DIY Walsh driver revisited

[jerryrigged]

"It's Alive!?"

Hi, Steve...and agreed. I been precoccupied for quite awhile, but finally dust thing off.

What material are you using for the cone(s)? I've had various thoughts on what could be printed in an appropo thickness yet light, ridgid, and durable enough to withstand the abuse...

...and sound good after all that. *G*

There are those that now capable of extruding carbon fiber laced polymers, but I'm unsure as to what the minimums are in extrusion widths.

Not that a 'ribbed cone' would be 'bad', per se.....

I've been rolling Ti & Al; the Ti maintains a nice smooth satin finish.

The Al.....a 'gentile' touch is mandatory to minimize dimples, creases, and just denting in general. 2mm Al is 'touchy'.....even half-hard....

Anyway....info (and pics?) at your leisure....and just in time for the weekend...

 

[jerryrigged]

BTW, what diameter of voice coil have you opted for?

 

[tagis]

3D model

Hi Thomas,
Thanks, I am about two weeks away from starting the build. I found a local 3D routing service to do my wood work at a reasonable rate and will start at the end of next week to print the Walsh cone. The Walsh cone is a exponential shape 200 mm at the base and 28 mm at the transducer with a 100mm hight. I am printing it with a blend of plastics that gives it a density of human tissue. The reason for this is it gives great impedance matching to the air. Here is a 3D mode.
Cheers,
Steve

 

[tagis]

Hi Jerry,
I been playing around with some plastics similar to ones that Duke university has developed for their meta-material that the use in their acoustic lab.

I am using PUI Audio ASX0540 HR exciters their diameter is 28mm and a frequency response of ~80Hz-20KHz.

With the PLA fiber with chopped carbon fiber one can print with 0.3mm nozzle that is high wear resistance. I am using a 3D Delta printer with an enclosure.This really helps in warping by having a constant print environment.

I plan to print some wood drivers to along with the carbon fiber The biggest issue is print time Its running close to 16 hrs to print a driver with a 30% infill.

Cheers,
Steve

 

[jerryrigged]

Meta-materials.....

...sounds like alien tech to me....*L*

Interesting choice of cone shape; less the geometric versions i'm doing. More in line with the curves of a 'conventional horn', but rendered as a full radiused version....similar to the 'bell flare' on a brass wind instrument...

It sounds like, from your description, that the drivers are typically for DML applications. First time I've 'heard' of that type used to drive a cone.

Should be interesting to hear when the deed is done. *G*

It also will be educational as to how and what fq. your cones radiate.
And the weight of the cone itself will be of interest....

I received a comment from Dale Harder of HHR that my 5mm cone material was too heavy. Towards that end, now using 2mil Al & Ti.....much more in line with preffered designs vs. weight and mass.

16 hours, huh.? And what seems a lot of infill...but not having all that much experience with 3D printing, it seems somewhat reasonable.

A nearly 8" dia. exponential cone nearly 4" high seems like it might take a while to print. What with a constantly reducing diameter to process and all the infill supports the program tacked on...

We're all ears on your endeavour....

Good luck with the 'horny cone'...(I know....hideous pun....)

 

[jerryrigged]

"It's Alive!?"

....but the Big Question is?

How did tagis'/aka Steve's 3D printed cone turn out?

Frankly focused curiosity would love tube' known what hath occurred.....*S*

Would wood work like the good woodworking does? (..couldn't resist....I have only the usual 'native resistance'...) (...which, mentally, grows lower almost daily...*L*).

Been working at working a lot lately, but my alliteration as a actual advantage as an attention-activating activity almost...

...causes cringing...

 

[jerryrigged]

MWAF '22?
...not at this rate....
Been jabbed twice, looking forward to a 'booster', still masked, still recognised (*damn*)...
You done/doing same? Yes?

 

[tagis]

H Jerryrigged,
I was disappointed in the results of the 3D printed cones and of the DML groupies they keep chasing their tails and not paying attention to the physics but enough said about that...
My current attention and love is thermo-acoustic emitters They are so linear in frequency response 200->150KHz (my measuring equipment gives up around 150KHz) and in power response. The down side is that they are very inefficient currently it takes 50 watts to get to 65 Db at 1 meter sound pressure. That said the fidelity is so amazing it is like ESL on steroids These emitters are truly massless in the way the generate the acoustic signatures they just heat and cool the air the truest way in my opinion.I only have to supplement the bottom end of 20-200Hz and I currently doing this with a OB subwoofer.

Cheers
Steve

 

[jerryrigged]

"Thermo-acoustic emitters"...
Well, a new potential SOTA perhaps.... Also a subject of study that may prove to be only available to the 'fanatic' audiophile with 'cost no object' means at present.

Do carry on, but expect a steep slope in making the Db response 'respectable' to them.

Pics? What would a TAE emitter look like for an audio application in ones' listening room? Would SAP require mass divorces? A 'house note' expenditure?

I'm frankly teasing, Steve....but appreciate your efforts, even the 'fails'. All involved in audio as a pursuit are wondering what the 'Next Thing' might be, beyond the self-powered BT units which haven't broken into the 'high-end market', as small as it may be or declining as some are concerned over.

Change is going to come, as it usually does. 'Bigger concerns' will outweigh the desire for better home reproduction, but the interest will as before, exist.

'Bleeding-edge audio" already can cost the equivalent of a M. Benz...and a really nice one at that. If the only market would be the .1%....or less....��*��

 

[jerryrigged]

...end emoji didn't xlate...one more time...

��* and ��

 

[tagis]

Hi jerryrigged,
The thermo-acoustic work is coming along the issue now is getting a good current amp.Since the material is a joule heater one needs to bias the film thermally so that when the signal goes negative it's reducing the film temperature. With this in mind I have also been exploring thermoelectric inks (gives a new meaning to hot and cold writing)
One last side note since the thermo-acoustic film makes a great ultrasonic transducer (200KHz) thinking about a ultrasonic parametric speaker (those pesky, disembodied voices that people hear)....
Cheers,
Steve

 

[jerryrigged]

Hi, Steve *G*

I was considering your 'hot/cold writing' and thought "How apt is that, damn!" *L* Knocked a few neurons loose, remember a comment on

"Jazz; Delicious Hot, Disgusting Cold"
(Bonzo Dog Band: Gorilla; Dixieland, Bent. You'll hate it, or love it. Not much between....*L*)

Thermoplastic ink.....*mind wanders into 'letters that change the copy...while in transit....*

You'll have to explain that concept further to allow a feeble (feverish? Happy 'bout that being a No.)
I'll sign a non-disclosure if you'd 'spain that...a sketch, perhaps?

 

[jerryrigged]

If the element(s) actually transmit heat to some degree as well as sound, the Class A gang and the owners whose mono amps can (to some degree or degrees ��) will love it or hate it...
...so it's worth trying if only to annoy and have some laughs...

Another variant on the whole concept of a 'driver' could use a push.

 

[zastin17]

Anybody here figure out how Ohm Acoustics figured out the CLS driver?'

This driver is oxordinary! It seems to flex and bend on long excursions. Which seems to keep all the frequencies propagating down the sides of the cone. All aligned at the same time. Just freaking nuts!

The CLS driver cone does not excurt uniformly like a normal driver. Very odd.

Even in "free air" I can't wrap my head around the composure and coherence all at the time time!!

I have played with probably 40+ fullranges of many types. Treated the cone. Did everything I could. But I absolutely cannot get anything like the CLS driver. It simply doesn't work. I'm using my Ohm Walsh Cabs aswell for this experiment.

John figured something out. Does anybody know precisely what it is? How did he make this driver too Propagate sound like this? The CLS driver seems to be very specifically contoured. And curled slightly near the bottom.

Listening to the driver "straight on" yeilds a very strange, "sucked in. Almost inverted sound. As if the frequencies are all inverted within time. Something else ive never seen on a Driver before.

 

[mcspack]

Hello All,

Just discovered Walsh Tweeters yesterday while looking for a decent tweeter for a diy Omnipole. I 'think' I have the rest of the speaker figured out. Just needed to cross something above 2k-4k. Been doing a bunch of reading. It seems to me the Infinity Walsh tweets can go quite high. Weren't those speakers rated up to 28k? And they just used their Walsh tweet for super tweeter duties? There has been a ton of work done here which is quite interesting. I know I have to get the cone 'right' if I want to roll my own. Just wondering what thickness of the hard foil is best for a super tweeter type Walsh? How low do these Infinity tweets go? I see them pop up on ebay here and there. My plan is to build a two way. Does that make sense? Does anyone have a good idea on a 2 way XO?

 

[jerryrigged]

zastin17, go here and go back to the 'source' and the how & why a Walsh works from the man whose name it bears.

https://patents.google.com/patent/US3424873

tagis ...so how has the 'disembodied voices' experiment gone? A 'super supertweet' might add to the 'felt' aspect of music, but more likely pick up on the really 'microacoustics' of ones' equipment....but just a wild guess by yours squirrely.....G

mcspack , a small Walsh of the Infinity 'ice cream cone' tweeters scale could do just that, since I've done it. G
I used to own a pair of the WTLCs'...

https://www.davidsaudio.com/Infinity_WTLC.pdf

Also had the opportunity to trade posts and emails to one of the 2 that 'kitchen table'd' the prototypes. There were some approaches that imho didn't work as well as they could....the Infinity Walsh has an interesting 'back story'...

The foam infill (acoustic foam, somewhat dense) seemed to damp the output of them, and they were upside-down; the radiation from the cone was pretty much aimed at your feet. The edge, much like a conventional driver, ought to have a surround of sorts but the cone material (alum) is very thin. I'm using 2 mil half-hard alum which forms (and deforms) easily. Making a seamless cone in carbon fiber works (see https://www.german-physiks.com/german-physiks-loudspeakers ) but there's trades on weight v. rigidity...

Ebay Walsh tweets have generally been or need repairs last time I looked. Infinity had a center core in the foam, but my understanding is that it was of a 'former' for the foam itself and wasn't anchored to the voice coil....just the cone itself. Personally, I've 'freed up' mine, but a foam core is still being used....
Damps the interior waveforms, which give rise to what I call 'cone honk'....

Think 'megaphone', as in an old fashioned one. The 'Rudy Vallee effect'...

If the cone is made slightly larger, it can 'go' a bit deeper in frequencies. The WTLC had a pair of typical cone tweets (front and rear) which a proper Walsh can do in a snap.

One can have a simple capacitor xover, or play with an digital one that allows for 'nuance' in slope and where they are...there's plenty of info on xovers online, but one has to dial in some details on the drivers you choose to use.

 

[mcspack]

Wow, those are cool. So you built a Walsh Mid Bass? How low do they go? It appears that you have rolled your own cones. What thickness foil did you use? I'm thinking of buying some hard aluminum foil .0001 thick and folding it if I need it thicker? Maybe just put a coating of PVC 'varnish' on one side to dampen it, or between a folded version if I need/want it thicker?

As far as original Walsh tweeters, There are some available that need new voice coils or vc repair. I am wondering if it would be better to just find a cheap tweeter that has the Thiele Small and power handling I need and convert that? I think it is interesting that the Walsh Tweets only need a basic cap as a XO? I'd love to know more about that! ;-)

Thanks!

 

[bentoronto]

I think the secret sauce is: omnidirection. This seems to be the trend of the times, with great interest in dipoles, even when trying to make 'em work with Rice-Kellogg drivers. Great sound depends on how the speaker inter-acts with the room.... like Linkwitz's surprise discovery of the value of a tweeter facing backwards. As far as I can guess, the Walsh concept has nothing going for it except being round. And ditto for that metal balloon horror.

But there are ways of making omnidirectional sound, even for tweeters. Just mounting two or more in-the-round. Easy to try and saves buying Russian titanium foil.

B.

 

[mcspack]

Why not hard aluminum foils? I'm sure titanium is good too but so expensive. I heard the MBL speakers once, Not the giant ones that Bill Gates owns but a little brother. They were out in the room a ways and gave a fully 3d sound from 2 speakers. What I really like about Omnis is they can also work well outdoors.

 

[bentoronto]

What I really like about Omnis is they can also work well outdoors.

I guess you mean they work well when people are seated around them? Or you want to "entertain" your neighbours? Otherwise, more focussed speakers would seem right for out of doors.

B.