31 SECRETS TOBETTER SOUND31 SECRETS TOBETTER SOUND31 SECRETS TOBETTER SOUND31 SECRETS TOBETTER SOUND31 SECRETS TOBETTER SOUND

Avantgarde-USA

Dear Music Lover,These “31 Secrets to Better Sound”

were gained from nearly thirty years ofsolid installation and live music record-ing experience. After hearing the results,clients and staff often asked, “Whydon’t you write that stuff down?”

Frankly, I never thought it was anybig deal. But as the years have gone by,there’s still not much that’s been saidor written about some of these topics.Finally, the time seemed right to do it

now that the next millenium is here!The following topics may sometimes be related

to Avantgarde Hornspeakers, and sometimes not atall. When appropriate, the topic’s applicability to theHornspeakers will be indicated with a symbol .

Since some of what you are about to hear goesagainst “common knowledge,” I only ask two things:

1) Keep an open mind until you’ve heard theentire position and you’ve thought about it a bit.

2) If you disagree with one point, don’t assumethat’ll happen with the rest. I guarantee that you’llfind some topics that’ll have you nodding in agreement.

31 Secrets to Better Sound is divided into twogeneral areas. The first is “Optimizing Your System’sPerformance,” and the second is “Thinking Outsidethe Box.”

I hope you’ll find most of what follows to bepretty good advice. In general, it’s applicable toalmost every system, at most levels.…

31 SECRETS TO BETTER SOUND™

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1PART ONE

OPTIMIZING YOUR SYSTEM’S PERFORMANCE

1) Why you should be sour on a wide“Sweet Spot”

A wide sweet spot is almost like having your ownharmonic distortion generator! There’s simply no waya serious listener should be satisfied to sit more than afoot away from the “equal path length intersection”(center point) of sound from a pair of loudspeakers.Inter-channel phase and timing information has justbeen badly compromised, destroying instrumentaltimbres. How is it that audiophiles will accept onlyphase and time-aligned loudspeakers and then expectto sit off the acoustic center-point, totally destroyingthe inter-channel phase/time information? Look at itthis way…

First, since you probably know this stuff, pleaseforgive the simplified averaged wavelengths, but forpurposes of illustration, let’s assume that a 1100 Hztone (or harmonic) has a length of about 12 inches.Then 550 Hz is almost 2 feet in length (from the top ofthe sound-wave crest to the top of the next). And 2kHz is almost 6 inches in length, 4 kHz is 3 inches, etc.

Imagine that a female vocalist is recorded withher image centrally located in the stereo stage. If yousit two feet off center, that means that any funda-mental notes and their harmonics from at least 500Hz and above have been altered, some dramatically,some slightly. This is audible, and it’s depressinglymeasurable! Before we examine the disastrous effects,let’s look at what’s happened to cause the problem…

Wait a minute! What about imaging? Let’s saythat now you’re about a foot closer to the left speakerthan you are to the right one. Imagine a centrally re-corded image that is reproduced at equal volume (am-plitude) from both speakers in order to give the illu-sion of a precise center image.

Without going too far into recording techniques,a panned mono center image (such as in a studio) willappear to have shifted left somewhat. While a centerimage recorded from a stereo pair of mics seems to“stay put” a little better. But these are phantom images

at best, lacking in the ultimate richness of tone andbody. Here’s why…

It’s not the potential “image wander” that’stroublesome. It’s the harmonic distortion! (Techni-cally, it’s not distortion, but the alteration of harmonicrelationships.) The positive cycle (top of the wavecrest) of a 1000 Hz overtone arrives at your ear fromthe (closer) left speaker before it does from the rightone. There’ll be an audible—and very measurable—change at that frequency (or harmonic overtone).

Should the distance be equivalent to a half-wave-length further (6 inches), then that particular overtone(harmonic) will arrive exactly out of phase. And youknow how your stereo plays less bass when the speakersare out of phase? Well, the effect is exactly the same—a reduction in level at that particular frequency.

Why is this important? You’ve heard of voice-prints. That’s where a recording of your voice can beused to positively identify you, no matter how hardyou try to shift the sound of your voice. How does itwork? The unique relationships of vocal overtonesare different for each voice. For example, the first har-monic may be 87.3% of the fundamental, the secondjust 48.1%, the third 54.7%, etc.

The exact relationship of these overtones (theirrelative strength, compared to the fundamental) is theidentifying “genetic code” of your voice. Well it turnsout that all instruments and voices have their ownparticular set of harmonic ratios. That’s how we knowto differentiate two different instruments that areplaying exactly the same note—say A (440 Hz). Andthat’s how an original Guarneri will be chosen over a“replica”—it’s all in the “tone”—which is actually theharmonic—or overtone structure.

So, if you’re sitting where the path lengths aresignificantly unequal from the left and right speakers,you are absolutely guaranteed to hear wild shifts inthe harmonics, meaning that an instrument or voicewill not sound exactly as it should. This is not justsome subjective acoustic theory. It’s not only audible;it’s also measurable in your room at your listening seat!

In fact, you’ve just altered your system’s har-monic relationships. So why did you buy all that stuff

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But did you know that stereo separation—oftena matter of a few inches—can make a difference inperceived “warmth?” Most audiophiles would suggestmoving the speakers a bit further apart (to get closerto sidewalls for bass reinforcement) as a way of warm-ing up the sound. But 30 years of experience contra-dicts this idea. Getting a bit closer to the sidewallsmay add more bass (and more unpleasant reflections),but the overall sound often gets thinner.

Actually, if your sound is a bit thin, and you’dlike a bit more fullness, mid-range body, or warmth,the best way is often to bring your speakers a few inchescloser together. I’ve encountered situations where onlyan inch or so apiece toward the center gave me thebalance I was looking for.

Of course, when you do this, it changes your toe-in slightly so as to aim more to the center, so if you’vepicked the angle of your speakers for toe-in, you’ll needto toe them out just slightly to accommodate for themove. And you may just find that you don’t need thespeakers as far off-axis as you thought when you origi-nally settled on the toe-in.

After doing this for hundreds (maybe thousands)of people, I was still baffled as to why this should bethe case. About 18 years ago, after observing the effectwith spaced omni microphones (where an inch or twodifference in separation could yield a warmer or coolersound), I at least developed a theory about what’shappening. We perceive warm or cool sound to someextent by the amount of energy present in the lowermid-range/upper bass. Well, the wavelengths of thesefrequencies are fairly long, say 2’-6’ in length. If webring our speakers a bit closer together, the reproducedsound “couples” ever so slightly better, slightly shiftingthe sonic temperature to “warmer.”

Whether the theory is correct or not, you defi-nitely can change the balance of your system withsubtle changes in loudspeaker separation and toe-in.

3) Set up a grid to begin your speaker installationSince stereophony depends on precise time arrival

from each channel to a centrally located listeningposition, as you move your speakers around in the

with “vanishingly low distortion” if you’re going tointroduce a far worse version by not sitting in thecenter point where the path lengths are equal? Inci-dentally, this is an incontrovertible law of physics that ispart of the good—and the bad—of stereophony.

It doesn’t matter if your loudspeakers produce asmooth response off-axis. The varying wavelengthsat a position off the acoustic center will always pro-duce uneven response on centrally recorded images.

Here’s a simple test for you. Put on a Sheffield orother disc that contains pink noise in both channels(pink noise is best, because it contains equal energyper octave, just like music). If you can, put your preampin mono. What you want is equal amplitude in eachchannel. Now, from the center position, slowly moveyour head to the left or right. That huge change in tonalbalance is exactly what happens if you sit off axis.

And because the wavelengths vary according tofrequency, the varying time arrivals of harmonics alsoproduce an unpredictable (well, it is predictable in thatit’s never a good thing) cancellation effect. And a ‘widesweet spot’ isn’t really so sweet…

Now that we’ve told it like it is, let’s also admitto having wonderful experiences listening to musicwhile others have occupied the best seat. If a systemhas dynamics, if it’s effortless, if it at least starts outbeing pretty accurate timbrally, then it can be quitelistenable off-axis. Just remember that the phantomimage produced off-axis is only an approximation.Sweet, it ain’t!

2) Fine tune your tonal balance with stereoseparation and toe-in

Most audiophiles know, that—by aiming aspeaker a bit off-axis (perhaps to crossfire behind youa foot or two)—they can take the “edge” off the sound,when compared to aiming the speakers directly at theprimary listening seat. Aiming straight ahead—forsome loudspeakers—results in the best overall fre-quency balance (generally when this is the case, themanufacturer or their dealers will make a point ofadvising you of this). Aiming more toward the listen-ing position is commonly called “toe-in.”

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room, you’ll need a temporary floor grid to keep fromarriving at erroneous conclusions. Here’s an accuratetechnique:

Find the position (from side to side) where you’llbe sitting (we’ll discover the front-to-back positionin the next part). If your room is symmetrical, andyou plan to sit in the middle, measure how wide theroom is; divide that measurement by two, and that’llbe your centerline. I recommend you use tape thatcan be lifted easily from carpet or flooring. Lay downyour tape between the general speaker placement area,and also in the general listening area. You’ll have tomove the seating furniture out of the way while you’reinstalling your grid.

If your room isn’t symmetrical, decide on how faryou think you’ll want to sit from the nearest sidewall.Mark it on the floor (your seating has already beenremoved). Measure the distance. Now, at the speakerend of the room, mark the floor at the same distancefrom the sidewall. This is your centerline, from thelistening area to the speaker area. At the speaker end ofthe room, mark the floor every six inches or so awayfrom the centerline, beginning in the area where yougenerally suspect the speakers may be placed.

Now, swing your tape from the general listeningposition on the centerline so that it crosses the speakerspacing marks you’ve just laid down. While you’reabout it, place some marks on the floor that repre-sent about six inch intervals—varying distances fromthe proposed sitting area. It doesn’t matter if you don’tend up sitting there; we only need an equal path lengthfrom the centerline to aid us in moving the speakersforward and back repeatedly and equally.

At the end of the next part, you’ll be making somefine adjustments in speaker position, considerably lessthan six-inch increments. At this final point, you’llneed to recheck your measurements from yourcenterline for final positioning.

4) A simple three-step speaker installation tech-nique for satisfying results

This three-step technique will get you to a satis-fying sound faster than any other system I’ve seen.

The three steps must be followed in this order.1. Bass2. Image3. Frequency response or tonal balanceOK, what do we do at each step?First, you’ve got to get the bass generally pretty

good. This means that if you have a full-range speaker,it should reproduce the deepest bass with the great-est smoothness.

Why does the bass come first? Until you knowhow far away you’ll be sitting (speaker position andlistening position), how can you proceed to step 2,getting the best stereo image? And we’ve seen that wecan make some adjustments in the overall frequencybalance with subtle changes in position (separation andtoe-in). But first we’ve got to at least get the distanceto the speakers from the listening seat before we canbegin to decide how far apart we want our speakers.

1) The best bass—a throwback to early TVs.Here’s how long I’ve been teaching this technique

for getting the best bass—I started out using a TVanalogy that asked the installer to compare this stepto the tuning methods from TVs of the ‘60s and early‘70s! Those TVs had a “fine tuning” knob and “chan-nel selector” switch. Here’s the analogy:

Finding the best placement for the speaker in theroom is a bit like fine tuning for best reception. Butfinding the best place to locate the listening seat is abit like using the channel selector! In other words,the most important consideration (whenever possible)is to discover where in the room you should sit totake advantage of the least negative room interactions(obvious peaks and dips in the bass), and the mostpositive room interactions (the most extension andattack without annoying overhang).

This is because your room (unless it’s exception-ally large—say 20 x 35 x 12 or larger) will have obvi-ous standing waves developing in the bass region(we’ll call this region 25 Hz to 250 Hz). These stand-ing waves are very measurable and they are quite au-dible as resonances or “suck-outs.” They exist due toyour room’s particular geometry. Moving a speaker

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forward and back in the room can make a noticeabledifference in the bass. But moving the seat forwardand back the same distance in an average room willresult in much more dramatic differences in bass per-formance.

Although these resonant room frequencies can beconsidered axially, tangentially, and obliquely, ourprimary concern here is with axial. These consist ofdestructive (to varying degrees) waves and construc-tive (to varying degrees) waves. A destructive stand-ing wave is produced when two or more wavelengthsmeet at a point in a room, and—due to the time ar-rival of these waves—some will arrive slightly (or evendirectly) out of phase with others.

The varying time arrival is based primarily onroom geometry (for example—length of the room vs.height). This results in a cancellation of frequenciesat that particular point in the room. Destructivestanding waves produce dips in frequency response.Conversely, constructive standing waves can producepeaks in response.

The following system assumes you’ve placed thespeakers in a generally acceptable position in the room:

A simple way to prove this theory is to put on aCD recording with a repetitive bass line (preferablythe upright acoustic bass—maybe Ray Brown). You’llneed to move your listening seat out of the way, per-haps to the side of the room. While it’s playing onrepeat (that’s why I chose CD as the source), walkback and forth slowly through the larger proposed lis-tening area. You’ll notice dramatic differences in bassquality and quantity in a space of +/– 2-3 feet.

Listen closer and you’ll find the smaller “window”of acceptability for that particular bass line. Onceyou’ve found the best spot to locate the seat (again,only for that particular series of bass notes), you’llnotice that moving the speaker forward and back anequivalent difference makes much less of a difference.

This is all to say that your room resonances aregoing to be pretty much the same for most likelyspeaker placements, so find out where in the listen-ing end of the room these resonances are least objec-tionable, and that’s where you’ll sit.

A quick note on finding the overall best bass lis-tening position in a room—the quickest way to do itis with a real-time analyzer, preferably 1/3 octave.You’ll need to use pink noise as your source, set onthe slowest filter, using flat or C-weighting. You’reonly looking at the region from around 25 Hz up toabout 250 Hz. You’ll notice immediately that fairlysmall movements forward and back in the room arevery obvious on the display as the various peaks anddips become quite easy to see.

Don’t have a RTA sitting around? Try to borrowor rent one for a few hours. By the way, I do NOTrecommend using a Radio Shack SPL meter and testtones for this procedure. Actually, if the tones were1/3 octave pink noise bands, it could work, but un-fortunately the Radio Shack meter simply isn’t veryaccurate in its frequency response. You could use thetest disc and your ears, though!

Can’t find a RTA, or you’re uncomfortable tech-nically with the idea of looking at how your roombehaves in the bass resonance region? Then find sev-eral recordings of music representative of the stuff youlike to hear, and adjust for the best bass by listeningwhile moving back and forth in the general listeningposition.

What you’re listening for is the majority of thebass reproduced with the notes neither emphasizednor diminished. You’re also listening for the deepestbass. But sometimes the price for getting the deepestbass in an average room is an uneven bass response inthe region where most bass notes occur.

This is where you’ll have to pick the best com-promise to your ears. At this point, you’ll find that adifference of six inches or less forward or back willusually present you with a choice of the bass com-promise you prefer. Once you’ve discovered this lis-tening position that is least affected by room reso-nances, mark this spot (or at least measure how far itis to the wall behind you and write it down).

Now you can play with fine-tuning where thespeakers go to make the bass better. Once you havethat position to the point that is best to your ears,you’ll need to recheck the listening position a bit to

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make sure that a slight distance forward or back isn’tnecessary now.

2) Imaging and the X-filesFinally you’ve established—pretty closely—where

you’ll be, and approximately how far away the speak-ers will be. Once you know “X,” you can start to workon “Y.” X is the distance from your ear to the plane ofthe tweeter (should be equidistant from the listeningseat to each speaker). Let’s say X is 10 feet. A generalguideline is to start Y at about 75% of X. Y is thedistance from the center of the left tweeter to thecenter of the right. We use the tweeter because it’sthe primary source for directional cues (imaging).

A note on separation—this is to your taste. I per-sonally like Y to be about 85% of X for most speakers.For planar speakers, Y may be smaller, maybe as smallas 70% of X. Some companies want you to use anequilateral triangle (X and Y are equal in distance), orgreater.

I suggest playing a mono source like female vocaland keep pulling the speakers apart until the voicebecomes a fairly precise point between the speakers.Pulling it apart any further results in a too small voiceor one that now begins to come from each speaker.Bring them back to the point where it worked, switchfrom mono to stereo and check out the image.

This technique assumes you’ve established a“grid” on the floor so that movements are the samefor both channels.

3) Frequency response or tonal balanceRemember how we said that changing the sepa-

ration could yield a cooler or warmer sound? And howtoe-in can also dramatically affect balance (particu-larly high frequency balance)? Well, now you’re at thatpoint (this assumes that your speakers are either non-adjustable, i.e. tweeter lever control, bass level con-trol, etc., or that you’ve selected the nominal “flat”position as a starting point).

Here’s an example—and listen, it’s just an ex-ample—you might feel quite differently. I find that ifI set up most direct radiating speakers on an equilat-

eral triangle, the sound (for my taste) is usually toolean. I can hear all the tiny sounds in the soundstage,but it’s become a precise, almost mechanical sound.It’s not “relaxed” for want of a better word. It’s makesgreat audiophile stuff, but the sound just doesn’t havethe body and warmth that I hear with live music.And yet, I know highly respected reviewers and manu-facturers who prefer to listen with Y being greaterthan X. That’s why it’s your taste—remember, it’snot about some notion of “accuracy,” it’s about themusic and you.

Step 3 is the real fine-tuning that will make thedifference for you. One final note—some audiophilesadjust toe-in to make the speaker seem to “disappear.”This is usually not on axis, but aimed to crossfiresomewhere behind your head, or even aimed straightahead. This is your call as well. I recommend goingfor the musical balance before going for an audiophilesound effect, but sometimes you can get both, so gofor it if you like…

5) Don’t forget to listen at different seatingheights.

If you have the ability to experiment with differ-ent seating heights, do so. You’ll find that those stand-ing waves affect your sound vertically as well. Some-times raising or lowering your listening position canproduce a more neutral and more alive sound, so ifit’s possible check it out.

At a friend’s home, we actually built a 3” plat-form under his sofa. The sound is better, yet the ap-pearance and utility of the sofa are largely unaffected.

Note that if you do plan to change the listeningposition’s height, be sure it’s standing waves you hearand not different time arrival from the speakers. Away to check that aspect is to slightly tilt the speakerbackward or forward to see if it’s simply an effectfrom the relationship of the speaker ’s vertical angleto the listening seat. About the only speakers wherethis might not need to be considered would be anyconcentric array, or one where the tweeters are be-side the mids.

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66) Don’t consider speaker placement final untilyou’ve discovered the correct AC polarity for allcomponents.

Incorrect AC polarity from just one componentcan make your system sound harsher than it should.Since I assume you already know this, and you knowhow to correct it, here is one thing you may not haveconsidered:

Components with incorrect AC polarity will ofcourse look for a ground path. Where do they sharethe ground? Usually it’s on the shield side of connec-tors and interconnects. Since this shield is commonto both channels, it can present a slightly “grungy”center fill that you may not notice until it’s beeneradicated.

If you have carefully set your speakers up for aprecise image, and then you correct the AC polarity,depending on the polarity’s interaction with the othercomponents, you may get a “hole in the middle” whenthe artificial center fill (mono) information is re-moved. With some systems, I’ve found that I neededto bring the speakers an inch or two closer togetherto correct for what had been a false center fill. Try itand see what you think…

7) Don’t place your components, especially sourcecomponents, in areas where there are bass rein-forcement modes.

Try to avoid placing components (especiallysource components) in areas where the bass is verystrong or exaggerated due to standing waves. CDtransports and turntables lose their life and dynam-ics when they’re being bombarded by resonance in-ducing bass frequencies.

The worst two places:1. In a corner, especially one on the wall opposite

the speakers.2. Anywhere on the wall behind you.Move your components out of these areas and

listen to how much more effortless the presentationseems to be (and with better bass).

8) Absorb or diffuse the area behind you (if it’swithin 4-6 feet)

OK, I think we should go light on all these roomtreatments (yes, I admit that the Hornspeakers facili-tate this position). But there’s one place that—depend-ing on where you sit in your room—you need to ab-sorb or diffuse sound, no matter what kind of loud-speakers you own.

If you’re sitting fairly close to the wall behindyou (if it’s within 4-6 feet), it’s good practice to di-minish the first reflections from the main speakersthat return from the rear wall. These reflections tendto smear articulation, add unwanted colorations, andmess with your musical enjoyment. Personally, I pre-fer absorbing them, since I don’t want to add addi-tional reflections to those already recorded, but thereare cases to be made for diffusing as well.

The best absorptive materials (producing the leastsound of their own) are natural materials like cottonor wool. But if you can’t come up with somethingsoft enough or thick enough, you’re better off to re-sort to some absorbent panels than leaving the rearwall reflective and undamped.

9) Thou shalt have no reflective surfacesbefore you

This isn’t always practical or possible, but if youhave a coffee table or other reflective surface in frontof you—at least when you’re listening seriously—ifyou can’t move it away from in front of you, try todrape a towel or blanket over it while listening. Andif you have a significant other, you’ve alreadystretched the boundaries with moving the table orcovering it, so be sure to PUT THINGS BACK…

Getting rid of early and unwanted reflections willallow you to hear more of the music.

10) Don’t look into a glare when you listento music

If you have a window on the wall at the end of theroom where your speakers are located, when you’relistening in the daytime, use drapes, shades or whateverit takes to reduce the light streaming in as you face the

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11speakers. Try it and you’ll find your enjoyment in-creases, and psychoacoustic “glare” decreases…

11) It really does sound better at nightMost audiophiles have noticed this phenomenon.

There are many conjectures. Here are mine:1. The power line feed is more pure—there’s less

machinery and motors to mess with it.2. There may be more power available, especially

in times of peak demand (weekdays in the summer).3. It’s quieter.4. You’re winding down and can be more atten-

tive to the music.5. There are less distractions.6. It’s generally darker in the room.7. You can make it very dark, which provides the

ultimate home listening situation, as you remove thedistracting visual cues that prevent a suspension ofdisbelief.

12) Precise Volume SettingIf you want to maximize your musical enjoyment,

you need a preamp, receiver, or perhaps a CD playeror DAC with volume increments of 1 dB or less.

“Good enough” simply isn’t—at least when you’resetting the volume for a piece of music. Learn to rec-ognize the point where the music speaks to you, andmake sure you play it there. You can’t set it and for-get it, because different recordings of the same musicwill likely have been recorded with a different per-spective and recording level.

The next time you play the same CD or LP, don’tassume that the position you used last time will workthis time. Your mood, your attentiveness, the noise/distractions around you, even the temperature andhumidity—all contribute to the “ambience” in yourroom at that time.

When you get the volume right for that music atthat time in your room, the result can be capable oflifting you out of your daily life experience and caus-ing your spirits to soar—just like live music does.

13) Bi-amp and get five times the effective powerGosh, I sound like I’m hyping bi-amping! This

info is useful only for those who have speakers thatallow bi-amplification. (Avantgardes do, but do youreally need to worry about more power when 5 wattscould chase you from the room?)

The “power break” in music, depending on thetype of music, is between 400 Hz and 200 Hz. Gener-ally, dense harmonics draw a lot of power. Bass notesbelow 100 Hz, although they can be loud, are almostsinusoidal in nature (simple rather than dense). Theymay be the easiest waveforms to produce.

So if you bi-amp at or near the power break foryour kind of music, when you add another amp of equalpower, each amp is having to work half as hard. Sinceyou doubled the available power, you have double thepower with half the requirement to produce the sameoutput. That’s four times the available power.

Where do we get five times the power? Bi-ampingvertically seems to add just that additional availablepeak capability before audible distress. We say it’s likehaving five times the power.

14) Bi-amp verticallyVertical bi-amplification is using a stereo amp for

each channel. For example, the right channel amp willhave one channel playing low frequencies, and theother channel playing high frequencies. There are sev-eral reasons we recommend this procedure, ratherthan using one stereo amp for the lows and the otherfor the higher frequencies:

1. Imaging is better. You’re separating power sup-plies and all channel information from one chassis toanother. The effect is the same as monoblocks vs. ste-reo amps.

2. Dynamics are better. Generally, when big basstransients occur, they appear in both channels. In thistechnique, when the power supply of the amp is hitby a big bass transient, the other half of the amp’ssupply is still unaffected (well, maybe not as muchanyway). So the overload capability is expanded,whereas a “bass amp” would have instantly and audi-bly crumpled under the demand. And should the bass

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15channel temporarily overload in a vertical configura-tion, you may not notice it as readily because the restof the music is not being clipped.

3. You’re forced to use the same amps…

15) Bi-amp with similar ampsWhen you use dissimilar amps for top and bot-

tom, the sound never really coalesces as well. Yes, thereare music lovers using a transistor amp in the bassand a tube amp on top. But these amps won’t haveequivalent transfer characteristics. Their sound willbe different. They’ll have different dynamics. Thesound may be interesting, but it’ll never really soundcontinuous and focused, top-to-bottom.

Here’s a test to check it out—Use a channel fromthe transistor amp on one full range speaker (say, theleft), and a channel from the tube amp on the otherfull-range speaker. Balance the left and right channelswith your balance control. Play a mono source, or atleast a vocalist whose image is panned to the center.What happened? You can’t get a good center image!Why? The amps have different transfer characteris-tics, even slightly different phase characteristics.

So if the combo were no good for basic stereo,why would you want to use it in a manner that willonly serve to subtly alter dynamics and instrumentaland vocal timbres?

16) When adjusting bass levels with a bi-amplifiedsystem, if you can’t adjust spectral balance to.5dB, forget about biamping

If you’re attempting to use one of those electroniccrossovers with only 1 dB level adjustments, you’llhave a hard time relaxing and enjoying your music.No matter how good its line stage sounds. Unless youhappen to get lucky and the setting is close to whereyou need to be.

Even though 1 dB is theoretically almost impos-sible to discern as a difference in volume, years of prac-tical experience (and even blind testing) has proventhat we humans can easily resolve shifts in spectralbalance to well below .5 dB! And once you get it“nailed,” it’s unmistakably right. Until then, you’ll feel

the urge to get up and change settings for each re-cording….

17) When bi-amping, make final tuning adjust-ments with vocals and high frequencies

If you’re crossing over between a bass driver andthe rest of the musical spectrum, DO NOT use bassinstruments to adjust your balance between basslevel and mid/highs! A starting point could be malevocals, but ultimately you need to use female vocals.Adjust by ear to get the sound to neither be a “head”sound or a “chest” sound. When you get the levelright on a variety of female vocals, you’ll stop feelingthe need to change levels with different recordings.Of course, you did this by fine adjustments below.5dB level…

If you’d like to refine your bass crossover leveleven more, the sound of wooden drumsticks on cym-bals is a great “finisher.” Most folks wouldn’t thinkthat adjusting bass level could affect the timbre ofsuch instruments, but one listen and they find outthe truth…

18) Angle those panel speakers! (vertically)If you have electrostatics or planar magnetics (or

even D’Appolito dynamic arrays), if you want to in-crease your musical impact, angle those speakers for-ward or backward (if it’s safe)! Obviously when you’rethrough listening seriously, put them back in their“natural” position.

Essentially, you want to put the middle of thepanel speaker (or D’Appolito array) at 90° to your earheight. If it’s a tall model, this usually means it’s tobe tipped forward. Now, I didn’t say this was attrac-tive. Of course with such speakers as InnerSounds,Quad 63’s (with the grilles down), and Martin Logans,it’s easy to see if you’re in the 90° position, becauseyour reflection will appear dead center of the panel’sheight.

But all you have to do is listen (I first discoveredthis in the mid ’70s, when I was Magnepan’s NationalSales Manager), and see if you don’t appreciate thedifference. Please do be sure it can’t fall over and hurt

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19some one or some thing. When these speakers are notangled, they can still sound quite peasant, as long asyou don’t think about the “smearing” that’s going onfrom a lack of focus.

19) Brace those panels too!This is not very elegant visually, but try it some-

time when your significant other is away… If yourpanel speaker is fairly thin and it easily rocks backand forth with slight pressure applied at the top, thenyou ought to at least try bracing. If you have foundwhat number 18 (above) can do for you, you’re prob-ably in need of a brace anyway!

As a starter, just make a long pole that sits on thefloor, with a right angle “hook” that can fit over thetop of the speaker (from the back, so as not to inter-fere with the output from the front of the speaker).Use some piece of metal already shaped to do the trick,or even use duct tape temporarily to test the effect.You’re ultimately gonna want to firmly brace the poleto the floor, but just wedging something against it sothat it can’t move on the floor is enough to test it outfor yourself.

Once you’ve heard the effect, a little creativethinking and you can come up with your own braces.

Don’t want to go too far here, but a brace thatprevents the speaker panel from torsional flex (side-to-side) is also worthwhile.

I don’t recommend that you do numbers 18 and19 unless you are slightly compulsive and you don’thave a situation that demands full-time visual appeal.But if you were into full-time visual appeal, youwouldn’t have those big panels (or horns or coffins)anyway, would you?

20) Equalization vs. notch filters—or—no bandboosters here

Here’s a tip of the hat to Richard Vandersteen. Inhis model 5 Loudspeaker he introduced equalizationin the only place that it makes sense in high-fidelitymusic systems—the bass!

The only thing I might suggest is to refrain fromboosting bass frequencies that appear to be room de-

pendent. These dips in response are a product of can-cellations from positive and negative wavefronts crash-ing into one another. If you boost these dips (withequalization), the only outcome is that your amp worksharder, your woofers work harder, but—as a rule—you’ll get no more output at that frequency at yourlistening seat, no matter how much boost you apply!

Since the negative wave is boosted as much asthe positive, increasing that frequency can’t producemore output at your listening position. Your systemwill probably sound worse, and it’ll overload sooner.

Judicious use of notching the peaks (meaning thatyou pull down the peaks in response and ignore thedips, except through physical location, never throughequalization boosts) will yield an astonishing improve-ment in the overall sound, assuming that the basicspeaker is already very good. There are some simpleways to introduce this concept when bi-amping.

21) The moving peak (vibrating seat)You probably don’t have this problem, but you

might know someone who does! As the guy whowrote the owner’s manual for the Magnepan Tympani1Ds, I thought I pretty much knew it all when it cameto installing these speakers and getting the most fromthem in any room.

That’s why I’ll never forget the humbling lessonI learned as an audio “guru.” Here’s what happened:

As a high-end dealer in the early 80s, I had sold apair of Timpani 1Ds for use in an Audio Research sys-tem. I went out to install the system (which I alwaysinsisted on—and your dealer should do it for you aswell). I always carried along a 1/3-octave real timeanalyzer so that I could quickly see where the bassstanding wave problems were.

Within an hour or so, I had found the best placeto locate the speakers (somewhat tricky due to thenegative bass wave emanated from the rear of thespeaker), and the best place for the listening seat.Using the 3-step installation technique outlined above(number 4), I worked to get the sound to where I’d beproud to send a prospect over to my client’s house tohear what the Maggies sounded like in a home.

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As I left, my client was effusively thanking mefor getting him better sound than he thought waspossible. I was a hero.

A week later, he calls me to complain about a“thickness in the mid-bass.” I don’t know if you re-member the Tympani 1Ds, but bass definition andtimbre was their best quality (HP, writing in TAS,adopted the T1D as the bass unit for his hybrid QRS/1D system). There was NO WAY we could have athickness in the loudspeaker ’s bass, he must’vechanged some component or something (in otherwords, I was convinced it couldn’t be my installation!)

Well, I finally stopped by later that day, expectingto point out the offending component. But nothingwas changed in the system! And boy, was the upperbass thick! I got out my trusty RTA. Sure enough, therewas at least a 6dB peak at about 125 Hz. Where didthis come from? Well, I couldn’t figure it out, but as Imoved the RTA about two-three feet in front of thelistening position I’d selected (and even marked!), thebass peak disappeared. So we moved the seat forward,and just to be sure, listened to hear what the guru (me)had fixed. Woah, the peak was back!

I measured the response behind the listening seatwhere we had originally determined was the best seatin the house (literally). Now the peak was gone!

Anyway, I started to think I was on Candid Cam-era, I was looking so foolish. Then I noticed it. Myclient had a shiny new sofa. When I had set the sys-tem up, we had used an occasional chair for the lis-tening sessions. This sofa had a tightly stretched backpanel (leather/leatherette). It was stretched so tightly,it produced its own tympanic sympathetic resonancesat 125 Hz. Removing the sofa solved the mystery.

So check out any system where the seating couldcause a similar effect. I’m still surprised at how manysystems can be affected…

22) Install a wood floor on your existing concreteslab to improve your sound

Before spending lots more money on new com-ponents (even Avantgardes!), if your listening roomis on a concrete slab with wall-to-wall carpeting, for

a modest investment you can transform the sound ofyour system. I discovered this phenomenon first whenmaking master concert recordings. When we recordeda concert in a venue with concrete flooring, the soundof instruments took on a whitish coloration. Thosesame musicians, when playing at a venue with awooden surface, made a wholly more musical sound.And they would comment on the live sound them-selves. The difference is a slightly colder less involv-ing sound vs. a warmer more compelling sound.

All you need to do is put down some 2x4s on theirsides and fire the nails that hold them in place intothe concrete. Consider putting some insulation in thevoid between the concrete and the bottom of thewooden floor that gets screwed to the 2x4s. You wantto keep the solidity of the concrete surface, onlychange its timbre. The floor doesn’t have to be ex-posed hardwood planks. It can be plywood subflooringon which you re-install your wall-to-wall carpeting.No amp or preamp or cable can make such a tremen-dous improvement!

23) Breaking in your Components—From Cold andDead to Warm and Alive

You already know the advantages of breaking incomponents. Some folks say a week is enough. I’d liketo suggest that I haven’t heard any component thatdoesn’t continue to “relax” in the first 200 hours (ifnot more).

With speakers, placing them face to face and outof phase is the best method for maximum level thatisn’t as intrusive.

With amplifiers and speaker cables, you mightconsider an 8-10 ohm wire wound resistor from Ra-dio Shack across the positive and negative tips of theload (speaker) end of the cable.

With preamps and source components, it’s easy—just run the piece without turning on the amplifier.

I suggest three sources for break in:1. The Purist Audio break in disc. Fastest and most

effective. But, if you’re gonna have to hear it, thismight not be the one. I got mine from Terry Combsat Sound Mind/ViVA in Dallas (214 327 2073)

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2. The Cardas “surf ” technique. This exercises thecomponents nicely, and if you have to hear it, thereare companies who sell similar sounds as a sleep aid!Check with a Cardas dealer. I usually refer to CaseyMcKee at Ne Plus Ultra in Austin (512 241 0000).

3. This gets tricky, but if you have any MUSIC,try playing that …

24) Vinyl and VTA—listening and compensat-ing—including temperature shifts—tracking forceand the sound of LPs

Although I can’t take credit for inventing VTA(or the Internet), I WAS there when the guy who re-ally discovered its effects was demonstrating it to usall. It was in 1976. The guy was David Shreve, whowas marketing his modified version of the Rabco SL-8E straight-line tracking tonearm. At Audio Researchwhere I was working at the time, David would rou-tinely drop by to install updates to his arm.

So I began to investigate the effects for myself.Not long after that, Jim Winey’s tonearm appeared,and a simple VTA adjustment was included on it. Itmade it easy to hear the differences. I think this armis still one of the better arms ever produced, but ulti-mately—with the encroachment of CD, Jim couldn’tjustify making it any longer.

As a side note, Jim understood that a low massarm is of no particular value. What is of value is alarge ratio of moment of inertia at the headshell vs.the counterweight. That’s why his arm had such ex-plosive dynamics. The counterweight had adjustableweights so that you could keep it snuggled up tightlyagainst the pivot point.

OK, if you have the VTA of your phono cartridgedialed in, the question is, what was the room likewhen you made the final adjustment? If the roomwas warmer by about 5 degrees (maybe you had tubeelectronics helping to warm the room), then whenyou first start playing your records next time, chancesare that your VTA will sound as if it’s “off ” slightly.That’s because the effect of a slightly colder and stiffercantilever is the same as slightly raising your VTA.So, in a cooler room, it’s likely to sound cooler!

To avoid having to readjust the VTA, and therebydistract you from the music, there’s a shortcut. Sim-ply add about .1 gram to the tracking force. Do thisonce and you’ll know how much it requires next time.As the room warms up (and the cantilever becomesmore flexible from use and temperature), just resetthe tracking force to its former position.

The reverse is true with a warmer room thannormal. You’ll need to back off the tracking forceabout .1 gram or so.

25) Fine tune your stereo image with anti-skateOK, let’s assume you have tracking force, VTA,

overhang, and all that good stuff adjusted to your lik-ing. Of course, we’re assuming that your arm is not astraight-line tracker, but is pivoted. So how do you setanti-skate? After setting it to the manufacturer ’smarked position, try this:

While listening to a LP with a voice known to becentrally located in the stereo image, listen to wherethe voice appears in the stereo image at your seat (thisassumes you’ve already performed the speaker instal-lation and properly located the listening seat on equalpath-lengths). This adjustment is best performed atabout mid-way into the side of the LP. Then, add aslight amount of anti-skate. The image should shiftvery slightly to the right from its former position.Reducing anti-skate will shift the center image slightlyto the left. Simply make the appropriate adjustmentuntil the image is locked in the center of your stereosoundstage.

PART TWOTHINKING OUTSIDE THE BOX

26) Don’t believe the “experts” when they tellyou that, since bass is omni-directional, you onlyneed one subwoofer.

Unfortunately, while this theory is based on somefact, the end result is far from correct. Low bass may be“non-directional,” but the Experts are dead wrongwhen they say you only need one good subwoofer.

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No matter how great a single sub is, it kills themusic. Over the years, we’ve proved this fact to manyskeptics by playing acoustic recordings that containedno apparent bass at all!

Here’s the reason why: Direct and reflected long-wavelength low frequency cues will arrive at each ste-reo microphone at slightly different times. Therefore,stereo subwoofers play these differing time-arrivalspatial cues in each channel.

Subwoofers provide the cues for a sense of spacethat can transform a system from simply soundinggood to sounding real. This is accomplished becauseour ears decode spatial cues by picking up reflectedsounds off of walls and ceilings. The time of arrivaltells us how big the space may be.

Low frequencies have long wavelengths (mean-ing greater travel distances), and our brain decodesthem as spatial cues. Acoustic recordings carry theselow frequency spatial cues which are essential in ourability to suspend disbelief. This is how we hear andaccept the illusion presented by recordings with a “weare there” perspective.

A virtual three-dimensional image can be created,with each instrument or voice seemingly occupyinga palpable space in the stereo sound stage in front ofthe listener. This is related to the ear-brain low fre-quency spatial cues.

When the bass is combined into one channel, thediffering time arrivals from each channel are simplycanceled as out-of-phase information. The acoustic sig-nature of the space is irretrievably lost. It no longer quali-fies as a realistic recording of real instruments in areal space.

As a dramatic test of our theory, we’ve playedour master recordings of hand-bell choirs recorded ina church or cathedral (predominantly high frequencieswith some mid-range and no bass).

Sophisticated skeptics (an oxymoron?) are dumb-founded when they hear the ambient soundfieldcollapse when we use one monaural woofer instead ofa stereo pair. (Of course, the bass level was preciselyadjusted to match that of two woofers when onewoofer was played).

It’s important to note that the practice of usingtwo subwoofers for home theater does not solve theproblem for music. Although there are two subwoofers,they are both getting the same monaural signal fromthe A/V processor, so the stereo sound-field informa-tion on your CDs or LPs is still irretrievably lost.

In fact, increasing the mono bass channel to evenmore output than is required adds nothing to the acous-tic signature of the space. As a high-end designer, I typi-cally wouldn’t install a single subwoofer in a music sys-tem due to its detrimental effect on the illusion.

27) Why you should forget about reproducing themost “slam” and the “tightest” bass if you’re inthis hobby for the music.

Forget about reproducing the most “slam” and the“tightest” bass if you’re in this hobby for the music(this DOES NOT endorse boomy bass). For example,some transistorized gear tends to “dry up” the bass,often robbing it of the weight we hear at live con-certs. Weight can be subtle or strong in its effect onthe illusion of live music in the home. Weight is fun-damental in producing the body of an instrument orvoice, its palpability. Without weight, the sound isdisembodied, lacking believability. Weight is a functionof bass quality, as well as bloom (not boom).

Some audiophiles rave over how “tight” the bassis with certain transistorized electronics, as if tight-ness alone is a desirable musical attribute. This “tight-ness” is a drying—a shriveling—of the very founda-tion of music.

Ask yourself, “Have I ever commented on howtight the bass was at any acoustic concert? How dothe string basses sound in your concert hall? Aren’tthey gutty, stringy, and resonant?

Along those lines, ask yourself when have youever evaluated how much ‘slam’ you heard in a jazzor blues club? Or in a concert hall?

How about the bass at amplified concerts, includ-ing most clubs? Can you imagine telling a guitarist thathis carefully selected electric guitar amp (usually alwaysa tube unit, such as a Marshall) needs tighter bass,especially since he picked it for its “full and rich” sound?

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302828) Why a woofer’s “speed” is irrelevant to bassquality.

This is another belief that persists in hangingaround with no basis in fact. Looked at another way,speed is a measure of how many cycles per second adriver can reproduce with low distortion and flatfrequency response. A “fast” driver is one that can playhigh frequencies (say 20 kHz). That’s a Tweeter, nota Woofer.

What IS desirable is good rise time/transient re-sponse—and equally as desirable—excellent settlingtime. Speakers that exhibit this characteristic aresometimes said to be “fast.”

Most bass speakers are asked to travel great dis-tances and then immediately settle down to nothingto await the next signal. In fact, that never occurs.The best speakers do a better job of this.

An excellent technique to overcome the problemis to employ big motors on low mass drivers that havetheir peak excursion requirement reduced by using ahorn or multiple drivers.

29) Low driver mass alone doesn’t determineloudspeaker transient response.

Ok, I used to propagate this notion when I workedas the National Sales Manager for a famous loud-speaker manufacturer back in the ‘70s. I later foundout I was wrong. But the idea has persisted to thisday. Maybe I did too good of a job…

Here’s an analogy—Suppose you had two NHRAtop fuel dragsters. They both weigh the same (theirmass is equal). What’s required to get one down thestrip faster than the other?

The answer is a more powerful engine. It’s nodifferent in audio. A driver could theoretically havetwice the mass of another, and still respond asquickly if it has a twice as powerful magnet/voicecoil “motor.”

Of course, if the motor were equal in strengthwith two speakers, then the lower mass unit wouldtheoretically have the better transient response. Still,having a “low-mass” driver means absolutely noth-ing by itself.

30) Why wide dispersion might be a bad ideaIf we don’t have speakers with wide dispersion,

we can’t be real audiophiles. That’s what the Expertstell us. But which Experts want to talk about speakercoloration off axis? And how much room reverbera-tion do we need? In a moment, we’ll examine theseeffects.

First, when recording engineers make a record-ing, they carefully decide how much direct vs. rever-berant field to include in the recording. When youlisten to the recording, its reverberant field is alreadythere. So why would a music lover want to create afalse “soundstage” with reflections that are adding tothe originally recorded reverberant field? Recordingengineers use near-field monitors solely to remove anyunwanted room reflections/colorations from their re-cordings. Again, why would we want our rooms tointroduce a sound that was originally unwanted?

This dubious argument of purposely introducingreflected sound into music reproduced in the homewas debunked by J. Gordon Holt, in Stereophile in the’70’s. The product? The Bose 901 (Bose was claiming89% reflected sound, 11% direct—a ratio they mea-sured in the concert hall).

Holt correctly pointed out (the lone voice of rea-son in the face of scores of rave reviews for this “break-through” concept) that adding 89% more reflections(to a recording that already had captured most of thehall sound) was a recipe for sonic disaster. Of courseBose kept telling the reflected sound story and the rest isthe stuff of marketing legend!

Today we’ve forgotten that lesson from Holt. Wespend lots of time and money in placing acoustic treat-ments just to absorb or diffuse the reflections fromwide dispersion speakers. But even diffusing the re-flections doesn’t remove the extra energy. It can add‘spaciousness’ to the recording, but as usual, there’sno free lunch…

No matter how wonderfully a speaker performson axis, it’ll be badly colored off-axis, especially as thedrivers reach their crossover point and begin to “beam.”Depending on how colored the speaker is when heardoff-axis (and they all are badly colored off-axis—just look

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at their polar responses), we end up diffusing/dispers-ing some of the worst kind of colorations!

When we add that badly colored sound to thesound of our rooms, we may have an interestingly“spacious” sound. What we end up with is “hi-fi,” andnot really related to the live event (even if it’s a multi-tracked studio recording).

This is essentially the phenomenon known as theHaas Effect, which basically says that reflections ar-riving soon after the direct sound will smear (obscure)inner detail because the late arrival confuses the earand prevents discrimination.

“Controlled dispersion” loudspeakers project therecorded sound with amazing detail because the eardoesn’t have to decode unwanted and colored reflec-tions. Why waste our time and money on expensiveroom treatments that only serve to further the ad-vancement of a questionable practice?

31) Why digital room “correction” might not be agood thing

OK, this one is just for you to think about. If youdon’t agree, that’s OK . For a moment, consider howour ears adapt to what is natural. If your friend speaksto you in your listening room, from a location betweenwhere your speakers sit, his/her voice will be verybelievable. Your ears know the voice and it’s in afamiliar (not necessarily perfect) environment.

If we record that voice in a sound recording booth(a space generally devoid of room reflections), and playit back on your system, the voice will be very believable(assuming any reasonably good loudspeaker). Sincethere is no room sound in the recording, it will be as ifyour friend is in the room, since the listening room’seffects are now introduced. In other words, yourfriend’s voice wasn’t artificially “corrected.”

Now if we were to introduce mid/high frequency“room corrections,” that same voice, when played back,would most likely sound quite unnatural. That’s becauseour hearing is wonderfully adaptable. It factors in thesound of the listening room. When we’ve becomeaccustomed to a space’s acoustics, changing them tomeet some arbitrarily chosen tailored response may

yield a new sound, but will it actually make instru-ments sound more like themselves in that room?

There is a stronger case to be made for “room cor-rections” in the boundary dependent region (perhapsfrom 300 Hz down). Most rooms, especially averageor small in size, will have some unfortunate peaksand valleys in the lower frequencies, caused by stand-ing waves adding or canceling certain frequencies. Inthis low frequency region, the sonic effects of a nastypeak at 120 Hz are not pleasant. Introducing a notchhere to remove such a peak will make for a more mu-sically natural sound.

However, you cannot electronically correct for acancellation (frequency response dip) that is due toroom effects. A cancellation is still a cancellation. Asyou add progressively more output in that region, itwill progressively introduce more cancellation!

If a loudspeaker has a peak somewhere in its 30-300 Hz response region, that may be corrected, butgenerally, when we encounter large peaks and dips inthis region from a good loudspeaker, it’s almost alwaysa room interaction. Actually the best way to deal withthese—where possible—is to find a better location tosit (and to some extent, re-locating the speakers).

You’ve Made It!Well, you’ve survived 31 Secrets to Better Sound! If

you picked up an insight or two, it was worth it towrite all this stuff down. Please drop me a note if youfound any of it worthwhile. Sorry, but I don’t havetime to debate any points—this was a think-piece,not a basis for arguing differing positions…

Use anything here that seems useful, and thenforget about all this tweaky stuff and listen to somemusic! After all, at Avantgarde-USA, when it’s all saidand done, “It’s About the Music…”

All the Best,

Jim SmithPresident, Avantgarde-USA

Jim Smith

Part OneOptimizing Your System’s Performance...................21) Why you should be sour on a wide “Sweet Spot”.....22) Fine tune your tonal balance with stereo separa-tion and toe-in..............................................................23) Set up a grid to begin your speaker installation.......34) A simple three-step speaker installation techniquefor satisfying results........................................................35) Don’t forget to listen at different seating heights....46) Don’t consider speaker placement final until you’vediscovered the correct AC polarity for all components..67) Don’t place your components, especially sourcecomponents, in areas where there are bass reinforce-ment modes.....................................................................78) Absorb or diffuse the area behind you (if it’s within4-6 feet)............................................................................79) Thou shalt have no reflective surfaces before you.....710) Don’t look into a glare when you listen tomusic........................................................................711) It really does sound better at night.........................812) Precise Volume Setting............................................813) Bi-amp and get five times the effective power......814) Bi-amp vertically......................................................815) Bi-amp with similar amps.......................................916) When adjusting bass levels with a bi-amplifiedsystem, if you can’t adjust spectral balance to .5dB,forget about biamping...................................................917) When bi-amping, make final tuning adjustmentswith vocals and high frequencies..................................9

18) Angle those panel speakers! (vertically).................919) Brace those panels too!..........................................1020) Equalization vs. notch filters—or—no band boost-ers here..........................................................................1021) The moving peak (vibrating seat).........................1022) Install a wood floor on your existing concrete slabto improve your sound.................................................1123) Breaking in your Components—From Cold andDead to Warm and Alive..............................................1124) Vinyl and VTA—listening and compensating—including temperature shifts—tracking force and thesound of LPs...................................................................1225) Fine tune your stereo image with anti-skate.......12

Part TwoThinking Outside the Box......................................1226) Don’t believe the “experts” when they tell youthat, since bass is omni-directional, you only need onesubwoofer......................................................................1227) Why you should forget about reproducing themost “slam” and the “tightest” bass if you’re in thishobby for the music......................................................1328) Why a woofer ’s “speed” is irrelevant to bassquality...........................................................................1429) Low driver mass alone doesn’t determine loud-speaker transient response...........................................1430) Why wide dispersion might be a bad idea...........1431) Why digital room “correction” might not be a goodthing.................................................................................15

INDEX TO THE 31 SECRETS TO BETTER SOUND™

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Copyright © 2001 James F. Smith, Avantgarde-USA LLC

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