Walsh tweeter

September 1, 2018
 by Paul McGowan

I remember with great clarity my first meeting with Infinity founder Arnie Nudell after he left the company. My friend and TAS publisher, Harry Pearson, had called me out of concern for Arnie’s mental health hours after the incident.

“Arnie’s left Infinity,” said HP, after having tracked me down while I was on vacation in Colorado. “He’ll no doubt be devastated.  You have to help him. He’s our friend.”

Turned out that Arnie too was in Colorado, not more than a few thousand yards away from me. Infinity had been founded in his garage some 40 years earlier. It was his life, his passion, his entire raison d’être. I expected to find a broken man. What I found surprised me. Instead of depressed he was almost effervescent as if the weight of the world had been lifted from his shoulders. The first thing he wanted to show me was a new tweeter: a round ribbon he was excited about.

“The basis of every great loudspeaker begins with the tweeter,” he proclaimed, and that’s something I’ve managed to cling to ever since.

Reader Steve Bruzonsky asked me about a tweeter made famous by Infinity in its 2000 II model called the Walsh. He owned a pair back in 1974 and wondered how they worked and whatever happened to them. Here’s a picture of it.

The Walsh Tweeter is that inverted gold cone on top of the Infinity box. Essentially a standard tweeter motor of voice coil and magnet attached to an ice cream cone shape of thin metal with damping inside. Invented by Lincoln Walsh, its best known association is with the Ohm Loudspeaker company who acquired the patents. The technology seems rather simple: instead of a traditional horizontal dome acting as a hemispherical piston facing the listener, the Walsh was a vertical pump attempting a 360˚ sphere of high frequencies. Many people still covet this design though it struggled with higher frequencies because of its high mass and large shape.

The technique reminds me of another similar driver approach in the MBL speaker. The MBL incorporates the same idea of a vertical diaphragm attached to the voice coil and magnet of a standard driver. Instead of the ice cream cone shape of the Walsh, a flexible metal balloon is used instead. Here’s a picture of an MBL type driver. You can see the spider and magnet of a standard woofer that drives it.

Both are designed to produce radiating 360˚ spheres of sound pressure: the MBL as an expanding and contracting balloon, the Walsh as a rigid pump.

Of course, we understand there’s no such thing as a perfect radiator unless we want to get into massless plasma drivers which get us as close to perfect as we’re likely to come – though they are as impractical as monkeys typing novels.

A fun bit of audio history.

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39 comments on “Walsh tweeter”

  1. There was an underground movement during 76-77 promoting the imaging qualities of the Ohm F loudspeaker. Turned out they were right, it’s just that the cone-shaped, aluminum foil wrapped spherical driver rolled off @ 12khz sounding flat.

    The Infinity 2000 II inspired the Victor Brociner designed model Avid 105.

  2. “The basis of every great loudspeaker begins with the tweeter!” Is this one of those many audio myths you earlier listed here, Paul, or even an audio dogma? I doubt this is true. A great speaker starts with a decent widebander and a clever designed cabinet – crossover less of course. For a two way design a great speaker starts with woofer and subwoofer (or woofer and tweeter) best matched in the crossover region. Concentric or D’Apollito design. Phase coherency is mandatory! I never found a plasma tweeter being successfully integrated. These beasts only added some sparkle. It’s obviously some kind of mesmerising happening here.

    1. This was Arnie’s mantra and he lived by it. To him, the tweeter was the hardest thing to get right. In later years he softened that approach and began to believe that actually, it was the midbass that was the hardest to get right. He spent a lot of years n the subject.

      1. I agree. I love building loudspeakers. I have found that everything between 500 to 5000 takes real skill to get right. I frequently say to young guys on forums: “Any bozo can do bass. Mid range far more difficult.”

    1. Thanks, I needed that : ). Better way to start the day than reading the News. Again, as with The Queen, you’ll get no argument from me.

      Although….I hear that Mozart kid is pretty good on the piano. Not sure if he can sing ; )

  3. I’m afraid this post is going to start a COMPLETELY USELESS discussion about “what is most important” in a speaker, woofer, tweeter, crossover…
    Like what is the most important organ in the human body, heart or liver.
    If one component doesn’t function (well), the total doesn’t function (well).
    BTW., I remember the Infinity Monitor 2A, a tall column with the same kind of tweeter.

    1. Back in college, for some reason we used to have Completely Useless Discussions about questions like, “If you could keep only one – your sight or your hearing, which would it be? I was the only one in the room that chose hearing over sight.

      1. A real dilemma.
        I’m not sure, but I tend to think that I’d choose for sight.
        With your choice you probably bump into your turntable all the time.
        Cost you a lot of needles. (just listen to Neil Young’s “The needle and the damage done”).
        Or try to push an lp into the drawer.

  4. About 60 years ago I am sure that I read, probably in New Scientist, about a novel speaker in which the amplifier signal was used to modulate the gas flow of a burner, resulting in sound generation by the flame. I have not been able to find any reference to this; most of the links point to plasma tweeters or decorative Reubens Tubes. It would not have been a high frequency device, so would need to be complemented by a plasma tweeter, but it would provide a very memorable listening experience. Obviously the heat generation would put a class A amp to shame, and room conditioning might consist of fireproof panels. For some reason there does not seem to have been any commercial exploitation of this approach.

    1. Full range flame speakers have been scaled up to forty feet tall, but turbulence and toxicity made it impractical. I corresponded with a retired radar operator in the Seychelles who made flame speakers from a rectangular array of small jets, roughly the size of a Quad electrostat. He reported less bass and dynamic range than an ESL57, but essentially massless HF extension, probably to MHz; and of course, less inter-modulation than dynamic tweeters and inherent linearity. His environment was quiet enough they were optimum for orchestral music, and most days he could leave windows and doors open.

  5. Paul,

    I really enjoy the reading your history of audio technology posts.

    No design ideas are ever completely original. We all build on the successes and failures of the geniuses and crackpots that preceded us.

  6. The Ohm F was the speaker that many of us lusted over back in the college days. We had a couple on the dorm floor and guys would go down to have a listen with complete fascination. I never did own a pair, although have watched local auctions from time-to-time in case a set pops up, which they did a few months ago but they were in horrid condition based on the photos (had lived in a damp crawl space for years it seems) but still brought $700 at the auction. The company is still in business actually, hand-making speakers in New York (ohmspeaker.com). I didn’t realize this either until I was in a neighbor’s the other day and he had a set of Ohm speakers he said he just bought last year new, they sounded quite nice in his living room.

    On another note, about technology, I got a notice today that Yamaha is coming out with a turntable this month that is totally Wi-Fi, including all the streaming services built into the turntable. You can place it anywhere and then stream via Bluetooth to your devices the vinyl or stream from services. It has a phono stage too so you can connect it to legacy equipment and add streaming to that. I found that an interesting use of the Wi-Fi and BT, is anyone else doing this? This turntable and a pair of amplified speakers and one is all set I guess. They ship it with an Audio Technica cartridge but don’t say which one.

      1. Great minds, etc
        You’re best off getting someone else to do the table and arm. Look at Harmon’s Levison tt, designed by VPI, with a price that would make me just buy the VPI. If it was me I would try to work with the EAT people. They are putting out some nice tables that seem under exposed.
        After the speakers and Octave, a PSA turntable, one stop shopping.
        Imagine the package deals, from the Sprout, to Stellar, with a top of the line BHK, P20, AN1 system. Include the cables, and you have turnkey systems.

    1. I can predict that it will be s cheap cartridge, and the last place you would want that other stuff.
      If you were willing to have a turntable with a separate box, about a meter away, connected by two cables, that could be a decent device. If you care about SQ, you don’t want any extra gadgets attached to the table, but as a “lifestyle” product it may be a success.
      I always hope that people who start with these products will get the desire to upgrade. They don’t all need to be complex, just better.
      I know I am a dinosaur, but I like a system that any idiot can not operate.

      1. It looks like the price point is $700 so of course it will not be top-shelf cartridge and it just plugs in from the photos without any separate power supply or box. I submit it will be better than those Crosley groove-grinders though and will be able to take an upgraded cartridge. It looks like it is designed to be nice and tidy! I could see it used with a Sprout actually to provide streaming services and network radio and app control. I’m with you, that it’s nice to have things that are easy to operate. There is no app so far that will remove the vinyl from the sleeve and put it on the table however, still need human intervention for that (oh, wait, that is what streaming is ha ha). Have a great day.

        1. Someone needs to build us an Audiophile Jukebox that handles 12” LPs along with 45s and maintains them in a temperature and humidity-controlled cleanroom environment, just add the TT of your choice : )

          But I would actually miss the process.

      1. While that may be true, I am all for any product or medium that moves people beyond the standard crappy earbuds or playback device. Someone out there will use something like this and then think “is there more” and will move beyond to become an audiophile hobbies! Anyway, that’s my profound thought of the day!

  7. “The music is in the midrange” – Paul Klipsch

    This is confirmed by Greiner & Eggers compilation of spectral content of music recordings. Most genres of music look like pink noise with a peak in the speech frequencies and a steep high pass around 80Hz. Piano in particular is nearly all midrange, with the sound board rolling off the highs and lows.

    Human hearing mechanism is most sensitive between 300Hz and 4KHz, the “speech frequencies” that were the focus of Bell Labs. Bass and treble are afterthoughts to pick up danger signals from Nature. Our hearing is much better at fine time differences, phase and transient waveforms than decoding tones above and below our physical bandwidth.

    Consider that our neural processing has better than 3 microsecond discrimination of sounds starting and stopping, some forty times faster than the corner frequency of ears and eight times typical tweeter response. Besides, if tweeters are so important, how come most of them are too small and too slow to reproduce real musical transients?

    Arnie was tuned in to this, because he was always experimenting with BIG tweeters like electrostats, EMITs and Walsh. All of these have tradeoffs, which were surpassed by Heil tweeters – the only kind I use to listen to music. Arnie came to the same conclusion. Now about that midrange…

    1. While the amount of energy in the top octave to octave and a half is small, the difference it makes is astonishing. Not only is its presence or absence easily noticeable but all other aspects of it are also subjectively very critical and small changes to any of them makes a big difference.

  8. Paul
    I maybe wrong but I believe it was at CES in Chicago in the 70s there was prototype Plasmatronic speaker system I recall a very eccentric inventor named
    Dr Hill ?? The reason I recall it he and the speakers were crazy looking :!)

    1. Hill Plasmatronics. Dr. Hill was was a research physicist (atomic) at Los Alamos, New Mexico. At the Chicago show I spent some time with him and after that show he dropped the speakers off at my store (Speaker Craft) in St. Louis. They used ionized helium plasma in a small horn for frequencies above 600 HZ. They did some amazing things sound wise.

      On his way back to New Mexico he dropped them off in St. Louis and I later sold them.

      Their greatest problem was the large tanks of helium and the by-products from the ionized gas and the ozone by products.

      1. Thanks edM
        For the clarification it had to be one of the most unusual speakers I had ever seen!
        The fact that you had a pair is even more fascinating were they even UL approved ?
        I do remember the Helium tanks . Dr Hill was having an issue at the time so never actually heard them always regretted that 🙁

  9. There are no spherical or cylindrical nearfield wavefronts in Nature. Musical instruments are typically quasi-dipoles, horns or flexible membrane monopoles. The exceptions to this are bar type resonators and wind instruments with tone holes, which have highly asymmetrical spatial patterns, and the latter large scale irregularities that change from note to note. Therefore a radially symmetric radiator like Walsh, MBL and Gallo resembles no known musical sound sources.

    A 360 degree tweeter also maximizes room reflections, which wreaks havoc with frequency response and spatial perception in lieu of covering all walls plus ceiling and floor first reflection points with ab/fusing acoustic material. Metallic diaphragms also have nasty resonances, which I heard in Walsh and MBL speakers.

    The Linaeum tweeter was a much better approach, but escaped widespread usage through odd channel selection.

    Note: there is a “Laptop Orchestra” that uses Walsh speakers, although most use conventional powered two way monitors, hemispherical or spherical speakers. None of these are correct.

  10. Paul,

    Am I missing something here? You state that Arnie had left Infinity when he came up with the idea of using the Walsh tweeter. Yet the Walsh tweeter was in the Infinity 2000IIs that I bought new in 1975 (I had said 1974, but I’m gettin’ old. Now I recall it was 1975 about five months before I moved from Minn. to DC to start law school). So did Infinity get the idea of the Walsh tweeter and the design of the 2000II speaker from Arnie before he left?

  11. The MBL driver is peculiar. It’s like a hollow melon rind that has been sliced from nearly the top to nearly the bottom in segments. The magnetic field created by the voice coil on a pole down the center pushes and pulls the segments up and down. As the center segments push air out, the top and bottom pull air in. So the sound wave goes from 0 phase around its equator to -180 degrees at its north and south pole. Roy Allison had a similar idea in the 1970s for his own tweeter with even wider dispersion than his AR3a tweeter. the top cap of the hemisphere was attached to the bottom part of the dome by an elastic membrane. The voice coil was attached to the perimeter of the top cap. When the top cap moved forward, the perimeter equator pulled in. Again the movement of the cap of the dome was 180 degrees out of phase with the base but in this case the phase transition was abrupt. Do these tweeters make sense? Are they any better than dome tweeters or other types like ribbons?

    I will agree with one thing, if you don’t get the treble right nothing else matters. As hard as the bass is, the treble is even harder and more important. In my own experiments I’ve discovered that a directional array of inexpensive tweeters, in my case 3/8″ polys, the kind you see everywhere because a gazillion of them were made and sold can best produce the sound fields I need to achieve my goals. That’s why there are 600 of them in my basement. For about 200 of them I paid 28 cents each and for 400 of them I paid 5 cents each. The first six I bought were about 11 dollars each. The first manufacturer of these drivers was Audax. they have a small diffuser over the cone which looks like a Mercedes Benz emblem. There are many different variants but I stay away from the metal cones and the silk cones and I favor the smaller drivers over the larger 5/8″ and 3/4″ variants although that probably doesn’t matter much. The power handling advantages of these drivers in multiples is the same as the advantage IRS V has. Each one is rated at 30 watts and an FR down to about 3khz. They are never crossed over at less than 6 khz the way I use them and I only use a single series capacitor. Dispersion can be anything I want it to be. They can be arranged to play at different loudnesses and crossed over at different frequencies in the same system. They also create the high frequency reflections that are inadequate or even missing altogether from commercially bought speaker systems. By my way of thinking IRS V does not produce nearly enough high frequency reflections. So these tweeters not only overcome the shortcomings of the speaker system’s own tweeter but they compensate for the frequency selective reflection of the room boundaries. No matter what geometry I use, they can all be in the same phase over their entire range and in all directions. In the case of altering Bose 901 the high frequencies travel the same paths as sound from the rest of the system. Getting that one right was a bitch and a half. That’s why it took 4 years.

    One interesting thing about them, no matter how many of them I put in parallel, they don’t seem to bother any amplifier I’ve ever connected them to, even inexpensive receivers rated to not handle less than 8 ohms.

  12. Nelson Pass on his plasma loudspeaker made from photo copier elements. (It produced ozone in quantities that were dangerously hazardous to one’s health.) :

    “It was the perfect high end audio product: Exotic, inefficient, expensive, unavailable, and toxic.”

  13. Of course the beauty is in the midrange. The test of any speaker is the human voice and last I heard that was in the midrange. Its called midrange because its in the middle, and what’s in the middle tends to be rather more central to the issue than what’s at the extremes. If you’ve got rubbish midrange nothing can save a speaker from the skip.

    There are serious leading speaker companies with proprietary midrange drivers that are the basis of their brand, who are quite happy to get others to make their tweeters, to their specification. Can’t think of any that built a reputation based on their tweeters.

    1. While they certainly didn’t build their reputation on them, Vandersteen’s carbon fibre tweeter is considered by those who are fans or owners as the final detail. He was one of the first I was aware of with powered woofers that offered a lot of analog adjustment. I believe Richard and maybe one other person is capable of building those tweeters.
      I personally prefer the various ribbon tweeters.
      Now Vandersteen sells a tube amp that is only for the Model 7 version 2. And he has completed a solid state amp that I briefly heard with the Quatro. I am sure they will work with the 5a too. If you buy the amp for the 7 it includes a pair of speaker cables.
      The only difference between a self powered speaker is that each component is in a separate enclosure with no dsp.
      He perfected bass in his own way, then developed the carbon midrange, and finally the tweeter.
      Your statement is still correct, I just think his carbon tweeter is pretty special.

  14. Every part of the audio spectrum influences the other parts which makes them all quite important. Most of the music lies in the mid-range but the low and high frequencies have great influence on how it sounds. To get a really good sounding mid-range one has to have really good high and low frequencies. No cutting corners across the entire frequency range if one wants really good sound. Also, the entire frequency range has to be uniformly good. Put a much superior tweeter with an inferior mid-range or a superior mid-rage with inferior low frequencies and the discontinuities become audible immediately. Well balanced audio spectrum is the key to good sound. Of course better the sound more expensive the parts used. No free lunches. Regards.

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