Katz’s Corner Episode 12: Throwing Down the Gauntlet

Hello everyone! I’m sure some of you have noticed my absence from this column. I will try to be here more often, but I’ve been very busy, mastering some great music! I’m also designing a new mastering product that will be manufactured by a major pro audio manufacturer, which has been taking up my non-copious free time. I also do a bit of Facebook-based audio education and sharing as some of you may have noticed.

Recently I upgraded my loudspeakers. These new loudspeakers truly up the game. You might ask, “Why is Bob talking about loudspeakers on our headphone-based site?” Please bear with me while I lead up to the answer. My previous loudspeakers were no slouches—A-grade mastering quality. These were the fabulous Revel Ultima Gem 2’s, crossed over to a pair of JL Fathom F112 subwoofers with an 80 Hz Neville Thiele linear phase digital crossover implemented in Acourate Convolver. Response was flat to a target from 20 Hz to 20 kHz plus or minus 1 dB as measured in Acourate and also Room EQ Wizard!* It was flat to -3 dB at 16.7 Hz! I would never kick Revels out of bed; Revel makes full range loudspeakers which are even better and which I’ve never owned.

So, what did I just replace the Revel system with: A pair of Dynaudio Evidence M5P monitors, also supplemented by the JL subs, but this time crossed over at 60 Hz, extending their response from a native 27 Hz down to 15 Hz (-3 dB). Corrected response is flat to a target plus or minus 1 dB, 20 Hz to 20 kHz. Here’s a frequency response graph of the Acourate-corrected response in my room. Each horizontal line is 1 dB apart. That’s right, 1 dB/step!


12A Amplitude response, Dynaudios & JL woofers, corrected by Acourate Convolver. Blue = Left, Red = Right.

This ups my game: response is more linear, accurate and extended. The sound is smoother and rounder. But frequency response is just one small part of the improvement: These Dynaudios are taller than me! They produce a very large and impressive horizontal and vertical soundstage which reveals all the layers of depth in a good recording. Their specialized smoothed-edged cabinet reduces diffraction distortion which would smear an image and add an edge to the sound. Although the Revels are no slouch, with their own special tapered enclosure. Audiophile loudspeaker designers around the world have learned their lessons and have been focusing on reducing diffraction for a number of years: Bravo.

A special crossover design implements what they call “Dynaudio Directivity Control” (DDC). DDC reduces floor and ceiling reflections by, they claim, 75%. This serious development reduces the phantom images from floor and ceiling which would smear the sound quality. Lastly, and to my mind most importantly, Dynaudio implements a first order (6 dB/octave) crossover, since their drivers have the bandwidth to support such a gentle crossover. Very few loudspeakers today use first order slopes. Back in 1971 I owned a pair of Dahlquist DQ-10s which had a five-way, first order characteristic and were very transparent. Odd order crossover slopes permit all the drivers to be in the same polarity, and first order can potentially produce a perfect impulse and step response, unlike any other analog crossover design, unless the designer implements a phase-correcting all-pass filter, which can be an improvement. But to my mind, first order is the purest technique to approach a perfect impulse response.

With the right design and cabinet configuration, a multi-driver loudspeaker can approach the coherent sonics of a single point source and deliver a more linear polar pattern than planar loudspeakers like Quad and Magneplanar. The Revels needed considerable excess phase correction, which resulted in an impressive transient response and impact. But out of the box the Dynaudios are already phase-coherent so I did not need apply any phase correction for the main loudspeaker and just a bit of it to improve the performance of the JL subwoofers. With or without correction, the Dynaudios have the most impressive and accurate transient response I’ve heard from any speaker in my entire career! Here is a graph comparing the corrected step responses of the two loudspeakers.


12B Step Response, after excess phase correction. Green: Revels & JL woofers. Red: Dynaudios & JL woofers.

In both traces we can see a distinct single positive-going impulse followed by the recovery back to 0 volts. Even though the Dynaudio contains four woofers, two midranges and two tweeters! A remarkable achievement. It took a lot of correction to get there with the Revels and to my ears the sound is not as coherent or tight as the Dyns.

I’ve also improved my power amplifiers, using a pair of ATSAH 500s, by AcousticImagery, which use the Hypex NCore 500 modules, and can deliver instantaneous peaks up to about 1200 watts short term and continuous power of 700 watts into four ohms.

This Dynaudio loudspeaker is the most transparent loudspeaker that I’ve ever heard, probably beating or at least equaling Quad Electrostatics, Magneplanars and Apogee ribbons. But the Dynaudio’s transients and microdynamics exceed that of the other phase-coherent speakers: Snare drums have the impact of real life, orchestral dynamics are stunning.

Throwing Down The Gauntlet: Headphones versus Loudspeakers
This kind of performance leads us to this question: Can a pair of state-of-the-art loudspeakers placed in the far field of a room sound as transparent, defined, impacting and pure as the world’s best headphones? These Dyns give my Stax 007 MkII headphones a good run for their money. The Stax are driven by a KGSS amplifier. And what about dynamic headphones? I upped my game here, selling my Audeze LCD-X to invest in a pair of LCD4’s. And I borrowed a Deckard headphone amp on reviewer’s loan. No slouches here!

Regarding transient response, considering that headphones are placed directly on the ears, avoiding room interference, loudspeakers in the far field begin at a transient response disadvantage. I have found my Stax headphones to be slightly more revealing than my Revel loudspeakers, the Stax revealed sonic differences that were masked in the loudspeakers. For example, I was able to prove that a D/A/D chain was subtly lossy by auditioning through the Stax whereas in the loudspeakers I believed the D/A/D to be audibly transparent! Let’s try that test again comparing the Dynaudios to the Stax and Audeze. I’ll also throw my Oppo PM-3’s into the game as these are amazingly transparent, impacting, and pure. Compensation headphone EQ will be allowed. After all, I used compensation EQ on the loudspeakers! Let the games begin: Who is going to win the transparency race — state-of- the-art loudspeakers or state-of-the-art headphones?

As I write this column I honestly don’t know the answer to this question yet. As soon as I get to spike the speakers to the concrete slab I’ll begin the listening comparisons. May the best transducer win!

* In REW, for those who wish to follow along and perform measurements using the same criteria: I used a Tukey 0.25 window, left side 40 ms and right side 200 ms, for a good assessment of the perceived bass response in the room. I used my preference, the psychoacoustic weighting (instead of 1/6 octave) because it correlates very well with the psychoacoustic technique used in Acourate. I did not use the frequency-dependent-window in REW because I find it to be problematic.

Editor's Note: While not having to deal with room reflections and absorption, headphones do have the problem of internal reflections causing mid-treble resonances. These can disrupt the clean transient response needed for precise "localization." I put localization in quotes as headphones do disrupt the normal interaural time differences and pinna reflections heard with normal sounds and generally prevent headphones from possessing the type of out-of-head perception of acoustic images heard on speakers.

Though not step responses as shown by Bob above, impulse response is a related measure, and you can see in the two plots below that the impulse response from a Stax SR-007 and Audeze LCD-4 are not particularly clean.


I think Bob is going to find that these two types of acoustic presentation (speaker and headphone) may be so different that an apples-to-apples comparison may be very difficult. Still, I'm intrigued and look forward to reading his impressions.

tony's picture

You've got the NEW ( only one pair existed in Oct.2016 ) M5P, phew! Those things have a 6 week lead time to build annnnnd they're Custom Order only ( speakith the Dyn guys ). Lucky you! , they aren't even revealing the Cost but it's supposed to be quite expensive. It will be available in "Audiophile" versions with piano paint and other pricy options. Are you having any trouble selling those Revels?

Soooooo, Audeze 4 vs. M5P ! E-gads! JA ( John Atkinson ) seems to consider those LCD4s to be as good as transducers get. Hmm, now you own em too.

And, you're gonna do a big Shootout.

The finest Mastering Transducer System vs. the Finest Transducers.

I'm sitting here, tightening up the Seat-belts on my reclining "Internet" Chair, baited breath, stocking up on Kettle Potato Chips & Popcorn and Vodka-free Cokes.

Woweeee, Stereophile stuff keeps getting better and better, Bob Katz is "in the building".

You might include the Story of how you convinced Mrs.Katz to allow another pricy purchase ( investment ).

I wish JA would convince you to contribute more stuff, you could inspire the peerage to do less of the fluffy social and more with the "useful"

You put a smile on my face as I opened up Tyll's stuff, ( I was taking a break from a Bathroom remodel ), I had to stop and read.

Welcome back and thank you to Tyll for hosting.

Tony in Michigan

Bob Katz's picture

tyll. Looks like the Stax have inverted polarity.Well, all other things being equal far field yields less transient peaks than nearfield and cans. Yes, reflections in cans distort perceived transients but I know just by listening experience that headphones do have the transient advantage and normallya greater perceived peak to loudness ratio. That said, these Dynaudios have the best perceived transient response I've ever heard from loudspeakers. Snare drums have the impact of real life! So, apples and oranges, but it's worth a subjective try I think to compare the best of one genre to the other. Despite differences in our individual HRTFs. It's going to be my subjective judgment and perhaps some special guests. Also of interest is the transparency test. Can these special loudspeakers allow me to perceive a difference which previously was only audible in cans? Tony, Mary and I celebrate our 30th today! Marriage and 32 years living together and running an audio business together. Together we let each other have our desires when possible and it makes a happy marriage and a happy Corporation!

tony's picture

Hmm, 32 years ( three decades ) of being in Business together is a "Commitment" we don't see often ( any longer ).

I saw Mary's Video of you in the Garage doing an "Un-boxing", e-gads, Bob Katz is getting his Video feet wet. Video is where Journalism is going, good to get started on it now. Plus it can pay nicely if you do it well. ( Wranglerstar, DiResta, Total Boat and quite a few others). It's important to be a recognized and established Master of your field ( Paul Sellers, Tyll, Bob Katz, Lou Sauzedde, etc. ).

The M5Ps look impressively large & heavy, I went right to Dynaudio's Factory videos to see how they're built, etc. It's an impressive outfit, kind of no compromise way of doing things. I like what I saw and will have a closer look at their little Actives for my Florida retirement.

I also get the feeling that the M5P will raise the bar for your gear, I'm wondering if your suppliers will be Cueing up to learn of their gear's performance?

On an aside: B&O are releasing the "Finest" loudspeaker ever!, the BeoLab90 with built-in 8,200 Watts of Amplification. Stereophile is reviewing them now ( or has just completed the review ). Apparently the design includes some sort of DSP to control room interactions ( making them "perfect" sounding?). I'm pretty sure I won't be owning them, they're the ugliest darn things I've seem in a loudspeaker ( the decorator rules my wife's household! , one of the little secrets supporting 5 decades of marriage )

I am particularly interested in your garage, hmm, it's Air Conditioned and it's filled with heavy duty shelving ( no basement ? ), where do you park your car? Your neighborhood looks quite nice, wide streets and clear sky ( in November ). You guys aren't even wearing jackets, I didn't see any Cold weather tools or gear. I'm freezing here with 17 degrees outside ( warmest part of the day ). brrrrrrr and Winter won't begin for another 2 or 3 days.

Well, you're bringing exciting news and developments. Now, for the Audiophile World, you're establishing just how far up the Bar is possible of being placed.

I wish you and Mrs. well,

Tony in Michigan

Bob Katz's picture

Believe it or not!

Bob Katz's picture

A lucky friend nailed me for 3 grand. Such a deal!

tony's picture

Right place at the right time.

Tony in Michigan

Rthomas1990's picture

Hi Bob,

Welcome back! It has been too long without a Katz Corner on IF. I missed your incisive reviews of overpriced cans hyped to the skies on the other website :D

Could you please explain the selection process that led you to the LCD-4? You don’t seem the type to spend 4K without auditioning the other contenders. Have you heard the Focal Utopia or Elear?

If not Tyll could you please send these to Bob? :D

I’m sure most of your readers would welcome his take especially on the 4K Utopia which are being proclaimed to be the ‘best in the world’.

Thanks to both of you for the great work.

JRT's picture

Avoid a fool's errand. There can be no global generalization of "best" in this. We all have different HRTFs. Without custom tailored signal processing, the headphones that sound best to someone else (such as Tyll) might not sound as good to you if your physical geometry exhibits a very different HRTF, and if you hear differently than Tyll. It is better to take other people's opinions as loose guidance and do your own headphone auditioning, and/or apply suitable processing tailored to a combination of your own HRTF and the response of your headphones as fitted on your own head and your own personal preferences.

Bob Katz's picture

Well in that case why read subjective headphone reviews at all? I would love to see a scientific correlation between personal HRTFs and personal reactions to headphone responses. Until then, I'll go by my ears :-)

Bob Katz's picture

Thanks, RThomas! I may not seem the type to be compulsive but I am! I had already heard and loved the lcd-4s and a lot of top contenders at Tyll's that I did not like! Don't know if the ones you mentioned were in Tyll's batch. It's hard for me compared with Tyll to arrange shootouts without paying so I just went for the 4s, which I know sound great and very accurate. helped to finance them by selling my x's. Haven't sold them yet. They have maybe 20-30 hours of use! I usually don't attend can fests but would like to when I find the time and when I do I'll audition the models you mention with material I know and well, let the chips fall where they may. If I think the other is superior I will still rest assured that I did not make a bad choice with the 4s. They haven't even arrived yet so don't make me get buyer's remorse!

Arve's picture

Bob: I find your correction curve to be slightly … odd … being essentially flat between 20 Hz and 12-1300 Hz, with a pretty sharp dropoff above that.

Mind sharing your pre-correction measurements as well?

Bob Katz's picture

Research has shown that a measured HF roll off is quite a common preference. This has been my curve Now for several years. I'll look up the pre correction and post it. The Dyns measure flat and sound bright. That's the way of the speaker world.

Arve's picture

I should have given some more context, and perhaps chosen a better word than "odd", because I intended no offense - it's just that the curve deviates a fair bit from say, the reference curve Harman uses in their listening room (and AFAIK, recommends for general use) [1], which is a bass shelf that's +5 dB @50 Hz, 0 at 200, with a tapered rolloff starting at 1 kHz, to -5 at 20 kHz, whereas your target has a fair bit more treble roll off, and no bass shelf. It makes our life as speaker-listeners in a state of confusion about what is "correct", and makes me wish that music was distributed with a target curve in the metadata (or that a standard for this emerges)

[1] http://www.innerfidelity.com/content/acoustic-basis-harman-listener-targ...

Bob Katz's picture

Thanks for clarifying. My target curve is currently flat from 15 Hz (3 dB down at 15, flat by 20) up to 1 kHz where it starts a linear diagonal to Nyquist at 48 kHz sample rate. At 24 kHz it's -7.26 dB relative to 0 below 1k. I used to have an 0.4 dB bell boost at 20 Hz reverting to flat by about 100 Hz but that's gone after linearizing the bass response with three AVAA traps against the back wall and improved subwoofer time alignment. Choice of the exact HF rolloff to use varies due to: ear sensitivity, personal taste, music preferences, pros versus consumers, spl being played, polar pattern of loudspeakers, reverberation versus frequency curve of the room, low frequency extension and wall treatment! If the response only goes down to 60 youre going to want more HF rolloff than if it goes down to 20 etc. I arrive at my curve empirically by using my set of about 50 best recordings that i know intimately and have heard in many places. My object is to find a curve that allows me to produce masters that are smack dab in the middle of the distribution of those reference recordings so my masters appeal to the widest audience and venues possible with flat tone controls.

Arve's picture

Thank you. After reading your previous reply, I was reminded to sit down and experiment a bit with the house curve, and created one that is very similar to yours in shape, and it brought out a sense of scale and space that I enjoyed very much with certain recordings.

Bob Katz's picture

Targets are not transferable from room to room, system to system, except in the most general way. There are many reasons why, I started a post on my Facebook page about this subject. Boosting the bass subjectively affects the treble and vice versa. I used to have a very slight bass boost, but it's gone now that the subs are more properly aligned and with the active traps. I find the Harman curve with a bass boost to be very troubling, but his research showed that consumers like it on the average. Pros like a more accurate and less artificially "entertaining" bass. Flat bass in this room sounds terrific, but how do we know? There is so much variation in recordings that I seek an average and it's working. If you would like to discuss the ideal target even more I'd be happy to join you over on my Facebook page.... where there is a vigorous discussion!

Arve's picture

Thank you - found it very good read - I may even end up asking a few questions there.

Bob Katz's picture

In addition to personal taste, the distance at which we listen to the loudspeakers affects the high frequency rolloff that we prefer. And I'm listening to these Dyns farther in the far field than I've ever listened in this room. Because that's where these speakers like to be auditioned, where the drivers seem to "congeal". But even one foot extra distance (now I'm at about 8-9 feet from them) is enough to demonstrate a greater measured high frequency loss. Yet they sound "just right" on all my reference recordings. So we go by the ears, I measure in order to be repeatable and compare. No one knows what rolloff should be right for your room, your acoustics, your speakers, your tweeters, your gear. We only know that there should be a rolloff.

Bob Katz's picture

.... reasons why HF target curves are not transferable from room to room at my facebook page.

JRT's picture

Bob, welcome back.

24bitbob's picture

I thought this was a great article, thank you Bob. There's lots and lots could be commented on, but instinctively, I pondered how much time and effort is given in this hobby to the less than 1%. I mean the tweaks and adjustments sought through cables and whatever, which probably amount to the square root of damn all, if anything at all.

Speakers > room > calibrate (or should that be Room > speakers > calibrate?) Loved it, thanks Bob.


ADU's picture

I wish I had the knowledge to follow all his comments. Gives me somethin to aspire to for the future.

bang.hs's picture

Mr. Katz could you please share the approximate room size in which you've installed these new thangs?

Bob Katz's picture

4000 cubic feet! 18 to 22 feet long. 14 feet wide. 12 feet high in front. 23 feet high in back! (cathedral ceiling) I should post reverberation time, Schroeder curves, energy time curve. It's a reflection free zone as well. In other words, a very good room.

bang.hs's picture

I had no doubts about that.. heh. Its top class, indeed.

Scientist1's picture

Price =/= performance

babmusician's picture

Hi all
I'd suggest to try the fantastic "jecklin float QA" electrostatic earspeakers! You will love it : - )
I had the audeze lcdx and sennheiser hd800 before and the difference is a world. the jecklin is stunningly precise!

Bob Katz's picture

Got the LCD-4's a couple of weeks ago, folks. I am in love, it's definitely a world-class headphone, certainly the best I've ever heard. I still have to sell my LCD-X's, if you know anyone who wants them, please let me know.

The reason I haven't posted the next episode yet (Throwing the Gauntlet) is this surprise: A good friend will be coming down next month and bringing ----- are you ready for this???? his Focal Utopias!!!!!!

We'll have a barbeque, I can smell the beryllium cooking (just kidding). But, seriously, this party's gotten very serious: We will be comparing three TOP world-class headphones: Audeze LCD-4, Focal Utopia, Stax SR-007/KGSS against an absolutely superb reference: a pair of Dynaudio M5P with a pair of JL subs.

I can hardly wait. I'll keep you posted. Not having heard the Focals (very few people have had the privilege, and very few have had the privilege of hearing the LCD-4's either) I have no idea what we'll discover.

Now to leave you guessing: What does Bob prefer so far, the LCD-4 or the Stax? You'll find out when we throw the gauntlet in late February.

theaudiorefinery's picture

Hi Bob,

I hope this finds you well. Will you still be comparing the Oppo PM3 in this comparison?


Bob Katz's picture

Hi, Eric. Good question. Sorry for the late response: Yes, I will be including the Oppo PM-3's "en passant" in this review. I think some people will be shocked to find out where I rate these Oppos in the hierarchy.