The Ohm A's used two different sections of cone and the F's used three different sections of cone, all seemed together mechanically. The Ohm A's had a larger cone with a non-linear flare rate whereas the F's had a smaller diameter cone that maintained the same flare rate for the length of the driver. The differences in materials, cone mass and driver geometry all add up to differences in radiation pattern, transient response, etc... As such, even though the A's and F's are TRUE "Walsh drivers", even they differ from one another in design and performance.
As a side note, the Ohm G used a smaller version of the Walsh. Due to the cabinet design, the radiation pattern was not nearly as omni as the A or F. This not only changes the sound that one hears, but also negates many of the spatial properties that make the Walsh design special.
Due to using a smaller cone with the reduction in piston area, Ohm was looking for a way to augment the bottom end of this driver. They did this via the use of a passive radiator. Passive radiators have the slowest transient response of any vented design*. As such, the bass on such a design typically sounds very "heavy" i.e. thick and powerful, but lacking in definition due to slower rise times and a lack of damping i.e. excessive "ringing" once excited.
While passives are great for HT use where "earth shaking" bottom end is more desirable, they really have limited use in a "hi-fi" system. Passives are, once again, another form of venting that achieves "quantity" over "quality". Sean
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Sean, I purchased my first pr. of OHM WALSH on Nov.3 1987, the 4-XO's. A Technical White Paper came with those speakers to explain too the purchaser how they operate and here is what it says in part....
This cone is fabricated of special materials which have a super-sonic velocity of sound propagation. By engineering the cone angle and propagation velocity properly, a coherent, cylindrical sound field is synthesized in the air around the cone; the listener, in fact, receives simultaneous sound.
As described previously, the apex of the cone is initially dent, and a sound-wave originating at the apex moves into the air at 1100 feet per second. Similarly, every point on the cone contributes its output at exactly the right time for ALL the wavelets to coherently merge into a cylinder, as shown in Figure 3. Wherever the listener sits, all the sound produced by one pulse reaches the ear at the same instant. There is no "time-smear" or "time-delay distortion". END QUOTE
That is a description of a Walsh driver; the angle of the cone is just different from the F's angle because the material used to make the cone is different. The speed in witch sound travels in materials is dependent on what kind of material is being used and the cone angle has to be adjusted accordingly. This is why the angle of the cone in the newer Walsh drivers is different from the F's cones.
Just because the newer Walsh drivers are not mounted on a sealed cabinet does not change the fact that the driver itself is operating as described above.
What Eldartford said:...That there is a mechanical crossover at the point where the two dissimilar materials meat, is indeed a crossover. |
Line: Stop reading and believing the propoganda put out by various manufacturers and start learning for yourself.
Pull your Ohm's apart and find out what you've really got once and for all. Once you find that out, maybe then you can tell us what the "special materials which have a super-sonic velocity of sound propagation" really are.
I'm not certain that i'm ready to hear or experience a "sonic boom" up close and personal. Sean
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Sean, The term "super sonic" literally means faster then the speed of sound in "air". Sound travels faster in solids then it can in air. Therefore the sound wave traveling down the cone material of a Walsh driver, is at "super sonic" speeds. This is a scientific fact. How much faster the wave travels down the cone depends on the material being used to form the cone and the speed determines the angle of the cone. The correct angel lines up all the waves generated in the air to form a single coherent sound source, with no time-smear or time-delay distortion.
Sound travels at different speeds in different materials such as steel, plastic, water, air, etc. No, it does not create a sonic boom because there is nothing traveling in the air itself at "super sonic" speeds, the wave is traveling down the material. This is how the F's work and all speakers that work on Walsh's principal. |
Line: I understand this and was joking. One of the basics of physics teaches how sound conducts through various materials, etc.... I'm sorry if my attempt at levity failed and / or was unclear. What i was attempting to do was to show how marketing can be used to manipulate one's point of view and understanding of a subject, let alone bamboozle one into thinking that they have something other than what they really do.
As to the drivers having a mechanical crossover, this is true. Due to the aforementioned differences in conductivity of materials, the rate of transfer between them will come into play. As i also mentioned, the flare rates on the Ohm A and F drivers themselves are different.
Like i said, look inside of the mesh can. There's a reason why these speakers are built in this fashion. After all, we all know that placing a grille in front of a driver changes the sound, so do you really think that placing all of the drivers behind a resonant metal screen would be of benefit to the sonics? Could it be that they simply want to keep something "secret"? Do you really think that there are no user serviceable parts inside? Sean
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Where does German Physiks come into the discussion? can any comment on their version of the walsh driver. i have read that they are a great speaker however i've also read that the drivers were prone to warpage. |
Here is a link to a description of the 'bending wave DDD driver'
http://www.german-physiks.com/NewFiles1/DDD.html |
That post didn't look like a joke, so I did a little research too find out just how fast sound does travel in some of these materials and here is a little of what I found...>> In general, sound travels fastest through solids, slightly less fast through
liquids, and slower through gases.
This is because the particles (atoms or molecules) in a solid are touching
each other and rather fixed together. That is why a solid is "solid." Since
the particles are bonded together, a sound wave moving one, immediately
transfers the motion the one touching it. A sound wave hitting one, is
almost immediately transferred to a neighbor.
In a liquid, the particles are touching each other, but they are not fastened
to each other quite so strongly as they are in a solid. Some of sound's
energy is wasted pushing the particles around because they can slide past
each other. Some of sound's energy is wasted that way and that is why it
moves slower.
In a gas, the molecules are rather far apart. For sound to travel through a
gas, the molecules must move quite a distance before they collide with other
molecules. Sound energy cannot move as quickly when the molecules are not in
contact with each other. Here is another from a different site...>> In air at room temperature, sound travels at about 340 metres per second. In water, sound travels about four times as fast as it does in air, while in steel, the speed of sound is about fifteen times as great as in air. Here is one I found interesting,..Why do we sound like Donald Duck when we talk with helium...>> We talk like Donald Duck because sound travels faster through helium and, in effect, shrinks our heads.
When we speak, the sound speeds from voice box to lips. Since sound travels faster in helium, the sound reaches our lips sooner with helium than air. Its as if the path were shorter. The faster sound speed raises the resonant frequency of our vocal tracts. We, sort of, become Oz Munchkins with high squeaky voices.
Every pipe, from our vocal tracts to an empty Coke bottle, has a resonant frequency. Blow air across a bottle. The deep sound we hear is the bottles natural frequency in air. Fill the bottle with helium and blow across the top. Now, sound travels faster and the tone sounds higher. The resonant frequency of a tube depends on the length of the tube and the speed of sound through it. The faster the sound speed, the higher the frequency. Well anyways, I bought my first pr. of Ohm speakers from a big box store called ABC Wharehouse purely on what I was hearing out of them, and at that time I did not know what was going on under that can, just liked what I was hearing. Some 15 years latter, I started hearing something that I should not be hearing out of one of them, so I opened it up and found the surround tore and replaced it with a new one. I left the can free so I could slip it on or off any time I wanted to. "And yes, I always wondered what they would sound like with the can off." So, many times I would listen for a different in sound between the can off and on, and I could 'not' here any difference. The driver is not a mass projection driver; this is very apparent when it is looked at. They look hand built, and I believe they are. This tells me that this driver is NOT ordinary. No; I can not know what is going with this driver by looking at it. The cone is some sort of plastic, the magnets look massive, and the can is essential to protect some kind of (what I believe to be) some kind of sound absorbing material that is placed is certain places. The driver is not pretty, in fact, I think it is ugly, but it can't be seen anyways. I don't have the XO's anymore because I upgraded too the Walsh 5 Mk-2 drivers and mounted the on the original trapezoid cabinets. I do not know what the new divers looks like with the can removed. Now Ohm does have models that are box speakers, and I would bet that the drivers in them are production speakers, (not hand built). Sean, I have a question for you...Do the F drivers have a spider? I think that they would have to. |
http://fullrangedriver.com/forum/viewtopic.php?pid=6485If you read this thread, you'll find someone else commenting on the type of drivers used in newer production "Walsh" series. For the record, i never posted to this thread in any way, shape or form, even if one of the participants shares the same name. As a side note, there's a "funny" story pertaining to the design motivations behind Decware's "Radial" speaker mentioned in this same thread. John, the owner of Van L Speakerworks ( aka Chicago Speakerworks ) had previously verified to me that newer "Walsh series" used conventional design woofers firing face down into the cabinet. He has re-foamed many of these drivers over the years. Yes, the F uses a spider. Sean > |
Sean, I appreciate you sharing your knowledge, but there is something I don't understand after reading this quote from the German-Physiks files. The transmission line type has commonly employed a steep, straight-sided cone and a fairly conventional voice coil and magnet assembly. But where it differs from an ordinary mass loaded cone is that the diaphragm is securely anchored at its mouth and flexed by the motions of the voice coil rather than pushed to and fro. Sound propagation is normal to the slope of the cone rather than parallel to the path of the voice coil in the gap as is the case with a mass loaded cone. The diaphragm is securely anchored at its mouth. Wouldn't this mean that there is no spider employed ? And is sounds as though there is no surround employed ether. What I am trying to get at is; the F's do employ a spider and a surround, and I am wondering if the sound emanating from the F's is a mix of conventional speaker sound and transmission line sound. What do you think? Am I missing something? |
Sean, Glad you are looking at this thread again. Not being one to accept all claims, I decided to do some investigating. First, I wanted to find out just what constituted a Walsh loudspeaker. I looked up the Patent #3424873 (in case anyone is interested) and began my research. The following is from the Abstract: "Abstract of the Disclosure The coherent-sound loudspeaker is a development derived from a theoretical concept of ideal sound reproduction by means of a conical diaphragm operating as a wave transmission line. Such a conical diaphragm will produce sound as it would be produced by a small cylinder pulsating radially with every portion of its area moving in and out simultaneously, and in phase with the input audio signal. This is coherent sound. The requirements of the theoretical concept are closely approached by a sound producer of the following character: (1) The angle of the conical diphragm, measured from a plane perpendicular to its axis is quite high, causing the speed of the mechanical vibratory waves in the diaphragm to be greater than the speed of sound in air, and to have a component in the desired direction of sound radiation equal to the speed of sound in air. (2) Absorbing material absorbs the wave energy in the diaphragm to eliminate or minimize wave reflections from the non-driven end, so that a vibratory wave transverses the diaphragm substantially only once. (3) Sound is radiated to the listener only from the convex side of a vertical conical diaphragm to obtain full frequency range, high quality sound omnidirectionally from a single radiator." Four models are mentioned in the patent. Models B and J's diaphragm were made of felted fiber. Models L and M's diaphragm were made of aluminum. Other variations between the models are described. If you want to know more about them, lookup the patent (it's in file DImg-11.tiff). Quoting from the results: "The low end of the useful frequency range of all of these loudspeakers is approximately 40 cycles per second. The upper end was about 14,000 c.p.s for Models B and J, 16,000 c.p.s. for Model M and 34,000 c.p.s. for Model L. The frequency range of the Model L extending to 34,000 c.p.s., well beyond any person's audibility limit, confirms the theory that this new loudspeaker can be designed for any frequency range desired, although at some sacrifice of efficiency for wider ranges." Throughout the patent, several items are mentioned to "fine tune" the design. One item is the basket for the driver. Normal drivers usually cover 30% to 100% of the convex side of the driver. A Walsh driver should be obstructed by less than 20%. The only other item I will mention is that the angle of the conical driver must be at least 50 degrees. From the patent, I have concluded that only the Ohm A and F meet these criteria. The Ohm G is a hybrid version and is therefore not a true Walsh loudspeaker. (as you have already said) All of the other models are not "true" Walsh loudspeakers. However, a Walsh driver can be "designed for any frequency range desired". So the claim that Ohm's "Walsh" line of speakers use a Walsh driver could be true. I had asked a question earlier (please see prior post) that if Ohm is not using a Walsh driver, how could they reproduce the midrange using a downward firing driver? (still looking for an answer) I went looking for any photos that would help verify Ohm's claim and I came across these Ohm FRS 11's (I think). From Ohm's website: "The FRS-11 is a tall square tower with each corner cut about 2''. One of the cut corners displays the Ohm logo near the top, just below the grill. The FRS-11 is a true Walsh speaker designed for small to medium sized rooms. They create a precise stereo image from a very wide Sweet-Sweep. We call the effect Full Room Stereo and we named it after this benefit." Looking at the picture, if indeed this is an unmodified FRS 11 (except that the diffusion cans have been removed) there is no Walsh speaker/driver to be seen, and it is truly just a conventional woofer/tweeter combination. My question now is, is it ethically, morally, politically... correct to keep calling the line a Walsh speaker? |
Jamscience, thanks for the patent info. and picture.
One thing I would like to say, is that the cans are not diffusion cans, they are as transparent too sound as grill cloth is. |
Jamscience: Thanks for all the research and leg-work. I have to agree with all of the points that you brought up. That's one of the reasons why i've "harped" so hard on the fact that these units are NOT actual Walsh drivers. This can be seen on the Ebay photo's that you provided for us. All i can say about that one is that if they had shown the other side of the speaker i.e. where the crossover network is attached, most people would be appalled.
As a side note, these drivers do appear to have some type of a "plastic" based cone material as Line described above. This would lead me to believe that they are the original equipment as supplied by the manufacturer.
As to the basket design, Ohm used two different baskets on the F's that i'm aware of. One has very "skinny" flat metal rails with wood glued to them to damp their resonance. The other has much wider "U" shaped metal channels with wood glued inside of the channel. Common sense would dictate that the thinner rails would cause fewer problems so long as resonance induced ringing was controlled. I have a set of each and to my ears, the thinner flat rails sound better than the wider "U" shaped channels.
As far as the Ohm G goes, i think that it is a Walsh driver by basic design, but i'm not sure about the flare rate on the cone. It obviously has a LOT less surface area than the Ohm A or Ohm F Walsh drivers. The "standard" cone driver that you see in the G cabinet is a passive radiator, not a driven woofer. I've never seen one of these in person though, so i'm kinda sorta guessing on this one based on photo's / technical info that i have.
As far as treble response goes, the internal factory wiring in the F's did a number on that. I would recommend plugging your speaker cables directly into the Walsh driver itself, which bypasses the internal wiring. I could NOT believe how much the 2 - 3 ft of internal wiring could demolish the sound after hearing the difference. I also have some Walsh "tweeters" that Infinity made, but i've never tinkered with them.
Once again, thanks for the legwork and sharing this info : )
Line: The info from the German Physiks website that you quoted sounds more like the design ideas behind the Manger driver than the Walsh design. How someone that manufactures a Walsh based product could confuse the design and description of operation is beyond me. Then again, they are a German based company and maybe something is getting lost in the translation.
As to your comment about the cans NOT acting as diffusors and being acoustically invisible, i almost had to laugh. Just placing a very thin layer of felt on the baffle around a midrange and / or a tweeter can cause major differences in reflections, diffraction and frequency response. This is VERY measurable in most cases and easily audible.
If you don't think that surrounding a driver with a perforated metal screen and placing it directly in the firing path between one's ears and the drivers would make any audible difference, you should think again and / or have your hearing checked. I don't mean this to be rude, but that screen also has grille cloth material in it, making an even bigger difference at high frequencies. Sean
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Line, Sean, Your welcome. As I stated before, I am just searching for the truth. Line: One thing I would like to say, is that the cans are not diffusion cans, they are as transparent too sound as grill cloth is. Sorry, I have to agree with Sean on this one. I know of no grill (cloth or metal) that does not affect the sound in some way. (of course I have not heard all speakers with and without grills; I could be wrong, I could be right!) ; ) Sean: As far as the Ohm G goes, i think that it is a Walsh driver by basic design, but i'm not sure about the flare rate on the cone. It obviously has a LOT less surface area than the Ohm A or Ohm F Walsh drivers. The "standard" cone driver that you see in the G cabinet is a passive radiator, not a driven woofer. I've never seen one of these in person though, so i'm kinda sorta guessing on this one based on photo's / technical info that i have. Yes, the Ohm G does use a Walsh driver but is not a "true" Walsh loudspeaker since it uses the energy from the concave part of the driver to power that passive radiator. (I am being a stickler to the original parameters of the patent) I also have some Walsh "tweeters" that Infinity made, but i've never tinkered with them. I almost bought a pair of Infinity's with the Walsh tweeter back in '76. I wish I had, it would have saved me money on a Transcriptors Skeleton turntable! (They were both part of a system I was pondering at the time) If anyone is curious about the Walsh Loudspeaker, I encourage you to take a look at the patent (see previous post). There is a lot of technical information there but there are also things such as: " A single very large coherent-sound loudspeaker might be built to serve a stadium of 100,000 listeners with high quality music and voice. It might have a vertically oriented conical diaphragm with an angle of 60 to 80 degrees, a diaphragm diameter of approxmately 60 inches and a height of 60 inches. The diaphragm might be of a composite aluminum and elastomer to substantially attenuate 16,000 c.p.s. waves in a vertical distance of 3 to 6 inches, and 4,000 c.p.s. waves in 12 to 14 inches, to obtain good diffusion of sound vertically. It would inherently have uniform diffusion in all directions horizontally. Its frequency range might cover 60 to 16,000 c.p.s. and it could handle well an electrical input of 500 watts with extremely low transient effects and other types of distortion. Its uniformity of response might well be about 1 db over the rated frequency range." I would love to see this become reality! Any takers? Also, any takers on my question; is it ethically, morally, politically... correct to keep calling the line a Walsh speaker? |
Very nice information being posted. Thank you.
Question - What is preventing a Manufacturer from building an authentic Ohm F again?
Is it the licensing?
Is it the technology?
Is it the patent?
Is it the cost of producing them correctly?
What is it?
It has been approximately 30 years since they first appeared with such great potential, but later proven to be flawed. Why hasn't someone taken today's computer based designing techniques and applied them to this speaker in an effort to make them a reality. IMHO, there would be a viable market for them in 2-channel as well as HT.
I would definitely put my name on the list of future owners if they weren't priced ridiculously. Heck, when I purchased them in 1974 I was just out of undergraduate preparing to go to graduate school. IOW, I was flat broke but had the foresight to scape enough coins together to purchase them. I now have a coin jar spilling over. LOL |
Lngbruno, I believe that Ohm has claimed that their original technicians have all retired and that they could not find suitable replacements. German Physiks have done just what you have suggested. The German Physiks speaker line does deviate slightly fom the original Walsh description. Most are augmented with additinal woofer/sub-woofer(s) with added cross-overs. Some use mulitiple Walsh type drivers. Most would consider their offering on the expensive side.
All in all, I agree with you complelety. While I haven't actually heard them in decades and I don't trust my memory of those experiences, the Walsh drivers still look like the most promising design to date. I would imagine that they may even be more relevant today than yesteryear. |
If anyone has any doubts about what exactly constitutes Ohm's new version of a "Walsh" speaker, check out John Strohbeen's Patent #4440259. It is all spelled out. (Click on the images button to see the drawings) |
This type of design would have to be hand built using custom parts i.e. minimal off the shelf componentry. As such, it would be a relatively large economical undertaking for someone to attempt as compared to starting up a speaker company that uses off the shelf parts. On top of that, the market for such an item isn't all that big in the grander scheme of things, hence the lack of anyone jumping in with both feet.
Having said that, i can see this type of thing taking off if someone were to build "one off" products out of their garage. That is, IF they could achieve the type of results that we know this design to be capable of AND doing so with a high level of consistency. I have thought about this myself, but not too seriously. Sean
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PS... Due to their radiation characteristics, these speakers are more difficult to set up. They also don't have a high WAF due to the placements required. This further limits their marketability. |
Jamscience, now we can argue over...'Is John actually marketing what he had patented .
When I said, "the cans are not diffusion cans", what I meant is that the meshed cans are not employed to create a the widely dispersed sound that they are know for. That widely dispersed sound is still there with the cans removed.
And what I mean by acoustically transparent is...If I were to put a singing canary in one of those meshed cans, I personally, would not be able to distinguish a difference in sound of the canary, (Is the singing canary in or out of the can?). Similarly, when I am inside the house listening to birds that are outside through an open window, I cannot distinguish the difference in sound weather there is a screen on that window or not.
I did eventually affix the cans back over the drivers for shipping purposes, they would be more vulnerable to damage without them. The foam that lines the interior of the cans is there (I believe) to help keep out dust and potato chip crumbs etc. The foam is thin, in the area of 1/32" or 1/16".
I know what the Mk-2 driver looks like, because I can see it without removing the can with the use of an LED flashlight, and the picture Jamscience posted of the FRS-11 is reminiscent of the Mk-2 in looks. The sound absorbing material that is so unattractive is no longer visible; the driver is no longer ugly. The tweeter and it's mounting DO look quite different from the picture of the FRS-11. The tweeter and it's mounting is now much more attractive.
I do not know which earlier models are ugly, except for the one's I had, which were the 4XO's. |
Unsound, thank you for pointing out the German Physiks again. I guess you must own a pair of their speakers. So, I will ask if you ever had the Ohm F's and would share your thoughts on how they are similar or dissimilar in overall sound? I am interested in a true Walsh driver, which has no crossover and stands up to the riggers of day-to-day performance.
Sean, I do recall from an earlier thread/post about you contemplating the possibility of taking on this type of project/venture. It would be nice if one of the smaller DIY companies out there would take this on. I mean between you and Bill Legall, there is a wealth of knowledge that could be shared with the right party. Right? When I look around Audiogon, Audio Circle, Audio Asylum, and other sites, I see dozens of sole proprietor speaker builders. Heck, with China now very serious OEM electronic/speaker builders, one might subcontract them to build the drivers by hand and have the bases built here in the States, or visa versa.
Someone out there must know someone who skilled, talented, and would be curious /willing enough to take this challenge on.
What was the MSRP of the Fs back in the mid to late 70s? I cant recall because when I purchased mine pair it was part of a package deal which included an amp and preamp and I traded in a pair of EPI 201s (another great speaker in its day). |
Lngbruno, I have never owned Walsh or German Physiks speakers. If I could afford them the Huffs would certainly merit an audition. |
To complicate this subject even further, IF I understand this link
http://home.swipnet.se/~w-61372/artiklar/article3.htm
correctly. DDD's generate (what I would call) surface wave ON the cone, like waves on the surface of water and the Ohm F's generate (what I would call) compression waves IN the cone, like two cans and a string. (If you don't know what I mean by two cans and a string, here is a link.
http://home.swipnet.se/~w-61372/artiklar/article3.htm
The DDD's and the F's generate sound in two distinctly different ways. I believe the DDD's do not have a spider or a surround for that very reason. What do you guys think? |
Does anyone know if the DDD driver used by German Physiks has any built in mechanical cross-overs like the Walsh driver used by Ohm? |
Sorry: I posted the wrong link for 'two cans and a string'.
Here's the right one.
http://science.howstuffworks.com/question410.htm |
Unsound, reading this over, I could not find any signs of mechanical cross-overs.
http://www.german-physiks.com/NewFiles/WhiteBook.html |
Lngbruno: I have all of the various Audio magazine buyers guides dating back to the mid 1970's. If you give me a specific year, i'll look up the MSRP ( Manufacturer's Suggested Retail Price ) that Ohm submitted for that given year. I had a 1980 "Complete buyers guide to stereo / hi-fi equipment / speakers edition" handy and it showed a price of $2300 per pair. This was using the standard finish with other finishes rising in cost.
Having said that, i have talked to MANY people that have told me that the F's were marketed at WAY, WAY above MSRP by specific dealers i.e. much like Harley's were in the past. Due to their unconventional looks and specific performance attributes that no other speaker could match, some dealers jacked the price of the F's WAY, WAY up. This not only made them appear to be even more "exotic" i.e. the average person couldn't afford them, but also made them more desirable for those equating price with performance.
Between price gouging and discounting, MSRP's are simply a reference point that may / may not be of any value. Some look at it as reference to deduct percentages from, others ignore it all-together and charge what the market will support.
Line: The German Physik's DDD driver HAS to have some type of suspension to it. You can't rigidly mount the mouth of a dynamic driver and expect it to work for any period of time, especially if feeding it any type of measurable power. The fact that you have to displace larger quantities of air also dictates that the driver has to be able to move a reasonable amount in order to produce "reasonable" spl's. If the drivers were rigidly mounted at the mouth and driven by a free floating voice coil, they would literally be "trembling" or "ringing" when fed signal. The end result would be a driver that was phenomenally limited in output, extension and linearity.
The bottom line is that you are reading WAY too much into the marketing hype from a couple of different manufacturers. Sean
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Sean, I examine it, question it, go into it and find out on my own whether what I read makes sense to me and so far, it does not.
I agree with you on...how could reasonable SPL's be achieved without suspension. But on the other hand "with suspension", what is the cause of increased SPL's? You said yourself that the wave alone could not achieve the necessary SPL's. So I wonder if the sound being emitted from the cone is a mix of wave transmission line and conventional piston action? I do not know what else could be responsible for the higher SPL's.
I looked at the Ohm 5 Mk-2 again and there is no longer any back damping. It is omnidirectional now except for the tweeter. The can measures 9 3/4" high and the bottom 1/3 of the can is omeni, 360 degrees.
Sean, how far from the back wall did you position your F's? |
Warning! Ohm posting that failed to, well post. (Sorry, some of this was written 2 days ago and I am trying to catch up.) This is a recreation of what I think I said: Line: Jamscience, now we can argue over...'Is John actually marketing what he had patented . No way, no, no, NO! And my Mom says you can't make me! ; ) BTW, I think someone just put up a pair of 4XO's on eBay. Lngbruno: What was the MSRP of the Fs back in the mid to late 70s? According to Ohm: Production Period 1972 - 1984 Nationally Advertised Price originally $900 - $3995 per pair Question - What is preventing a Manufacturer from building an authentic Ohm F again?
Is it the licensing?
Is it the technology?
Is it the patent?
Is it the cost of producing them correctly?
What is it? IMHO it is the cost associated with building them. I am not a lawyer or a telephone sanitation engineer, so please excuse any mistakes I may make and feel free to correct them. The patent ran out in 1989 (20 years if you keep up with the maintenance fees). (I personally believe it should be 42 years) :) If I understand correctly, once a patent is up, anyone can create that object according to the patent. If you modify it in any way, you have to apply for another patent or risk having someone or corporation competing with you using your modifications. I have a problem with Ohm's excuse of running out of craftsmen to build these speakers. People can be trained to produce just about anything. It's just a matter of time and money. I also realize that it does cost a lot more to have something built by hand instead of by automation. John Strohbeen's patent refers to the cone and voice coil in the original Walsh patent as being expensive to manufacture. My take on this (and this is only opinion) is that the bottom line was being eaten up and to justify continuing to produce a "Walsh" speaker, a new design was needed to be equal in performance but less costly to make. Whether they succeeded is a matter of opinion. Why does Ohm still use the Walsh tradename? IMO because they own the trademark indefinitly (as long as they pay the maintenance fees) and because of brand recognition. At least German Physiks had the cojones to name their driver by the inventors name; DDD (Dick Dipole Driver) yet give credit to Lincoln Walsh. Ohm could just as easily name their driver the SCD (Strohbeen Coherent Driver) or even the STD (Strohbeen Transmission-line Driver). OK, maybe that last one might be a marketing mistake! Sean: This type of design would have to be hand built using custom parts i.e. minimal off the shelf componentry. As such, it would be a relatively large economical undertaking for someone to attempt as compared to starting up a speaker company that uses off the shelf parts. On top of that, the market for such an item isn't all that big in the grander scheme of things, hence the lack of anyone jumping in with both feet.
Having said that, i can see this type of thing taking off if someone were to build "one off" products out of their garage. That is, IF they could achieve the type of results that we know this design to be capable of AND doing so with a high level of consistency. I have thought about this myself, but not too seriously. Sean Maybe after creating a new prototype, an ingenious mechanical engineer could build a machine for mass producing these speakers (or at least cut down on some of the handwork. Of course one would have to charge outraegous amounts of money for these. (maybe in the range of $15,000 - $40,000) I don't know if there would be a market for such an expensive speaker? Would anyone buy a $40,000 speaker? ; ) When I hit the Lotto, I'll be giving you a shout! |
Sean and Jamscience, thank you for your very informative posts.
Sean, I purchased the Ohm F's in early 1975 while I was working on Long Island (Huntington). When I auditioned the speakers, the gentleman who was fielding questions at the Audio store was from Ohm. I can't recall his name but he seemed like the #1 guy. I remember the price of the speakers was not in outer space and were a little more than the Bose 901's. My friend bought the Bose around the same time I got the Ohm F's and couldn't believe how stupid he was for purchasing something that sounded so inferior to what I had. To add insult to his injuring himself by self inflicted dope slaps upside his head, the F's were a couple hundred more (rememebering the details are foggy due the fact I was just out of college and hmmmmmm...maybe using some party substances at the time. LOL) I'm sure I am not alone in this aspect of youth. Regardless, I loved those speakers with or without being under the influence.
Based on what Jamscience stated about the patient (my cousin is an attorney for the US Patient Office and she had already stated as much this past weekend), then there is hope some very creative and gifted person will look at this design again and give it a whirl. I think, even built by hand, these speakers wouldn't be as expensive as was stated above. Remember, a well connected in the bizz person is going to have connections for some if not all the parts. Case in point, look at where the Von Schweikert line of speakers are being made, plus many many others. |
Line: You've lost me in terms of "where do the extra spl's come from?". What "extra" spl's are you talking about? Sean
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The difficutlty of manufacturing a Walsh driver is something that I believe could be resolved by good reengineering.
In my former life as an aerospace engineer, we worked closely with a university lab who were the primary designers of very sophisticated military electromechanical equipment. Our company's part of the design job was to refine their original designs, which often disregarded little details like "how do you make it?". The term used is "producability engineering" and it appears that the Walsh driver design never had the benefit of this kind of engineering. |
Lngbruno: I think, even built by hand, these speakers wouldn't be as expensive as was stated above. Actually, I was being facetious. (just thinking of those 60" cones!) The real problem is recreating what has already been done. It's one thing to modify an old Model F; it's another one to build it from scratch. Just a crude guess would be (per pair): Materials - $2,000.00 - $3,000.00 Labor - $2,500.00 - $3,000.00 Outsourcing (for things that you could not afford to do as an individual) - $2,000.00 - $3,000.00 Testing and breaking in - $500.00 Things not thought of - $1,000.00 Total cost - $8,000.00 - $10,500.00 Plus the cost of getting a new patent for any new improvements. $????.?? Am I anywhere close to the mark Sean? |
What is a pure Walsh driver supposed to be? This is what I think is should be. Please correct me if what I say here is wrong.
A pure Walsh would emit sound 'only' by means of transmission line, and if the driver had suspension, that would introduce a sound that is not transmission line sound, but that of a conventional speaker. So the sound being emitted from a Walsh with suspension would not be pure transmission line sound, but rather a mix of the two.
A Walsh driver generates waves down the cone material, whatever that material my be. And from what i understand, this can be done one of two ways.
One way is to generate waves by bending the cone material itself and the waves are moving at supersonic speeds and different wave frequencies will have somewhat different supersonic speeds. From what i have read, this is how the DDD works. This method requires a very thin and ridged material.
The second way, is to generate a compression wave, in which the waves are not on the surface, because there is no bending involved, the cone material itself is being compressed, (not bent). Compression waves are also super sonic.
In ether of these methods, the proper angle of the cone will depend on the speed of the wave on/in the material being used. The greater the speed, the steeper the proper angle will be. The F's use metal and sound travels much faster in metal then in plastic, therefor the steeper angle is required if a metal matteral is used for cone material. Now, if the wrong angle is used, the waves generated in the air will not line up to form a single coherent sound source, and this will create time-smear or time-delay.
The use of suspension may or may not be necessary (i don't know), but if it must be used, i do not see how it could be pure transmission line.
This is what i understand as how a Walsh driver works. Am I wrong?
From what i understand, the DDD employed the first method and the F's the second method. |
the cone material is some type of metal and apparantly they can deform permanetly with what i believe was described as ripples. |
Line: I'm not going to go into the design of the German Physiks vs the Ohm A's and F's as i think that they are more similar than dis-similar. Other than that, i'm still trying to figure out what these "extra spl's" are that you're talking about??? Sean
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Sean, I wonder if a Walsh drive (which does have suspension) would also emitting sound by means of piston action like a conventional driver does, and if it indeed does, that would boost the SLP. You see, I don't know, but would like to know. But I don't see how it could not.
And a steep cone like the F has (which looks to be about 60 degrees or so), would be less efficient at this then a cone at 35 degrees would be.
An I making myself clear? |
I could very well be wrong about this, but, it appears as though the DDD is a single driver and the Walsh is a compound(?) driver. If I'm correct, when run full range (20 Hz - 20 KHz) The German Physiks speaker system with its DDD driver and more traditional electronic crossover to subwoofers may have less cross-overs than the Ohm speakers system with its Walsh driver with it's mechanical cross-overs. The German Physiks cross-over may be in a less critical region? The Walsh's inherent cross-overs might still be more coherent as they cross-over to a more similar driver(s)? The German Physiks seem to be easier than the Walsh's to power? Any thoughts? |
The Ohm versions of the Walsh drivers suffered from very poor assembly techniques. That is, the voice coil was not properly placed in relationship to the magnet / pole piece and the suspension ( spider, surrounds, etc...) were not properly slected. The end result is less than optimum performance in most every respect and drastically reduced efficiency / drastically increased compression.
This is why Bill Legall of Millersound referred to the Ohm A's & F's as being "broken from the factory". Addressing these problems basically means rebuilding the driver, but the results can be staggering to say the least.
I'm quite certain that the increased efficiency of the DDD stems from FAR greater attention to detail in the design & assembly of the driver. By limiting bandwidth of the driver, efficiency is also increased. If one were to read Walsh's original patent info, Walsh specifically stated that this design could be built to cover a VERY wide frequency spectrum. Only problem is that the wider the spectrum, the lower the efficiency.
Line: I'm lost as to what you're trying to say. Then again, i've not gotten much sleep in the last few days, so...
Unsound: The German Physiks speaker uses a passive crossover, not an electronic crossover. While the passive could be considered "electronic", that terminology is typically reserved for an "active" crossover. Don't know if that's what you meant, but thought this should be clarified for those that aren't familiar with the design. Sean
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Sean, I stand corrected. Yes, that's what I meant. Thanks for clearing it up. |
Amen, Sean!!!
Once you hear the Ohms rebuilt as they were intended to be implemented, the results are quite staggering. It sounds more than obvious, but the voice coil being outside the gap of the magnet just doesn't really fly. Like having the propeller of a boat outside of the water, but relying on the turbulence it creates in the air (but, NOT a fanboat) to somehow at least also exert enough influence on the water to get you moving.
Didn't know the A uses an 18" driver, and the F uses a 12" driver, but the discourse in this thread is teaching me a lot.
I'm incredibly lucky to be able to listen to Bill Legall's own pair of Walsh A's, and though I haven't heard them yet in a good system (I have to push him harder on this), or with the drivers tightened down (maybe I'll just do this myself while he's working on something...), I'm not sure they don't disqualify every other speaker in the "Best speaker you've ever heard" thread. Personally, I put them easily over Bill's pride and joy, the Infinity IRS in his living room. |
Trelja: Now you know why i said what i did in a ( WAY ) earlier thread on Agon. That is, even though they most certainly have their flaws, i don't plan on giving up my F's anytime soon. I'm quite certain that mine don't perform to the level of Bill's "completely re-designed" Model A's, but none the less, many of the sonic attributes are still there to a lesser extent. Even with just that hint of performance to them, i knew that they were "special" from the very begining. Sean
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Regarding Bill's Ohm A, it is indeed a very interesting and unique type of sound. Along with the very special "you are there" characteristics, it is a frustrating design with the most complex theory behind it I have ever seen. At first listen you are aware that something special is indeed happening to the sound...a more 360 boundary-less type of envelope, yet as wonderful as this quality is, on say a female vocal and guitar, it tends to not handle the complex music quite as well, or with as much reality. Bill's IRS is the much more univeral product. While it may lack the Walsh's seduction (I know its very alluring), I can bet the house that its dead accurate. If a new recording is purchased and one wants to really know how it sounds, the IRS is the one. Now I am sure countless mods have been performed since I last heard them a year ago,and judging from the above praise, a breakthrough must have occured. Interestingly, the speaker was spectacular when auditioned outdoors with no room interaction at all. Bill can attest to this. Bill is, of course, a very gifted and visionary engineer with the most unerringly correct (almost scary) intuition regarding audio on the planet. There is no question the Walsh driver in his hands may someday surpass his IRS, but, I am sure he will tell you he sleeps better at night knowing his IRS is there as an absolute reference...........Frank |
Frap: I would tend to agree, but maybe from a different perspective. The Walsh makes music with both depth and ambience whereas other speakers may produce FAR greater "hi-fi resolution". As far as being immersed in sound, as one is at a concert or sitting nearfield of a bunch of acoustic musicians, i know which one is more realistic. This could be because you don't strictly have a left /right presentation with the Walsh's like you do with more conventional speakers.
Either way, i like the presentation of the Walsh design. I also like specific attributes of other more conventional designs. That's why i have several different systems, all quite different from one another. They all have their drawbacks to one extent or another. Some are just far more blatantly lacking in certain areas. Sean
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Funny you mention "hi fi resolution", the greatest example of this being the ESS AMT HEIL 13 pound driver. To this day, it is beyond reproach from a hi fi standpoint. It does some things better than anything I have heard.It is hard to give up its special qualities once you hear them. Some music will never sound better than with this driver....yet some music sounds completely hi fi and wrong.
Isn't it ironic, Sean, that Heil and Walsh designs were of the most important variety, only to be executed without proper R&D to eliminate their errors.
The case for several systems is a good one, space permitting.
Here is a question for you Sean: Suppose the OHM A were reintroduced today with all of Millersound's R&D as a specially licenced product, and then marketed for a reasonable sum of money. Not 30K or the nonsensical current price schemes, but lets say $6500.00. Assuming respected ears on this site (like Trelja's above) were typical of the majority, could this technology/design be saved/ressurected? Vinh Vu are you listening |
I have no doubt that the Walsh driver stomps all over Maggies, which are the best selling "audiophile approved" speaker in the world. As such, i'll use them as a point of reference.
By re-designing the Walsh motor structure and suspension, thereby making it more efficient and higher in nominal impedance, you make it easier to drive. As we all know, Maggie's aren't the easiest to drive and are also "finicky" when it comes to placement. In this regard, the "modernized" Walsh walks away from the Maggie.
On top of that, the Walsh's have TREMENDOUS bottom end, something that you couldn't pry out of a pair of Maggie's. In this regard, the Walsh RUNS away from the Maggie.
The Walsh's also have the deepest and widest dispursion of any driver / speaker system that im aware of, making for a FAR more "engulfing" musical experience. One can gain the sonic "wrap around" feeling that one normally only obtains from listening VERY nearfield, a presentation so "thick" that it feels like you're walking through it ( varies with recording ). Compare that to the presentation of the Maggies, which sounds "ambient" and "spacious" only when sitting in a limited area, and the Walsh once again wins.
Given the single driver point source with no crossover parts to soak up power or add their sonic signature, you don't have time or phase errors. The "one driver, direct drive" approach also produces excellent harmonic structure, prat and coherence, as many of the "full range" afficionado's will testify to. Maggies have a crossover, use multiple drivers and lack the warmth and bottom end required to have great "prat" ( in my opinion ).
To sum things up, it is a fabulous driver with GOBS of potential that absolutely kills the "audiophile reference". Would the average audiophile recognize this? My answer is NO. Most audiophiles are sheep and led by their noses via printed reviews and the herd mentality of the internet. Even if the glossy rags and internet "herd" were to jump on the bandwagon, it would be a short-lived ride till the "next best thing" comes along.
Most audiophiles are more concerned with dimunitive size in a speaker ( monitors ) OR MEGA sized boxes with a lot of drivers. Maggies are kind of a cross of these two i.e. large frontal section but very "petite" in terms of depth. On top of that, the Walsh's are so unconventional in appearance, operation and placement that many would be turned off.
As such, i think that it would become a niche product, just like those using SET's, single drivers, nearfield listening, etc... That's because the design approach and presentation wraps up several different aspects of what these people love and are after, all into one package. As we all know, those specific types of listeners are but a small part of the audiophile market, which is why i think it would be doomed to remain a product of interest to only a select few. Much like it is now, but on a slightly wider scale. Sean
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PS... To be honest, i've never heard a Heil system that was worth listening to. Having said that, i'm quite certain that the installations and support componentry were to blame. This is probably most of the problem with those that had complaints about the Ohm's too, especially "way back when".
The technology behind the Heil driver, much like the Walsh, is pretty incredible as compared to more conventional designs. It's too bad we don't have any designers / engineers around today that are willing and capable of introducing and properly implimenting "ground breaking designs" like these. Instead, we keep getting re-hashed "monkee coffins", albeit better designed and better sounding "monkee coffins". |
I sure would be interested in an updated Walsh speaker! |
The Ohm A in its current state of Millersound mods may in fact surpass everything available, based on it's inherent design executed properly. That said, the Magneplaner wave launch is still bigger on piano music and the reason for its typical audiophile aproval. Dynamics on the Ohm A destroy the Maggie though, and the spooky 360 effect is just not there on the MG series in any model....Pick your preference.
I find the look of the Ohm A/F to be quite acceptable and even attractive compared to the boring "coffin" and mostly uninteresting designs being offered today. The Vadersteen 5 is somewhat similar in appearence and seems to do very well. The 70s offered the most innovation of any era in Audio and is unlikely to be repeated.
Regarding audiophile cattle, you know the outcome before it happens.........unless the price is real world. This is the number one factor. Seasoned music lovers will hear the reality of things, they will see the hobby reignited with enthusiasum because they will never have experienced this form of 3D. We are not talking ribbon driver clarity or transparency here, but genuine 3D..the likes of which no speaker in recent or past memory has achieved. I think with the right group of people,(like the Legall crew),this most important and exciting of designs can become a new reality.
My ears have been conditioned through the years with Quad, Infinity, IMF, LS3/5A, Apogee and many other audiophile approved items and I am quite sure of the value of this product.
"Ground breaking designs" seem to have ended in favor of the money and business realities of our current generation. This sort of dedication was part of a more serious and simple social climate where music, not money was the driving force. Is it any wonder that no current audio offerings remotely touch on these breakthrough items.
It does not have to be this way. Current (ad nauseum)loudspeakers with the same over and over drivers and /sound are everywhere....gauranteed to bore you...as much as "classic rock" FM radio. |
Frap, or anyone else, count me in as a future purchaser of a new and improved version of the Ohm F utilizing a true Walsh designed driver. If the speaker had a MSRP of around $5000, it may cause many audiophiles to give them a serious audition. I can imagine many listeners liking what these speakers do, even if they only sound identical to the original ones. My hope is someone who can make this happen reads this thread and has an ah-ha moment.
Check book and pen in hand and now just waiting to order...:>) |
As for me, keeping the price below 4K would make it a lot easier. |
> What was the MSRP of the Fs back in the mid to late 70s?
I bought a pair of Ohm F's new in late 1974; the price was $800 for the pair. I believe the price increased fairly rapidly after that. They certainly had a magic about them.
Three or four years ago I auditioned the Ohm Walsh 200 MkII's with their at-home trial and found them missing the special qualities I remembered. They were a bit on the heavy sounding side and lacked the sense of space I was after. That was a pity as I really wanted them to be as magical as the F's from many years before. |
