Show your aperiodic speakers

I'll start the ball rolling with a simple contribution.

Back in the early 1970s, my Wharfedale RS/12/DD full range 12" drivers first resided in a 3 cubic foot "distributed port" cabinet constructed to Wharfedale's published design.

In the back panel there were ten rows of fifteen, 0.5" diameter holes, covered internally by felt cloth for extra acoustic resistance.

No photos exist, unfortunately!

The bass performance was resonant free, resulting in good transient response and an 'open' sound.

Later, I found that I preferred the 'punchier' bass performance obtained by mounting the drivers in a reflex loaded, 3 cubic foot cabinet.
 
Wel, the one i have is more an happy accident. I put some old Philips AD1065 in an old ported cabinet made for a subwoofer, totally not aligned and the old philips got a qts of 1.663 (partly due to aging i think) so it should not work. But it was ment to have some music in my workshop and it sounds a lot like an aperiodic sealed (like the old Dynaudio's) with a resonant free bass and open sound. I actually quiet like it. the vent is not stuffed with something, it just to small to be working as a vent.
 

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frugal-phile™
Joined 2001
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GM

Member
Joined 2003
I suppose there are enough active DIY hobbyists who have actually built aperiodic speakers.

Please explain your design philosophy. Why did you choose that particular construction, shape, materials, etc. How do they sound? Are you satisfied with their performance?

I seriously doubt it since the cab alignment has to completely damp the driver's Fs/impedance flat in its pass-band.

As such, I only know how to do it acoustically with heavily stuffed TL [Alpha TL or similar] and reactance annulled horn loading [< ~0.5T hyperbolic].

Like as 'is it live or is it Memorex' within the driver's capability, so as satisfied as possible within its performance limitations. :D
 
frugal-phile™
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GM’s post reminds me that i have done a number of (close to) aperiodic midTLs.

Here the impedance from an early one:

133540d1242324223-thread-tysen-variations-waw-fast-tysen-vrs-freeair-ff85-imp-gif


These don’t make for pretty pictures, but this should give an idea:

A7x-xwT-midTL-extents.gif


Meant to sit on top of a miniOnen the same size.

And this the midTL in the big A12pw MTM:

midTL-snippet.png


That aperiodicTL is inside these boxes:

A12pw-MTM-comp.jpg


dave
 
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Dave, wasn’t there a small CSS FR125 enclosure early on that could qualify as an aperiodic? I can remember trimming the veneer around the numerous small holes on the rear was rather a bunch of fun. Couldn’t find a photo of that part.
 

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Does an H frame / OB count as "aperiodic"? Or does it have to be a traditional 6 sided box?

Yes and no in that you can push the main impedance peak below the driver's pass-band, leaving smaller ones in it wake to damp and of course OB isn't exempt from needing to be bigger to go lower unless starting with a [super] high Qt driver since its impedance peak will be lower to start with; to wit, Bob Carver's woofer array: Stereophile: Carver Amazing Loudspeaker (Platinum Edition)
 
My full-range build...the driver is the RS 40-1284E Philippine production, a 9.8 ounce magnet, 20W, five inch, NOS.
After reading lots of threads on others using this driver, I settled on a 0.7 cubic foot internal volume, fully stuffed (packed?) with cotton batting...with a one-inch hole bored in the back & the stuffing protruding.
Sounds great, more bass extension than I anticipated...but inefficient as it eats power....have not extended volume levels according to my meters on my Carver TFM-15CB amp.

--------------------------------------------------------------------------Rick...
 

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But heavily influenced by the fellow that did these: Perkins PR-2 Precision Reference Loudspeaker

Always a trip to click on a link to that guy's place! He's a real deal, isnt he?

unless starting with a [super] high Qt driver since its impedance peak will be lower to start with; to wit, Bob Carver's woofer array:

"Simply put, the idea is to introduce an under-damped or peaky woofer into the baffle and let the peak in the woofer response compensate for the front-to-back bass cancellation of the baffle". I think I understand, I've heard of it another time and place. Thanks!

"Speaker designers are a breed apart, junkies whose highs are derived from doing battle with the laws of physics"

Like the guy in Canada that buys lathes, tears them down and rebuilds them so he can make his own tweeters from scratch - and can sustain such an effort for 10 years? Blasts his own magnets with gigantic current pulses??
 
The designs to which you link - apart from the second chamber aperiodic loading of Fig. 1 in the patent link - are in accord with the Wharfedale design I described in post #2.

If you wish to experiment, there is an empirical formula for calculating the total area of the resistive vent.

A = 5.5 x V [0.818 (Fs/25) + 0.182]

Where A is the resistive vent area in sq in, V is the enclosure volume in cu ft and Fs is the resonant frequency, in Hz, of the driver in free air.

 
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