PS Audio High-End Audio Products Thu, 10 Jul 2014 17:34:19 +0000 en-US hourly 1 Woofing Thu, 10 Jul 2014 07:16:44 +0000 We’re discussing 2-way loudspeakers and the crossovers that make it possible for each of the two drivers to do what they’re best at.

To make sure the tweeter only “tweets” high frequencies, we place a capacitor in series with it, low frequency musical notes just won’t pass through to the tweeter.

The woofer is a different matter. Here we want the most bass we can get but limit how high the notes go. We don’t want our woofer “tweeting” the higher musical notes. We need the opposite of a capacitor; this is called an inductor.

An inductor is basically nothing more than a coil of wire. If you pass DC (battery voltage) through this coil of wire it passes without any restriction: it is just a wire, after all. So low notes go through without any hinderance. But a coil of wire has an interesting characteristic, it becomes a magnet when you put AC (music) through it: and the faster the AC moves the stronger the magnetic field it makes. This is important because the energy from the power amplifier, making the AC in the first place, never reaches the woofer because it is being used to make the magnet instead. Think of it like a bypass or detour for the music. At low frequencies there’s not enough back and forth movement (between + and -) to make a magnet so all the energy from the power amp goes straight to the woofer and we get bass. But as the musical notes go higher in frequency, the coil of wire starts to become a magnet channeling some of the power amp’s energy into making the magnet and never gets to the woofer; and we get less sound at higher frequencies.

So placing a coil of wire between the power amp and the woofer limits the amount of high musical notes it can play. Placing a capacitor between the power amp and the tweeter limits the low notes it can play. And together, they are called a crossover, allowing the sound to crossover from one driver to the other.

Choosing the proper point to make this crossover between drivers is tricky business and has much to do with how a loudspeaker sounds.

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Chuck Lamb Wed, 09 Jul 2014 07:10:51 +0000 We’ll get back to speakers and crossovers tomorrow. I wanted to share with you a wonderful musical experience Terri and I had on 4th of July.

We were invited to a friend’s home in Lyons Colorado to watch “some live music”. Little did I realize the live music was none other than Chuck Lamb, keyboardist with the Brubeck Brothers (sons of Dave Brubeck). I remember Chuck from The Chuck Lamb Trio and his collaboration with jazz vocalist Theano.

No one can replace Dave Brubeck, but Chuck comes as close as anyone I’ve heard; he’s brilliant in that same role with Brubeck’s sons.

What was truly fascinating to me was the venue; one I have often believed might become the new musical stage. Perhaps 50 music lovers gathered at the private residence, each bringing a bit of food to be shared. The host, Denny, is an excellent musician in his own right and organized the event. The ad hoc trio played for a couple of hours. Terri and I had front row seats, the sound amazing. At the end of the event a donation hat was passed, all the guests generously contributing for the evening’s entertainment. Clearly the three musicians there out of a love of playing, the audience out of a love of listening.

I have never been to a more intimate and musically satisfying event in my life. I wonder if this might just point towards the future of music and musicians earning a living doing what they love most.

Of course I had to whip out my iPhone and record Chuck and the guys when Brubeck’s signature piece Take 5 played, and I asked Chuck for permission to share it with you. I missed the middle bit, but most of it’s there and what a treat! Check out the very beginning of the video, where he shares a great story of Dave Brubeck.

Click here to enjoy.

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Crossovers Tue, 08 Jul 2014 07:13:53 +0000 Perhaps the single best reason to use separate speakers drivers is not to lower distortion, but to optimize performance. A woofer can move a lot of air because of its size, mass and length of piston movement; all necessary requirements for lower frequency musical notes. A tweeter, on the other hand, has the opposite characteristics: small size, low mass and small piston movement. Each is optimized for the task at hand.

A woofer will always be better and making low notes than a tweeter will be at the same task.

But how do you separate the low notes from the high notes? Through the use of a crossover network.

There are two types of elements used in a typical crossover: a capacitor and an inductor.

A capacitor cannot pass DC (battery voltage), but it easily passes AC and that makes it very useful for a number of purposes.

The difference between AC and DC is movement. AC is voltage that is constantly moving between + and – (on and off). It’s what music is. Move between on and off quickly enough and we mimic air pressure movement that pushes our eardrums in and out to hear. Connect the fast moving AC to a loudspeaker driver and it too moves in and out, on and off, and we hear sound.

DC does not move. Instead there is a constant + and -. Just picture a battery with its two terminals sitting there and you will understand DC.

Now let’s put this knowledge together to understand how a capacitor helps us with our crossover. Capacitors do not pass DC, they only pass AC. So far, so good. But as I mentioned earlier, the difference between AC and DC is movement: the first moves, the second doesn’t. But movement is somewhat of a relative term and it depends on how close you’re looking. DC actually does move, it only does it slowly; sometimes very slowly – like glass. Glass is actually a very slow moving liquid but from our perspective it’s so slow it appears as a solid.

If we speed DC up, perhaps moving from on to off once per second, we now start to call it AC because we can see movement. To a capacitor, any movement makes a difference in what passes through it or doesn’t and the determining factor in what moves through or stays put is size. The bigger the capacitor, the more low moving AC it will pass. Bigger equals lower in a capacitor.

So to use a capacitor in a crossover network, the simplest thing to do is put it between the power amplifier and the tweeter. Depending on the size of the capacitor, lower frequencies like bass notes will not push through to the tweeter, while everything above those frequencies will pass right on through unimpeded by the capacitor. The speaker designer need only choose the proper sized capacitor to suit his needs and we have our first crossover element.

Tomorrow the inductor.

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2-way loudspeakers Mon, 07 Jul 2014 07:16:15 +0000 Whenever I think of a 2-way loudspeaker I inevitably refer to them as bookshelves and I am not sure why. There are, of course, many big-box loudspeakers with only two drivers.

I suppose the reason might be that’s what you see the most of these days, smaller boxes with but two drivers. But the actual definition of a 2-way loudspeaker has nothing to do with physical size of the box itself. It is as simple as it sounds: the music is divided up in 2-ways, separating the bass notes from the upper notes.

In our continuing discussion on different loudspeaker types I wanted to touch on the idea of separating the duties of the speaker driver between multiple drivers; relative to everything on one full range transducer.

As discussed in earlier posts, the effects of multiple movements on a single driver, moving in and out slowly and quickly at the same time, causes sonic problems to be avoided if possible.

In real life sound – this happens all the time. Take a string on a guitar. When it is plucked it is moving both slowly and quickly at the same time. The difference is, that multiple movement is part of the actual sound it produces. If it didn’t do that it wouldn’t sound the same. But when we try and reproduce that sound we don’t want to repeat the process as that method will add unnaturally to what we hear. So it’s a Gordian knot.

One thing we can do is separate the duties of the slow moving driver from the fast moving driver, so the two don’t add anything more to what we hear, and let them combine back together as one sound in acoustic space – and that’s what happens when we go to a 2-way loudspeaker. We assign the slow moving duties to the woofer and the fast moving properties to a tweeter. This solves one problem, the same driver trying to do both jobs at once, but ushers in a raft on new problems: crossover, difference in actual driver construction, physical separation of the two drivers.

First, the crossover. Its job is to separate the frequencies of sound so the tweeter has only the high notes to reproduce, while the woofer only reproduces the lower notes. This can be as simple as a single capacitor or as complicated as you want. Typically a 2-way crossover has at least two elements, one to limit how high the woofer goes and another to limit how low the tweeter goes.

But problems with crossovers are just the beginning – yet they are perhaps one of the biggest contributors to speaker sound.

Tomorrow let’s look at crossovers.

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Speakers and mics Sun, 06 Jul 2014 07:40:05 +0000 Reader David Blank pointed out something interesting to me in yesterday’s post. There are, in fact, two nearly perfect speakers that are full range: a headphone and a microphone.

A headphone, like the excellent sound Audeze LCD2X that I am going to purchase, has a single planar driver that covers the entire range of frequencies we need to reproduce sound. So why does this work when a loudspeaker driver trying to do the same thing struggles? The simple answer is the amount of movement. The headphone diaphragm moves very little as a piston and has a very small overall area of movement. This works in a headphone because your ear is only a couple of inches away from the diaphragm and it sounds quite loud. Try moving an entire room full of air and you have a very different set of requirements.

I mentioned also microphones. A microphone is actually the same as a loudspeaker diaphragm, only it is being used in the opposite manner. I remember the first time I understood this was when my father was working on a design of a hands free intercom system. His design had a single 3 inch speaker driver that doubled as a microphone.

Tomorrow the 2-way as promised.

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Chuck Loeb Sat, 05 Jul 2014 13:58:22 +0000 There are a handful of musicians whose songs I never get tired of listening to. One of those musicians is jazz guitarist Chuck Loeb. As a matter of fact, I’m listening to the very first song that I heard on the radio that got me hooked on this amazing artist.

This sounds so good-Really? If there was ever a bad time for the phone to ring…..trying my best to disguise my disgust, I answered. “Hello.” “Hey Keith, what’s up! It’s Paul.” Ah….Paul is a pretty cool dude, but he has been peppering me with questions about different jazz artists that that he has been listening to. I would really like to get back to my music, but since I’m primarily responsible for introducing him to the genre, it’s time for a break. “Paul, what’s goin’ on?” “Well…..I’ve-uh-I….I know that I’ve been hitting you up with a whole lot of questions about jazz stuff, but there’s this dude that I heard on the radio today that blew my mind! He’s a guitar player and I’m not sure if I wrote down the right name. Let’s see…..Chuck …um-L-o-b-e. Ever heard of him?” I couldn’t help but chuckle out loud. “What’s so funny, man?” “No, no, no-It’s just that I was listening to some of Chuck Loeb’s music when you called. His last name is spelled L-O-E-B by the way. So, yeah, I’m very familiar with him.” “Awesome! Let me correct his last name…….got it.

So, can you tell me a little bit about him and his music? I mean….I don’t want to take up too much of your time….” Oh boy-this could take a while….”It’s cool, I have some time. Let me put you on speaker phone.” Paul was thrilled. “Sweeeeeet!”

“There are very few people that I know that are even aware of Chuck Loeb. The few that do think he is a new guitarist on the jazz scene. In fact, his career spans over four decades and he is a Grammy nominated guitarist, composer and producer. In fact, he has composed over 250 published songs, network TV show themes and scores, produced over thirty world-renowned recording artists and is an in-demand clinician and educator. You still with me, Paul?” “Yeah man, I’m still here. Keep goin’!” ” Chuck’s first big break was when he joined the late great saxophonist Stan Getz’ band in 1979 in addition to touring and recording with him for several years. In 1984, Loeb joined the All Star group Steps Ahead that featured the late great Michael Brecker on sax.”

“Some of the artists that Chuck has played and toured with include Hubert Laws, Chico Hamilton, Freddie Hubbard, Ray Barretto, Gary Burton and Wayne Shorter.” Paul interjected, “You mean Gary Burton the vibes player and Wayne Shorter the sax player?” “Wow, that’s right! I’m impressed, Paul!” “Well, you know……what can I say. You’ve got me hooked on jazz!” I graciously accepted his compliment and continued. “Have you ever heard of the group Fourplay? Chuck plays with them.” “Oh yeah! But I thought that Lee Ritenour was their guitarist? Those dudes are amazing!” Paul has really been doing some research! “Correct again. Lee used to be with them and, in fact, was the group’s original guitarist. He was replaced by Larry Carlton. So, the guitar chair had been occupied by some living legends before Chuck stepped in. In my opinion, he has put his own stamp on the group’s sound by contributing his own signature sound. That is no easy feat for a jazz guitarist! Trust me!” “Hey Keith, thanks a lot, man! While you were talking, I found that list of Chuck Loeb CD’s that you gave me. I’m gonna let you go and run down to the Jazz Corner to find some of his stuff. Thank you for helping me out. I really appreciate it! Check back with you later, Keith!” “No problem. Let me know what you get. Later, Paul.” “Back at you! Bye.” Looks like I’ve created a jazz monster! Now, back to my music!

(An obvious nod to Wes Montgomery)

(Amazing band, amazing solos!)

I went a little overboard with Chuck Loeb’s Music. My Bad!!! I just really never get tired of his music. It has touched me from day one…..and still does! Thank you Mr. Loeb. You, sir, are a living jazz guitar legend!!!

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Just one for the road Sat, 05 Jul 2014 07:30:26 +0000 If you wanted the perfect loudspeaker it would be what we call a point source. An infinitely small point where a full range of sound comes from. To date achieving this has been impossible.

The penultimate loudspeaker is a single source of sound, one that closely mimics real life where each sound we hear generally comes from a single source: a violin, a human voice, a trumpet. A single driver loudspeaker gets us close to that, but can never be as perfect as the original sound source. That single driver is plagued with a number of problems: FM being the worst.

Imagine a single woofer cone, let’s use an 8″ woofer for our example. The cone moves back and forth to produce sound. At low frequencies, the cone couples nicely to the air, acting as a good piston, pressurizing and depressurizing the air so we hear sound. If we limit the frequency range to something below 500 times a second, we’re in pretty good shape. But when we try and use it as our full range driver we run into trouble. As our imaginary woofer moves back and forth 500 times a second, we are now going to ask it to simultaneously move at 5,000 times a second to get some higher frequencies. What happens? Frequency modulation, sometimes known as Intermodulation (IM for short). It is also known as the Doppler effect, which describes how sound changes frequency with movement of either the source or the listener, relative to each other.

And that’s what’s happening when our 5,000 times a second tone is moving away from us and towards us 500 times a second. We generate yet another tone, one that is a combination of our two frequencies; an extra tone that’s not supposed to be there in the first place.

All this to suggest that while a single driver is great because all the sound comes from just one point in space, like that of a real instrument, there are other reasonably serious problems that most loudspeaker designers avoid by using more than one driver to produce sound.

Tomorrow we’ll move on to 2-way loudspeakers in this, a very simplified explanation of speaker types.

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Is simple always better? Fri, 04 Jul 2014 07:32:55 +0000 Happy Independence Day. It’s good to be independent.

Spending time a few days ago with a wonderfully nice visitor from Australia in Music Room One prompted the subject of this post.

On first look at the massive IRS V loudspeakers, my visitor Chris was struck by the speaker’s complexity (84 drivers IS a lot of complexity) compared to his system’s simplicity. Chris, like many of you, chose a 2-way loudspeaker because of the simplicity of the design. A 1-way loudspeaker being the simplest of all designs.

While there are 1-way loudspeakers out there, they are few and far between. That is because it’s extremely difficult to properly reproduce both high frequencies and low frequencies on a single driver; and for a number of very valid reasons.

Loudspeaker designers generally choose to assign the duties of drivers to separate units: higher frequencies handled by a tweeter, lower a woofer. The philosophy is to optimize each driver design for its assigned task. That’s why tweeters look so radically different than woofers. This idea can be taken further in what is known as a 3-way or even a 4-way loudspeaker, dividing even further the duties of frequency reproduction to specially purposed drivers.

The more the speaker designer divides the duties of drivers the greater of several problems arise: the crossover that is used to separate and route the sound to the proper driver becomes tricky to design properly, the physical placement of each sound source on the speaker is different, and like Humpty Dumpty once you take something apart it’s hard to put it back together again.

Tomorrow we’ll look at each of the three aforementioned problems in greater detail.

BTW, despite the massive number of drivers used in the IRSV, the main panels are only a 2-way. Just sayin’.

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Is passion contagious? Thu, 03 Jul 2014 07:24:53 +0000 I can’t tell you the number of times I’ve gotten passionate/excited about something and shared it with someone who might care, only to have them say “that’s nice” and go about their business.

More often than not that’s the case.

Sometimes, of course, you get excited, you share your passion with someone and that kickstarts them into high gear as well. That feels really good.

I am not sure what the mechanisms are for starting a fire under someone.

I suppose it has something to do with their interest in the subject, certainly, but perhaps more importantly it must be timing.

Yes, I suppose, timing is everything. And how hard it must be to find a person interested in the same subject as you, ready to receive your input about the very subject they are interested in at the same time.

Passion is contagious but only through a very narrow window of time and circumstances.

Passionate today, not interested tomorrow.

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Is it pure? Wed, 02 Jul 2014 07:48:07 +0000 We all work so hard trying to achieve purity in our reproduction systems, and that’s a good thing.

One of my readers, Mike, pointed out to me it’s paradoxical, the lack of purity found in a recording studio making the music in the first place; most modern studios awash in DSP and manipulations of all sorts. Anything but pure.

These two observations may not be at odds with each other as it might first appear. Take modern film for example. Years ago, the best films were pure: photographed on film with beautifully crafted 70mm Panavision rigs and projected with the best optics at fine theaters. You could tell the level of purity and craft going into one of those films.

Today the best films are digitally manipulated: DSP, if you will (not literally, but you get the idea). The goal is the same for both methods: make gorgeous, believable images that help tell a story.

Regardless how each process works, pure film or well crafted (highly manipulated) digital, the results can both be stunning when reproduced by pure means.

And here’s where the rubber meets the road (as we Americans like to say). It is every bit as important to have a pure playback system for these films, or your music, regardless of the method they were produced with.

It is not ok to accept post processing just because the source files were subjected to it. One plus one doesn’t always equal two.


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