INTO THE HEART OF SPEAKER DARKNESS

FURTHER DOWN THE PATH SEARCHING FOR

THE OPTIMAL TUBE AURAL MATRIX

Jean Paul Satre said, "Speakers are hell", and he is right because there is so much hype, and so many choices, which explains why I receive so many emails.."Dr. Gizmo, what speakers should I buy for my tube amplifiers?"

Am I too vain to claim that I have been America's number one critic of the prevailing "transistor speaker" orthodoxy?

Thank you for your applauds.

Why am I the most articulate critic of loudspeakers? Have you noticed how difficult…almost impossible, it is to find a truly critical review of loudspeakers in the audio press, in spite of the fact that loudspeakers are the crudest component in any audio system, and contributes the most distortion?

Have you noticed that there isn't one loudspeaker company that ever prints accurate frequency response curves, or distortion figures? Have you ever seen a graph that shows time alignment, one of the most critical characteristics of speakers? Are they cynical, or do they think, because you are dumber than dumb, that in the real world a loudspeaker is linear…in any regard?

SMOKE THIS PARADOX A WHILE: When gifted listeners compare the sound of tube amplifiers to sand amps, they reach the conclusion that tube amps sound much more musically natural. And they reach that conclusion, 99.9% of the time, when using speakers that don't permit the tube amp to operate at its full potential. Let me say this another way: Even when tube amplifiers are seriously handicapped they sound more musical than sand amps!

FACT: It is impossible to isolate the performance of a speaker from the amplifier used, and the room, and speaker cables, which are always filters. I remind you that, though it is possible, to some extent, to measure the interaction of a speaker and amplifier, not one audio magazines attempts this…because it would be much too scary…. For you.

Let us quickly pierce another "conspiracy of cynicism" which is endemic to audio shopping:

You walk into an audio showroom to audition speakers. The room is filled with other speakers, and this room bears no resemblance to your listening room, and the amplifier used in the auditioned is your amplifier. The first thing the salesmen does is shove a review, from an audio magazine, in your face that says..RECOMMENDED COMPONENT.

Have you ever seen an audio review that screams out NOT RECOMMENDED? How peculiar! You ask the salesmen if this 84 db efficient speaker, that is rated at 4 ohms, is good for your tube amps, and he responds…"Look what the review says…AUDIO MAGAZINES NEVER LIE….of course…just listen to how great it sounds". You ask the salesmen how this speaker compares with others, and what compromises are in its design, and he looks at you with a scowl.

I marvel at this often-repeated question that appears in high-end audio rags: What is wrong with the high-end audio business? Here's a simple answer based on the thousands of emails I have received: Consumers have been sold a lie, and it has backfired very fast: For example…There is no such thing as a reliable big powerful pentode amplifier driving a "normal" speaker. Soon it will become unstable, and its tubes will fail, creating a very unhappy customer. Yet, I have not seen one comment, in one audio magazine, addressing this issue of speaker/amplifier compatibility…and, I mean a serious investigation.

Why don't audio magazines say THIS SPEAKER SHOULD NOT BE USED WITH A TUBE AMPLFIER", when the speaker is not right for a tube amplifier. This answer is…they would have to say this about 99% of the speakers they review. The answer is that this truth would harm short-term sales.

So it naturally follows, that I ask again for the zillionth time…..

IS TOO MUCH KNOWLEDGE DANGEROUS?

FOR THE GILLIONITH TIME: How much truth can we humans tolerate? The Greek poets and playwrights, the authors of the Bible, Shakespeare, every great writer, poet and philosopher, every great musician, and artist; Freud and Satre, asked us to consider this very difficult question. And the answer is not always sanguine, my dear Oedipus Rex. How much truth can we, my dearly beloved bros', tolerate in our search for beauty? How much intellectual integrity should we demand from the audio arts? How high is our musical taste? Can truth and passion co-exist? How much truth can we tolerate in the creation of our illusion?

DR.GIZMO’S CRUSADE EXPLAINED FOR THE GILLIONITH TIME

There are three basic reasons you want to use speakers that have high flux density magnets:

You will have more choices in amplifiers. High flux density translates into higher efficiency, which means you can use an amplifier that has from one to 1,000 watts per channel.

Because amplifiers always sound best when they are not taxed, they will sound better, because it doesn’t take much energy to get high flux density magnets shaking.

Your amplifier will be more reliable and your tubes will last much longer

PUT ON YOUR POTTY SAFETY BELT SO WE CAN NOW GET

VERY DEEP INTO THE HEART OF SPEAKER DARKNESS

A loudspeaker, an amplifier, the speaker cables, and your room are ONE ELECTRO-MECHANICAL DEVICE. They are one and inseparable. It is impossible to describe the performance of a loudspeaker disconnected from an amplifier and every time you change the amplifier you dramatically change the personality of the loudspeaker…and the same applies to changing rooms and speaker cables. Do you now have an eye twitch?

When you shop for a speaker do you ask about the electrical characteristics of the speaker magnets? Do you ask to see the passive crossovers so you can judge the quality of the parts used? Yet, when you buy a car you want to know the specifications of the motor. Our high IQ car magazines normally will take the motor apart and analyze it. The same magazine will show you a picture of the transmission and undercarriage. Look at all of the different measurements car magazines make.

The paradox here is that it is impossible to measure music quality…but not impossible to give you more information about the drivers, and crossover parts used. Do you remember the time when American cars had great bodies, but junk motors?

TUBE AMPLIFIERS REQUIRE DIFFERENT TYPES OF SPEAKERS THAN TRANSISTOR AMPLIFIERS: Now you know why there are so many DR. GIZMO, WANTED DEAD OR ALIVE posters in the bathrooms of audio dealers. The revolution is now picking up steam because you now know what the audio industry was hiding from you: 90% of the speakers made are designed for transistor output stages, which are all wrong for tube amplifiers.

At one time speakers had the right electrical characteristics for tube amplifiers, because there were only tube amplifiers. Most of these vintage speakers are now vacationing in Japan. When a loudspeaker is listed as 4 ohms it is a speaker that demands high current, and probably has an impedance curve, at lower frequencies that dips down to 1 ohm. This is a formula for tube disaster because tubes are not current amplifiers, but voltage amplifiers. The toxic combination of 4-ohms/85 db efficient must be avoided at all costs.
The problem is that most speaker manufacturers overstate their speaker’s efficiency and impedance.

Because tube amplifiers are voltage amplifiers they want to have an optimal match between their primary and the secondaries of their output transformer, which are connected to your speaker. A sixteen ohm secondary winding will give the most efficient relationship between the tube and speaker..and this coupled with high efficiency will mean that our output tubes will be liberated to demonstrate their unique virtues, especially their dynamic range… and last for a very long time. Even an 8 ohm secondary tap on an output transformer will be happier with a 16 ohm speaker, than an 8 ohm speaker.

EVERY SPEAKER IS A CRUDE ELECTRO/MECHANICAL DEVICE: Why are there so many speaker manufacturers? Anyone, including you, and me, can design and make a loudspeaker because they are such crude electro-mechanical devices. We can buy a computer program and some raw drivers, and have a box constructed by our local carpenter, and voila..we are in the speaker business. Paradoxically this is what Japanese audiomaniacs do, which is exactly what American hot rodders do: we buy a higher performance "crate" motor from General Motors or Ford, which has higher performance than any motor that is available in their standard showroom models, and we install it in our custom car body. Japanese audiomaniacs buy "high performance drivers", sometimes paying as much as $10,000 for a single driver, and then build their own "hot rod" loudspeakers. They often use vintage American drivers by Altec, JBL, Electro-Voice and Western Electric.

I will soon post an article about my latest building project…Making my special "SANDORMA™" cabinets for the Sunlight Engineering 307 Drivers. Another one of Dr. Gizmo's dual concentric speaker at the edge and weighing only 175 pounds each..and takes less than a watt to peel paint.

Look inside your loudspeaker. What is in your Monkey Coffin? The reason I suggest you look at www.madisound.com web site is to get a better idea of what is in your speaker. Check out their passive crossover parts. How much do those coils and capacitors cost? Are you aware that there is no such thing as a "passive crossover" and that there is a strong interaction between the crossover the driver and the amplifier and its electrical values are constantly changing?

Have you noticed how your speaker cabinet vibrates? It stores energy, because that is the nature of MDF and plywood. If it were made from concrete it wouldn't store energy, and you could use it as a bomb shelter.

EVERY LOUDSPEAKER IS A TRANSFORMER: A speaker converts electrical energy into mechanical motion to set up waves of vibrations that travel through the air and impact our body and make us feel like we are floating on the ceiling. This is not an easy task. I know of no other technology that has such lofty existential goals…which is why we must be compassionate to all speakers. They try hard…but we must act like Higher IQ adults and recognize the limitations of this process. Any speaker can make noise. It is easy to make a speaker that plays loud. When we are seeking the subtle beauty of tube circuits we must be more demanding of what we know is a very limited technology. This implies that we know more about the amplifier/speaker interface. This also means we must narrow and focus our choices. We must consider every element of a speaker much more seriously. We must go way beyond the compromises and high cost of store bought speakers…designed for transistor gear.

EVERY SPEAKER IS A MICROPHONE: When this was demonstrated to me, thirty years ago, it blew my mind and it is very easy for you to discover it if you have an oscilloscope. Attach one speaker to a tube amplifier that is on, but no making any music. Connect your oscilloscope across the B+rails. With your other speaker and amplifier turn up the music and watch the oscilloscope trace bounce up and down, as the loudspeaker, acting as a microphone, is producing an AC signal that is surging back into the power supply…as a form of distortion. By this way this phenomenon will not affect your amplifier if you are using actively regulated power supplies.

While your speakers are creating sound waves in your rooms, those sound waves are bouncing back at some time delay and striking the driver, which generates an AC signal. The bigger the loudspeaker driver the more efficient it is as a microphone.

The use of an electronic crossover also diminishes this effect.

EVERY SPEAKER IS A NOISE GENERATOR: "Why not use a two ton concrete speaker cabinet?", our Japanese audiomaniac bros' ask. That is a good question, and the answer is very painful for American men, because American women are not yet artistically developed enough, to appreciate the beauty of huge concrete totems in the living room. The more powerful and dynamic a speaker is, the greater is the challenge of eliminating the energy stored in the cabinet, which distorts the clarity of the speaker. I have now explained why my speakers weight eight hundred pounds each.

One of the traditional benefits of electrostatic and planar loudspeakers is the fact that they have no cabinets to store energy..BUT..they have their own noise problem, which arises from the necessary plastic film that covers the diaphragm, which with use soon begins to "buzz". When I was president of the Quad Owners club I was discussing how to keep this plastic film tight. This is also a problem with Quad 57s.

Do you get my drift? All speakers make noise, in the same way that all humans make gas…facts of life.

One of the great advantages of separate woofer or subwoofer cabinets is the elimination of the low frequency stored energy that clouds the midrange. The mysterious beauty of small monitors is related to this factor. A small speaker in a very heavy cabinet can take this advantage even further.

Soon I will tell you about SANDORAMA™ technology …revealed to me by Major T. E. Lawrence…of Arabia. With this technique a pair of "normal" speakers arrive at your house and you fill their empty cavities with sand.

Sand is a transformer…it converts vibration into heat, dissipating the energy in the speaker walls. Knock on the walls of a SANDORAMA speaker and you will know why this is such an effective way to eliminate the common speaker noises that cloud our midrange and diminish the quality of our tube aural matrix.

EVERY SPEAKER IS A COMPROMISE: I started my audio career dedicated to a speaker with great limitations: the Quad 57…because I manufactured a sublime amplifier for it. Even with all of its compromises, or because of them, the combination of the Quad 57 and Futterman OTL has set a still unbeatable standard for a natural midrange. Forget about the highs and forget about the bass with this speaker.

And the same is true for my gigantic horn speakers: serious compromises, but what they do, no other speaker can.

And the same is true for one way speakers: serious compromises, but they can do what no other speaker can do.

And the same is obviously true for cars, and all other high performance machines. The narrower the focus, the higher the performance possible, with their inherent compromises.

Is it possible to create speakers with "fewer" compromises? Yes and No. We create bigger and more expensive electrostatic speakers and loose the midrange magic.

We create enormous horn speakers and we must then deal with the massive cabinet's ability to store energy..and time coherence problems.

If we want very high efficiency then we are going to use higher flux density/ higher compliance drivers and loose low frequency response.

If we use planar loudspeakers we get a huge sound field that creates Jolly Green Giants playing the harpsichord…but no speaker box coloration.

And we must never forget the relationship between the room and speaker. Is it unable to move the room's air effectively, or is it overpowering the room?

EVERY SPEAKER IS A MUSICAL INSTRUMENT: Now you get it…every speaker has its own unique personality..and it is changeable depending upon what amplifier and room is connected to it…and soon you will have the ability to properly tune…exactly the way every other music instrument is tuned for optimum performance.

PASSIVE CROSSOVERS EXPOSED: Fact: take the same crossover design with exactly the same electrical values, and construct a different one using different types or brands of parts, and you will create different sounding speakers. Many of you have tried this based on my advice with superb results. Yes, passive crossover construction and parts quality is a major determinate of aural matrix quality…and most speakers, because they are hidden; they have mediocre parts quality.

FACT: Passive crossovers that are outside your speaker cabinet will operate better because they are not exposed to both mechanical vibration and electrical fields from the speaker magnets. The other added benefit of external crossover networks is that you can change them…upgrade them…fine-tune them.

Are you ready for silver foil inductors? Do not start with them. Start with the passive crossover made with "normal" inductors, and then when you are ready you can install "higher performance" copper foil inductors.

When it comes to crossover slopes I tend to be a very mild kind of guy..first order networks with high quality drivers…because these networks use less parts. But this requires high quality linear drivers.

I have read all about the technical advantage of high slope (24 db) networks, and every time I listen to a speaker that uses them I sense that there is a big hole in its aural wholosity…as the price paid for some of nice things it does. I don’t use them.

THE CHALLENGE OF MULTI-DRIVERS: Getting three different drivers to act as one is akin to climbing Mt. Everest in a bathing suit. It can be done, but few have succeeded. This is where aural wholosity becomes a very critical critic. One of the most important considerations here is the proper time alignment of all of the drivers. Then there is matching the tonal aroma of drivers made from different materials with different magnets. The more drivers you use the more parts in your passive crossover, the more congested your amplifiers output stage becomes. I have now explained why I gladly accept the compromises of two-way speaker systems…and have never enjoyed speakers that had more than three drivers.

What if your voice came from three different parts of your body (no farting jokes)?

SPEAKER MAGNET QUALITY MATTERS: Does the quality of your race engine matter? We are now in the land of the major taboo, because discussing speaker magnet quality is a way taboo subject. There is a hierarchy of magnet quality and I have the distinction of being the only audio writer discussing this subject. At the top is Alnico and neodydnium magnets and they are expensive and hard to get.

An efficient speaker needs lots of magnetic force..GAUSS…or as we say high horsepower to cone weight ratio, just like a race car.

SUBWOOFERS: I like subwoofers but I don't like the way they interface with speakers..generally speaking. This is always a problem because of the weird way rooms behave at lower frequencies and how large the sound pressure wave is at low frequency. My experiments with getting a subwoofer off the floor have given me hope about this interface challenge.

 

DR. GIZMO'S GUIDE TO REAL WORLD

SPEAKER BEAUDACITY

AURAL WHOLOSITY: This is the highest standard for any speaker and it is rare indeed. For example the newer Quad 63, sounded more aurally whole than the Quad 57, but there was a thickness over the sound; a masking and loss of clarity, relative to the '57. Most of the mods to the '63 were to diminish this masking, and many were successful. Mini-monitors can create a very authentic, but, limited aural matrix, and usually suffer in terms of tonal quality. Most high quality dual concentric drivers are outstanding in this regard..especially when they are used with tube amplifiers dedicated to each driver through an electronic crossover. One-way, like the Lowther drivers, can really excel in this arena, for obvious reason, if you can accept their eccentricities. Do not confuse "big walls of sound" that is possible with line array and planar speakers with wholosity, because wholosity is also about natural proportions.

TONE: My articles about tone are a ton of truth. Complexity kills natural tone…especially in speakers. Spurious speaker noise kills tone. Directly heated triode amplifiers have the best tone…if you use the right speakers to reveal this quality.

TIME: What time is it? Is it time to finally have time coherent speakers? The cheapest best way to get different drivers to time align…and any speaker designer can figure this out with an oscilloscope and "synchronized pulse" trigger, is to slant the front baffle, or to mount the midrange/tweeter in their own special enclosure. This is the strategy used by Vandersteen, and Alon. Using a slanting baffle also works. Mounting all of the drivers on a perfectly straight speaker face is a guarantee of aural discombobularity. When I was in into Quads 57s I created a new frame for the electrostatic panels so that they were in better time alignment.

TRANSIENT RESPONSE: Horsepower to weight ratio = speaker cone weight to magnet flux density, in the speaker matters here, and the old idea that a powerful amplifier is the key to better transient response is bogus. If the speaker has a weak magnet then no matter what you do you will never get the proper transient response. A powerful amplifier may be able to give better bass transients because the woofers electrical impedance dips down to 1 ohm, but will be mediocre in the midrange and top end, because of higher output transformer inductance. My optimal aural matrix strategy solves this problem. OTL amplifiers are the transient response Kings of tube amplifiers.

DYNAMICS: Dynamics are about music peaks, and if you want one approaching real music life at low distortion…there is only one way..with a horn loudspeaker..and it would be very large indeed. Dynamics is all about moving a large aural wave front that can start and stop very quickly. The love of large tympanic speakers is an attempt to create big dynamics, without really facing the challenge, because you are able to create a big sound field, but the dynamic range of tympanic speakers is very limited.

Quasi horn speaker..speaker that use a midrange horn, and an acoustic suspension woofer have a great challenge of matching two completely different wave fronts, that have different dynamic characteristics, and can sound very weird.

CLARITY: Nothing beats electrostatic speakers and mini-monitors for midrange clarity, at limited dynamic range, and if you are a chamber music freak, and are into the details this is a tantalizing strategy. If you want to improve the clarity of speakers, hot rod over to better quality crossover parts, rewire your speakers with pure silver solid wire, and externalize your crossovers.

WHAT IS YOUR FAVORITE SMOKE?

ELECTROSTATIC SPEAKERS: No speaker is better for small scale clarity and resolution, and demanding of a tube amplifier, because these speakers reveal the tonal Spam that sand amps produce. The only electrostatic speaker I know that is properly designed for tube amps is the original Quad 57. The Quad 63 is a transistor amp speaker, though many like to use an OTL and big pentode amps to drive it. The other well-known brands of electrostatic speakers are designed for big transistor amps because they have very low impedance and are very inefficient.

The purpose of large electrostatic speakers is to move more air because smaller electrostatic have very limited dynamic range..making them sublime for chamber music. By their very nature, electrostatic speakers can not efficiently produce the lower register. Decades of effort have been devoted to getting a subwoofer to blend with an electrostatic…. a very difficult challenge because of the big difference in radiation patterns.

Because electrostatic store so little energy the first thing you notice is that they do not have the cabinet colorations that all wooden box speakers have, and this may explain their extraordinary midrange purity.

Some comments on the very popular Quad 63: As soon as this version of the Quad appeared Quad 57 lovers flocked to the new model and then discovered that Peter Walker had….how shall I explain this?…do you know what it is like to make love with a condom on, when you are used to not using one? The combination of very heavy textured polyester knitted cover, and stamped metal protective screen acted as a major filter, and we all undressed the speaker so it could breath properly.

In time you will notice that electrostatic speaker have their own colorations especially if they are protected by a plastic film membrane to keep dust and dirt from accumulating on the membrane.

Of course there is the ultimate exotic electrostatic which is like the Beveredge Speaker that had a direct drive high voltage amplifier, which eliminated the tube amplifier output transformer and the speakers input transformer…. holy cow…talk about purity.

Okay let's talk about purity? Why aren't the input transformers of electrostatic speakers of a higher quality?

MINI-MONITORS: Talk about a category that needs development because of the enormous undeveloped potential.

The reason that mini-monitors are so cool is because they are so small and they don't get in their way..meaning big wide imaging, three dimensional sound stage, and excellent transient response. If we take the crossovers out of the cabinet, and we improve the magnet quality and efficiency of these speakers, we have the possibility of creating a new category of speakers, if…you are willing to give up bass, and more bass response, because by making these extremely inefficient speakers, more efficient we would have to give up more bass…meaning using a subwoofer…which is SOP.

Mini-Monitors need very stable heavy stands to work right.

Most of the problem of these speakers is their tweeters, because it is not easy getting a dome tweeter to sound natural.

My article which describes my suggestion of NOT USING A SUBWOOFER ON THE FLOOR, BUT ON A STAND IS WORTHWHILE READING.

Do not expect the type of dynamic range that approaches real music because little drivers can not move much air. Accept their limitations and you can be very happy.

A 10-30 watt per channel push/pull amplifier of refinement driving these speakers can produce a very pleasureful experience.

TRANSMISSION LINES: I love transmission line speakers, but none have ever been designed for tube amplifiers. Though transmission line design theory is slightly voodoo, if you know what you are doing it is possible to create a speaker that approaches the wavefront of horn speakers…in a smaller cabinet.

PORTED ENCLOSURES: This is a very tough modality for tube amplifiers, and the price we pay for their increased low frequency efficiency is their "double note" sound…we can hear the port doing its own thing, which stands out from the rest of the system.

SEALED BOX/MONKEY COFFIN: Of course there is no shape that is worse for a speaker than a box, but it is easy to make. Have you ever seen a square instrument? Yet, most attempts at creating an organic speaker box have failed because boxes look totemic, and organic shapes look like large vegetables. Getting a box to sound "unboxing" is possible, but expensive. My rule is, at the minimum for every foot of height, your speaker should weigh 25 pounds.

LINE ARRAY: A tall speaker that consists of lots of drivers has many advantages in terms of coupling to the room and creating a very wide image. The technical challenge here is getting, as many as ten drivers, to act as one. This is like the challenge facing push/pull amplifiers who are theoretically supposed to be able to divide the signal and then recombine it perfectly…NOT. In other words it is impossible to get ten or twenty different drivers to act as one because of the mechanical/manufacturing differences in the drivers, and the load they present to an amplifier. There are some very interesting line array "electro-magnetic" drivers, and they too are faced with the problem of needing to match to dynamic woofers.

THE ULTIMATE CHALLENGE

If you are stuck in the old modality of thinking about speakers separate from amplifiers and your room you are screwed.

Be especially careful in the interface of speaker/amplifier…be sure they are compatible. HERE IS A GOOD RULE:: Buy the best high efficiency speaker you can afford, because every amplifier is happier with these speakers.

You must decide what type of aural matrix you want to create, and that means you must consider the compromises inherent in the process.

 


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e-mail Dr. Harvey "Gizmo" Rosenberg: drgizmo@meta-gizmo.com

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