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DIY Walsh driver revisited
DIY Walsh driver revisited
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Old 31st August 2012, 02:05 AM   #21
thundermntn is offline thundermntn  United States
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Default 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.
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Old 31st August 2012, 04:22 PM   #22
el`Ol is offline el`Ol  Germany
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Already posted in the MBL clone thread, maybe also interesting here:
DC Gold drivers have polymer baskets (good for slaughtering) an voice coils that touch the pole-piece (teflon on teflon), what abandons the annoying voice coil centering problems.
http://dcgold.com/
An interesting material for the cone:
Task Board, Model Making Cardboard
On the second video someone is knocking on it.
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Old 31st August 2012, 05:16 PM   #23
Cambe is offline Cambe
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Good to see some activity here!
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Old 3rd September 2012, 11:48 AM   #24
tvrgeek is offline tvrgeek  United States
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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.
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Old 3rd September 2012, 12:36 PM   #25
DeonC is offline DeonC  South Africa
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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
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Old 9th September 2012, 08:39 PM   #26
tvrgeek is offline tvrgeek  United States
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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?
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Old 11th May 2014, 12:19 PM   #27
OhioTanner is offline OhioTanner  United States
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Quote:
Originally Posted by tvrgeek View Post

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?
good question!
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Old 11th May 2014, 04:16 PM   #28
loquatious is offline loquatious  United States
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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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Old 11th May 2014, 06:16 PM   #29
glorocks is offline glorocks  United States
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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
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Old 11th May 2014, 06:33 PM   #30
Ron E is offline Ron E  United States
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Quote:
Originally Posted by loquatious View Post
... high density to allow for very fast propagation through the cone material.
Increased density reduces sound speed.
Speed of sound - Wikipedia, the free encyclopedia
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