Tag Archives: microphones

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Microphone madness

Without microphones we’d not have much in the way of recorded music. We’d instead be stuck back in the days of yelling into a horn in the hopes of directly moving a cutting head. This was the state of recording onto wax cylinders when Edison was inventing them.

At about the same time Edison was yelling into his phono cylinders, another inventor, Emile Berliner, had managed to leapfrog Edison in two major ways: the invention of the carbon microphone and the flat disc we now know of as an LP.

Berliner, while working in a livery stable, came up with the idea of using carbon granules to regulate an electrical voltage in response to sound. He invented what became known as the carbon microphone (and as is almost always the case, two other inventors—Edison and David Edward Hughes—were also working on the same idea).

Carbon makes for a good resistor. In my early days of designing audio equipment, we used only carbon resistors. Relying upon carbon’s resistive nature, Berliner layered a handful of ground-up carbon between two round discs of metal with an outside diameter of a few inches. The first disc had a thickness similar to that of a tin can, while the second was extremely thin and flexible. The layer of carbon granules was thick enough that the two plates did not touch. Using a battery for a power source, a current was passed between the two-plate-carbon sandwich. The amount of that current was regulated by the resistance of the carbon (itself regulated by the distance between the loosely gathered carbon granules).

This formed the first microphone (or transmitter as it was then called). When a source of sound came close enough to the microphone, its pressure flexed in and out the thin front metal plate. This compressed and decompressed the carbon granules, thus changing their resistance. As we remember, a changing resistance in the path of a current changes the voltage.

Bingo! A changing voltage in response to sound. A microphone.

Today, Edison is credited with the microphone’s discovery but only because he was a notorious prick when it came to sharing credit or having his ideas challenged (just ask poor Nikola Tesla or any of the hundreds of animals and people he electrocuted – wait, can’t do that because they were dead :)). The two battled it out in the courts and Berliner lost.

A calmer view of history suggests that really the first microphone was invented by Hughes, but I wanted to write about Berliner because of his greater contributions to the recording of music: the invention of the flat phonorecord and its vertical cutting head, not to mention founding The Gramaphone company (including Deutsche Gramophone), and the Victor Talking Machine Company that would one day become RCA Victor.

In fact, one could accurately suggest that Berliner’s microphone, coupled with his flat vinyl discs and the fact they could, for the first time in history, be easily duplicated, single-handedly invented what we all love today, recorded music.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl

Ringside seating

On most recordings, there is a combination of close and distant miking. The close miking gets us a closer-than-natural intimate view of the instrument or performer, while the distant microphones add the missing ambiance and space close-miking cannot capture.

What’s odd about this miking technique is that it works despite the fact we are never as close to the instruments as the microphones.

One way to think about this is to visualize actual musicians in the room. Let’s use a single cello in our example. Mentally place the cellist a few feet behind the loudspeakers. Now, close your eyes and imagine how that would sound from your listening seat.

What you are hearing is a combination of the direct sound from the bow and string coupled with the room’s interactions.

Now, mentally replace our imagined performer with the close-miked cello. It sounds “the same” because the distance between the loudspeakers rendition of the close-miked sound and the listener mirrors the distance between our imagined performer and where we’re sitting.

It may seem counter intuitive to place microphones closer than our ears ever go, but that’s how we get musicians in our rooms.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Setting a high bar

We work so hard achieving sonic purity that it’s easy to forget just how flawed some of our tools are. Microphones and loudspeakers, for example, are so far away from neutral that we accept their colorations as normal. I am not sure that’s a very high bar from which to set standards.

My friend Dan Schwartz has developed enough of an ear to identify which microphone was used in many recordings. The fact that microphones have so many colorations as to be identifiable from just listening is pretty telling and we haven’t even scratched the surface. Walk the halls of a HiFi show and listen to how wildly different music sounds from room to room.

To me, this is a good news, bad news situation. On the one hand, there’s enormous room for improvement in our reproduction chains, something that always gets me excited as we delve deep into making better sound systems for the home. On the other hand, it’s a little unnerving to consider how much further we have to go.

As we move forward by building better speakers and using only the best microphones to capture music, my hope is we reset our standards. That once we hear better we will be unwilling to settle for what was once “normal”.

Progress has many benefits, but the one that makes me smile is setting the bar high enough that we’re unwilling to accept less in the future.

A high bar helps us all.

 

Asheville, Walnut Cove, Weaverville, Waynesville, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

PS Audio will be using interesting transducers, otherwise known as drivers, in their new line of speakers, mostly designed by the late Arnie Nudell of Infinity loudspeaker fame. However, there are lots of different types of transducers, including those used in microphones.

I look forward to hearing PS Audio’s new speaker line.

Transducers

Every recording is squeezed through the lens of a transducer. Microphones for acoustic instruments, magnetic pickups for electrified string instruments, and even DIs for electronic keyboards.

And as we know, each interface or transducer has a sound to it, an insulator from the sonic thumbprint of the instrument or voice. It’s not much different than the problems we have capturing light with cameras or even our eyes. Their lenses twist and distort the truth to fit the medium.

Transducers are also needed to playback captured audio. Speakers or headphones.

In fact, the definition of the word itself gives us a big clue to its impacts. “A device that converts variations in a physical quantity, such as pressure or brightness, into an electrical signal, or vice versa.”

We’ve come to take for granted all that’s good and bad in a transducer. Put another way, we’ve learned to live with them.

But acceptance should never dictate complacency. Our quest towards the perfect transducer is never-ending.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Perceptual hearing

Maybe our focus has been to narrow. We think of our ears as mere microphones. We then design measurement equipment to unravel all the distortions and intricacies that might trip up a microphone, only to wonder why those measurements and our hearing perceptions don’t line up.

Our ears are microphones, but that’s only the simplest of their tasks. The ear is a complex instrument, from its outer shape, called the Pinna, funneling sound through a curved canal into the microphone’s diaphragm—quaintly called the eardrum from years before we understood its full nature—and onwards through other archaic names like the Vestibule, Round Window, and Oval Window, continuing through the three tiniest bones in our bodies: the malleus, incus, and stapes, collectively know as the Ossicles (which literally means tiny bones).

The ear’s sorted electrical signals including those of position and balance are fed to our massive CPU, the brain, for further processing—and this is where we form an image of what we hear. Yes. A literal holographic multi-dimensional image with far more information than any recording or measurement device yet imagined.

You see, we hear not only with our ears but our brains. It’s called Perceptual Hearing.

What a wonderful invention it might be to someday devise an analog of perceptual hearing. We could then quantify that which we perceive as sound.

Some work has been done already. Studies of three-dimensional audio holography have made great strides.

But, for now, we are our best analog. The real deal.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

From Paul.
Impossible feats

Speakers should disappear, which seems impossible. The drivers are pointing straight at us!

Much to my surprise this fact, along with another—the soundstage should come from behind the loudspeaker—continually baffles people.

I am at the Japan Audio show today and watched as two setup guys had the right combination of disappearing source and rear presentation, only to change placement to pinpoint the source and move the sound up front. When questioned they had a simple answer—it seemed more logical to them.

And so it’s true. Logic suggests the source of sound should be obvious and the fact the drivers are pointing straight at you implies the stage should unfold between you and the speaker. Logical.

But wrong.

Here’s a way of thinking about this that might help you. Picture a live group playing in the room and imagine the speakers as microphones. The “microphones” point at our band and record the sound. When we magically reverse roles, microphones back to speakers, we should expect the band’s position to remain unchanged and disconnected from the microphone/speaker.

Our goal in any recording/reproduction chain should be to recreate the live event.

Asheville, Walnut Cove, Biltmore Forrest, Brevard and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

The sound of magnets

We know that every element in the signal chain imparts a sonic fingerprint: bipolars, tubes, JEFETS, MOSFETS. And let’s not to forget film, foil, beeswax, ceramic, and electrolytic capacitors.

One piece of the puzzle has only never been eliminated. Magnetism. Most everything you listen to when reproducing music arrives to you through the lens of a magnetic field. Without magnetic fields most of us would not be able to enjoy recorded music.

Just about every loudspeaker or headphone is based on a magnetic field. In fact there are only four exceptions I can think of—two we all know, the other two I’d be surprised if more than a handful had ever heard music reproduced through them. The two we know are the original Gramophone, which worked more like a tin can and string arrangement—and didn’t sound much better—the other the classic electrostatic loudspeaker.

The two exotic ones are the Ionovac and the Hill Plasmatronics. Two highly impractical sound reproduction exceptions .

Those playback exceptions aside, when we listen to music on home reproduction systems it is mostly through opposing magnetic fields, one fixed, the other variable (either recorded with a magnetic based microphone or reproduced through a magnetic based speaker). And magnets are not linear, nor is the motion of drivers pumping air into our ears or the microphones that pick up the music we record.

There are non-magnetic based microphones that are similar to electrostatic loudspeakers. And thus in a modern system with electrostatic loudspeakers and hand-selected recordings using condenser microphones, one could avoid magnetic fields, but it’s rare.

Microphones, phono cartridges, tape heads, the laser reading mechanism on a CD transport, hard drives, all depend on magnetic fields for their movement, conversion of motion into electrical impulses or storage and retrieval.

The original switch from the Edison Gramophone to the microphone/loudspeaker combination still in use today came about because of the magnet. And it’s been with us ever since.

One way or the other, if you listen to recorded music, it’s likely colored with a magnetic lens.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Inc.

Audio myth 5

Myth: Amplifiers based on vacuum tubes sound better than solid state designs, and a good tube preamp can even restore clarity and warmth that has been lost in the digital recording process.

Fact: Both types of amplifiers can have a frequency response flat enough for audio reproduction. But modern solid state amplifiers have measurably lower distortion than any tube-based design. Most tube-based power amplifiers also require an output transformer, which increases distortion – especially at the frequency extremes.

Further, solid state power amps always have a better damping factor.

Many people – including me – like the sound of tubes, especially in a good guitar amp.

Even if you prefer the sound of tubes, please understand they simply cannot restore any quality that was lost earlier in the recording process. All a tube preamp can do is add an effect that you may find pleasing. Studio monitor amplifiers should never have a “sound;” if they do, they are in error. Tube circuits can affect the sound in a way that is similar to analog tape recorders, and you may in fact find that pleasing. I won’t dispute that even-order distortion can sound good, by adding overtones that are richer than odd-order distortion, which is, musically speaking, dissonant fifths. However, all distortion adds intermodulation (IM) products that are not harmonically related to the source material, and are thus decidedly non-musical.

As we have come to learn with Ethan’s posts, there is much truth in what he writes, though the conclusions based on those truths are sometimes suspect–occasionally just wrong. Let’s take a look at several of these often believed quotations.

“Studio monitor amplifiers should never have a “sound;” if they do, they are in error.” Well, that’s nice to say and makes sense. Only, it’s inaccurate. All amplifiers impart a sonic signature; some more, some less–as do the other tools of recording engineers, from microphones to loudspeakers. Of course the ideal would always be to use amplifiers, microphones, monitors, wiring and recording apparatus that are sonically neutral. The problem is, they do not exist.

“…tube amps simply cannot restore any quality that was lost earlier in the recording process. All a tube preamp can do is add an effect that you may find pleasing.” This is a very common myth – and a carefully written one at that. The author is 100% correct that nothing can restore that which has been lost. It is for this very reason we cannot restore MP3 and lossy files to their original splendor. Once lost, forever gone. But it is to the second sentence where we have our differences.

“All a tube preamp can do is add an effect that you may find pleasing.” Poppycock. I have numerous examples of circuitry, both tube and solid state, that hide information less than other configurations. And this is a point I try to help people understand. Great circuitry does not bring out more information, instead, it hides it less. And therein lies a big difference.

I recall the first time I listened to DirectStream playback a CD. One of my coworkers mistook the playback for high resolution (we had both a CD and high resolution copy on the server of that track). He was right! For the first time, it was evident the gap between CD and high resolution audio had been nearly closed–and not because DirectStream revealed more–but because DirectStream hid less.

So, the next time you listen to kit that uncovers missing details, remind yourself that your previous reference had been hiding it, not the opposite.

Asheville, Walnut Cove, Biltmore Forrest and Western North Carolina’s Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Glue

High end audio progress comes in chunks, driven by generations of designers in concert with generations of listeners.

Of course there was the Edison inspired group of mechanical designs with wax cylinders, cranks and horns. And Alan Blumlein’s stereo invention which, along with vacuum tubes, microphones, vinyl, and startups birthed in garages, ushered in the electrical age. Marantz, Fisher, Klipsch, and Villchur broke free of the cottage industries, and were eventually challenged by Morita, Yamaha, and Matsushita. Nudell, Walker, Tiefenbrun and Harmon lead the charge in the 70’s and 80’s, giving way to Rowland, Hanson, Schifter, Burmeister and my generation. And now we see the next coming of age: my son Scott, Matt Weisfeld, EJ Sarmento, and so many new faces I can’t keep track.

Each generation put forward fresh ideas and products that reflected their love of music and how it is enjoyed in the home.
And those who enjoy the fruits of their labors come and go in the same generational chunks, yet… there is one common bond we all share, the glue that holds us all together.

Music.

Walnut Cove, Asheville, Biltmore Forrest and Western North Carolinas Audio and Home Theater specialists present Cane Creek AV and Paul McGowan – PS Audio, Intl.

Anti sound

You may be wondering how my idea of Active Walls might work and what is taking place.

Imagine taking one of your loudspeakers and placing it against a wall, facing into the room. Next to it place a microphone pointed in the same direction. If the microphone is connected to a clever circuit, the sound picked up can be rebroadcast by the speaker out of phase, actively canceling sound. Once cancelled, the sound that would formerly have reflected off the wall and returned to your ears is cancelled. You have created a non-reflective wall.

Active noise cancelation is nothing new. Bose and others have used it for years in their noise canceling headphones. The headphone is a small powered loudspeaker and outside of the ear covers are tiny microphones that pickup sound, reverse its phase, and rebroadcast it to your ear. Thus, any sound entering the headphones is nulled by the out of phase loudspeaker output. Here are two diagrams I found on the internet describing how this works:

In the destructive interference picture you can see as one wave goes up, the other opposing wave goes down, creating a sum of zero. Think of a vessel with water and a pump. If the pump is pulling water out of the vessel it drains quickly. If another pump pushes water in, the vessel fills. If both pumps push and pull at the same time and in equal measure, the water level never moves. The push of one pump cancels the pull of the second pump.

That is how active noise canceling works. One of the challenges of mechanizing such a scheme with loudspeakers is the microphone will also hear that which the speaker produces as well as what’s around it, a problem not encountered when using headphones.