much of a "threat" to steal members/viewers. A forum in the UK could think very differently though. How long would it take for you to start another thread at AVforums with all of your data...20-30 minutes? They have already invited you to post ALL of your data on their forum(you just can't post it on a RIVAL forum and use AVForums to generate more traffic for a competing forum.....so why even introduce the idea that there are "hidden motives" at play here? There is so much drama in the subwoofer world as it is...I don't see any need to invent it when it isn't there... 

Tom V.
SVS


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## Sonnie (Apr 11, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

I know we ain't the biggest game in town right now... but we are supporting you all we can. We definitely don't mind the links... several guys from that forum post here anyway and are a big part of our success thus far. I suspect AVF is probably a little upset that you wouldn't allow them to host the actual tests and it might be a backlash of sorts. I'm thinkin' AVS is getting some feedback from some of their advertisers. 

Hey... you turned us down too... I suspose we'll have to delete your threads too, huh? heehee... :sarcastic: 

You are always welcome to post the links here, but do remember the offer is open if you decide you want a forum for your tests and you want to moderate it... you can have it right here. I do think it would be nice to have a U.S. forum to post the tests results in addition to the Finnish forum.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Tom Vodhanel said:


> Hi Ilkka,
> 
> I think you'll find most forums frown upon "linking" to other competing forums. You may get away with it more in the states because they(forum owners) probably won't consider a finnish forum much of a "threat" to steal members/viewers. A forum in the UK could think very differently though. How long would it take for you to start another thread at AVforums with all of your data...20-30 minutes? They have already invited you to post ALL of your data on their forum(you just can't post it on a RIVAL forum and use AVForums to generate more traffic for a competing forum.....so why even introduce the idea that there are "hidden motives" at play here? There is so much drama in the subwoofer world as it is...I don't see any need to invent it when it isn't there...
> 
> ...


I apologise my wording. It was not needed. I have edited my post accordingly.

I just can't understand how a 99.9% Finnish forum (they have one section for English speaking people) could be a threat to any English speaking forum? They can't read any post, they can't make posts or join in any conversations.

If forums don't allow linking to other forums (our DVDPlaza doesn't have any problems with that), that would basically mean that I would have to post my results on EVERY forum. If you have checked the subwoofer tests forum over at DVDPlaza, you will see that it's impossible to post that data on every forum. It can not be posted in one thread, it needs its own forum section. Yes, Sonnie has offered me my own section here, but what would it really help? This forum is very small (this thread has now 183 views, my DVDPlaza thread has around 47,000) and I couldn't link this site to (for example) AVForums etc.

Imo it's more professional to have the results posted only in one place. For example AV Talk doesn't post their results on any other forum than their own. That way I can better reply to questions and I don't have to follow multiple threads in multiple forums. I simply don't have time for more. I know it will limit the discussion and less people will see my results, but I have to draw the line to somewhere. Keep in mind that I don't get a single penny from these tests. Actually I have invested huge amounts of money for test gear etc. Not to mention hundreds of hours of work that it took to arrange the measurement session and sort out the results.

I'm sorry but the results will stay on DVDPlaza.


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## Sthrndream (Apr 21, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Hi Ilkka,

Believe me, I can “feel your pain” in all of this subwoofer drama. I have seen you disparaged and called every name in the book by certain individuals. But now that “their” subwoofer did well in your latest test…these same folks are saying what a great guy you are..

Some of the SVS products you have measured did great, some just okay. We take all constructive criticism of our products very seriously and we value your measurements in helping us better all of our products. As we have been discussing in our private emails, I don’t always agree with *all* of your testing methods…but please don’t think of that as a major criticism or something unusual. I have disagreed with things Don Keele used to do, same with Keith Yates, John Johnson, ect. Tom Nousaine and I have had many debates on this very topic. And if you ever got all of those guys in the same room together...you can bet they would disagree on certain levels in this context(measuring bass) too..

When it comes to forums, you have to remember how expensive it is to keep a big forum running. The way they pay for that is with sponsors(ad banners). The more people that SEE the banners, the more people that click on the banners. The more people that click on the banners, the more money is generated for that forum(either directly or indirectly). So any large forum is not going to want to have their entire membership redirected to a COMPETING forum. Anyone going there(to the competing forum) is going to see different banners…and they will inevitably “click on” any banner that interests them. You can’t blame them…I would do the same. A lot of those banners will be in both English and Finnish(or have both finnish and English translations/websites for potential customers after you “click-thru”. So you are using one forum to generate income for a competing forum(or at least that is how some people will look at it).

Anyway, I hope to be able to finally look over your latest test sessions this weekend. Been too busy lately. Thanks for taking the time to provide all this data!

Tom V.
SVS


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## russ.will (May 10, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Hi Ilkka,

If I may drag this back on topic, and Tom V may be able to help here - Amongst many eyebrow raising results, I notice that, almost without exception ALL of the subs suffer significantly worse spectral contamination via their right hand input. As I like many probably assume it to be a siamese of the left input, I'd be interested to hears your (and Toms, as his subs were no exception) thoughts on this.

It may be stupid, but I imediately checked and then changed my input over. I was using the right input as BK make no recommendation. It's a free upgrade with objective foundation, so why not?

Russell


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## Jack Gilvey (May 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



> Believe me, I can “feel your pain” in all of this subwoofer drama. I have seen you disparaged and called every name in the book by certain individuals.


 As I've mentioned in regards to Illka, you can tell more about a man from his enemies than his friends. Says very good things about Illka.


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## Manic Miner (Jul 4, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

So this is where you have been hiding! First of all, congrats on the test Ilkka. It must have been a mammut task to say the least. I still haven't found the time to examine the data in depth, the weather has just been too nice, and when choosing between the beach and girls in bikinis, or internet and THD graphs the beach will always come out on top 

Being an SVS owner I have of course taken a look at the data for the 12.3 Plus/2, and I must say that I'm a bit surprised. The FR looks more arched then before, and I don't know if this can be seen as an improvement?

Also, the THD data for the PB10 looks very different to any other test of it, including your previous. Is this because the methodology has changed, or was the PB10 you measured a rotten egg?

This will have to do for now, I'm of to the beach


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Mark Seaton said:


> Now that I look at the data again, I am curious what process you are using to measure THD?


It was done via SpectraPro's internal datalogger. Of course it isn't very flexible, meaning some heavy research was needed before I could use it how I did. I have also shared my findings with Ed Mullen. I can tell you more if you are interested, but it won't really benefit you if you don't use the specific software. 



> FYI, if you haven't checked out WinMLS before, I think it might be a good program for you to experiment with as well. Lars Morset, the creator of the program, is a *very* sharp guy. If you contact him he might also have some useful suggestions towards streamlining such a measurement process.


I have checked the WinMLS and I would love to have it, but it costs something like $3500!  Unfortunately I don't have that kind of money to spend on software.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



russ.will said:


> Hi Ilkka,
> 
> If I may drag this back on topic, and Tom V may be able to help here - Amongst many eyebrow raising results, I notice that, almost without exception ALL of the subs suffer significantly worse spectral contamination via their right hand input. As I like many probably assume it to be a siamese of the left input, I'd be interested to hears your (and Toms, as his subs were no exception) thoughts on this.
> 
> ...


I assume you found this information (which input was used) by looking at the pictures? We tried to always use the left input (some subs required Y-connector), but sometimes we may have used the right one instead. It really doesn't matter which one is used. Regarding SC or any other variable.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Manic Miner said:


> So this is where you have been hiding! First of all, congrats on the test Ilkka. It must have been a mammut task to say the least. I still haven't found the time to examine the data in depth, the weather has just been too nice, and when choosing between the beach and girls in bikinis, or internet and THD graphs the beach will always come out on top


Hi Manic!

Thank you so much.  It was a bigger task than maybe many of you even understands. I'm on a well deserved vacation now (behind a bloody 56k modem!), so excuse me if you don't get any replies from me.



> Being an SVS owner I have of course taken a look at the data for the 12.3 Plus/2, and I must say that I'm a bit surprised. The FR looks more arched then before, and I don't know if this can be seen as an improvement?


I don't know if you remember my first round results (20-39PC+ results), but already the dB12.2 had this same arched/rounded frequency response compared to dB12.1. So it isn't really a surprise that also Plus 12.3 has it. It gives us worse extension but works better with room gain. Wider F6 bandwidth also gives less GD and less ringing near tuning frequency.



> Also, the THD data for the PB10 looks very different to any other test of it, including your previous. Is this because the methodology has changed, or was the PB10 you measured a rotten egg?
> 
> This will have to do for now, I'm of to the beach


Which other tests do you mean? Anyone else hasn't measured the PB10 using a similar 'THD sweeps' method like I have. Ed used only a simple 10% THD limit. Their results are not comparable due different signals (30 s sweep vs. 2-3 s single sine wave per frequency). The PB10 I tested wasn't a rotten egg.


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## Manic Miner (Jul 4, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

You're right. Every other test has been done using 2-3 second sines. I was just a bit surprised by the level of THD in the higher frequencies, and especially when compared to the Monolith that seems to tackle the 30s sweep better.

And trust me, noone admires you more then I. I hate repetitive tasks to such a degree that I would probably have comitted suicide after measuring sub #4


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## russ.will (May 10, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> I assume you found this information (which input was used) by looking at the pictures? We tried to always use the left input (some subs required Y-connector), but sometimes we may have used the right one instead. It really doesn't matter which one is used. Regarding SC or any other variable.


Thanks for the reply, I know you're a busy boy. If it doesn't matter, why measure it? I'm only really asking as a point of interest - it was a common discrepancy with ALL of the subs tested. In practical terms, what would be the audible difference in day to day use.

TomV, I'd like to hear your take on this aswell, as obviously, you're in a better position than most to comment on the technical reasons why.

Regards

Russell

PS1. In my early forum days, I got 'uppity' with you on AVF on the 'PB10 What Hi-fi? review' thread. May I make an unreserved apology for being an ignorant git?

PS2. Is there any way you can persuade AV Sales to get CE certification on the 20-39 PC-Plus? I've been experimenting with room positions and found a spot with really nice room gain that won't fit a box sub. And it's bonus time soon.:devil:


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



russ.will said:


> Thanks for the reply, I know you're a busy boy. If it doesn't matter, why measure it? I'm only really asking as a point of interest - it was a common discrepancy with ALL of the subs tested. In practical terms, what would be the audible difference in day to day use.


I'm not sure if I follow you anymore? Let me say it again. It doesn't matter which input is used (left or right).


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Manic Miner said:


> You're right. Every other test has been done using 2-3 second sines. I was just a bit surprised by the level of THD in the higher frequencies, and especially when compared to the Monolith that seems to tackle the 30s sweep better.


Yep, that is true, Monolith has much lower THD above 40 Hz. This is good example why I won't take those 10% THD tests anymore. They won't tell the whole picture.


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## Manic Miner (Jul 4, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

A couple of follow up questions. Even though they are For Ilkka, anyone can give their opinion.

-Why is it that the 30 second sweep shows more THD then the 3 second steady tone?

-Which one of the two comes closest to mimicing real world material?

I think it's about time I dove into the material, I've been to the beach so much lately that I'm actually tired of looking at scantily clad women! Also I'm so sunburnt that I'm not sure what will come first, autumn or skin cancer


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## Chrisbee (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Ilkka

One of the major problems involved in posting on a single forum then linking to it on others was your clear copyright notice.

Let me ask this bluntly: How would you feel if I had posted some of your graphs on AVF to illustrate a discussion?

In the absense of data or graphs it is very difficult to have a meaningful conversation on something so technical (on another forum).

In the absence of data and graphs it is much easier for doubters to downplay your results on that other forum. They did and succeeded well (rather than nicely).

Thanks Tom V for expressing your balanced views on forum politics and commercialism. 

Personally I hate the way commercial interests try to block the widespread consumer democracy spreading through the internet. 

One day somebody will explain (to forum moderators, owners and advertisers) the difference between linking to another forum and how that is different from having to actually browse "longhand" to find that forum and then struggle to find the item of interest in unfamiliar surroundings.

If I click a direct link I can go straight to the material without being sidetracked by any other "goodies". My attention is focussed right onto the linked material. I scan the linked material then quickly return home to my original forum. I am now prepared and more able to get involved in a discussion on the linked material in my "own" forum.

If I have to browse to find a particular forum and then have to wade through all the material there before I find the particular point of interest. Then I am much more likely to be hooked by the other material during my forum search for the item I wanted in the first place. I am also exposed to all the advertising on that other forum for a considerably longer period during my frustrating search for the exact item I wanted. 

Instead of just scanning the linked material and then returning home to eagerly discuss the linked material I am much more likely to spend time joining that forum. I may even enter into a discussion there once safely registrered.

Using a simple clickable link on my favorite forum I would be very much more unlikely to do any of these things

So: 

Direct linking to other forums keeps members fixed on the original forum. Or they will miss out on the ensuing discussion about the linked material amongst their regular posters. 

Not directly linking to other forums loses members and/or dilutes their forum interests and loyalties. It also exposes them to far more advertising for competing products while they search, join and post on the new forum.

I rest my case.


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## JimP (May 18, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

This is a no win situation for parties on both sides.

Give it a rest.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Chrisbee said:


> Ilkka
> 
> One of the major problems involved in posting on a single forum then linking to it on others was your clear copyright notice.
> 
> Let me ask this bluntly: How would you feel if I had posted some of your graphs on AVF to illustrate a discussion?


Hi Chris,

I wouldn't mind at all. Copyright notices are for magazines and sub manufacturers etc., so that they can't use my graphs to make money or advertice their subs. It is perfectly okay to post the graphs on internet forums.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Manic Miner said:


> A couple of follow up questions. Even though they are For Ilkka, anyone can give their opinion.
> 
> -Why is it that the 30 second sweep shows more THD then the 3 second steady tone?


That is due VC heating. It is most obvious at the end of the sweep (low frequencies).



> -Which one of the two comes closest to mimicing real world material?


Hard to tell. I'd say neither is one is very close, but we are forced to use them because there is no other way (for example use music to measure THD).



> I think it's about time I dove into the material, I've been to the beach so much lately that I'm actually tired of looking at scantily clad women! Also I'm so sunburnt that I'm not sure what will come first, autumn or skin cancer


LOL! That was a good one. I've been also getting plenty of sun lately. +25-30 C for many weeks now. :sn: Lakes (the water in them) are almost too hot already.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Hopefully Sonnie won't mind me using this thread to answer to some question rised in the AVS forum thread.



ManicMiner @ AVS said:


> Thanks for chiming in Ed, even though your comments have eased my mind a bit I'm still not totaly convinced. Even though just a fraction of a second is spent at each frequency it still adds up to 30 seconds, and every second is spent taxing the driver and amp without any time for the sub to recover. I'm by far no expert on how a sub works, but I guess that it adds up to a hot VC and empty capacitors by the time the sub gets down to the deepest frequencies.


You're being right, long sweep heats up the VC and that is the reason for higher THD readings. Capasitors won't have any effect, they are already emptied after a few hundred ms' of signal (one more reason for trying out the 6.5 cycle tones).

But IMO the longer sweeps (we've already used them for output compression measurements without problems) aren't that far away from the real deal. Many soundtracks have long scenes with almost constant rumbling which heats up the VC pretty well. If the sub can't hold up for longer than 2-3 seconds, it will be heard during those scenes. 



> This seems to have an impact on performance, at least if you compare the numbers Ilkka and Charlie got for the Monolith DF. I know that I shouldn't compare measurements of two different subs, but I can't help myself From what I can tell their numbers match well until they hit 30hz, and by the time they are down to 20hz there is a 3db difference in Charlies favour.


You can't see my previous results at the moment, but I can refresh your memory by telling that the first Monolith I tested hit 98 dB at 20 Hz, that is 2 dB more than the second one and only 1 dB lower than what Charlie got. Charlie is using 14 second sweep vs. my 30 s sweep. Also ambient temperature can and will cause some variations. And different units will also perform differently, for example the first PB10 had noticeably different FR than the second one I tested (ambient temp can also change FR).

One reason for the differences below 30 Hz is due the impendance curve of the sub. A 20 Hz tuned sub will have its impedance minimum near 20 Hz, meaning the max amount of current is pushed through VC. Add that to high ambient temperature and you will understand why sub's performance can and will vary quite a bit.


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## Chrisbee (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Thanks Ilkka. 

I would have had much more to say on AVF if I'd known I could post your graphs there.

The new comparison of the PB10 and Monolith didn't go down very well. :devil:


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Mark Seaton @ AVS said:


> Every time I scan through the measurements, with the exception of the Axiom EP600, which I suspect might have had complications in measurement, I see trends which do in fact lend to correlation to common listener descriptions. I'm throwing a question mark at the EP600 since I recall Ilkka having some earlier issues with longer duration test signals and such. One factor I don't see anyone ever discussing is that in the 6 Moons review, there was a note about a curious feedback that was generated when placed near the main speaker. This confirms my suspicion of there likely being some form of current-feedback in the system which accounts for their claims of "keeping the driver linear, etc., etc." You can't have feedback without some loop back to the input. This characteristic, combined with some creative limiting could account for problems in measurement.


Some of the Axiom EP-600 results do look somewhat strange, but not impossible. For example the FR and the max output results are being very close to Axiom's own measurements. Also their THD measurements (although done pretty differently than mine) show a pretty good correlation with my THD results. 

Of course we would need to test some more units in order to exclude the possibility of a bad unit.



> It looks like Ilkka took down the 25-31PC+ measurements with the 12.3 drivers, but those were some interesting comparisons. Even the Plus/2 with the 12.1 vs. 12.3 driver makes some interesting comparisions that clearly show that these are different subwoofers and should sound different.


I haven't took down any results. I never tested the 25-31PC+ with the Plus 12.3 driver.

25-31PC+ with dB12.2
PB12-Plus/2 with dB12.1
PB12-Plus/2 with Plus 12.3

were tested.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Jack Gilvey @ AVS said:


> Fair enough, we'll leave out the 600 in that case. What would you look for in a SC measurement that would indicate what people commonly call "musicality"? And, to Jakeman's point above, what bandwidth would such a measurement of a subwoofer have to cover to be useful? Ilkka's only go to 200Hz.


I could easily show the SC up to 20 kHz, but I decided to limit the range up to 200 Hz, because there isn't really much signal above it. I can show you some examples if you want (choose a sub you would like to see)?


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## Chrisbee (Apr 20, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

What variations can one expect from changing atmospheric pressure, humidity and temperature? Are we talking about large variations in performance?


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Chrisbee said:


> What variations can one expect from changing atmospheric pressure, humidity and temperature? Are we talking about large variations in performance?


At the moment I can't give you an exact answer. Making such study would be very interesting though.

Regarding ambient temperature I can say that most subs (probably not all) will gain around 1-3 dB of output when the temperature is lower (1 C difference won't matter but 10 C will do). The difference is most obvious at the freqencies where the sub has its impedance minimum(s). Of course the length of the sweeps and the time between the sweeps affects also.


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## Jack Gilvey (May 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



> I could easily show the SC up to 20 kHz, but I decided to limit the range up to 200 Hz, because there isn't really much signal above it. I can show you some examples if you want (choose a sub you would like to see)?


 Didn't realize you were answering here.  Maybe we could see those same ones, the 600 and PB10? As you say, your other results matched Axiom's. I'd just like to see if anyone can spot anything over 200Hz that could possibly mean anything in a subwoofer.
I'm trying to find an anecdotally "musical" sub and an anecdotally "amusical" one and compare the results for tests which people claim show a sonic signature in a more revealing fashion than the standard "big 5" measurements.


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## Sonnie (Apr 11, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> Hopefully Sonnie won't mind me using this thread to answer to some questions raised in the AVS forum thread.


I don't mind at all and I'm sure JohnM doesn't either.

This kindly puts a whole new twist on replying to posts. :R 

This is Ilkka looking at AVS... :neener:

Okay... back on topic. I don't need to steer us off course here.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Okay, Sonnie has twisted my arm enough. I will post my results also on HTS. We'll open a new sub-forum on Sunday the 16th. :rubeyes:


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## Jeje2 (Jul 4, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Chrisbee said:


> The new comparison of the PB10 and Monolith didn't go down very well. :devil:


:scratchhead: OK, now you got my attention, care to explain... 
(Last autumn Ilkka testeed my PB10 :T )


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## Jeje2 (Jul 4, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> Okay, Sonnie has twisted my arm enough. I will post my results also on HTS. We'll open a new sub-forum on Sunday the 16th. :rubeyes:


Hi Zipman,
I hope crosslinking to DVDplaza and here will be freely allowed, or? 

:raped: Dang, now one has to follow two sites for the discussion on your excellent results... :R :yes:


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## Sonnie (Apr 11, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

We do not have a problem with linking to another forum as long as it's not blatant advertising tactics. That really wouldn't be a concern with DVDPlaza since they are a Finnish forum for the most part. We are not solely U.S.... we are global but all English. We also have several members here that have been members for a long time at DVDPlaza and quite a few post here. I'd like to believe we could have a mutual relationship with DVDPlaza and it's members as it relates to linking.

This will hopefully accomodate the two languages easier. Viewers that don't understand Finnish won't have to worry about trying to figure out what the Finnish conversations are and vice versa. For those that understand both languages... it could be a lot to read if they follow both forums. I think I said what I meant to say... :scratch:


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## SteveCallas (Apr 29, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

While we're at it :R 

Ilkka, do you still have working links to your previous subwoofer shootouts?


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



SteveCallas said:


> While we're at it :R
> 
> Ilkka, do you still have working links to your previous subwoofer shootouts?


Nope, I've taken them offline. But they will be posted on the same sub-forum as these newer tests as soon as I have edited them a bit to match (visually etc.) with these new ones.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Jack Gilvey said:


> Didn't realize you were answering here.  Maybe we could see those same ones, the 600 and PB10? As you say, your other results matched Axiom's. I'd just like to see if anyone can spot anything over 200Hz that could possibly mean anything in a subwoofer.
> I'm trying to find an anecdotally "musical" sub and an anecdotally "amusical" one and compare the results for tests which people claim show a sonic signature in a more revealing fashion than the standard "big 5" measurements.


Yes, I'm here.  I'll make those screens for you by tomorrow.


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

http://www.hometheatershack.com/forums/subwoofer-tests/

The new forum is up!


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## Ilkka (Jun 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> Yes, I'm here.  I'll make those screens for you by tomorrow.


Sorry Jack, I've been really busy lately. I'll plot those screens for you in a few days. Although I can already say that there isn't anything special above 200 Hz...


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## Jack Gilvey (May 8, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*



Ilkka said:


> Sorry Jack, I've been really busy lately. I'll plot those screens for you in a few days. Although I can already say that there isn't anything special above 200 Hz...


 Yeah, I wouldn't expect there to be. Thanks...


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## MrPorterhouse (Jul 29, 2006)

*Re: DVDPlaza Subwoofer Tests Round 3*

Very nice work. I can't wait to see how the SVS PB12-NSD compares to the data for the SVS PB10-ISD. The PB12-NSD just might be the best sub value I've seen in a while, now I just want to see some data to make the claim.


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