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Thread: Which center? Luna, S2, or Horizon?

  1. #141
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    Default Re: Which center? Luna, S2, or Horizon?

    Quote Originally Posted by djDANNY View Post
    I’m assuming there has to be some difference in how the tweeter and woofer sum at the crossover point since the RAAL has such different vertical dispersion vs horizontal dispersion and the two orientations (center vs bookshelf) directly changes this. Given that dialog is smack in the crossover range, I’d like to see measurements as well to see if it’s worthwhile for me to try to get a bookshelf orientation to work.
    Crossover summation, how the woofer and tweeter "blend" with each other is not related to positioning a speaker vertically or horizontally. What changes is off-axis dispersion at more directional frequencies. Sitting on axis of the speaker, there is no difference in the direct sound response of the speaker, be that vertically positioned or horizontally positioned.

    You can see the vertical response of the Sierra-2EX in the measurements on our site. Of course, in these measurements the tweeter is not rotated 90 degrees. If the tweeter was rotated (as it needs to be for horizontal placement) the high frequency roll off you see starting at about 13 kHz wouldn't be there. You can also see that 5 degrees off vertically is nearly identical to 0 degrees off horizontally. On-axis, 0 degrees vertical would be identical to 0 degrees horizontal.
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    David Fabrikant
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  2. #142
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    Default Re: Which center? Luna, S2, or Horizon?

    Quote Originally Posted by Spamilton View Post
    Is there a significant difference in measurement when using the 2EX as a center (horizontally with tweeter rotated)? I'm trying to make it work vertically, but my cabinet is making it difficult.
    If sitting on axis, no - there is no difference at all. There will start to be differences the further off-axis you get. Note, it is very important that the ribbon tweeter is rotated properly such that the longer "length" of the tweeter is vertical.
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  3. #143
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    Default Re: Which center? Luna, S2, or Horizon?

    How about the Sierra 1 with Nrt tweeter? It's the center I'm considering. It's also less power hungry than the Sierra 2EX.

  4. #144
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    Default Re: Which center? Luna, S2, or Horizon?

    Quote Originally Posted by SunByrne View Post
    OK, time to wade in on two different topics, ASR and the Duos.

    First, on ASR
    I have confidence that ASR's measurements are correct; I'm sure he knows how to operate his Klippel and the other equipment he uses to measure things besides speakers. If all he did were take measurements and publish them, that would be fine.

    But that's not all he does. He adds interpretation to the raw data, and subjective reviews. He does both of these things very badly. On the first point, nobody who takes their own data seriously should ever say anything like "where do you draw the regression line?" A regression line shouldn't be drawn by anything other than THE EQUATION FOR A REGRESSION LINE, which is well-understood math. This kind of thing is nonsense and nobody who claims to be in interested in the science should put up with it. If I did this kind of thing with my own research, reviewers would (rightly) crucify my papers. It's bush-league garbage. Toole, for instance, would never say anything like this.

    As for his subjective reviews, I don't know how anyone takes those seriously. He writes like he thinks his own opinion is a gift from the gods, and it's just so off-putting. They are also so obviously Harman-biased that they are basically worthless, as every objective sin for any Harman product is subjectively forgivable but for many a Harman competitor every wiggle in any graph is the death knell. He needs to do his subjective review before he collects the data in order to not be biased by the results and his own interpretation of those results. This is basic behavioral science methodology and he's just so damn cavalier about ignoring it. He apparently thinks that because he includes the "I work for Harman" disclaimer that people will give him a pass on this or something. I mean, I guess it is actually working for him but I can't read it or take it seriously.


    Now, having said that, the objective measurements on the Duo are... not very pretty, are they?


    Luna Duos
    I just got a set of these (LCR) and have had them for a little over a month. As Dave well knows, I'm a long-time very happy Ascend customer. I usually post my reviews/impressions pretty soon after I get anything new from Ascend, and I have not done so for the Duos. (If Dave hadn't been so busy, it wouldn't surprise me if he has been wondering when I'd post about them.) I haven't because [1] I've been crazy busy myself, and [2] my impression of them is somewhat mixed, and I've not been sure what to say about them.

    It was interesting to see the measurements, as they kind of support some of my experiences with the Duos.

    First, the Duos do indeed have tremendous wide dispersion—it's fantastic. The sweet spot is generously wide, such that two people can be sitting on the couch in my living room and both get decent imaging out of the deal. Just not at all true with my previous speakers, which were not bad speakers at all (older PSBs). Real rooms often make ideal placement impossible, and anything that gives you leverage on this problem is not to be underestimated.

    Second, vertical directivity is indeed pretty tight. The good news is I'm pretty much always on the couch when I listen and I was careful with mounting height so this is not a problem, per se, but it's pretty obvious when you stand up that something is missing. I expected this and it's no big deal.

    Third, there's something not quite right about the mids. Maybe that's too harsh. What I mean is that it's not as good as I expected from Ascend. When I first set them up and ran Audyssey, it said the LRs could handle being crossed over at 60Hz and the center could cross over at 40Hz. While that's impressive, I know Audyssey is sometimes overgenerous about that and I set the center to 60Hz as well. And they overall sounded mostly OK, certainly for normal HT use, but for music, well, there's something kind of choppy going on in the midrange. Not bad—nothing like what ASR describes subjectively—but something just not quite smooth in the Ascend way I'm used to. Noticed it mostly in female vocals, which sound a little... I guess the best word is uneven. I actually considered sending them back, but there are other practical reasons for the choice, and given those constraints I have few other viable options anyway. (PSB PWM1s are pretty much the only reasonable alternative at a similar price point and then there will be timbre-match issues with the surrounds. Too much hassle.)

    But after listening to some music (the Duos are used mostly for HT anyway) I had the bright idea to change the crossover to 80Hz. They sound much better. They still don't sound as good as my 2EXs—not a giant criticism, I've never heard anything two-way that sounded appreciably better—or even base S2s, but it evened things out to where I'm much happier with them. I'll admit I'm suspicious that this is just in my head, since my understanding is that a lot of the issue with port noise for front-ported speakers isn't really from air moving through because of low frequencies, but reflections of midrange from inside the speaker, and setting the crossover higher shouldn't really change that. Sure seems like it does, though.

    It's funny because I've never heard a speaker with a front slot-style port that I've really liked. I figured when Dave went there after all these years of not using them, well, he'd finally cracked it. Maybe still a little work to be done. (Since I'm crossing over at 80Hz, maybe some kind of port plug?)

    So, for primarily HT use (with sub) at my seating distance (about nine feet), I'm fine with them. I'm not overwhelmed like I usually am with Ascend, but given my constraints, they get the job done and it's a marked improvement over what I had before.


    Anyway, I'm glad to see Dave's response to all this is "we need to look into this and possibly fix something," but that's what I'd expect from Dave.
    I reposted this response as I feel it makes some excellent and honest observations. Since this thread has evolved into an ASR commentary, I too agree that the responses posted by the site were what were measured with the Klippel.

    Also as noted in the above post, the site owner really showed that his subjective commentary was unnecessarily unkind, and unprofessional. He basically called out Dave's integrity, whereas I can think of no one else in this industry that has gained and deserves more respect for supporting his customers with the best products that he possibly can, posting far more technical information than almost anyone in the business. Where else do customers get to participate in what types of products a company will develop?

    Speaking of this subject, the Lunas/Duo were developed strictly as a response to the desires of Ascend customers for a front ported, wall hung RAAL equipped surround, and a less bulky center solution. Dave clearly does not prefer front ported designs, and has avoided them for the better part of Ascend's history. With all that said, Dave himself uses a pair of Lunas in his personal bedroom system, whom could possibly be a more critical listener than Dave?

    Regardless of what agendas third party reviewers may or may not have, I will go on record that I trust Dave implicitly, and without reservation. He has shown himself to be a person of great character, passionate about creating excellent products at reasonable prices, and just an all around gentleman even while facing criticism. If I sound like a fan, that doesn't bother me in the least, some folks just do it better than others!

    I'm looking forward to the information that has been uncovered regarding this issue.

    Jay

  5. #145
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    Default Re: Which center? Luna, S2, or Horizon?

    Quote Originally Posted by davef View Post
    I will post my findings once things slow down over here (lots to share). We have been working 12 hour days for the past 2 months. Holiday season typically starts to slow down for us towards the end of January.
    Since this thread is being revived? Can we get this update now?

  6. #146
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    Default Re: Which center? Luna, S2, or Horizon?

    I appreciate everyone’s patience regarding this matter. As some of you know, I suffered a serious E-Bike injury on July 4th requiring several nights stay at the trauma center at my local hospital. My injuries were/are serious (7 broken ribs, 2 lung punctures, broken scapula, mild head trauma). I was very lucky as I cracked my bike helmet in 3 places and even luckier as I managed to somehow avoid surgery.

    As I am sure some of you know, recovering from injuries like this takes quite a bit of time, patience and assistance. I am at the 6-week mark now and while I feel my lung has healed and I am finally able to breath normally and I have more mobility, I still have high levels of pain every now and then and my mobility is maybe back to 50%. I am hoping 4 more weeks and I will be back to 100%. Obviously, this is has presented me with a major setback on the timing of a few items. Of most importance is this discussion regarding the Luna and Duo. Most of this was worked out prior to my injury and the final touches were finally taken care of this weekend.

    There is much to post so I will break this up into sections, with the goal of posting one section each day until everything is covered.

    Part 1.

    With the tests of our Luna and Duo, measured by Amir at Audio Science Review – the results were poor. Their measurements did not match up well with our measurements and horrible accusations were thrown our way. I have been open, honest and as transparent as possible about Ascend and we have always and will always manufacture exceptional products with the highest levels of integrity.

    Seeing those measurements (and some of the comments) threw me for a loop, I did not even recognize what I saw. I had to ask myself, “how could it be possible for a speaker to measure that way yet have such a high customer satisfaction rate?” (Sales of our Lunas eclipsed our forecasts)

    Could this customer’s speakers have a problem? I didn’t think so since Amir measured a Luna and a Duo, and both showed pronounced port resonances that negatively influenced and changed the overall frequency response. As such, it became critical for me to get back this customer’s speakers and I am thankful he reached out.

    During that waiting period, I set out on endless computer modeling and took detailed measurements of more than a dozen Luna’s. While I was able to measure some port resonance, it was not even close to what Amir’s measurements showed. The differences in our measurements were so dramatic that I broke out my reference CBM-170 that was measured at the NRC in an anechoic chamber, and then compared those measurements with measurements I took. My measurements were within +/- 0.5dB from about 200Hz and up (no reason for me to spend the time and accurately measure the low end) I was really puzzled, I could not replicate Amir’s measurements.

    Since the measured port resonance exhibited a very high Q behavior (extremely narrow bandwidth) I assumed this must be an issue using gated measurements (a method to remove the influence of a room / reflections). Gated measurements are common and have been universally accepted. This method does reduce frequency to frequency resolution with the smaller the gate time the greater the reduction. With larger gate times, reflections get included in the measurement which then throws everything off. Our testing procedures and gating times have been the standard for decades now, something I used from my days developing THX certified speakers, which had to meet very stringent measurement standards. I further enhanced these over many decades of use and in designing 40+ commercially successful loudspeakers.

    For many decades, the common thoughts on what we hear is that, at best, we hear at 1/6th octave. Meaning all the frequencies within an individual octave are averaged into 6 points. Some argue we hear at 1/12th, but I personally don’t believe this, other engineers will say we hear at 1/3rd octave. A decent article on this can be found here: https://www.prosoundtraining.com/201...-octave-bands/

    With the gate times we use, resolution is typically about 1/12th octave, fully covering what human hearing can detect. However, the port resonances measured by the Klippel NFS are so narrow that these would typically not be picked up with standard gated measurements and are also not audible to human hearing. After evaluating a half dozen other front ported speakers measured by Amir and comparing the NFS measurements with other published measurements, I can confirm this issue is not isolated to our Luna and Duo. Some of these other speakers displayed even worse port resonance, but other published measurements do not show this and like our Luna, these speakers have been widely praised and have sold well.

    The Klippel NFS changes things, it is capable of measuring at resolutions previously not possible, resolutions far greater than what the human ear can hear. I like to use the comparison of looking at Jessica Alba’s face at 3 feet away, compared to looking at it with magnifying glass. Near perfection at 3 feet vs nothing but flaws close up under magnification. What do we see / hear that actually matters to our senses? I have discussed this issue in depth with a well published audiologist and his thoughts echoed my own.

    Still, the results of the NFS measurements were not acceptable to me so it was time to move to the next phase.
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    David Fabrikant
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  7. #147
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    Default Re: Which center? Luna, S2, or Horizon?

    Part 2.

    One major benefit of our MLSSA test system is that it is highly configurable. Every parameter can be set, FFT resolution and size, windowing methods, stimulus length, amplitude etc. It operates mostly in the time domain so an experienced user can easily see every reflection, including the intensity of each reflection. There are techniques to increase resolution while still gating reflections out of the response. I set out on reconfiguring the test parameters to increase resolution and take measurements of just the front slot port in the hopes I can see what the NFS picked up.

    Now using an FFT size of 32,768 combined with a mic distance of ~ 2ft, with no gating and no smoothing, (yielding a resolution of 4Hz) I was able to see the port resonance. This was a few dB in amplitude and extremely high Q (very narrow, covering a frequency range of only ~50Hz). Certainly not audible and still not close to what Amir picked up, but at least this was at the same frequencies. Normally, an experienced loudspeaker engineer wouldn’t pay much attention to this being so narrow and with low amplitude – which explains why so many front ported speakers measured by Amir show very similar port resonances. However, Amir’s tests and his analysis of these tests do not take into account what the human ear is capable of hearing. Plain and simple, we cannot hear such high Q peaks.

    If you have ever looked at an actual in-room frequency response of a speaker, it is riddled with similar high Q peaks throughout the speaker’s entire response. If you take the best measuring speaker on the planet, take an in-room frequency response measurement and examine the results, most would be horrified by what they saw, and the prominent question would then be “how could this possibly sound good”. The reason the speaker still sounds so good is that we don’t hear these high Q peaks (or dips). As I mentioned previously, we hear an averaged response that is either smoothed to 1/6th octave or possibly even 1/3rd octave, this flattens out those peaks (and dips) and what you visually see on the smoothed frequency response graph ends up being more representative of what we hear.

    With a review site like Amir’s, things are changing – not necessarily for the better in my professional opinion. Speakers will be judged by measurements only, measurements that are of such high resolution that no human ear could ever actually hear. A bit like ruling out a performance car because after dyno testing, one has more horsepower than another without ever test driving the lesser power model.

    Let me back track a bit…

    We were the first ID audio company to publish detailed measurements of our speakers, and possibly even the first loudspeaker company to publish in-depth measurements (on and off axis, CSD etc.) Our measurements have always represented what the speakers are expected to sound like, a terrific method to compare one of our models to another one of our models. We have multiple test systems, including 4 reference grade measurement microphones, a fully automated turntable for directivity measurements, (2) MLSSA 2000 systems both with RCAI controllers (remote controlled analog interfaces), as well as a half dozen other test systems (less powerful, but still useful) One critical aspect of loudspeaker testing is to “trust” the results of the measurements. This is complicated and requires using different setups and different gear, something we always check for. We have our acoustic lab and our production line facility, very different locations with both being able to take accurate and repeatable measurements.

    MLSSA systems have been the industry standard for decades and the same equipment used to design most non-hobbyist loudspeakers. This is expensive professional equipment of the highest standards and certainly not a hobbyist system. The same measurement setup has been used by Harman, the NRC in Canada, Stereophile, Apple, BMW, M&K, Lucas Film, THX, Disney, Dolby – the list goes on and on and is impressive. The mic in our lab is an ACO Pacific 7012, this is a fully calibrated true reference grade mic, accurate from 3Hz to 40kHz within 0.5dB – it is a more capable microphone than what is included with the Klippel NFS. I believe we had originally paid about $4k just for the mic and the pre-amp. This is a system I have been using practically every day of the week since about 1988. Few if any engineers have as much experience with it as I.

    For about 2 full decades we have done our best to avoid front slot ported speaker cabinets (many of you know this). Reason being is they are often subject to port issues, but times are changing and there is strong demand for compact on or off wall speakers that offer excellent performance and can be crossed to a sub at 80Hz. Thus the Luna and the Duo were born.

    Now armed with the ability to at least “see” the port resonances using our test equipment, I started tearing apart Luna cabinets to find out what could be going on with the port. The slot port in the Luna and Duo is complex. This specialty woofer needs to be matched with a ~60Hz port tune to perform at its best and to tune that low requires a very long port, far longer than the depth of the cabinet.

    As such, the slot port relies on very tight tolerances in order to function properly. I started to assume that with this customer’s speakers – perhaps there was too much tolerance drift throwing it out of whack, and that I did not pick this up during our production line testing because we use a smaller FFT size (to speed up testing) and these measurements are gated to remove reflections, so very high Q (narrow) spikes in the response could be smoothed over. I also demand a lot from our domestic cabinet manufacturer and perhaps there was just too much room for error in assembling these complex and very compact cabinets.

    With cabinets torn apart, I did not find any significant issues with the port, and now I was getting angry as I destroyed several thousand dollars’ worth of cabinets. Next step, I purchased a high-resolution borescope and went about looking deep inside the slot port of each Luna and Duo cabinet. While things were not perfect, I still saw no real issues that would cause what Amir’s measurements revealed.
    It was at this point that I had to take a step away from this and I decided to wait until the original test speakers arrived at our facility.
    Last edited by davef; 08-18-2021 at 10:51 PM.
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  8. #148
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    Default Re: Which center? Luna, S2, or Horizon?

    Part 3.

    The day finally came, both the Luna and Duo tested by Amir arrived. I was hopeful I would find the issue quickly, that I would be able to pick up what Amir picked up and thus set about a course for correction. Unfortunately, my frustration reached its peak when I was not able to do this. The suspect speakers measured closely to the samples in my lab.

    The scientist in me then decided it was time to take a different, more logical approach…

    I spent the next 6 hours reading more about the NFS and how it takes its measurements. Had email correspondences with Amir, the engineers at Warkwyn (Klippel NFS experts and the US reps), and over a dozen emails with my various contacts at Klippel. This eventually led to a wonderful 2+ hour zoom call with one of my engineering contacts at Klippel where I was basically hands on with DB-Lab (the software that does the NFS calculations and graphing).

    Upon Klippel’s request, Amir was kind enough to share the measurement database and as such, I was able to really dig into the data. The Klippel NFS is truly state of the art, but it does measure in the nearfield. In short, for directivity measurements (what it was essentially designed for) it measures at calculated near field points in 2 cylinders around the speaker, with one cylinder being at a slightly larger diameter compared to the 1st cylinder. With these measurement points, it uses complex field separation algorithms combined with some gating (from about 3kHz and up) to effectively remove the “room” from the measurements thus producing a high-resolution 3D anechoic far field directivity scan. All the measurement points (can be several thousand if needed) are taken in the nearfield and all far field data is then calculated.

    What is especially interesting is that besides the data needed to calculate CEA-2034 specifications, one can quickly see the response for any off-axis angle at any distance. This is far superior to using a turntable in an anechoic chamber as this measures in only 2 planes, either 0-360 vertically *OR* 0-360 horizontally. One cannot measure, for example, 45 degs horizontally *AND* 45 degrees vertically without physically moving the microphone. I have always thought soundpower and predicted in-room response measurements were very limited because as mentioned, this data only measures in 2 planes and that is not fully representative as to what we actually hear. I estimate that at some point in the near future, CEA-2034 standards will be updated to include a true spatial response, a measurement technique I was required to use when developing a THX certified speaker ~ 30 years ago. This required taking measurements by having the speaker fixed in one position of a room but taking many different measurements each with different mic positions and heights. I have always felt this was a more accurate technique than current soundpower standards, but it requires a ton more work than simply using a turntable and repeatability is difficult.

    Now armed with much more knowledge of the NFS, with the key points being the distances used between the mic and DUT, and voltage levels Amir used, I set out to match Amir’s measurements using our own test gear.

    Using MLSSA to do nearfield testing is rather simple, but to gain maximum resolution I had to reconfigure various setup parameters to make sure I was using the same measurement distances as the NFS. After much research and even more trial and error, I found that allowing a few minor reflections so that we can increase the time window from about 8ms to a massive 23ms, we were able to match Amir’s measurements from about 200Hz and up.

    Bam, there it was… that nasty high Q port resonance.

    I have designed many dozens of commercially successful speakers using the same gear and configurations over the past 4 decades, many of which have been intensively reviewed and measured – the same configurations used by many of the companies using MLSSA systems as I mentioned above. This new configuration was something different but obviously now necessary because the Klippel NFS is sure to become the new standard.

    With this new testing configuration, I then coded new macros to automate the 72 measurements needed to measure soundpower, including the weighted averages needed for the calculations. From this data, I can then fully automate all the data needed to generate more accurate CEA-2034 measurements. This is something we have been doing for a while, but now our processes and the results are more accurate and of higher resolution – far exceeding previous standards.

    With the results from ASR and our new measurement configurations, we made significant investments into our R&D. The most critical project was obviously going to be reducing the port resonances in these 2 models. One can only go so far with modeling, and I suspected this would require a specially designed sample cabinet whereby I could try various slot port configurations. Considering Covid, which has truly devastated small businesses in California, lead times for these special sample cabinets from our domestic cabinet maker were far too long to work for my timing. As a result of this, we purchased our own industrial grade CNC router, (2) 3D printers, and extremely advanced CAD/CAM software that now allows us to go directly from 3D CAD to accurately cutting the baffles on our CNC, and/or printing various parts on one of our 3D printers. I made several fully 3D printed Luna cabinets (wood filament is very interesting!). Unfortunately, each cabinet took about 24 hours to print, and that was if I got lucky and didn’t run out of filament or experience a jam. The move to a full blown CNC was expensive but a massive time saver.

    This is now about as fast as rapid sampling can get in this industry and I doubt ANY similar sized or even many larger loudspeaker manufacturers have the capabilities we now have. This would be considered a sizeable investment for businesses that are even significantly larger than we are, especially during Covid but we take the performance of our products very seriously.
    Last edited by davef; 08-21-2021 at 04:46 PM.
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  9. #149
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    Default Re: Which center? Luna, S2, or Horizon?

    Part 4

    (getting to the good stuff)

    I prefer to skip over all the various processes between back then and where we are currently at, but after intense engineering work on reconfiguration of the slot port, we ended up exactly back where we started. These woofers simply perform better at the original port tune (~60Hz), and to do this meant there would be no changes to the slot port dimensions, that or we would have to significantly increase cabinet sizes and that defeats the entire purpose of these speakers.

    Some will ask about going with a sealed cabinet. I tested this approach, and the losses in bass extension were just not acceptable. We would end up with a speaker that would start rolling off at about 200Hz, also defeating the purpose of these speakers.

    It was then that I took a different approach, going back to the development of our Q-Plug “B”, which effectively mass loads and damps the port in the Sierra-1. Would a similar approach work for the Luna and Duo?

    After much research and sampling, we found a specialized foam that offers exceptionally high damping at the frequencies we needed, combined with allowing air to flow through. We determined the appropriate size and layout and in combination with changing the internal damping of the cabinet, this solution turned out to be extremely effective at eliminating port resonance and air turbulence. It also dramatically reduced any port leakage and all with almost no changes to the critical port tune. In addition, overall bass extension was slightly improved due to reducing turbulence and slowing the airspeed in the port.

    The results were dramatic.

    Original Luna port response:

    OG4IN.gif

    Luna V2 port response:

    V2P4IN.gif

    Comparison: (Luna V2 port response in purple)

    COMPARE.gif

    With port resonance now fully resolved, next step was to rebalance the crossover as the bass response of the speaker was now slightly different than the original (a good thing). In working with this, I came across something most interesting that required investigation.

    The measurements I posted above of the port response were all taken in the nearfield (with a 23ms time window). My port measurements of the exact same speaker that was measured at ASR now closely match the port response measured by the Klippel NFS. However, the port response measurements dramatically change when measured at 1 meter.

    Port response at 1 meter:
    (Note, at 1 meter we are also picking up the woofer response)

    OGP1M.gif

    Using the exact same windowing with no gating, thus seeing the influence of the room (minor reflections) – you can see how the high Q spikes of the original speaker are significantly reduced. These resonances behave differently than the response from a woofer, which when examined anechoically, the frequency response will not change at different distances (other than in overall amplitude)


    To be sure this wasn’t due to the room, I now gated the impulse response to remove the influence of the room (at 1 meter with a 23ms time window, the room will have influence).

    Port response at 1 meter, anechoic.

    OGP1MG.gif

    The prominent high Q spikes at 600Hz and 1200Hz are mostly gone. I found this puzzling. As I mentioned previously, the Klippel NFS measures in the nearfield and the farfield response is calculated mathematically. My measurements clearly show that port resonance propagates differently than, for example, a woofer. Could there possibly be an issue such that NFS measurements are somewhat exaggerating front port resonance? There is no way for the NFS (or for any measurement system for that matter) to inherently know the difference between the output of a port or driver. Could the NFS be picking up all that nearfield turbulence and using it in the algorithms to determine the farfield response?

    I didn’t know and the engineer I was working with at Klippel also could not confirm one way or the other. This would certainly explain some of the other front ported speakers measured at ASR that showed prominent port resonances that didn’t show up in other published measurements. For example, the Salk WOW1 measurements published on the Salk website differ from ASR’s measurements in the area where the NFS picked up port resonance.

    Could this simply be a matter of microphone distances? It has long been the standard to measure a speaker at either 1 or 2 meters. We typically measure at 1 meter. In the case of the NFS, it measures at nearfield distances and 1 meter response (or any farfield response) is calculated mathematically.

    Or is it that the NFS is simply much more accurate? (which is also possible)

    To check this, I went back to the basics. MLSSA can operate in a power spectrum mode, reading the response of the room very much like an analog RTA (real time analyzer). I often use this mode when I don’t trust a particular measurement. In this case, I started to question everything, so I connected a low distortion oscillator to an amp and connected the amp outputs to the original Luna. I set the oscillator frequency to 600Hz and ran the sweep. I then ran 3 more sweeps, increasing the frequency by 200Hz each time.

    OGSPECT.gif

    As you can see, the amplitude differences in the fundamental peaks match well to the ungated 1-meter response. There doesn't appear to be a prominent port resonance showing up in this measurement at 600Hz, unlike the nearfield measurement. I do somewhat trust this measurement because it is as close to simulating human hearing with electronic test equipment as one can get.

    I should mention, I have already resolved the port resonance issue but the scientist in me took over and there was just no possibility I could let this question in my mind go. To be clear, I am not stating that the NFS measurements of front ported speakers are inaccurate, but there are differences showing up that need to be further examined…

    Please wait for Part 5…
    Last edited by davef; 08-25-2021 at 04:27 PM.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

  10. #150
    Join Date
    Aug 2003
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    USA
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    Default Re: Which center? Luna, S2, or Horizon?

    Part 5 (conclusion)

    Introducing the Luna V2 and Duo V2

    I have mentioned several times how important it is to trust measurements. This is not as simple as it sounds. It takes years / decades of experience to look at a loudspeaker measurement and trust it. It also often requires using different test gear as secondary confirmation. MLSSA, LMS, CLIO, TEF, Audio Precision, Praxis; add to that a half dozen software-based systems that use PC sound cards, I have experience with all of these. All have pros and cons, various limitations.

    It is difficult for me to estimate how many loudspeaker measurements I have taken over the past 4 decades – considering I test speakers 5 days a week, I estimate I have likely taken over a hundred thousand measurements at this point (realistically it is probably twice that).

    When factoring in my obsessive scientific curiosity, the situation I mentioned in part 4, my time spent with the engineers at both Klippel and Warkwyn, and the potential the Klippel NFS brings to R&D – I, unfortunately, quickly realized I had no choice in this situation.

    I am most pleased to announce that Ascend Acoustics purchased a Klippel NFS.

    I have spent the last 5 months learning, optimizing, and getting to know this game changing device. This is an insanely expensive instrument; its cost alone greatly limits what companies own or will ever own one. We have actually had it in full operation since this past April.

    We are the very first internet direct audio company in the world to purchase an NFS and it is simply unheard of for a loudspeaker company of our size to make this type of investment into R&D. I have stated we don’t mess around, and I most obviously truly mean that.

    What I quickly realized during my hands on zoom call with Klippel, that combining the power of our MLSSA systems together with the Klippel NFS puts us at the forefront of R&D and, this is not even questionable, Ascend Acoustics now has one of the most advanced acoustics labs on this planet. Firmly planting us back at the forefront of speaker design and measurement, a position we enjoyed for many years when we first got started ~ 22 years ago.

    There are many new and exciting things coming to you, our customers – our family, some of which no other company could possibly offer. I can not get into all the details of what we have planned, implementation will take some time.

    For now, and what is most important – we are most pleased to announce both the Luna V2 and Duo V2. Both of which now feature our unique NFS optimized port damping system combined with a re-balanced crossover that has also been fully developed using our Klippel NFS.

    With the port issue resolved to highly favorable conditions, I decided to experiment a bit more and devised an improved method to integrate the RAAL tweeter in both the Luna and Duo crossovers. This new integration provides a bit more of the classic in-room response curve but without sacrificing any of the remarkably wide horizontal dispersion. This new method would not have been possible without taking full advantage of the NFS directivity measurements combined with advanced mathematical modeling / optimization of that directivity. The Luna V2 and Duo V2 are warmer and smoother sounding, with improved midrange clarity.

    We had wonderful customer feedback and an extremely high customer satisfaction rate on both the Luna and Duo before ASR, so it will be an interesting real-time experiment to compare the original version satisfaction rates with the new V2 versions. The new versions sound warmer, cleaner and more relaxed, without sacrificing anything. There is no hint of audible port resonances (I don’t believe the prior port resonance was audible as human hearing cannot detect such high Q peaks), but now the measurements look fantastic and that means a lot.

    Here you go.

    Luna V2 CEA 2034:

    Luna V2 CEA2034.jpg

    Predicted in-room response:

    Luna V2 Estimated In-Room Response.jpg

    And what makes this little speaker so special

    Horizontal beam width:

    Contour Plot Luna V2.jpg

    This beam width is remarkable, it represents a very even +/- 100 degs, with no narrowing of the upper frequency ranges yet the predicted in-room response shows a classic and preferable downward slope. This makes both the Luna V2 and Duo V2 quite unique and unmatched in this regard. This translates to an exceptionally wide soundstage with precise imaging. This wide and linear dispersion is simply not possible with a dome tweeter and has been greatly improved upon with our new method of crossover integration.

    Early Reflections:

    Luna V2 Early Reflections.jpg

    Duo V2 CEA 2034:

    DuoV2 CEA2034.jpg

    Predicted in-room response:

    DuoV2 Estimated In-Room Response.jpg

    Horizontal beam width:

    Contour Plot Duo V2.jpg

    Early Reflections:

    DuoV2 Early Reflections.jpg


    We are now just waiting on crossovers to be delivered to us (we estimate 2 months, factoring in the current nightmare situation with shipping and part supplies). For those who do not wish to wait that long, please send me an email.

    My final thoughts on this issue.

    Based on much experimentation and various other measurement comparisons, I believe the Klippel NFS does slightly exaggerate front port resonance issues when calculating its far field measurements. The port resonance in the original Luna and Duo does indeed exist, as I mentioned and measured in Part 4, but I am not yet entirely sure if this is represented properly in far field measurements because this area of the far field measurements differs considerably between what the NFS calculates and what other measurement gear measures. Since there was no way for me to confirm this, one way or the other, the best approach was to simply eliminate / reduce the port resonance to the point where it does not show on both the NFS measurements and our other test systems. In this manner, I am assured it no longer exists.

    One additional item I found most interesting. Below are the CEA-2034 measurements of the Duo when positioned horizontally (as a center) with the tweeter properly rotated. Note how close these measurements are to the vertical Duo. The predicted in-room response is nearly identical.

    Horizontal Duo CEA-2034:

    Duo V2 Horiz Center CEA2034.jpg

    Horizontal Duo Predicted in-room response:

    Duo V2 Horiz Center Estimated In-Room Response.jpg

    As I originally mentioned when we first started discussing the NFS measurement results at ASR, we will take what we learned, and both the Luna and Duo will come back as better performing speakers. There is no question these measurements represent remarkable performance improvements, not only an improvement but with documented measurements of the highest resolution possible that now compare well with even the best passive speakers out there.

    The past 5 months has been an interesting time; exhausting, educational, exciting, and expensive. Add to this my accident and Covid and, well, I don't know how I will look back at this time period but I will say that I am most happy with the investments we have chosen to make for the future of Ascend and the benefits this brings to our ever growing family.

    As always, thank you all for your continued support!
    Last edited by davef; 08-31-2021 at 10:00 PM.
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    Good Sound To You!

    David Fabrikant
    www.ascendacoustics.com

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