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    KEF LS50 (David) Versus JBL 4722 Cinema (Goliath) Speaker Comparison with Binaural Recordings

    image1.pngHere are two extreme opposite loudspeakers when it comes to sensitivity, size, directivity, topology and looks. Does the big speaker sound perceptually larger than the smaller speaker? Do the speakers sound the same if eq’d the same and level matched? Does the LS50 sound perceptually bigger when a subwoofer is added? These are some of the questions I attempt to answer in this article.

     

    While there are objective measurements, I have included binaural recordings comparing the level matched loudspeakers so you can hear over headphones what the differences are. Prepare for an ear opening experience.

    I love big, high efficiency loudspeakers. I feel they sound more “dynamic” than smaller low sensitivity “audiophile” loudspeakers. Is it my biased belief or does it prove out audibly? You be the judge by listening to the binaural recordings.

     

    Finally, consider this article a review of the lovely and talented KEF LS50, a precision engineered loudspeaker designed to sound good in your room. This pair is staying in my room.

     

     

     

     

    KEF LS50

     

    There are many positive reviews about the KEF LS50 mini monitor from various publications like Stereophile and Soundstage. I am not going to repeat what has already been written, but I want to point out a key aspect on why the LS50’s sound so good, as evidenced by listeners and reviewers alike since its introduction in 2012 . KEF has written a white paper on their technology progression through the years called, The Reference. It is a wonderful 29 page read if you have an appreciation for fine engineering design. A key aspect of what makes these speakers sound so good is derived from this example set of frequency responses in this chart:

     

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    “Figure 12 shows a set of frequency responses for an early prototype of Reference 5. The curves shown in this plot are the figures of merit for assessing loudspeakers as suggested by the work of Floyd Toole. The curves are measured at 96 data points per octave without any smoothing. Based on these figures of merit Toole was able to predict real listener preference with a remarkable accuracy.” The last sentence is the key idea I want to bring to your attention and expand on a bit.

     

    The chart above is often referred to as a “spin-o-rama” in which you can read about it here in detail (from 2002!) or if you simply want to know how to read the chart. The science behind this enables the key aspect of, “predict real listener preference.” I have written a summary about this before, “The Science of Preferred Frequency Responses for Headphones and Loudspeakers”, peer reviewed by Dr. Sean Olive.

     

    image3.png I bring this up as I took a science leap of faith based on Floyd’s (and Sean’s) research, which was leveraged and acknowledged by KEF in the Reference whitepaper. I purchased a pair of LS50’s without listening to them. But I already knew from product reviews and measurements, and in particular, Floyd’s predictive model, that the LS50’s will sound neutral in my listening room. As one will hear on the binaural recordings and shown in my in-room measurements, the LS50 is a remarkably neutral sounding loudspeaker.

     

     

     

     

     

     

     

     

    LS50 Objective Measurements:

     

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    First, let’s look at a near field (30cm from driver on-axis) in-room frequency response measurement and compare to the NRC’s anechoic measurement:

     

     

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    Courtesy Soundstage/NRC

     

     

    Remarkably similar. My room is certainly not an NRC anechoic chamber, as can be seen in the room picture above. But I can capture the sonic signature of the LS50 with a 30cm in-room nearfield measurement. Thinking of it another way, it also verifies my acoustic measurement setup and capture is reasonably accurate.

     

    Note the gentle rise starting around 2 kHz. If listening to the LS50’s nearfield on a computer desktop, you may need to dial in a high frequency shelf starting at 2 kHz to reduce the high frequency energy ever so slightly. If I wanted to use these as computer desktop speakers, I would still put them on stands behind the desk and raise them up, and if possible, some distance back from the front wall.

     

    Moving the mic back ~9ft to the listening position:

     

     

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    Now we are seeing the room enter the picture, as I have done a fantastic job of placing the LS50’s directly in a room null at 70 and 80 Hz relative to the listening position. ☺ That’s a 20 dB dip and peak over a narrow frequency range. Yes, my room ratio is not good. As perceived by our ears, a 20 dB difference is 4 times as loud or quiet. However, given how narrow bandwidth the dips are, it is questionable on how much we really (don’t) hear it versus how much we just adapt to dips. According to this research, we are more likely to hear peaks over dips. It has been my experience as well. It seems my ears/brain fill in and/or adapt to the sound with dips in frequency response, but more sensitive to peaks. More research required. 

     

    Take a look at the picture of my room and where the LS50’s are located. Ideally, I would have moved the big JBL’s out of the way, and placed the LS50’s in a known good position, relative to the listening position. I have done this in my previous loudspeaker reviews with no nulls. However, this setup will give us a good audible test of a) can we hear the null? b) can we hear digital room correction doing its job?

     

    Beyond 100 Hz we see a smooth frequency response, with the characteristic downward tilt of a perceptually neutral sounding loudspeaker, as per the Science link above. Let’s see how the LS50 compares to my “reference” JBL 4722:

     

     

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    The LS50 frequency response is overlaid with my JBL 4722 system with dual subs, which uses the preferred in-room measured frequency response, as referenced from Toole’s and Olives research. Meaning, the 4722’s with dual subs have been DSP’d from 12 Hz to 21 kHz ±3 dB to my preferred target frequency response with a slope from 20 Hz to -10 dB at 20 kHz. The KEF LS50 hits that predicted in-room response based on its spinorama figures of merit quite closely. Validating Floyd’s predictive model… again.

     

    It is likely if I moved the LS50’s to the location where the JBL’s are, in an equilateral triangle, then the off axis response may drop those +1 dB bumps between 2 and 3 kHz, 4 to 6 kHz, and 20 kHz down a bit, as evidenced by the Soundstage NRC off axis measurements.

     

    I wrote a soapbox piece on why more loudspeaker designers aren’t using this publicly available Standard that is based on Toole’s research that clearly works for KEF (plus JBL, Revel, and a few others). Most speakers I listen to are too bright, as indicated in my other loudspeaker reviews. Only the Dutch and Dutch 8c came out of the box with nearly identical in-room frequency response matching the preferred target. The KEF LS50 is the 2nd speaker I have measured that matches the preferred in-room target frequency response for a neutral sounding loudspeaker, right out of the box. I would hazard a guess that most folks would enjoy its neutral response. Let’s listen.

     

     

     

     

    LS50 Subjective Listening

     

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    A little preamble before we listen. I used the same binaural recording setup in this article for reviewing a set of neutral sounding headphones. The binaural mic specs and preamp frequency response measurements are there. The headphones measured ±3 dB from 20 Hz to 7 kHz and then rolling off smoothly after that. What goes on beyond 7 kHz is largely due to ones ear and how the mics are placed in the ear. My article linked above shows some of this variability. Point being, the binaural mics are quite flat from 20 Hz to 7 kHz with a smooth roll off.

     

    I wasn’t striving for ultimate recording fidelity, I wanted to have the binaural recording sound good enough, and with high enough resolution, to capture tonal differences between loudspeakers. This comparative objective and subjective analysis is what I want to focus in on. As one will hear in the binaural recordings, the top end “air” (i.e. top octave 10 to 20 kHz) is down a bit in response, as compared to when I listen to the speakers “live”. Just wanted to point out that difference between what I hear live, versus what’s on the binaural recording.

     

    Another psychoacoustic effect is that I hear more of the room sound mixed in the binaural recordings versus when listening live. Floyd Toole’s research has indicated that we have a tendency to “listen through the room” and quickly adapt. Anecdotally, it seems the same for me. When I listen to the speakers live, I don’t hear as much of the room, as I do on the binaural recordings.

     

    However, one interesting aspect to listen for when we get to comparing wide directivity (LS50) versus narrower directivity (4722) speakers, even though the tone quality is similar, you can hear more room sound in the LS50 binaural recording versus the 4722 which presents more direct sound due to the speakers (much) higher directivity index. 

     

     

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    The graphic above shows the measured directivity over frequency for a double 15” and 90 x 50 CD horn, which are the JBL 4722’s. The 15” woofer and 120 x 100 CD are the JBL M2’s and the Domestic cone/dome system is the Revel Salon 2. The KEF LS50 is a cone and dome system and likely similar to the Salon 2 from a directivity perspective.

     

    As we will hear, the directivity index is an important factor on how much direct versus reflected sound one prefers. In the case of this JBL M2 versus Revel Salon 2 shootout, most folks preferred the Salon 2, with the lower directivity, even though both speakers have very smooth and similar frequency responses. This later spawned a thread at diyAudio on The Preference for Direct Radiators.

     

    The audible difference is significant enough that with a little ear training on what to listen for, one can tune into that direct versus diffuse sound and start to hear the difference right away. The other aspect one can hear on the binaural recordings is that the left side of my room is a bit livelier than the right, as I moved the acoustic drum kit that was there, and heavy quilt I put over top of it when critical listening, downstairs. The kit used to sit to the left of the couch, but currently is an open reflective space:

     

     

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    At 83 dB SPL reference level, which is the SPL I took the measurements and the binaural recordings at, while not overly loud, I can definitely feel the sound pressure level on my couch, not only bass frequencies, but lower mids as well. Of course, that feeling does not translate in the binaural recording. 

     

    There is deep bass on the binaural recordings with the subs added, so one might want to check with Tyll’s headphone measurements to see if the headset being used can reproduce down to 20 Hz. I used a pink noise wave file and a calibrated sound level meter to set the reference SPL and subsequently level match the other binaural recordings.

     

    With that in mind, binaural recordings are intended to be listened to over headphones. For best effect, close your eyes and visualize being seated in front of the stereo and turn it up a bit, as the dynamic range of the recordings are as good as the source.

     

    KEF LS50 binaural recording (53 MB wav DR12)

     

    I chose Mark Knopfler’s Back on the Dance Floor for a couple of reasons. It is a rock recording, with DR10, downloaded from iTunes simply as a “typical” recording. The drums and instruments are well recorded with a few notes of Mark’s famous “Money for Nothing” guitar sound resonating throughout. But most importantly, it is a simple sparse dynamic recording with Mark’s vocal up in level in the mix. This gives us a good opportunity to focus on the vocal tone and make some direct judgements when we listen to comparison recordings.

     

    Disclaimer: The binaural audio clips are not full song recordings and conform to the spirt of “fair use” for copyright material for the purpose of education and research. The author nor the publisher derives any financial benefit from these audio clips. The binaural recordings were made at 44.1/16.

     

    How does it sound? Remember you are listening to the speakers plus room sound combined. The binaural effect is intended for one to perceive feeling like you are situated in the acoustic environment. To my ears, the LS50 has a neutral tonal balance with some decent (perceived) bass from a 5.25” woofer in a larger living room area (30 x 16 x 8 ft). Not overly bright (yay!). Not much low frequency response, but you don’t miss it due to the nice neutral balance of this mini monitor. Sounds full, not thin.

     

    I can perceive a little bit one note-ish or coke bottle bass character effect at 100 Hz, due to room acoustics, but otherwise nice and smooth. Mark’s vocal sounds clear and the drums and cymbals sound dynamic to my ears. For me, I always envision being at the club or concert hall listening to the band live, as how I want the auditory scene to sound in my living room. 

     

    The LS50 mini monitors throw a huge image, as the off axis response is as good as the on axis response, especially in the vertical plane as well as horizontal. A key Toole figure of merit that results in a good sounding loudspeaker in a typical living room environment. The KEF whitepaper goes into detail on the variety of tech that makes the drivers and baffle subjectively disappear when listening. You can hear how big the image is on the binaural recording. KEF’s computer aided design has really paid off in making this mini monitor sound much larger than its physical size indicates.

     

     

    LS50 plus Rythmik L12 dual subs Objective Measurements

     

    I patched in the Rythmik dual L12 subs using Audiolense to supply the linear phase digital XO at 70 Hz and time alignment to the LS50’s. Additionally, Audiolense applies so called Digital Room Correction (DRC), both in the frequency and time domains. The combo of subs and DRC fill in the low end frequency response and gets rid most of the nulls at 70 and 80 Hz:

     

     

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    Pretty good given that the LS50’s are located right in a deep null, relative to my listening position. It is just sheer laziness on my behalf to not have moved the JBL 4722’s out of the way and placed the LS50’s there, where I know there is no deep null, as I have measured it before, with a variety of speakers. Also, I spent all of 5 minutes with the Audiolense correction, with no fine tuning. But close enough for rock and roll, as it is a pretty narrow dip of 5 dB as opposed to 20 dB null relative to 100 Hz in the measurement of the LS50 by itself. I wonder if we can hear the null?

     

    While I could have set Audiolense to only correct below the room’s transition frequency, (i.e. Schroeder frequency) that is often recommended, I went for the full frequency correction, as we want to make a few comparisons. I used the exact same target frequency response design as my JBL 4722 plus subs, so it would have also corrected for those little 1 dB high frequency bumps as measured on the LS50’s with no eq. Here is the objective comparison:

     

     

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    Still amazing to me how close the LS50’s are to my preferred target frequency response right out the box. You can see the little high frequency bumps on the LS50’s, with no eq, at 2 to 3 kHz, 5 to 6 kHz and near 20 kHz. Had I taken the time to position the LS50’s correctly, I suspect those bumps would be gone. It will be interesting if we can detect an audible difference in a comparison. But before we get to that, let’s listen to the LS50’s with the dual subs, which we see measures almost identical to out of the box LS50’s beyond 100Hz.

     

     

    LS50 plus Rythmik L12 dual subs Subjective Listening

     

    Here is the same Mark Knopfler tune, at the same level, as with the LS50’s, except added dual subs and my preferred frequency response target, which is virtually identical to what comes out of the box with the LS50’s

     

    KEF LS50 plus subs binaural recording (56 MB wav DR11)

     

    How does it sound? Certainly on my NAD HP50 headphones I can hear the extended bass response.

     

    Let’s see how it sounds when we compare the LS 50’s directly with the LS50’s plus dual subs on the same track. The Rythmik L12 subs are Rythmik’s entry level sealed sub for about $540 each. Rythmik’s subs with direct servo tech sound tight and musical to my ears.

     

     

    LS50 versus LS50 plus dual subs subjective listening comparison

     

    A common task working with Digital Audio Workstations (DAW’s) is to import tracks, line them up and switch back and forth to compare. That’s what I did here. I took the two binaural recordings and imported them into my DAW, lined up the tracks to be close enough to sound synchronized:

     

     

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    The top binaural stereo track is the LS50 and the bottom track is the LS50 plus dual Rythmik L12 subs. One is also seeing the DAW automation below each track where one track is unmuted for 10 seconds and then it mutes and switches to the other track for 10 seconds, and so on. In other words, every 10 seconds we alternate from one binaural stereo recording to the other.

     

    We start with the LS50, and then switch to the LS50 plus subs for 10 seconds, and then switch back on the LS50 for 10 secs and so on, ending on the LS50 with subs. Listen closely as the first 8 seconds is mostly intro and after two beats of the bass guitar, you are hearing the LS50’s plus subs. Meaning 10 seconds goes by quick as the first 8 seconds is the intro…

     

    LS50 compare to LS50 plus dual subs binaural recording (37 MB wav DR11)

     

    How does it sound? It may take a number of listens to tune into the differences. You may notice a “splice” or audible tick sound when the track switches. I left those in most places on purpose to give folks an audible cue when the track switches to the other binaural track. Some switches don’t make the tick sound, and requires a bit more concentration to hear the transition. It’s good ear training.

     

     In some switches, especially with the full on vocal in the chorus, it is tougher to hear the difference. But when it is just the drums and bass are playing, it is easy to hear the full range dynamic sound with the subs and fine tuning of the tone. Fuller sounding to my ears and not quite as boxy sounding. In some switches, I can hear the tone change. It almost sounds like a small pitch change.

     

    There is one switch near the beginning where the drums almost jump out when switching from the LS50 to the LS50 with subs. I checked the levels to make sure everything was properly level matched and could not find any errors. That’s also the same switch where I can hear the tone change with the drums are almost lower pitched when listening to the LS50 plus subs. Sounds more full range or “bigger” sounding to my ears.

     

    The vocals are a bit harder to tell apart, especially during the chorus with the layering and female voices, sounded more similar than different in a couple of switches to my ears. Now let’s compare this set up with the JBL 4722 with subs using the same target neutral frequency response.

     

     

    JBL 4722 plus subs Objective Measurements

     

    I have covered off detailed objective measurements of the JBL 4722 with dual Rythmik subs before and not going to repeat here.

    Here are the JBL’s overlaid with the LS50’s, both using the same subs (different XO point) and same target frequency response:

     

     

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    That’s a close match. Getting into Bob Carver territory ☺ Had I moved the LS50’s right in place of the JBL’s, would have gotten rid of the last little bit of low frequency dip. Plus may have balanced out the 2 to 3 kHz bump a bit more. OTOH, at that frequency range, there is more reflected sound with the LS50’s and I would say it’s showing up in the REW measurement as added amplitude. Why is that? Audiolense’s frequency dependent correction windowing can be adjusted and in my case, at this frequency, (i.e. 2 to 3 kHz), Audiolense is correcting more of the direct sound, like a tone control. However, in REW, the acoustic measurement software used above, the time window is fixed at 500ms and letting more of the room into the measurement at higher frequencies, which is possibly reflected in the measurement. Which is correct? This is where ones ears comes into play as to what one prefers, a more direct sound or a more diffuse sound. 

     

    Even if I lined up the KEF’s perfectly in place of the JBL’s, they would still have more room sound as their directivity is considerably wider than the JBL’s overall. And likely not quite the emphasis in the 2 to 3 kHz range either.

     

    When we listen to the compare, can we hear a difference in directivity, even though the loudspeakers are tonally (i.e. frequency response is) very similar? First, let’s listen to the JBL’s.

     

     

    JBL 4722 with dual subs Subjective Listening

     

    Here are the JBL 4722 with subs to get used to their sound:

     

    JBL 4722 with dual subs binaural recording (68 MB wav DR12)

     

    Depending on when folks listened to the other binaural recordings, and remember the room sound, this recording is different in the sense that there is (much) less room sound and more direct sound as the JBL’s have a much higher directivity index than the LS50’s. Really, these JBL’s are intended to be used in Cinema installations with hundreds of people in a much larger room than a living room. So in my living room, it almost sounds like headphones with little room sound.

     

    This binaural recording I find has a more focused stereo phantom image in the center than the other recordings with the LS50. I would say mostly due to the increased directivity. It is not that the LS50’s don’t have an outstanding stereo phantom image, it is simply that with their wider directivity pattern, and at my 9ft listening distance, has more room sound in the mix and sounds more diffuse, and as a result, not as focused.

     

    I spent quite a few years in pro sound and recording studio control rooms. The former used pattern controlled speakers and the latter was in rooms that were pretty absorbent. I got used to liking more direct sound than diffuse sound. If I was a classical music lover and frequented concert halls, likely my preference would be reversed.

    As an interesting aside, these JBL’s are horn/waveguide loudspeakers crossed at 630 Hz. I do not find them bright or fatiguing in anyway, no matter how many hours I listen to them. Again, I point to Toole’s and Olive’s research on what makes for a good sounding loudspeaker in a typical living room environment. Neutral sound is neutral sound regardless of the device used to present it. But as we will hear, the directivity index of a loudspeaker determines how much of the direct versus reflected sound one is listening to and can be used to determine ones listening preference. 

     

    Let’s take a listen to David versus Goliath

     

     

    JBL 4722 versus LS50 both with dual subs subjective listening comparison

     

    Like before, I loaded up the two binaural tracks in my DAW and in ten minutes, edited it to swap tracks back and forth every 10 seconds:

     

     

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    The JBL 4722 with subs starts first and then the LS50 with subs starts 10 seconds later while the 4722’s are muted and then switch back again 10 seconds later. It is tricky though, as it is only the first two beats of the bass in the first 10 seconds of the JBL 4722 with subs that one hears, before it switches to the LS50’s with subs. That’s because the first 8 seconds is the intro with no bass, and so it is hard to hear the initial transition. But over the course of recording, it is obvious in spots when hearing lots of room and then almost no room where one can readily identify the difference in speaker directivity.

     

    JBL 4722 compare to LS50 plus dual subs binaural recording (45 MB wav DR12)

     

    Tone wise, they are pretty close. What do you think? There is a small tonal change, as I can hear the room sound being added with the LS50’s. You can hear it almost like a slap echo (that’s an exaggeration) on the drum tone and vocal. It does open up the sound, as it is a bit brighter. Sounds more diffuse.

     

    The low frequency sounds similar on both, even though I cross the subs at 45 Hz on the JBL 4722’s and 70 Hz on the LS50’s. Focus in on the kick drum plus the bass line and try to notice any changes when the track switches. Should sound pretty consistent. For fun, go back to the LS50 and LS50 plus subs comparison and focus in on the kick drum and bass line again. One should start hearing the individual notes in the LS50’s with subs, as each one is equal loudness, but some low bass notes are missing on just the LS50, other than the 100 Hz overtone.

     

    Just like the other comparison, it may take a few listens or so to start repeatedly recognizing one speaker versus the other. While we may form an initial impression, repeated listening while focusing on different aspects of the sound starts to gather a collection of differences and more importantly personal preferences. For example, KEF has done an excellent job on making their mini-monitor sound bigger than it is with their computer aided design around speaker and baffle dispersion characteristics. Does one sound bigger or larger than the other on the binaural recordings?

     

    One area up for discussion is the lower mids. I do hear a difference in the lower mids between the 5.25” woofer and the double 15” JBL’s. Mark’s voice appears to have more weight or lower mid tone behind it. Of course, that is subjective on my behalf. It is very close sounding, but maybe the added room sound to the LS50’s is masking that.

     

    Will be interesting to hear what peoples thoughts are on the comparisons.

     

     

    Conclusion

     

    I hope folks find the binaural recordings fun and educational. For me it was an experiment on multiple levels and if done again, I would:

     

    • have moved the JBL’s out of the way and moved the KEF LS50’s right in the same spot. This would have accounted for any low frequency null differences, as it is a known good location. However, I really did hear a difference with the LS50’s with subs with the -5 dB narrow dips at 70 and 80 Hz compared to the JBL’s with subs. Do you?
    • moving the LS50’s to the proper location may also account for the small bumps in the high frequency response. However, the overall room amplitude would still be the same, but the frequency distribution smoother perhaps. I could have spent more time toeing the LS50’s in or out a bit more and re-measuring for proper set up with a few initial listening tests to check the tonal balance. I just placed the Skylan 24” stands and put the LS50’s on top – done.
    • Try a smaller equilateral triangle with the LS50’s just to compare the direct versus reflected room sound to see if it was proportionally less, as one moves closer to the speakers. It should be…
    • Replace my microphone preamplifier with a studio quality mic preamp. I ordered one based on these shootout results. The Lynx Hilo ADC is noted for its transparency and that has been my experience, but the mic preamp I have now is not as transparent.
    • Try different music material. Open for suggestions.

     

     

    Having said that, the differences between David and Goliath (with subs) are not that big. No pun intended. The LS50’s are keepers. They sound excellent and a steal for $1000. I am happily listening to them now without subs but will be adding the Rythmik L12’s later when I upgrade the subs for my 4722’s. KEF, and the science, can predict a neutral sounding speaker in most listening environments. The LS50’s measure and sound neutral in my room. It is quite the engineering feat for a mini monitor to sound this good with this size image reproduction.

     

    Spend another grand to get a pair of subs and I think you would have a hard time beating that $2K combo as a full range system. One would have to spend a great deal more for something that may be incrementally better or simply worse if not based on sound engineering principles (i.e. spinorama). There is a point of diminishing returns to achieve neutral sound if that is ones goal. Of course, there are some SPL restrictions in the case of the LS50’s, but if you mostly listen at reference level (i.e. 83 dB SPL), and your room isn’t huge, these can easily do the job and sound neutral.

     

    I do think the LS50’s sound “bigger” (i.e. full range) with the dual subs. I point to near the front of the binaural comparison track between the LS50’s and LS50’s with subs where the latter jumps out when listening to one of the transitions that is mostly drums and bass. I hope I got the levels right, but could not find an error. It sure jumps out to my ears sounds more dynamic, full range, bigger…

     

    The big difference I hear when comparing the 4722’s to the LS50’s, both with the L12 dual subs, is the room sound due to the large directivity differences between the two speakers. This is after eq’ing (i.e. with DSP both in the frequency and time domains) both speakers and subs using the same target frequency response, which is pretty much exactly what comes out of the box with the LS50’s down to its low frequency cutoff. My JBL 4722’s are a fully optimized triamped system with linear phase digital XO’s, time alignment of drivers, tight frequency response tolerance across the bandwidth, yet the LS50’s with subs sound similar tonally. One can hear it on the binaural comparison recording. Does one sound bigger than the other?

     

    After repeated listening, there is quite a bit of room sound with the LS50’s, as compared to the 4722’s. Once ones ears are tuned to the differences, it becomes much easier to listen again and identify which speaker one is listening to. Both sound full range. Using the same subs for both, takes away the low frequency differences. However, I do notice on Mark’s vocal that it sounds fuller or deeper in tone on the JBL’s. I can’t be sure if that has to do with the cone/box size difference or the directivity difference where the room sound is changing the tone of the lower mids on the LS50’s.

     

     

    Next Steps

     

    There are many variables to making a binaural recording that is transparent and high resolution enough to convey the characteristics of a loudspeaker or any piece of audio equipment for that matter. Are the binaural mics in the ears correctly? Is my head in the same location from one recording to another? Level matched correctly? And so on.

     

    However, I think with care optimizing the recoding chain and looking at how to adjust for individual HRTF, binaural recordings offer another level of equipment review experience on an item that you may not get to hear in person and can shed some light on its audible performance. Even if only the relative comparison is used, it is still a useful tool. In the case of completely opposite loudspeakers eq’d the same, one can hear the audible difference between a speaker with wide directivity versus as speaker with narrow directivity and what your preference might be. 

     

    Of course, there is no substitute to hearing the equipment “live” and perhaps in your own home. However, I am suggesting that it is time to kick up audio reviewing a notch by providing music lovers and gear listeners with more than just words. This approach can be used to identify fine details between gear not only over loudspeakers, but headphones as well. In the case where we might want to eliminate the room and listen to two different DAC’s for example. Sure, there are issues with HRTF’s and binaural mic placement, in addition to the myriad of different sounding headphones, but if there is a relative comparison change that is audible, then it would be captured in the binaural recording and available for all to hear.

     

    I am thinking of adding this ABX Switch Comparator to the mix to make it even easier to switch and record the comparisons, as opposed to having go through an editing stage. It would also make the process more reliable with less steps where things can go wrong.

     

    Based on this experiment of comparing the KEF LS50 with the JBL 4722, I feel I have only scratched the surface of what the possibilities are. This opens the door to compare digital signal processing as well, not only digital room correction products, but surround sound processing, upmixers, digital filtering of any kind, etc.

     

    As you may know, I am big on measurements, and will continue to do so, along with perhaps getting into electronics and digital signal processing measurements. More importantly, I wanted to find a way for folks to listen to the device under review, whether by itself or through a comparison, as added review information that is not currently available. I feel my first experiment comparing two very different loudspeakers and being able to audibly hear the difference is hopefully useful information. 

     

    I have a few details to iron out to make the binaural recording process predictable and repeatable, but I think that it will be worth the effort. I always found it odd in “audio” equipment reviews that up until now, there was no way to listen to the device under test. Hopefully, this approach will change that.

     

    Happy New Year and Enjoy the Music!

     

     

    image18.jpeg

    I wrote this book to provide the audio enthusiast with an easy-to-follow step-by-step guide for designing a custom digital filter that corrects the frequency and timing response of your loudspeakers in your listening environment, so that the music arriving at your ears matches as closely as possible to the content on the recording. Accurate Sound Reproduction using DSP. Click on Look Inside to review the table of contents and read the first few chapters for free.

     

     

     

     

     

     

     

    image19.jpeg

    Mitch “Mitchco” Barnett.

     

    I love music and audio. I grew up with music around me, as my mom was a piano player (swing) and my dad was an audiophile (jazz). My hobby is building speakers, amps, preamps, etc., and I still DIY today.

     

    I mixed live sound for a variety of bands, which led to an opportunity to work full-time in a 24-track recording studio. Over 10 years, I recorded, mixed, and sometimes produced over 30 albums, plus numerous audio for video post productions, in several recording studios in Western Canada.

    Edited by The Computer Audiophile




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    On 1/7/2019 at 10:20 PM, folzag said:

    Thank you, Mitch.

     

    The recordings were awesome and really took this review to the next level.

     

    To my mind, if money and space were no object, the JBL's are hand's down the winner. Their sound felt more natural and balanced. The song coming out of them had less of a reproduction feel, like the singers were present in the room. In contrast, the KEF's I coldn't shake the feeling that the song sounded like a playback of recording made in a studio. A very good recording, but a studio all the same. It didn't make me feel "presence" for lack of a better word that the JBL did. A little too "clinical" may be.

     

    Next, the KEF's with and without sub's were interesting to me because the difference is very similar to what I experience listening to my pair of Emotiva Airmotive 6s" powered monitors with and without sub's. Without sub's, it sounds nice and perfectly clear, but there's something missing... it doesn't get my body responding to the music. As soon as the sub's turn on, though, it's like the bottom half of the music comes alive and now I can feel it. At the same time, if I stop and consider it, it also feels a little made-up. Too much energy underneath. That is also something I struggle with on my sub's -- keeping the bottom from getting too strong where it starts to be fake. And again, I don't get that "fake" feeling from the JBL's.

     

    I reckon the million dollar question is whether it's from the room and the speaker placement that could be easily solved, or something else, like directivity, that can't be captured without big boxes like the JBL's. In any case, I am looking forward to more reviews and more binaural recordings.

     

    Many thanks and much appreciation,

    Allan F.

     

    Allan @folzag, thanks for taking the time to listen to the binaural recordings and your response.  It would seem our listening preferences are similar 🙂 I am still amazed at how much directivity difference there is between these two speakers, which is on the binaural recordings.

     

    I feel confident that the differences are predominately directivity related. My room has enough treatment to make the decay time (RT60) not only smooth across frequency range, but within industry guidelines for my size room. It does measure towards the livelier side of the spec...

     

    Thanks again,

    Mitch

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    12 hours ago, nefilim said:

    ps. When I started with AudioLense early last year, I was looking for a mic preamp to go with my RME ADI2-Pro ... it seemed like many of them added some kind of signature or colouration which I guess is desirable to many recording engineers (can we still not add any of this in post?). One of the few I could find that seemed more suitable for accurate measurements was the Grace Design m101 ... pretty pricey but bit the bullet, been happy so far. 

     

    The Grace Design m101 is really nice kit! Gets great reviews. It was a toss up between the Grace and the ART, and I just emptied my pockets on a sub upgrade, and went with the ART. I am happy to hear it is working well for you. Good to know. Thanks.

    Mitch

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    10 hours ago, mitchco said:

     

    Allan @folzag, thanks for taking the time to listen to the binaural recordings and your response.  It would seem our listening preferences are similar 🙂 I am still amazed at how much directivity difference there is between these two speakers, which is on the binaural recordings.

     

    I feel confident that the differences are predominately directivity related. My room has enough treatment to make the decay time (RT60) not only smooth across frequency range, but within industry guidelines for my size room. It does measure towards the livelier side of the spec...

     

    Thanks again,

    Mitch

     

    Oh yeah, I forgot to say...  on the other hand, for the vast majority of us where size and cost does matter, the KEF's are d*mn impressive. If one did not have a pair of big boxes to directly compare against, I find it hard to believe anyone would be dissatisfied with them paired with a properly tuned/weighted sub.

     

    There is incredible price-to-performance available to us today. It's good to remind ourselves of that from time to time, and keep a proper perspective, which you have. So thanks for that too.

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    Very interesting article -- a very welcome departure from the preponderance of cliched fluff pieces clogging up the 'net. Well done sir.

     

    I am really intrigued by the JBL 4722, so have to ask Mitchco (or anyone in the know): what do you lose or gain from a speaker like the sub $4,000 4722 (pair) versus the $5,000 JBL 4429 or the $15,000 4765? (other than the looks)  I know these are "studio" monitors not "theater" speakers, but the similarities are so many: very high spl, huge dynamics, very high/ high sensitivity, horn, etc?

     

    In other words, for listening at home, why not save a boat load of money and buy these 4722s instaed of the far pricier studio monitors? 

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    Outstanding article,  knowledge is power and I am looking forward to reading your book. Thanks for sharing your experience.  

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    15 hours ago, isleofskye said:

    Very interesting article -- a very welcome departure from the preponderance of cliched fluff pieces clogging up the 'net. Well done sir.

     

    I am really intrigued by the JBL 4722, so have to ask Mitchco (or anyone in the know): what do you lose or gain from a speaker like the sub $4,000 4722 (pair) versus the $5,000 JBL 4429 or the $15,000 4765? (other than the looks)  I know these are "studio" monitors not "theater" speakers, but the similarities are so many: very high spl, huge dynamics, very high/ high sensitivity, horn, etc?

     

    In other words, for listening at home, why not save a boat load of money and buy these 4722s instaed of the far pricier studio monitors? 

     

    Thanks @isleofskye The 4722's ($2K US a pair) are bit narrower directivity than the 4429 or 4365. If you biamp the 4722's like I have, then you require digital or electronic XO. A multi-channel DAC, four amps, protection capacitors for the compression drivers. I upgraded the compression drivers on my 4722's based on a really long thread on AVSForum where one of the members tried several different compression drivers. Some DIY along with DSP is required to make these sound their best. Whereas, the 4429 or 4365's are ready to go as is.

     

    The JBL M2's are the closest to the 4722's, as they use similar tech, but with upgraded components in the M2. If I had the dough at the time, I would have gone with the M2's. But if you have the space, like huge dynamic speakers and willing to diy a bit, the 4722's are a good choice, if you can stand how fugly they are 🙂

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    The one thing I note about the LS50's is that you are very aware they are a point source. If you don't have the center of the driver at the same level as your ears,

    imaging becomes  less persuasive.

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    On 1/10/2019 at 8:08 AM, mitchco said:

     

    Thanks @isleofskye The 4722's ($2K US a pair) are bit narrower directivity than the 4429 or 4365. If you biamp the 4722's like I have, then you require digital or electronic XO. A multi-channel DAC, four amps, protection capacitors for the compression drivers. I upgraded the compression drivers on my 4722's based on a really long thread on AVSForum where one of the members tried several different compression drivers. Some DIY along with DSP is required to make these sound their best. Whereas, the 4429 or 4365's are ready to go as is.

     

    The JBL M2's are the closest to the 4722's, as they use similar tech, but with upgraded components in the M2. If I had the dough at the time, I would have gone with the M2's. But if you have the space, like huge dynamic speakers and willing to diy a bit, the 4722's are a good choice, if you can stand how fugly they are 🙂

     

    Thank you very much for your reply. The careful integration of supporting electronics to make the 4722 viable for home use that you chose belies a degree of understanding that, if I'm honest, is way beyond the ken of this humanities major! The M2s and the 4367s are a bit rich for my blood but the 4429s might be contenders. But some irrational part of my brain is drawn to these 4722 monstrosities and the enormous sound they must surely produce...

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    On 1/10/2019 at 7:45 PM, davide256 said:

    The one thing I note about the LS50's is that you are very aware they are a point source. If you don't have the center of the driver at the same level as your ears,

    imaging becomes  less persuasive.

    To an extent that's my observation too, I had these for a while. But its off-axis response bothered me far less than with speakers with regular drivers. KEF did many things right with LS50.

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    47 minutes ago, John Fitzpatrick said:

    To an extent that's my observation too, I had these for a while. But its off-axis response bothered me far less than with speakers with regular drivers. KEF did many things right with LS50.

    Agree, they are very good for dispersion in the horizontal plane, especially compared to Magnepan's. Just be sure to buy the right height or adjustable height stands for your preferred listening chair. Maggies by contrast pretty much require you to sit at the sweet spot but act as a line source so  you can sit or stand, ear height doesn't matter.

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    Thank you Mitcha for a great review! Since you have reviewed great speakers like Dutch&Dutch 8c, Kii3, Genelec 8351, LS50, I need your help for a 5.2 set up for movies and use the same for a 2.2 set up. My living room is 38 m2 and the listening area is 25 m2. My listening distance is 3,5 meters and the speakers will be 4 meters apart. Moreover my living room is very lively with large glass windows on the side. I have done some minimalistic room treatments with curtains but more I could not do due to WAF. 

     

    Due to the room situation, I have to look for speakers with a great directivity index to prevent early reflections from the glass windows and use the room correction additionally. I had narrowed my LCRs earlier to Genelec 8351 (used with software GLM) or XTZ Divine Delta (use Anthem AVR or MiniDSP for room correction). With your review KEF LS50 seems to be back in the list and has the best WAF. Moreover I will be well within budget with LS50. I love JBL speakers especially M2, 708P but getting an identical center channel for my low board is difficult and the same goes for Kii/DD 8c. XTZ is a great price worth speaker with Accuton drivers providing great detail/clarity and very musical but they do not have a waveguide or horn like Genelec or JBL and I will have a difficulty in taming reflections with XTZ. Hence I am wondering to remove XTZ off the list. 

     

    How do you compare Genelec 8351 to LS50 with respect to sound quality. What amps would you suggest for LS50? I did listen LS50 in two different stores. One was excellent whereas the other was mediocre. Probably it had to do with amps. I have also listened to JBL 4429 and love them (issue with center channel). 

     

    Any recommendations/suggestion from you would be very helpful for me. 

     

    Kind Regards, 

     Ram

     

     

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    On 1/16/2019 at 1:14 AM, Ragera said:

    Thank you Mitcha for a great review! Since you have reviewed great speakers like Dutch&Dutch 8c, Kii3, Genelec 8351, LS50, I need your help for a 5.2 set up for movies and use the same for a 2.2 set up. My living room is 38 m2 and the listening area is 25 m2. My listening distance is 3,5 meters and the speakers will be 4 meters apart. Moreover my living room is very lively with large glass windows on the side. I have done some minimalistic room treatments with curtains but more I could not do due to WAF. 

     

    Due to the room situation, I have to look for speakers with a great directivity index to prevent early reflections from the glass windows and use the room correction additionally. I had narrowed my LCRs earlier to Genelec 8351 (used with software GLM) or XTZ Divine Delta (use Anthem AVR or MiniDSP for room correction). With your review KEF LS50 seems to be back in the list and has the best WAF. Moreover I will be well within budget with LS50. I love JBL speakers especially M2, 708P but getting an identical center channel for my low board is difficult and the same goes for Kii/DD 8c. XTZ is a great price worth speaker with Accuton drivers providing great detail/clarity and very musical but they do not have a waveguide or horn like Genelec or JBL and I will have a difficulty in taming reflections with XTZ. Hence I am wondering to remove XTZ off the list. 

     

    How do you compare Genelec 8351 to LS50 with respect to sound quality. What amps would you suggest for LS50? I did listen LS50 in two different stores. One was excellent whereas the other was mediocre. Probably it had to do with amps. I have also listened to JBL 4429 and love them (issue with center channel). 

     

    Any recommendations/suggestion from you would be very helpful for me. 

     

    Kind Regards, 

     Ram

     

     

     

    Hi Ram @Ragera Thanks.. I have not reviewed the Genelec 8531, so can't comment. Ram, the main issue is that few speaker manufacturers publish their directivity specs. I don't see any listed for the XTZ for example. You can  get some ideas from Soundstage measurements from the NRC: https://www.soundstage.com/index.php?option=com_content&view=article&id=16  

     

    While the LS50's are a steal for a grand, they are geared more towards near and mid-field listening and not best suited for your application given size of room and listening distance. Unless of course your preference is for more room sound, but you indicated you wanted to reduce  early reflections...

     

    Tough to recommend due to lack of speaker manufacturer's directivity data. As a rule of thumb, which you already know, is speakers with waveguides tend to have a higher directivity index than domes... This is why I use JBL, not only for the waveguide, but they publish their directivity specs. Without the data, it is difficult to recommend...

     

    Regards,

    Mitch

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    A well done experiment where you have actually done some effort to make it possible to listen for differences in the speakers alone, and you provide recorded samples so that we all can hear at least some of it.

    I am not that much into brands, especially other people's brands, so I will use the names big and small for the speakers.

    Listening to the samples in Room2 I find:

    - Big is dry with quite flat soundstage, small is livelier with more 3D and depth.
    - Big is much better in the low-mid and upper-bass, where small sounds like something is missing, transients and attack lacks power, big simply has more realism and power.
    - Tonal balance is different.
    - Minor differences in high freqs, where small sounds a little more colored.
    - The original sounds much better - clarity, bigger more precise soundstage with real 3d, better highs. But this is expected, and explained in your article. The big speaker comes quite close to preserve balance and realism on bass and lower mid.
    - Big speakers sound more like the original, but that does not mean is sounds better, becaus this is a recording that now includes the room. When I play back this on my system, all the room and coloration from my system adds to the sound.

    So why do they sound so different, when they measure equal. Thing is, they do not measure equal.

    If you look at the recorded samples, there is visual difference in the waveforms, wich is caused by differences in phase shift. Frequency spectrum reveals that there are quite large differences below 500hz. At 55hz the small has a huge dip. Differences are in the order 10dB, which is expected to be clearly audible.

    So even though the speakers where calibrated with room correction to the same target and measured similar, they actually are different, and this can be measured.

    Differences can be caused by radiation charactertistics, which alter not only decay and room contribution, but also frequency response through interaction with boundaries. The DRC did not fix all of that.

    The small speaker is most likely overdriven and compress in the lower mid - upper bass. If your calibrated playback is 83dB for -20dBFS each speaker, this is about the same as 0dB on my systems, and that is quite loud, louder than most trad hifi-systems can do. Lowering the master by 10dB will give a sound level closer to what many people listen to, and less chance of overload. I suspect this will still be bordeline for this small speaker, at least you should cross over at 120hz.

    To try to play at 0dB with this small speaker is not fair, they do not have the capacity needed, but they may still be good speakers and for someone who never play that loud, it would be interesting to know if there are other aspects of the sound that is compromised. Or can the small speaker sound as good as a big. This is what makes your experiment interesting.

    Reducing the master volume by 10dB is one thing to try. Then both system should be properly calibrated to the bass system, crossed over perhaps around 120hz, with proper eq on the bass system and delay settings for the main speakers. That will isolate the differences more to the speakers alone - big vs small.


    Regards,
    Øyvind Kvålsvoll

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    Hello @Kvalsvoll I see you just joined  CA and this is your first post. Welcome!

     

    Thanks for your feedback. The only fair comparison is the LS50 plus sub vs JBL with sub as they have a similar frequency response, but very different directivity index. The LS50 standalone was to let people listen to what it sounds like without a sub.

     

    Checking on the specs, The little speaker is rated at 106 dB SPL max output and 2nd & 3rd harmonics (90dB, 1m) <0.4% 175Hz-20kHz with 85dB (2.83V/1m) sensitivity. I don't think the speaker was overloaded. at 83 dB SPL at the LP.

     

    I follow these levelling best practices using pro gear. 83 dB SPL I do not find too loud and has the right balance of bass to treble. For overly compressed material I drop the level down to 77 dB SPL.

     

    Kind regards,

    Mitch

     

     

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    @mitchco, I should have specified exactly which of your recorded sample files I used for comparing. I am sure I used the speaker+sub files for both the large and the small speakers:

    JBL 4722 plus subs

    Kef LS50 plus subs

     

    Those recordings are not from 2 systems that measure equal, the differences in those samples show that there are significant differences both in frequency domain and time domain. I attached 2 pictures of the frequency spectrum, one smoothed and one raw. To see for yourself you can open the samples in audacity, look at the waveforms (phase differences), analyse frequency spectrum (just make sure you select exactly the same time interval from each sample).

     

    If the 2 systems measure equal, they would not present differences in frequency spectrum in such magnitudes. As to why they actually are different, when you measured them to be similar, that is another question, several possibilities exist. And finding what causes the differences in response has significance for the validity of this test, because it is not necessarily caused by the speakers alone.

    spect 0_2400ms nosmooth.png

    spect 0_2400ms.png

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    @Kvalsvoll I think you are taking my article too literally 🙂 I said similar frequency response, not exact. As already caveated in the article, several times, the LS50's were placed in a room null whereas the JBL's were not. This accounts for the difference in the 50 to 60 Hz dip. Again, as noted in the article, had I moved the LS50's to the exact same spot as the JBL's, would have resolved this issue and perhaps a few others. Also noted in the article, the science shows our ears/brain are not too sensitive to narrow band dips in frequency response below Schroeder.

     

    JBL 4722 Red Green KEF LS50 Blue Mauve both with subs.jpg

     

    The JBL has a near infinite baffle whereas the LS50 does not. This will cause a different Speaker Boundary Interference Response (SBIR) above 100 Hz to around 400 Hz (directivity related as the polar response will be different for both speakers in this frequency range, aside from the fact that the LS50's were not in the same physical position as the JBL's...).

     

    The JBL's "constant directivity" comes into play at around 400 Hz:

     

    JBL 4722 Directivity factory.JPG

     

    Where as the LS50's does not. The rest of the differences on up in the audio band are due to the directivity differences between the two speakers.

     

    As Floyd Toole and Sean Olive have often said, one cannot eq directvity. So both the measurement and correction software are "blind" to directivity, as we are measuring and correcting the sound power in the room (i.e. steady state response).

     

    The point of the article is to show that two speakers eq'd "similarly not exact" sound remarkably close, yet the big difference being how much room sound is let into the recording by the wide directivity differences between these two specific speakers that represent the near opposite ends of the directivity index scale. The intent is to have folks listen to binaural recordings to hear the audible difference and determine what one's preference is with respect to how much room sound one likes mixed in with the direct sound. It is nothing more than that.

     

    Enjoy the music!

     

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    3 hours ago, mitchco said:

    ...

    The point of the article is to show that two speakers eq'd "similarly not exact" sound remarkably close, yet the big difference being how much room sound is let into the recording by the wide directivity differences between these two specific speakers that represent the near opposite ends of the directivity index scale. The intent is to have folks listen to binaural recordings to hear the audible difference and determine what one's preference is with respect to how much room sound one likes mixed in with the direct sound. It is nothing more than that.

     

    Enjoy the music!

     

    And I believe you did a good job at that, the recordings show off those differences very well.

     

    My findings led me to suspect that some kind of minor configuration error during the recording session could cause the responses to be more different than your measurements indicated. Looking at the plots once more, and from reading your comments, I conclude the differences in music sample spectrums are within what can be expected.

     

    Would they sound more equal if setup was more accurate? Perhaps, but that would require more effort, which may not be worth it, considering the experiment actually show what you wanted as it is.

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