DIY Walsh speakers

Interesting pic Jerry! The white mid-portion of your design reminds me of a control valve actuator body. Hey, use what you can get right? Keep tweaking, watching with interest....
 
Looks, deceiving...

Hi, Tim. It's just a chunk of pvc attached to 3 pieces of pb. Makes the pair of drivers look like a home brew WMD. My 'weapon of choice'...*G*

Actually, they've served their purpose and will be disposed of. Since the 'null zone' isn't desirable, I'm going to switch the placement of the drivers into an 'hourglass' alignment. Preferably in some fashion that would allow varying the space between them vertically.

I've noted that the dispersion tends to center at a nominal right angle from the cones' surface. My thinking is that if there's a space between them, one may be able to 'focus' the dispersion, much like a convex lens is used for focusing light, by varying that gap.

And it generates another strange looking object, which is amusing on some levels...the "What the F is that?" response. *L*
 
Up to speed, or just up...

Haven't posted anything in awhile, so I guess it's time to fling some verbiage about...*G*

Moving forward on V3.5; parts are cut, and it's time to tackle assembly of the 3 way Walsh. Please refer to the attached drawing to see what yours truly has in mind and on the bench.

Ambitious, perhaps. It's certainly has had a long 'gestation period'... And actually more of a test bed for the tweeter and some construction detailing on individual segments.

The tweeter @ top will be able to be removed by just removing 4 nuts. In this way I can apply/try different 'routines', such as suggested by Glo, to see what effects occur. Hopefully this can be done in a non-destructive/'swappable' fashion, as it's made from the 2 mil alum that you graciously donated. That's the idea, anyway...

The 'midrange' at the center is similar to what I've done previously, just adapted to the physical details of the co-opted driver (plastic basket vs. metal). It'll just sit on the woofer's frame with some foam applied to damp any vibrations, as the magnet fits within the mids base. A lucky occurrence...

The lower 'woofer' is an excursion into finding out 'where' the cone transits from a dml to pistonic excitation as frequency descends. The base is made purposely to allow reducing the diameter of the cone by inserting 'shim rings' beneath the cone, which can be reduced in diameter and receive a smaller diameter surround. This obviously will reduce it's height; the posts can be cut down to accommodate this.

The cones will all align vertically, so that more or less addresses 'time alignment'. The cone's profiles are all the same (small up, big down), which hopefully will allow the radiation patterns to more or less 'blend/overlap'. I can't get them any closer together vertically, so I'll see if this works. A 'sonic layer cake', if you will... My earlier test of 'flipping' the top unit (much like the Ikonoklast units) didn't work IMHO, so here's my 'go' at it.

One thing I'm trying to simplify the surround construction is the use of 3M's 77 spray adhesive to apply the EVA foam to the base structure in lieu of the VHB film adhesive I have been using. A test with scraps went well, so I'm reasonably confident it'll hold up. I'll continue to use the 4475 adhesive to bond the EVA to the cones, as it's doing well with all 6 of the units I have now...

...and masking tape is cheap, and the spray is easy to apply. Applying the foam accurately is still a 'hold the breath/focus/steady hands process...*G*

I'm starting to sound like an advert for 3m products. *L* Maybe I can get some corporate support...*L* Yeah, right...

Actually, I've noticed that the 4 units that I've been running consistently are 'breaking in', flaws and all. Certain cuts that I play and the instruments played within them are 'smoothing out', and the occasional 'innocent bystander' that hears them are starting to ask when they could have a pair. They still need a lot of development before I'd consider that. I prefer to keep those around me pleased with what I do and/or subject them to. And it's just good karmic relations. *L*

It is exciting to have 6 speakers underway at once, but it's also 6 speakers in progress at once. I can only dedicate 'snippets' of time, and nibble away at what needs to happen when and what order for what... An obscure bit of multitasking...*G*

Let's see what happens when this jello jells...;)
 

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Assemble the V3.5 bass units, that's what...

Due to the size, they (there's 2) were actually easier to put together than a smaller unit. There's room for fingers to fit without bumping into something else...*G* You can see the foot ruler in the pic.

At this point, they're being glued at the surrounds and the voice coils. The 4475 needs 24 hours to cure completely, so patience becomes a necessity as well as a virtue. The tweets are essentially done; the mids' posts need a bit of shaping at their top ends before they can be assembled and enter into the 'adhesion cycle' (i.e., application of more patience).

The goal is to complete assembly prior to leaving Tuesday 7/7 for a business 'overnight speed tour' to Fayetteville and the Raleigh area for some deliveries and minor installs. By my return (Thursday-ish), everything should be cured and ready for hook-up and 'first voice'.

...and then we'll see what hath been wrought...
 

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I may have missed it, but what is the reason for the woofers firing into a rather narrow diameter tube?
 
Not a problem, Nat. *S* Because the 'woofer' isn't supposed to act like a conventional one. Technically, a Walsh-type speaker radiated sideways in a DML (distributed mode loudspeaker) fashion rather than a direct radiator.

The actual amount of sound from the bottom of the cone is minimal; in point of fact, I've built this as a means of finding out where on the cone it changes from a DML to a direct mode. It's part and parcel of the physics of the design.

Actually, the sound from the bottom sounds like music funneled through a megaphone with the smaller coned units. They actually seem to sound better with a minimal amount of volume or an enclosure beneath them.

I want to see if reducing the space beneath the cone will force it to remain in a DML state; kind of a variation of 'acoustic suspension' used with some speaker designs.

The post you see (actually a 6" dia. PVC pipe) is merely a stand. I've got a lot of it, due to a plumbing supply closing shop next door and leaving it behind; the price was right. ;)
 
I know that the walsh driver radiated outward from the sides of the cone, but something has to be done with the sound from the inside of the cone. The old Ohms like the F seemed to have some sort of sealed enclosure which I assumed acted in more or less normal fashion, keeping the two wavefronts from the front and back (or outside and inside) from cancelling each other. Your design doesn't appear to do that, and even looks like it might act as a form of duct loading. This is all conjecture, obviously, so I'm curious how it actually acts.
 
*L* And that makes two of us, at minimum. The Ohm F's & A's did utilize the 'bottom' wavefront into an enclosure, in a more or less typical fashion. The A's cones had a 3 part construction; titanium/aluminum/paper, top to bottom. The alum/paper joint had a different angle of the slope of the cone, which seemed to act as a physical crossover. This apparently was to allow the paper portion to act like a more conventional driver. It worked, but it's a real challenge to duplicate (query HHR on that). Personally I'm not going to try to 'go there'...but I'm curious to hear what happens with what I've made, what it does 'down 'dere' *G*

I'll share my impressions as soon as I have some. Construction is nearly done, but I've got to go out of town for a couple of days. But that will allow the adhesives to cure properly...
 
V3.5 first impressions

20150712_163939.jpgReturned from our biz trip to Raleigh yesterday and applied the original crossover to the fully cured units, and lit them up. Pleasant surprise, all drivers worked...

...as to how well, mixed bag...

First reaction was to adjust eq with a heavy hand; lots of high through mids, rolling off deeply on the bass. Woofers 'booming' like the bass drums of a marching band. Removed entire array from the wood 'X' supports, meant to keep it all from inadvertently toppling over, and placing directly on floor. Bass immediately tightened up. If placed on a proper enclosure, that could eliminate any need for a sub. But that is just an initial impression....

Output from the mid unit is considerably less than the V.2 units of the relative same size. I'll chalk that up to the size of the magnet structures, which are roughly a third of the V.2's. Sound from them is 'restrained' because of this, IMHO. Considerably more gain has to be applied to get them to 'speak'.

Tweeters work, but are even more restrained than the mid units. Again, I'll chalk this up to their magnet structures, which are probably fine for a typically coned 3". To get them to respond, they ask to be 'cranked up', which starts to generate heat fairly quickly. I monitor this by just placing a finger on the center backside of the magnet. You can easily feel the temp rise gradually....

Above was noted by connecting the xover individually to each element as an initial test. Attaching everything in pairs (T+M, M+W) roughly confirmed my immediate impressions.

Attaching all 3 units together, the woofers are what one hears above all. The response is still 'bassy', but is better when used without the supports. If one damps the surround manually by touch, they 'firm up'; first 'tweek' is to either add damping into the support column or adding additional material beneath the surround to absorb more movement.

Not perfect, but not 'broken in' either. As a test stand, a reasonable start...

More later as I run them more...
 
Current thinking on the 3.5's is I'll call the tweets and mids a 'fail'. Drivers too small to be effective. I'll keep 'the guts' around for later improvements. My current drivers blow them away with mere output...

I'll continue to goof around with the woofer, just for educational value...
 
Since it's been a month, I thought I might 'check in'...

My 'normal' activities have taken up the bulk of my time, but I've scored another pair of typ. 3 way speakers and was 'gifted' with a unmatched pair of Bose drivers for study's sake. I want to try some different cone materials, suggested elsewhere, and one that intrigues me as well. That, and some cone treatments with misc. materials. And a 'rewiring' of my current array to take advantage of what I've got available and could be used better...

But I'm still 'here'...*G*
 
Happy Pre-Xmas & Merry Next Year when we get there, y'all. Here's a sync to what the V.3's currently look & sound like:


V.4's are moving from planning towards Reality, whatever that might end up constituting....If I was in a hurry, I'd be there already so we'll all just have to be patient. As is said:

"Please stand by."
__________________
"The amplification of the eternal presence is the technology of desire."
 
Speakers for V.4 were bought and processed. First stage of cone construction completed. Other details in the works, but real life intrudes so progress gets to be sporadic. Photos were taken of the speaker 'surgery'; these will be captioned and YT 'slideshowed' when time permits.

Meanwhile, likely much to the potential abhorrence of the purist's out there, I've found that the V.3's love EDM. In particular, deadmau5. "I Remember" from the '5 Years' CD is like being bathed sonically. And as for 'resonances'....What Resonances? *L* The joys of synth music....
 
(Yes, I actually do 'go to the symphony' on occasion, if they're doing something I'd like to hear Live. I appreciate it, really. Play it All The Time, NO. I'm in, and you are too, in the 21st Century. Point and laugh, 'another grain bamaged freak who don't know good muzik if he fell into it' mutterings....) Old dead white guys we stand on the shoulders of. The audiences used to fight and complain Then, too...

*L* Go bite somebody who'd care.
 
*L* It's always a 'reach'... If I could hand you a beer through your screen, I would. But then the Pentagon would show up, demand that I do it 'elsewhere' to someone who wouldn't appreciate the 'gift' they'd got, and life would get even more difficult....

I'm sure you can appreciate that. ;) I'd like to remain anonami...*X-Files music swells up, fades out*
 
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