Dear Reader,

Another geeky newsletter issue. For more insight in how audio works, in this issue, read about

• Beyond the Baffle Part 2: Mics Mess With Our Minds
  ​By Mark Block
• The Absolute Reel Sound №3 - The Definitive Taxonomy of Tape
  ​Reviewed by Orest Voznyi

Foreword

If you have read last month’s newsletter, this month’s, and then next month’s, you will know exactly why different recordings sound so different on your system. For instance: a deep, layered soundstage versus a flat one; a soundstage wider than your speakers versus a narrow one between the speakers. Some of this is due to your equipment, but much of it is due to the recordings. If you consistently get the same soundstage across all recordings, a review of your system may be in order.

I invite you to join HIEND AUDIO WORLD, the global social network for audiophiles, a space where we can share our passion for sound, connect with fellow enthusiasts, and buy or sell audio equipment and music records and no commissions. Register today and contribute to the growth of an inspiring global audio community.https://hiendaudio-world.com/signup​

Cheers, Merrill Wettasinghe/Chief Music Officer 𝄞𝄞

AND coming soon, the PERFECT anniversary gift!

Beyond the Baffle Part 2: Mics Mess With Our Minds

By 🍄Mark Block 🍄

In Part 1, we discussed drastic manipulation of phase via flanging to create a swirl of sounds moving outside the speakers and around our heads. I never tire of hearing that kind of magical illusion. It’s almost a religious experience. But what does that have to do with most of the music we love—especially the music we love to hear live in a real space?

Johnson’s “celestial sound”

In a Zoom interview I conducted in 2021 for a few local audio clubs, the legendary recording engineer Keith Johnson discussed capturing the phasey spaciousness that surrounds us in a good concert hall. He called it “celestial harmony or celestial sound.” It matters to him, it matters to me, and it should matter to all audiophiles who enjoy “the absolute sound” of acoustic instruments in a real space (a philosophy popularized by Harry Pearson). In fact, most classical and jazz recordings fall surprisingly short in that regard—including many of the recordings that Harry Pearson loved. HP brilliantly promoted soundstage and depth, but he did not always seem equally attuned to stage width, or to the subtle, immersive, sometimes subversive effects of particular microphone techniques.

Professor Johnson’s Astounding Sound Show!

Professor Johnson’ Reveals all!!

How did “Professor” Johnson go about putting “celestial harmony” on tape? (Note: he’s not literally a professor; the tongue-in-cheek—but not inapt—sobriquet was given to him for the 1978 release of Professor Johnson’s Astounding Sound Show!! on Reference Recordings.) The story is hilarious (and brilliant). Mr. Johnson did not use a purist mic technique, although he avoided the extreme multi-miking that took over classical recording in the ′70s. His setup was pretty complicated when it came to mics. An article in Mix magazine from 2005 explained it this way:

“He models his setup after one used by longtime engineer Gordon Parry of London Decca Classical, using EQs on only four inputs, each optimized for a specific task: woodwinds, brass, voice and reverb. Mics include a pair of front omnis, a pair (or more) of semi-directional outriggers on either side, random incident omni pairs to capture hall reverb, ribbon or large-diaphragm condensers for solo instruments, and a directional center group between the omnis. ‘The main and center group are 90 percent of what you hear,’ says Johnson. ‘But I add what I call “time-panned stereo pair accents” to produce delays simulating inter-aural binaural listening.’”

Say again? With all those mics, why doesn’t the phasey interference turn things into mush? And what the hell are “time-panned stereo pair accents” that simulate binaural listening? Here’s the story he told us on the Zoom:

“Yes, it can be done, but most of the time it doesn’t work…. I learned that if I took a ghetto blaster radio—a simple, cheap thing, the cheaper ones the better—and put it on stage … I could aim the ghetto blaster either at the back of the hall or aim it up towards the ceiling, and then explore it around the place…. And my first time at Meyerson was when the hall had just been opened. Perot had spent whatever it was, hundreds of millions of dollars, creating the place. And it was a Dallas Wind Symphony. And here I had the ghetto blaster on stage.”

So now let’s picture “Professor” Johnson aiming a ghetto blaster at the back of this $100,000,000 hall and walking around to find something no other recording engineer cared about: a spot to place accent mics that would make his recording celestial.

“And in this case, where the ghetto blaster worked, first with just one pair of omni microphones, kind of very closely spaced, about the same space as our ears, was near a wall. I found the wall where … things were becoming kind of strange, phasing and so forth. I said, ‘Okay, I think that’s where I want to be.’ And sure enough, I went back to the [control] room, and there was the hall behind us.”

So those accent mics, only comprising about 10% of the mix, made magic by giving us a more realistic impression of the concert hall. The phasey ambiance placed some hall sound “beyond the baffles,” whereas many mic techniques simply create a phasey slop between the speakers. (I assume Mr. Johnson was talking about his first major recording with the Dallas Wind Symphony, the acclaimed 1994 album Pomp & Pipes; Reference Recordings RR-58CD, conducted by Frederick Fennell.)

Why stereo imaging works at all

So why do some mic setups produce ambiance beyond the baffles, while others don’t? For many audiophiles, recreating concert-hall sound, including its spaciousness, is the whole point of having a great stereo system. It’s the “you are there” experience. Where does it come from? To answer that, let’s rewind the tape and go back to the beginning. Stereo sound was invented because of a failure to produce a “you are there” experience in movie theaters when talkies took over in the early ‘30s.

The story goes that Alan Dower Blumlein, a British engineer born in London to a German-born father, saw a movie in 1931 and was disturbed by the monaural speaker behind the middle of the screen. The sound remained anchored to the middle even when actors moved to one side or the other. He told his wife that the sound should follow the actors, and he knew how to fix it.

Now, as a former professional film editor, I’ll put a small asterisk on Blumlein’s premise. He was mistaken about the need for dialogue to chase the actors’ mouths around the screen. But that’s another story. Alan Blumlein was a true genius who patented many breakthrough technologies, and probably has a hundred IQ points on me, but I think he stumbled onto the concept of stereo by mistake. Who cares? Almost a hundred years later, it’s still the dominant form of sound reproduction, even with multi-channel and Dolby Atmos making inroads with some consumers.

On a sad note, Blumlein died in WWII in a plane crash during a top-secret test of his radar system. An improperly tightened tappet-valve nut came loose, causing an engine fire and wing failure. Blumlein was only 38. He reportedly owned 128 patents, including stereophonic sound, the Blumlein Pair mic system, 45/45 record-cutting, moving-coil cutter heads, the Ultra-Linear (distributed-loading) amp circuit, scan-line television circuits, the flying-spot scanner for converting movies into video, a ground-scanning radar system … I could go on. Back to stereo and the Blumlein Pair.

Blumlein, who had worked for International Western Electric and was now at EMI, believed that an improvement on the binaural scheme developed by Harvey Fletcher at Bell Labs in the 1920s could solve the problem of movie sound. Fletcher’s work, in turn, stood on the shoulders of Lord Rayleigh’s “Duplex Theory” of sound localization, published in 1907, which proposed that our brains use arrival-time and volume differences to locate sounds. A high-frequency sound coming from the left will be louder in the left ear because the head blocks it from reaching the right ear at full volume. This Interaural Level Difference (ILD) helps us localize high-frequency sounds. (It’s a bit more complicated than that, but the Duplex Theory was a giant insight.)

The Bell Labs binaural system used an animatronic mannequin named "Oscar" with microphones in his ears. The head-spaced mics in Oscar’s ears worked perfectly with headphones, as the left ear hears only the left channel and the right ear only the right. Unfortunately, when you play those same two channels through loudspeakers in a room, the left ear hears the left speaker, plus a delayed, out-of-phase signal from the right speaker. The compatibility with two loudspeakers is poor.

Why coincident mics image so well

Blumlein's genius was realizing that if you feed pure volume (intensity) differences to two speakers 60 degrees apart, the physical head of the listener will shadow the sound, creating the correct phase delays at the eardrums. (Stanley Lipshitz and John Vanderkooy worked out the math for this much later, published in a 1986 AES paper.) Blumlein’s “aha moment” in the movie theater was realizing that to create a highly focused image with loudspeakers, you had to capture the audio without any time-delay differences at all. By inventing the coincident figure-8 pair, Blumlein ensured that sound from an instrument reached both microphone capsules simultaneously, without comb filtering. When played back through two speakers, the brain can pinpoint a spot between the speakers and say: That’s exactly where the violin is.

Among the most famous early Blumlein stereo experiments were the 1934 Beecham/Mozart “Jupiter” excerpts at Abbey Road. During these tests, Blumlein tried his coincident figure-8 pair, with one ribbon mic placed above the other and aimed 90º apart. While the primary commercial recording of that session was cut in mono, Blumlein had his experimental stereo lathe and microphone rig running simultaneously to capture test excerpts using his 45/45 orthogonal (vertical-lateral) cutting technique.
(See link.)

Amazing! ​ But wait, there’s more.

Blumlein specified a 90º angle between the figure-8 mics. (He used a pair of ribbon mics that he developed.) By design, a figure-8 microphone captures audio with equal sensitivity from both the front and rear of the diaphragm, yet it has absolute nulls—regions of total acoustic cancellation—at exactly 90 degrees off-axis. If a trumpet is far enough to the right, it fires strongly into the main lobe of the right-facing mic while falling near the null of the left-facing mic. Channel separation is therefore maximized. (Note: This is theoretical. No mic is perfect, but let’s not worry about that.)

On playback, when you sit in the traditional audiophile equilateral triangle (speakers 60º apart), the 90º pickup angle of the Blumlein pair will be compressed across the 60-degree spread between your left and right loudspeakers.

One slight anomaly: With a figure-8 mic pair, the mic aimed to the front right will pick up hall sounds from the back left. Is that a problem? Not necessarily. Rear-arriving sound is captured with opposite polarity relative to the front lobe, and that decorrelated ambient information can contribute to a strong sense of spaciousness. In a good concert hall, say, the Concertgebouw in Amsterdam, the sound hitting the back of the microphones is pure, diffuse, gorgeous reverberation, fooling our little pea brains into hearing a seamless space. However, in a smaller venue, the out-of-phase rear sound can partially cancel the front sound, and at a live jazz concert, an audience member coughing on the right will be heard on the left. Anyway, not a deal breaker.

But let’s go back to the main story. I hear you asking: If the mics form a 90º angle, why not spread the speakers farther apart to mimic the microphone angle? Yes, do that if it’s practical. While 60º is the conventional stereo standard, it is also a practical compromise: wide enough to create scale, but narrow enough that most pan-potted recordings still hold together as a whole. That’s “whole” with a “w.” Hole in the middle (no “w”) is what our brains hear when the speakers are too far apart.

The 90º speaker angle will work beautifully with Blumlein recordings, but the vast majority of recordings will sound unfocused. When close-miked vocals and instruments are pan-potted in the mixing studio, Interaural Level Differences (ILD, discussed previously) along with “pinna effects” (the shape of the outer ear acting as a variable filter depending on the location of the sound) can help the brain create a seamless stereo image. However, there is no natural phase information baked into the recording to glue the soundstage together. Also, as the speakers are spread apart to 90º, they are likely to get closer to the side walls. Acoustic treatment will help, but if the sound bounces off the side wall and hits your ear within roughly 20 milliseconds of the direct sound from the speaker, your brain fuses them together, pulling the audio away from the phantom center and smearing the stereo image (the Haas Effect).

If, however, you create the 90º angle by moving your listening seat closer and toeing in the speakers, you might end up close to or within the “critical distance” where the direct sound is equal to or greater than the reflected sound, and you will be creating a perfect facsimile on playback of the Blumlein mic pair that captured the music. Robert E. Greene of The Absolute Sound encourages this setup. Blumlein recordings will now be reproduced with a tremendously wide and realistic soundstage. Wonderful! But how many pure Blumlein recordings are there? Lots, including a few audiophile classics, but not enough. Sure, Kavi Alexander’s Blumlein recordings for Water Lily Acoustics sound wonderful, but do you want to move your chair and adjust speaker toe-in for Blumlein recordings, then go back to a different setup for almost everything else? Some obsessive audiophiles will be willing to do it—and audiophiles are nothing if not obsessive. I’m obsessive but also lazy. I’d rather have one system that works well for all recordings, and that is the venerable 8-foot equilateral triangle.

OK, here’s a weird thought experiment. Don’t try this at home—I did, so you don’t have to. If Blumlein recordings should ideally be played back with speakers at a 90º angle, and if the microphones have a figure-8 pattern, wouldn’t a dipole speaker (figure-8 dispersion) achieve the ultimate in realism from a Blumlein mic? No! I have a pair of Magnepan .7s (dipole) and a pair of Clarity 6.2s (smallish standmounts, close to point sources, with fairly decent dispersion). The full-range sound bouncing off the wall behind the Maggies adds “fake” depth, which mixes with and obscures the real depth captured by the Blumlein mics. My Maggies are 6' away from the wall, so it’s not too bad, but a traditional speaker like the Clarity 6.2 creates a better image. My friend Barry Diament from Soundkeeper Recordings says that for every foot you pull your Magnepans away from the wall behind them, you make a $1000 improvement in the sound. (In my experience and Barry’s, that generally applies to any speaker.)

One other note: Baffle size can play a role in stereo focus and image width. According to the Huygens principle, which REG has written about (see link), an abrupt physical boundary turns into a new acoustic source. The edge of the speaker cabinet literally acts as a secondary tweeter. It’s called edge diffraction, and it tells your brain, "I am listening to a box." It anchors the sound to the physical speakers, and it bothers me, all else equal. All else is not equal, of course, and arguments can be made for traditional baffles. YMMV. I have heard good imaging from wider boxes; an open mind should be brought to any listening party. However, most high-end speaker designers go to great lengths to minimize edge diffraction. So there is that.

Why perfect imaging is not the whole story

Getting back to the theme of this article, guess what a Blumlein pair can’t capture? You guessed it—Keith Johnson’s celestial sound, or the magic of hall ambiance appearing to come from outside the loudspeakers. A Decca Tree—typically three spaced omnis, with the center mic placed forward of the left/right pair to improve center fill—can create size, depth, and beautiful hall sound, but it usually does not create the same kind of phasey “beyond the baffles” lateral illusion I’m talking about here.

Nor can the three spaced omnis used by Bob Fine at Mercury (relatively tightly spaced, adjusted by Fine’s superb ears) or Lewis Layton’s setup at RCA (more widely spaced omnis, with spot mics required for filling in the holes). These recordings were highly prized by HP (and most of my audiophile best friends). While spaced omnis fall short with respect to “you are there” stage width, they have some advantages, most notably in low-frequency response. A pure pressure-gradient figure-8 has inherent low-frequency challenges that must be compensated for.

Engineers using coincident figure-8 mics can attempt to address this inherent problem by identifying spots in the recording hall where there is natural warmth or bass boost. I should also mention that because figure-8 mics pick up sound equally from front and back, they will sound much more echoey than what our brains hear at the same spot. Our brains process spatial information and can latch onto the direct sound. Mics don’t hear like ears; omnis (and to a lesser extent, all mics, truth be told) need to be placed relatively close to the performers in order to give the illusion of a good seat in a hall. Figure-8 coincident mics are not quite as bad in that regard, but placement is still critical. A few inches forward or back can result in too little or too much reverberant sound in the recording; it’s the difference between a beautiful soundstage and a collapsed mess. Will the best placement for acoustic balance and soundstage also be the best spot for bass warmth? Not likely.

But there are other ways to help the bass. Engineers can also tune the tension of the ribbon so that its natural resonant frequency is low enough to augment the bass. EQ is another solution. And finally, some engineers add a pair of omnis running through a low-pass filter, then blend in some low bass without disrupting the imaging.

Another way to get the bass back is to replace the figure-8 ribbons with cardioid mics (a heart-shaped pickup pattern). Cardioids can offer stronger low-frequency response than many figure-8 ribbons in a given setup, but they are still directional microphones, with their own low-frequency behavior and proximity-effect complications. The downside of coincident cardioids (known as an X-Y pair) is that they can’t capture the channel separation of a “deaf at the sides” Blumlein setup. Because X-Y cardioids have substantial overlap between the left and right pickup patterns, the stereo image is often narrower than Blumlein’s. So Blumlein wins the day on imaging.

But, but, but … what about “beyond the baffle” imaging? Didn’t we just establish that Blumlein mic setups can’t do it?

Blumlein’s coincident placement eliminates meaningful arrival-time differences between the two capsules, creating a laser-focused, holographic image (and a wide soundstage if the speakers are placed in a matching 90º configuration), but human beings rely on tiny time delays to perceive the size of a room. By putting both microphones in essentially the same point in space, Blumlein sacrificed beyond-the-baffle width. But hey, he was trying to create a system that kept the dialogue placed precisely on the actors within a movie screen, not beyond it.

Is there a compromise, a microphone system that maintains Blumlein’s beautiful stereophonic solidity while adding the illusion of a super-wide soundstage? Yes. But I think I’ve gone on too long already for one article. That will have to wait for Part 3.

​Blumlein​’s 1934 stereo recording.​

To hear what Blumlein is all about, start with one of Kavi Alexander’s Water Lily recordings, then compare it with a great Keith Johnson/Reference Recordings release.
​
​You might prefer Kavi Alexander’s approach, especially in a 90º speaker setup, but the difference between focused stereo and celestial spaciousness is the whole point of this series.

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The Absolute Reel Sound №3

The Definitive Taxonomy of Tape​
​Reviewed by Orest Voznyi

Prelude: The Elite Workhorses—The Professional Standard

If the mastering decks are the stationary altars of the studio, the Professional Tape Recorders—models like the Studer A810, Otari MX-5050, and Telefunken M15—are the elite special forces of the analog world. While they occupy a tier technically below the massive mastering platforms, they were the "daily drivers" that powered the global music and broadcast industries for decades.

The Reality of the "Tier Gap": It is important to be candid: compared to the "Big Iron," these professional units are physically lighter and utilize more compact electronic architectures. They may lack the absolute, earth-shaking low-end weight or the extreme signal-to-noise ratios of a 200kg floor-standing unit. In the pursuit of transportability and rack-mounting, the power supplies are smaller, and the tape paths, while excellent, do not feature the same degree of "over-engineering" found in a flagship master recorder.

The Advantage of the Workhorse: However, for many audiophiles, the Professional Workhorse is actually the superior choice for a high-end setup.

• Ergonomics and Footprint: They provide 90% of the mastering performance in a chassis that actually fits on a desk or in a rack.
• Maintainability: Designed for 24/7 service in radio stations, these machines are often more modular and easier to calibrate.
• The "Direct" Characteristic: Because they were often used for high-fidelity live broadcasts and archival transfers, these machines possess a "fast," rhythmic, and incredibly transparent sound.

A professional deck is not a "compromise"—it is a refined, agile tool. It remains a coveted part of any serious setup because it delivers the professional 15 IPS experience with a level of reliability and "punch" that makes the music feel alive, tactile, and undeniably real.

The Professional Workhorses

Studer A-810: The High-Resolution Compact

If the A-820 is the ultimate destination, the A-810 was the vehicle used to get there for most European broadcasters. It was the first Studer to embrace full microprocessor control in a "compact" 31kg frame.

• Technical Detail: A modular masterpiece. Its electronics are packed into vertical cards for easy access. It features four tape speeds (up to 30 IPS) and digital "soft-key" calibration that stores multiple tape profiles in memory.
• The Sound: Neutral, transparent, and possessing that unmistakable Studer "black background."
• The Catch: It generates significant internal heat. For long-term reliability, proper ventilation is a requirement, not an option.

Studer A-807: The Final Analog "Song"

Launched in 1986, the A-807 represents the "last of the line." Designed for speed and durability in radio stations, it features the "SAA" (Studer Auto Alignment) system for digital calibration.

• Technical Detail: Uses a lighter chassis than the 810 but handles tape with incredible gentleness. It was built for the 24/7 environment of broadcast.
• The Sound: While still an excellent performer, the sonic signature is not as clearly defined as its predecessors. The sound is noticeably more "modern" and lean compared to the richer, more muscular character of the A-80 or A-812. However, it still offers a top-tier experience in transient response and stereo imaging, remaining a highly capable and sophisticated performer for the contemporary listener.
• The Catch: Accessing the lower boards requires a partial teardown, and proprietary parts for the final production runs can be elusive.

Otari MX-5050 BIII-2: The Reliable Survivor

Likely the most successful professional recorder ever built. It was the "Swiss Army Knife" of American radio in the 1990s.

• Technical Detail: Features built-in XLR connectors, easy front-panel bias adjustments, and a three-motor transport that is famously easy to service.
• The Sound: The Otari MX-5050 is very underrated by the audiophile community, often overshadowed by its more expensive European rivals. In reality, it provides a remarkably powerful and rich sonic signature that excels in the reproduction of rock and jazz. It possesses a certain "drive" and low-end punch that gives acoustic bass and percussion a visceral, life-like presence.
• The Catch: It is a loud industrial machine; the "clunk" of the solenoids can be distracting in a quiet listening room.

Tascam BR-20: The Modern Refinement

Tascam’s final high-end 2-track, built for the transition e

ra between analog and digital. It is often cited as the best-looking machine of its era.

• Technical Detail: Features a sophisticated servo-controlled transport and a highly accurate digital counter. It was one of the few machines designed from the ground up to handle "modern" high-output tapes.
• The Sound: Very clean and "fast." It has a lower noise floor than many older professional machines, making it feel very high-fidelity.
• The Catch: Relies heavily on specialized late-90s integrated circuits. If a proprietary control chip fails, the machine is nearly impossible to repair.

Ampex ATR-700: The American-Japanese Hybrid

The ATR-700 was actually built by Teac/Tascam to Ampex’s strict professional specifications. It served as a mid-tier bridge between consumer decks and the "Big Iron" ATR-102.

• Technical Detail: A heavy-duty machine with a thick aluminum faceplate and professional XLR I/O. It includes a "Sync" mode for overdubbing, a rarity for 2-track machines.
• The Sound: It has a classic "warm" American flavor, likely due to its transformer-coupled inputs.
• The Catch: The Ampex ATR-700 is frequently confused with the consumer-grade Teac A-7300, as both share a common manufacturing origin. However, the distinction is critical: while the Teac was marketed for the high-end home consumer, the Ampex was built to more rigorous professional specifications specifically for radio stations and smaller recording studios.
• The Warning: When sourcing a machine, ensure you aren't paying "Ampex prices" for a standard consumer deck. While they may appear similar on the surface, the ATR-700 features professional-grade balanced XLR I/O and more rugged internal components designed for 24/7 industrial use.

Telefunken M-15: The German Industrial Standard

The definition of "overbuilt" German engineering. The M-15 is a purely industrial tool designed to be virtually immortal.

• Technical Detail: Uses massive, brushless DC motors and a unique AEG hub system. It often lacks VU meters entirely, as it was designed for external console control.
• The Sound: It has a "bold," muscular character with an exceptionally solid low-end foundation.
• The Catch: A minimalist, Cold War-era tool. If you want user-friendly knobs or meters, the Telefunken will feel like laboratory equipment.

The Final Outlier: Nagra IV-S

We conclude with the most famous portable recorder in history. While the Nagra IV-S is a stereo legend that forged the sound of 20th-century cinema, it remains a machine that I cannot recommend for a primary listening foundation.

• The Appeal: A 1/4-inch stereo machine with incredible internal preamps. The sound is organic, liquid, and intensely musical.
• The Reality: Unless you find the rare and expensive QGB large-reel adapter, you are limited to 7-inch reels, making it impractical for full-album playback.
• The Verdict: With the same respect I hold for the T-Audio, I must advise you to avoid dealing with the IV-S for your main system. It is a masterpiece of Swiss miniaturization, but it is also a "mechanical ticking clock." The internal density of the Nagra IV-S is extreme, and its proprietary parts are becoming vanishingly rare. The specialized, high-precision labor required to keep such a machine within its original factory specifications is a luxury that very few can sustain. Ultimately, one must ask: even if a technician could be found to maintain it, is there truly any point? When compared to the robust, serviceable, and sonically superior "Big Iron" alternatives, the IV-S remains a beautiful but impractical artifact for a primary listening foundation.

Send us your comments, pictures of your systems. ​
​NewsletterEditor@MerrillAudio.net​
With your permission I will print your comments in a future edition.