Acoustic Suspension Patent

[ninohernes]

Who owns the Acoustic Suspension patent now? The patent number is 2,775,309. It is viewable on the US Patent Office website, but it does not tell who the current owner is. After college, I am seriously considering designing loudspeakers, and I would like to use the acoustic suspension design. For that, I would like access to Villchur's original patent, and associated documents. I am dissipointed with the loudspeakers and studio monitors on the market today. I want to build quality loudspeakers, that use the acoustic suspension design that we all love!

[ninohernes]

I phoned the US Patent office, and found out that the acoustic suspension patent ran out in 1971, and has no current owner. Getting copies of the patent is very expensive, so I will have to make due with the low res version that you can access on the US Patent office website.

[ninohernes]

After college, I currently have plans to design and build three loudspeaker systems. They will be called Precision Sound Reproducers or PSR's for short. These systems will be target toward recording studios, and high end home users.

All cabinets will be made of solid wood. Five wood finishes will be available:

Glossy walnut

Glossy cherry

Oiled Teak

Piano lacquer black

Unfinished

The models are as follows:

PSR-12

The PSR-12 will be a three way loudspeaker with the following drivers:

1-12 inch acoustic suspension woofer, cross over to midrange at 400hz

1- Textile or paper based dome or cone midrange (size yet to be determined) cross over to tweeter yet to be determined.

1- Textile or paper based dome tweeter (size yet to be determined)

PSR-10

The PSR-10 will be a three way loudspeaker system with the following drivers:

1-10 inch acoustic suspension woofer, cross over to midrange at 400hz

1- Textile or paper based dome or cone midrange (size yet to be determined) cross over to tweeter yet to be determined.

1- Textile or paper based dome tweeter (size yet to be determined)

PSR-8

The PSR-8 will be a three way loudspeaker system with the following drivers:

1-8 inch extra long throw acoustic suspension woofer, cross over to midrange at 600hz

1- Textile or paper based dome midrange (size yet to be determined) cross over to tweeter at 7000hz.

1- Textile or paper based dome tweeter (size yet to be determined)

Pricing (per pair):

The PSR-12 will be in the $3,000-$4,500 price range.

The PSR-10 will be in the $2,500-$3,500 price range.

The PSR-8 will be in the $1,500-$2,000 price range.

These systems will incorporate a totally new driver cooling system that I have developed. This will allow the sealed cabinet to cool itself, greatly improving power handling. I also want to design a special extra high excursion woofer for the PSR-8, allowing it to be used without a sub woofer. This is also why I decided to make the system a three way, as opposed to a two way system.

[ninohernes]

After closer inspection of the US Patent office website, I was able to buy a high resolution PDF copy of the patent. I should have it in 12-24 hours.

[ninohernes]

Update on design

The line of PSR loudspeakers will consist of the following models:

PSR-12

The PSR-12 will be a three way loudspeaker with the following drivers:

1-12 inch acoustic suspension woofer, cross over to midrange at 400hz

1-Scan Speak 13M/8636 cone midrange cross over to tweeter at 7000hz. ($130)

1- Morel MDT-33 dome tweeter. ($130)

Running total: $260

PSR-10

The PSR-10 will be a three way loudspeaker system with the following drivers:

1-10 inch acoustic suspension woofer, cross over to midrange at 400hz

1- Scan Speak 13M/8636 cone midrange cross over to tweeter at 7000hz. ($130)

1- Morel MDT-33 dome tweeter. ($130)

Running total: $260

PSR-8

The PSR-8 will be a three way loudspeaker system with the following drivers:

1-8 inch extra long throw acoustic suspension woofer, cross over to midrange at 600hz

1-Scan Speak 13M/8640 cone midrange cross over to tweeter at 7000hz. ($93)

1- Morel MDT-33 dome tweeter. ($130)

Running total: $223

Pricing (per pair):

The PSR-12 will be in the $2,000-$3,500 price range. Ideal- $3,000

The PSR-10 will be in the $2,000-$3,000 price range. Ideal- $2,500

The PSR-8 will be in the $900-$1,500 price range. Ideal- $999

I would like to prepare the PSR-12 as my final project for the Acoustics class I will be taking in college this fall. I would eventually like to debut the entire line at the 2007 AES show in New York, and then eventually at the CES show.

The tough part of this, will be building the woofer. I will most likely be modifying a good woofer, to work properly in an acoustic suspension cabinets, by replacing the stiff spider, with a light compliant one. If anyone has any input, please feel free to reply!

[ninohernes]

I have been working a lot lately, on the design of the woofer for the PSR-8. The system will use a special high excursion 8 inch acoustic suspension woofer, based somewhat on the design of the early AR-3 woofer. I want this system to be able to be used without a sub woofer. The voice coil on the new 8 inch woofer will be 2 inches in diameter, and 1 1/2 inches long. The length of the gap, will be 2 1/2 inches long. This extra length will ensure that even on the longest excursions, when the cone comes rushing back in, the voice coil will never strike the back plate of the magnet. The pole piece will be made of a special heat conducting metal, that will draw heat away from the voice coil.

[ar_pro]

I seem to recall a true acoustic-suspension 15" woofer from Altec-Lansing that paid special attention to both heat-conduction, and protection from bottom-out...it was available as a raw driver, and would have been in their catalogs from the early '70s. The Altec literature went into some detail regarding its design & capabilities, and perhaps this could be helpful in the plans for your drivers, Joe. Anyone here remember this big woofer or have old Altec catalogs?

[Guest OpusX]

The best known of the big Altec 15" woofers were the model 515 and 515B which found their way into many of the Voice of the Theater configurations and even some of the big home systems. It is a bit of a hunt to find information on the Altecs, but a good starting point is the Altec Heritage website and follow some of the links. The more I have looked at some of the history and information out there, the more I see that here was another company the 'did it right'. Check out some of the pics from the old production lines. I know a guy who works for a sound company here in Omaha and he loves getting his hands on the old Altec Lansing drivers.

I broke ranks last year and couldn't pass on an incredible deal on a pair of Altec Valencias (first pair of non-AR speakers I've ever owned) when Richard picked up his AR-9s from a guy up in Minnesota. The guy had the 9s up front and the Valencias in the rear...and did it ever sound good. The Valencias behaved nicely and shared the playground well with the 9s. Played on their own they sound good, but noticeably different than the AR-9s or the LSTs or even the AR-11s, but that big woofer sounds good without being overpowering. For a great view of what some the Altec/JBL fans have done with these big woofers in home systems check out this link: http://www.audioheritage.org/html/readers-...ders-photos.htm

[ninohernes]

I have made several sketches (on the computer) of my new 8 inch woofer. Now comes the hard part, actually building a woofer from those drawings. I do not have any of the equipment to do this, and even if I did, I would not know where to start. When I get to Columbia in the fall, I will talk to the acoustics department, and see if they can help me find someone that can help me make my design three dimensional.

[soundminded]

Out of sheer curiousity, why would you design and build your own acoustic suspension woofer when you can buy one OEM. For example;

http://www.partsexpress.com/pe/showdetl.cf...t_ID=7489&DID=7

I'm sure you will go to someone already tooled up to build speakers if you want something custom. Just tell them what you want and they will not only build it for you, they will grind out the design details too and far faster and at lower cost with no mistakes.

On my first job out of school, they told me "never build what you can buy." Still seems like good advice to me.

Good Luck

[ninohernes]

The magnet on that woofer is very shallow. This will cause the cone to bottom out on long excursions. Also, the surrounds are so small, they are limiting the excursion of the woofer. I had one of these woofers, and the suspensions, and spider are far to stiff for use in an acoustic suspension cabinet. This woofer would work well in a ported system, but not in an acoustic suspension system. The woofers I plan to build are going to be nice and beefy, much like the original alnico magnet AR-3 woofers. I want a gap that is longer than the voice coil, so that the voice coil will never come in contact with the back plate, on the return of a long excursion. I also want the magnet to be large, so it draws heat away from the voice coil.

There are simply no woofers on the market today that are suitable for placement in an acoustic suspension cabinet. The situation today is much like the situation was when Villchur invented acoustic suspension. All of the woofers today are mounted in vented cabinets. They all have stiff mechanical suspensions.

[soundminded]

You'll have a tough sell with recording studios. They seem to have settled on the B&W Matrix 801 and 802 as a kind of industry standard. Also, people engineering studios like to go with suppliers who have been in business for a long time and have an established reputation. It's a hard nut to crack. You'll probably have better luck in the home audio market but it's relatively small and there is an awful lot of competition.

BTW what do you think of:

http://www.partsexpress.com/pe/pshowdetl.c...tnumber=300-764

You can buy all of the parts separately but the package looks good on paper. With that huge powerful driver with a 20mm max X a 1000 watt amp and a parametric equalizer, it looks like a pair of them could put out some serious bass. Here's the driver;

http://www.partsexpress.com/pe/showdetl.cf...tnumber=295-420

[ninohernes]

Honestly, I am not much of a sub woofer person. I much prefer the sound of a good bookshelf or floor standing system. However, if you like sub woofers, that one certanly looks like a good one, especially for the price.

[soundminded]

If you download the sealed box project on the driver page, you will see that in a two cubic foot enclosure, performance is remarkably similar to the curves for the 12" AR drivers posted here some months back.

So are you saying that the four 12" drivers in my AR9s are about the best ever on the market? I can tell you from experience that they can produce one hell of an undistorted low bass output. They can shake the walls, the windows, and the fillings in my teeth. They can make a rumble like rolling thunder and a bang like a canon shot. BTW, you'd be surprised at how many cds have rumble on them, maybe room rumble from the original recordings. You don't hear that on most speaker systems. They are truely subwoofer's crossed over at 200 hz. If you read Tim Holl's excellent technical description of the design concept, you will see how he overcomes the room mode cancellations at very low frequencies and his trick of placing the two subwoofers facing sideways and as close to the wall as possible while placing the 8 inch lower midrange on the front facing forward was extremely clever at integrating the speaker into the room. IMO, it works exactly the way he said it would. I have to wonder what a faceoff between the four AR9 woofers and a pair of 15" Titanic IIIs would sound like. I wonder if my house could stand it.

[ninohernes]

Yes, those woofers are the best! The AR-9's are the best loudspeaker ever made! (I am designing my woofers based on the ones in the AR-3, which are similar to the ones in the AR-9) I think that the AR-9's would win the competition. I like all AR speakers, because you can get excelent bass response without a sub woofer. I dislike subwoofers because all of the low bass for both channels is summed into mono, and is pumped out of one box. Even with a pair of subwoofers, they never seem to integrate well with the upper range speakers. It always sounds disjointed. Thats why I like the AR-9's (and all of the AR speakers), all of the parts of the system are designed to work together. Also, you get super stereo seperation, even in the low end. If a timpani is on the right side, it is not summed to a single sub woofer, it comes from the right side.

[soundminded]

Were I to design a system based on subwoofers, I would use at least one for each channel and place them sideways the way Tim Holl describes. I would put the main speakers directly on top of them. Then you have a fighting chance of integrating them with the rest of the system. The reason why a single subwoofer or even a pair can't integrate with other speakers IMO is that by physically separating them, you will inevitably get phase cancellations and reinforcements in the transition range. they must be physically close to each other. 200 hz was the optimum crossover frequency IMO because according to early measurements by Dr. Bose, phase shifts above 180 hz are far less audible. That's why he chose 180hz as the resonant point of the 901 system. He knew he would get phase shifting at the resonant frequency. Below that frequency, the response falls off linearly. Not only will the frequency response of the equalizer be the inverse of the falloff but so will the phase response allowing the drivers to potentially respond to very low frequencies, as low as AR9. The single pair of original 901s I have doesn't quite equal the AR9s in deep bass but I think that with several pairs and sufficient amplifier power, it could also give it a run for its money. It is definitely in the same league with AR3, AR3a, and AR 10 Pi. I will probably over the next few years try to acquire several more pairs of original or series II 901s and modify them the way I modified my own and acquire a high powered amplifier like Crown CE-1000 or Studio Standard II. One of my great regrets is that I passed up the opportunity to acquire a second pair of AR9s around the late 1980s. That was even a wose mistake than not buying the McIntosh MX110B for $75 from the Authorized McIntosh repair station in 1983

[ninohernes]

>One of my great

>regrets is that I passed up the opportunity to acquire a

>second pair of AR9s around the late 1980s. That was even a

>wose mistake than not buying the McIntosh MX110B for $75 from

>the Authorized McIntosh repair station in 1983

Ouch, you were not very... sound minded! (I know, my humor is dry, sorry, I couldent help myself)

[ninohernes]

Another update on the PSR. I have been doing a lot of thinking about woofer surrounds, and the material that they are made of. Foam dries out, and turns to dust, and rubber dries and cracks. Cloth seems to be the best, because it does not crack or turn to dust! However, if it is not sealed properly, it will leak air. I have come up with the perfect material to make surrounds out of. This material will not dry out, crack or disintegrate. This material is vinyl. 18-22 gauge vinyl would work perfectly for surrounds. This type of vinyl is normally used in inflatable mattresses, pool toys etc. It is the perfect thickness, its air tight, it’s flexible, and it does not dry out! I am going to be experimenting with making my own vinyl surrounds. I am going to try to locate an AR 12 inch woofer with a bad surround, and replace it with my new vinyl one. I think that it will be easier to work with the larger woofer. If it works, I will then try it on a smaller woofer. Vinyl can be purchased by the foot at most large hardware stores.

[Guest molecules]

I would research vinyl a little closer. I don't know if they have made improvements over the last few years, but flexible vinyl contains plasticizers that make it soft and they can leach or evaporate out, leaving very stiff PVC behind.

Good luck on your project

[soundminded]

I'm curious about why you chose a 5" kevlar cone midrange for your 10 and 12 inch models and why you chose a cheaper midrange which retails for only $30 less per for your 8 inch model. You know of course that AR stuck with dome midrange speakers in their top models from AR3 to AR9 where they split the midrange and used a dome only in the upper part of the range. BTW, how did you arrive at these particular drivers. I assume that the Morel tweeters are their top of the line. I think they are rated to handle 200 watts RMS per.

[ninohernes]

Woops! I forgot to change that! All of the models are going to use the Kevlar midrange. When I was looking at drivers and specs, I saw the paper ones first, then I read further, and found out that it came in a Kevlar version. Kevlar makes an excelent midrange, it is really smooth and natural sounding.

I decided upon the Morel tweeter, for two reasons. Reason one is that the power handling is wonderfull! 200 watts RMS!! Reason two, I have heard good things about this driver.

I chose to use a cone midrange for two reasons. Reason one, I am crossing over to the midrange fairly early. (400cps for the 10 and 12 and 600 for the 8)The cone midranges go down that far quite nicely, because they are larger. The second reason, is power handling. The Scan Speak drivers that I am going to use have excelent power handling, 100 watts RMS.

I am going to stop here. I have said a lot about my plan for these speakers, because they are being designed after vintage AR units, and that is relevent to this forum, as is HiFi in general. However, I do not want to reveal any more of my design details on this public forum, because it is public. The details that I have shared with you are relitivly few, there are many many more. If you have feedback, or you would like to discuss my new designs, please feel free to contact me via email. I trust you guys on this fourm, but its the rest of the people on the internet (that have access to this website) that I dont trust!

[soundminded]

Both drivers are very impressive and likely would make for an excellent loudspeaker system. The only concern I would have is the crossover point of 7khz. Parts express has an Acrobat download file which you already probably have. If for any reason you don't, you can download it from this web page.

http://www.partsexpress.com/pe/pshowdetl.c...r=296-504&DID=7

By 7 khz, the off axis response falls off rapidly while interestinglhy the on axis response is rising. Just a suggestion that you might consider 5 khz as an alternative. Have you built a prototype yet?

Good luck with it.

[ninohernes]

No, I have not built a prototype yet. I need to have the woofer built first. Then I have to have the cabinet built. I have no woodworking skills what so ever, so I will have to go to a carpenter.

The next step is desgining the crossover, and deciding what kind of capactiors to use, and what kind of inductors to use.

[soundminded]

I was going to ask you about your crossover philosophy and if you don't want to discuss it I would understand. AR's crossover designs apparantly ranged from the rather primative in AR3 to very sophisticated later on in AR9. Would you use a Butterworth or Linkwitz-Riley alignment or something else? Any idea which orders you'd use? I suppose it's something you can play around with an awful lot. The LC impedence compensating pair in AR9 was ingenious I thought. Read Tim Holl's description. It not only makes the speaker sound better but much easier to drive. Of course, it success is dependent on the cabinet design which controls the resonance frequency. Funny how so few designers put driver level controls on their speakers anymore. No tone controls or filters on their amplifiers either. They when the users have absolutely no control over anything, they go out and shop for expensive cables to solve their in room frequency response problems.

[ninohernes]

Honestly, I am not sure yet. I dont know much about crossovers, and I am going to have to do some reading, to weigh out the pros and cons of each crossover type. For short signal path sake, I would like to keep it as simple as possible, but I am not sure if that will be efective. If you have any knowledge of crossover types, please email me and we can talk about it.