Tag Archives: loudspeaker

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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.

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I don’t think Martin Logan makes transmission line boxes and not sure that Zu or Audio Physic use transmission lines either, although PMC is famous for that.

Lots of ways to skin the bass cat. For instance, Daedalus loudspeakers uses aperiodic loading and this technique, which is basically resistive venting, works great with extended bass for a relatively compact enclosure, which maintaining very high sensitivity, which most TL’s do not have.

My own Altec 604 based speakers are vented, but only to let the driver do what its designed to do, which is breathe freely and not designed to extend bass response.

Battle of the boxes

In my post about Dr. Suess and HiFi, I mentioned the work on loudspeaker enclosures by British engineer Leslie Bucknell while at the company my father worked for, Stromberg Carlson.

Bucknell’s approach to loudspeaker design was to create a speaker enclosure that would eliminate distortions that occur because of cancellations and additions due to standing waves internal to the cabinet. By carefully controlling the way that the sound waves travel through the speaker enclosure—routing them through a complex maze of tuned baffles—he felt that his Labyrinth design was the cat’s meow.

During this same time period, another British-born engineer, Arthur Bailey, was taking a slightly different tack to speaker design called the Transmission Line.

The transmission line uses a long narrow folded duct behind the woofer. The woofer’s output travels through this unimpeded maze until it exits out of the port. This technique differs from the traditional port (basically, a tuned hole in the speaker enclosure) because it is carefully calculated to arrive in phase and add to the low frequency performance of the speaker. In addition, as sound waves travel through the transmission line, they are gradually damped and absorbed, which helps to eliminate resonances and other distortions.

Of the two approaches, it is the work of Arthur Bailey that lives on today in speaker designs like those of PMC, Martin Logan, Audio Physics, and Zu Audio, who all (best I can tell) still use the transmission line approach to making better bass.

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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.

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Creepy woofers

In the world of loudspeaker design, there are many unique and descriptive terms used to describe various components and their functions. One such term is a bit creepy: “spider,” which refers to the rear of a woofer’s suspension system.

The spider is a flexible, disc-shaped material that is attached to the inner circumference of the speaker frame and connected to the rear of the woofer cone. Its purpose is to act as a suspension mechanism, allowing the cone to move back and forth while keeping the voice coil centered in the magnetic gap.

The name “spider” likely came from the component’s radial web shape, which features “legs” that connect the outer edge of the spider to the inner speaker frame. The spider-like appearance of the component is what sets it apart from other suspension components and gives it its unique name.

Here’s a picture of a typical spider and then below it, how it is used in a woofer.

It kind of does look like a spider’s web.

As we’ve discussed before, the spider along with the surround play major roles in how a woofer performs.

How’s that for creepy!

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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.

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High end audio is full of people that are constantly pushing the envelope in both electronics and loudspeaker deigns. Some work great, while others do not.

The bass/midrange driver in my Altec 604 based loudspeaker is tried and true cellulose (paper), while the tweeter diaphragm is made of aluminum. Of course the tweeter is a compression driver and mounted inside a horn, so much different sounding than a more traditional speaker design.

None of the components are anything radically new, although the cabinet is new and a one off thing. Both both work great inside the cabinet I designed and had custom built. No MDF or HDF in my speaker. Layered with 12 pieces of 1/8″  void free plywood that were laminated one at a time and put into a press to  create the curved cabinet shape. It’s a great cabinet and a great sounding loudspeaker.

Starting and stopping

Ever wonder why loudspeaker designers get so excited about woofer cone materials like Kevlar, aluminum, paper, sandwich cones of carbon fiber, and other materials?*

Their excitement comes from understanding the challenge of making an air piston (which is what a speaker driver is) that can start and stop in perfect synch with the instructions from your power amplifier.

To accomplish that feat one would prefer a cone (the piston part) that had zero mass (so it could start and stop without offering any resistance) and yet was stiff and strong enough not to deform when moving (its mass and shape determine its strength). Two impossible requirements: light enough to move yet heavy enough not to get deformed.

In engineering speak the designer needs to worry about mechanical compliance.

The mechanical compliance of a woofer is determined by its mass and suspension (surround and spider). The more massive a woofer is, the more difficult it is to move (and stop moving), and the less compliant it is. A less compliant woofer will have a slower response and will be less sensitive to high-frequency signals (transients), but will have a greater ability to produce low-frequency sounds with high output levels.

Taken to extremes, a massive heavy woofer cone (like one machined out of an aluminum billet) will not deform but at the cost of not being able to start and stop quickly (distortion from a lack of transient speed and overhang). Or the opposite: so low in mass that it wrinkles and deforms with the smallest blush of power applied.

The next time you listen to your speakers you might want to give a tip of the hat to all the engineering that goes into making bass.

Woof!

*(The new aspen FR20, for example, utilizes an exotic low-mass PMI foam core with non-woven carbon fiber skins on each side to accomplish its impossible task and it works great!)

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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.

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PS Audio is building their own loudspeakers now and although I’ve not heard them, Anthony Cordesman, a reviewer I’ve enjoyed reading in the past, bought his review sample. Im pretty sure he didn’t pay retail…. 🙂

I built my own loudspeaker and with just a bit of EQ, it’s great sounding and beautiful, if a bit large. Very different than PS Audio’s offering in that mine is a coaxial design with a horn tweeter/midrange with a single crossover at 1500 Hz.

The perfect loudspeaker

As much as one would like to have such a thing as today’s headline, a perfect loudspeaker is a theoretical concept that does not exist in reality.

If there were to be such a beast, what would it look like?

Here’s a short list to get us started:

  1. Accurately reproduce the full audio spectrum: A perfect loudspeaker would be able to accurately reproduce all frequencies in the audio spectrum, from the lowest bass notes to the highest treble, without emphasizing or suppressing any particular frequency range.
  2. Have uniform frequency response across all frequencies, meaning that it would produce the same level of output at all frequencies. This would allow the listener to experience music as it was intended to be heard, with a neutral and balanced tonal quality.
  3. Be distortion-free producing no added harmonic content. The listener would hear only the original signal and not any artificial artifacts.
  4. Be time-coherent, producing sound that arrives at the listener’s ears at the same time, regardless of the frequency or location of the speaker.
  5. Be phase-coherent producing sound waves that are in phase with each other, meaning that their crests and troughs are aligned, with no phase cancellations or peaks.

While it is not currently possible to build a perfect loudspeaker, we can get pretty close.

I look forward to showing off what I consider to be about as close as it gets, the aspen series of speakers.

Perfect? No.

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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.

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My Altec 604 based loudspeaker has an outboard crossover and I did this to remove vibrations from the cabinet to the crossover. I believe it makes for clearer sound, although a crossover can be isolated inside a cabinet for close to the same effect.

External vs. internal

I was recently asked an interesting question.

Is it better to have the loudspeaker crossover inside or outside the loudspeaker?

At first, the answer seemed rather simple. Inside, of course. Shorter wires, fewer binding posts, etc.

Yet, in thinking about it, I can see at least one advantage to an external box filled with speaker crossover parts (like we did on the IRSV). I would imagine there would be benefits from lowering internal vibrations. When external in their enclosure, the crossover parts are not vibrated by the loudspeaker’s output.

We know that anything one can do to dampen or isolate sensitive parts from the speaker’s outputs is almost always a benefit.

The problem with any of these ideas is the simple matter of trade-offs. What are you giving up, and what is it you hope to gain?

My guess would be that a slight overall advantage would be gained with an external crossover enclosure. And with that in mind, one would have to ask the second question.

Would it be worth the hassle?

As in any noble experiment, one must always ask the right questions: cost vs. gain and hassle vs. ease of use.

My vote would be to keep your speakers build as the designer intended.

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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.

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Sub sats

I often get asked why we need reasonably sized loudspeaker boxes. After all, if we’re willing to include a subwoofer in our mix, why couldn’t the midrange tweeter boxes be tiny?

There was a time when this thinking produced an entirely new category of system called the Sub Sat.

I was one of the first to embrace a 3-piece Sub Sat system. Mine was from M and K, a long-ago company founded by LA audio dealer Jonas Miller, and engineer Ken Kreisel. (*I believe the company, M and K Sound still exists but it’s more name than anything else).

This was back in the day when subwoofers were first appearing on the scene. At that time, people thought a good sub could replace a proper speaker enclosure, which is how this 3-piece sub sat system came to be.

The idea of the sub sat was simple: two small satellite speakers with a tweeter and tiny woofer/midrange, and a single subwoofer would finish the system. It was a grand idea, but it didn’t live up to its hype.

If memory serves, I believe I owned that system for a total of about two weeks before I ofted it to a friend who wasn’t as crazy about sound as I was.

As you might have guessed, the problem is that subwoofers only work when they don’t have to play very high frequencies. Once a subwoofer is asked to produce audio above 30 to 40Hz, you start to hear the sub as a separate entity.

Thankfully, the Sub Sat genre died out rather quickly, but it was a nifty idea that I bought into just because it was novel, cool, and filled with potential.

Today we know that in order to produce seamless sound, the satellite part of any system has to have a big enough enclosure to support a decent bottom end.

In other words, your left and right main speakers need to be reasonably full range in order for a subwoofer to do its job.

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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.

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Life’s changes

As long as I am reminiscing about what feels like a past life of (almost) a different person—the me of decades ago—I am struggling to remember how we ever got business done before email.

I remember well being at Genesis Technologies, the loudspeaker company Arnie Nudell and I founded in 1990. In those days, my habit was to open the daily incoming mail, read each letter sent to us, place them in a stack on my desk, and spend the next few hours pecking out replies on my computer/printer.

Days later, those mailings would elicit a phone call or, sometimes, another letter.

There were no forums, chat rooms, or websites to visit for information. Rapid communication happened via the telephone, and snail mail happened over days and weeks.

Today, all that has changed. Like all changes, there are better and worse results. On the one hand, thanks to Wikipedia and other knowledge base resources, I have the entire sum of human knowledge available to me at the click of a mouse. On the other hand, there is almost no person-to-person interaction.

Unlimited knowledge and instant communication with thousands of people traded for limited knowledge and instant communication with only dozens.

I don’t know one is better than the other.

Had I to choose, I would lean in towards what we have today. The fact I can communicate with so many people all over the world is, I think, a blessing.

In the end, today I feel much more connected than yesterday.

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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.

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Theoretical, I say. Stereo cables are controversial in my world and after spending big dollars on some, supposed, really good ones, like Transparent and MIT, etc., they have all been sold and there’s not a cable in my current system that’s over $100. I’m back to relatively inexpensive and happy for it. As long as they are good, meaning good quality conductor material (Litz or solid core type wire for me) and built well, some cables are a little better than others, as long as they are good to begin with. Different gauge wires in a cable for different frequencies seems like a stretch to me.

Multi gauge cables

If you had a chance to read my post of several days ago titled The Bypass Cap you might have been thinking it was about headwear. Or, you might have gotten my analogy of using a super tweeter to augment a standard tweeter.

Here’s another for you.

If you were to take a thin, 22 gauge wire and use it to connect your loudspeakers to your power amp, I am quite certain it would sound dramatically different from whatever you are now using. What you would likely hear is a reduction of bass and a focus on higher frequencies. Thin sounding.

You might also notice that the highs you do hear are perhaps more extended sounding than your typical speaker cable setup.

This experiment is the basis of one way to design a cable, using multiple wire gauges in parallel: a slim wire gauge for the treble, a thicker and with more surface area conductor for the midrange, and a brute for the bass.

This technique is somewhat like designing a 3-way loudspeaker. Big woofer for the bass, a smaller driver for the midrange, and a tiny tweeter for the top end.

When PS Audio was making cables this is the technique we used to craft some really good sounding ones.

There are any number of ways to maximize the sound of cables.

This multi-gauge method is but one.

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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.

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Micro and macro

While it might feel counterintuitive, it is often helpful to zoom in for a micro view in order to perfect the macro view: focusing closely on the smallest details of microphone placement in recordings or exacting loudspeaker placement in the playback chain are both secrets of success.

But, like many endeavors, there’s the threat of a trap.

Focusing too hard on the smallest bits of a product or project at the expense of the whole can turn something great into a muddled mess.

The real skill in both the recording and playback arts is having enough experience to effectively balance the micro and macro.

And that experience is earned by making countless mistakes.

Which is why I am so delighted to making as many mistakes as possible (and I make a lot).

Zoom in, zoom out.

Get it right, get it wrong.

It’s how we learn.

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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.

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Much improved

Over on the PS Audio forums, there’s a thread about audio cable lifters. You can read it by clicking this link.

Elevating the speaker cables off the floor works to improve the sound.

Should you run out and grab a set of cable lifters today?

Much depends on the state of your stereo system. If you’ve managed to dial it in to where there’s nothing more to gain, then yes, by all means, nab a set of cable lifters.

What sometimes troubles me about these exotic tweaks is our tendency to use them as a crutch.

A freebie.

An excuse not to dig in and do the work of proper setup.

Proper setup takes a bit of work and dedication. Rolling up the proverbial sleeves and getting down to business.

If this idea of really digging in to make sonic magic is appealing to you, I will mention the long overdue book and SACD (and download), The Audiophile’s Guide: The Loudspeaker is finally (and really) available.

Click here to grab your copy.

And once you’ve put in the afternoon’s hard work at getting your system to sing, it makes sense to then elevate your loudspeaker cables.

Icing on the proverbial cake.