DIY Walsh driver revisited

Walsh tweeter filler

Very interesting, I am about to tackle the same project. Just acquired a pair of WTLCs. Spent many many hours with them driven with GAS equipment in the 70s so I knew them well. Aside from the filler and the termination at the end of the cone, the material and method they are dampened must be one of the most import single items in producing the sound they were known for. They will either be too bright or dead. Question, as with the use of employng dissimilar materials in the construction of the cone, has anyone played with dissimilar materials as fillers in layers moving up the cone to the cap ? Would that affect the linear response of the wave or help tune the frequency response ? Thinking that there appears to be a mix of materials as opposed to a single catch-all filler.
 
Just found this thread. I don't look here much as "exotic" drivers usually mean physically large and don't fit my room situations. It seems the Walsh has possibilities a better candidate for a wide range driver than many of the cones in use. Is 1K to 10K a reasonable target or is that way to much for the motors in question? If so, then this could be an answer to getting the crossover problems out of the critical range.

So, the foam plug on top acted both to damp the standing waves as well as the upper spider?

Might be fun to build a driver. My last one I built many years ago was a corona effect. It did make sound, but made a lot more ozone.
 
Just had an idea. How about using a cheap, large format compression driver. Pro units are made so that they are easy to service, and as long as we are not expecting any bass from it, it might just work. I'm thinking a modified compression driver in the range above 500Hz, with a bass driver used below that. Good idea?

Deon
 
High power too. Worth thinking about.

Is a Walsh really about some surface wave propagation as the ads in the 70's said, or is it really just a very steep cone to provide some dispersion as a wide range driver where we just happen to be listening to it on the side from the back?
 
the infinity walsh tweeters are transmission line drivers and not dynamic drivers. they do not move air like a dynamic speaker. they are more akin to the bending wave driver. the key is to have a very thin cone material with low mass, but extremely high rigidity. low mass for ease of acceleration. rigidity to hold its form, and high density to allow for very fast propagation through the cone material. in the case of the infinity tweeter, propagation speed is 3 to 4 times the speed of sound in air (1,128 ft/sec).

the cone angle is a bit of math, but suffice it to say the angle is chosen to produce a cylindrical wave front that is perfectly vertical in nature emanating from the cone. it also, assures time and phase coherence.

the original tweeters used aluminum foil off the shelf. some was diamond foil and some was scribed. the purpose of the diamond or the scribing was to stiffen the foil, since most aluminum foil off the shelf has been annealed and is very soft. this does not bode well for the bending wave driver and can cause the cone to fold up or crush under high loads. the production drivers were very simple consisting of one layer of foil with about .0015" to .002" thickness. X-max [linear cone excursion] was on the order of + / – .004" without damage.

there is a big walsh tweeter thread over at audiokarma that has a ton of info on the subject:

walsh tweeter design/rebuild - AudioKarma.org Home Audio Stereo Discussion Forums





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Nice to see you again, Loq.
tvrgreek: Loquacious's explanation is spot on. I'm going to have to find the patent number again and post it. The patent discusses the operation in detail.
Question for Loq- Last time we met, your forum was more concerned with repairing the Infinity loudspeaker as opposed to building a Walsh device. Has this changed?
Cheers,
J
 
Nice to see you again, Loq.
tvrgreek: Loquacious's explanation is spot on. I'm going to have to find the patent number again and post it. The patent discusses the operation in detail.
Question for Loq- Last time we met, your forum was more concerned with repairing the Infinity loudspeaker as opposed to building a Walsh device. Has this changed?
Cheers,
J

hi jay,

the AK infinity forum is still mostly restoration oriented, though every so often someone will try to reinvent the wheel. my big walsh tweeter thread on AK died a natural death, but not before it paid dividends. in fact, the thread resulted in us figuring out how to repair the walsh tweeters, and several AK'ers have. then an AK'er in florida took the next step, and started reproducing them, based on a titanium dome tweeter. he was selling them on ebay under the seller name audioman23 to much acclaim, but seems to have stopped after only producing half a dozen or so pairs. here is a thread that covers them:

New "Walsh" style replacement drivers - AudioKarma.org Home Audio Stereo Discussion Forums

here is an old ebay ad for them that hasn't beed deleted yet (but i'm sure will be soon):

New Infinity Walsh Tweeter Pair | eBay

i did finally get a pair of walsh equipped infinitys, monitor IIa's, which i restored. i'd be remiss if i didn't say after all that research, and despite my high hopes, i was (am) somewhat less than impressed with the original walshes and have to consider that much of their appeal is a result of their novelty. with the reviews of the reproduction walsh, i was toying with the idea of an upgrade, but they seem to have gone out of production.




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Who is this guy?
OK- here is some of the information I promised:
The Walsh patent: US Patent 3,424,873
Dale Harder's website: HHR Exotic Speakers
The "non" Walsh speaker: www.german-physik.com (if it looks like a duck...)
Also, check the link that Loquatious recently posted. Some good photos of the Walsh tweeter and lost of great background and experiences.
Back to the amp layout.
Cheers,
Jay
 
Who is this guy?
OK- here is some of the information I promised:
The Walsh patent: US Patent 3,424,873
Dale Harder's website: HHR Exotic Speakers
The "non" Walsh speaker: www.german-physik.com (if it looks like a duck...)
Also, check the link that Loquatious recently posted. Some good photos of the Walsh tweeter and lost of great background and experiences.
Back to the amp layout.
Cheers,
Jay

Me? Dang I thought this was exotics subforum I am actually working on something similar and have spent the better part of 2 years studying walsh, German Physics and a host others. As well as making contact with quite a few . Either way I was just getting exited to see people doing something along my line. http://www.diyaudio.com/forums/plan...ject-replication-mbl-loudspeaker-101mkii.html
 
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Is anyone out there still playing with home build Walsh drivers?

I don't know if you have considered this but a Walsh concept driver can be built as a planar diaphragm you just need to use the right materials. Not only can this be done but you can achieve a true hemispherical wave front capable pf 10KHz 180 degrees off axis to the voice coil. I did this way back in 1988 and sold them commercially through Sumo. Just thought I would mention it stimulate some out of the standard box thinking. Best regards Moray James.
 
Take a look at Dale Harder's driver at the HHR site. I haven't heard Dale's driver, but I have spoken with him, and he knows what he's doing. Also, visit the German Physik site. These may give you some ideas as to how to elongate the driver's basket.
Look around for Bud Purvine's posts here. His work on controlling cone break-up is must read material.
I've used 3/4" MDF donuts to mount the magnet assy and connect the legs. You can also use the donut to mount the basket and then add legs.
You can buy replacement rubber surrounds at any number of speaker repair supply sites. Just look around with Google.
PM me your email address and I will send you a .pdf of the Walsh patent.
Cheers,
J