Testing one two three. No pics yet. Working on making a particle board prototype baffle board. Think I’ll replace with solid cherry or walnut later on. End of test. 
Edit: My 2026 InDIYana theme project will be a 3-way re-make of my 2014 Plan-tanic speakers as follows:
Tweeters: GRS PT2522-4 planars.
Midrange: B&G RD40 (4 octaves).
Woofer: Dayton 7" Esoteric
Crossover targets: 150Hz and 2400Hz
What’s the theme??? Didn’t see it on the search
I just noticed that if you accidently hit the trash can delete icon on one of your posts, the system will bump your thread up to the top again, even if there is no new post. I accidently deleted my last post in this thread, then quickly undeleted it. I was looking for the edit icon, but could not find it. The edit icon must disappear after a very short period of time for newbies.
I will look and see what the edit time limit is for the different user levels. Also, I need to manually bump up the levels of people who have been around for a long time.
4 octave midrange essentially - seeing how peeps might tried to flex the boundaries.
For myself, thinking make something that plan to keep together rather than an experiment. Intend to go WMTMW, 30-32” tall staying within 1.5 gross internal volume. For woofers, put a quad of epic 7’s which seem to frequent my Indy projects… For mids planning on faital pro FE35’s, have one pair with some wheel cutter butchering so add a pair and rear mount them. Then tweet undecided, small form factor to handle 4k ish and up.
With 2 four’s, what reasonably the lowest can reach, directivity-ish or just general enough Sd to keep up with the epic7’s. ??? In my head was thinking 250 (250*16=4k), but wonder if will need to stretch to 300/4800.
New challenge not yet on the indiyana site, InDIYana
Well I know a pair of PC105s will go down to mid 50s ported
WinISD can give you an idea of excursion usage.
Same here. I’m going to go with a keeper this time around. Single woofer in a relatively small box tuned to 32Hz and crossed at 150Hz to a 4 octave midrange. I was reading a thread on the project pad where the thread starter argued that most of the high powered bass energy in most music is centered at 32Hz or so. So a single woofer tuned to 32Hz should be able to handle more musical power, all else being equal, than a woofer tuned to a higher or lower frequency.
Two fours can move the same amount of air, all else being equal, as a 5.656" midrange. (4 x 1.414). I’d say you could cross them as low as 100Hz. Biggest problem will be the size of inductors needed.
Got bored, decided to start building Indy26 1.5ft^3 box - in my shoestring workshop heh. Intention is WMTMW, middle section separate changeable baffle where forcing self to make chamber cups (3d print as needed) to have max volume for epic7’s versus having walled
off section for mtm (guestimate of 0.25cutft)
My box will be a little thinner and taller, with a wider bottom box for the woofer. Total of 1.5ft3 as well. .75 for the midrange and .75 for the woofer. Just one 7" esoteric per channel, tuned to 32Hz. Hoping to keep the total less than 60lbs. You’ll probably be up to about 70lbs each with those heavy 7" woofers. I’m thinking about mounting a couple of 2" casters on the bottom edge of my box so I can roll it into and out of events.
I’m rebuilding my Plan-Tanic speakers, reusing the B&G RD40 drivers and tower cabinets for next year’s Indy theme. I brought these to Iowa in 2014.
Plan is to bolt a Neo3 clone tweeter onto the face of the old RD40 cabs, near the center, creating an MTM configuration. The top and bottom of each RD40 will be blocked off to help widen the vertical lobe:
The back side of the RD40 will be aperiodically loaded into alternating layers of 1/2" compressed fiberglass and acousta-stuf material. I will be attempting to implement the “infinite box concept” described by G.R. Koonce and R.O.Wright, Jr that appeared as a 2 part series in Audioxpress magazine (April & May 2002).
There will be about 8 or 9 inches of the RD40’s ribbon exposed above and below the tweeter. The masking tape and thin cardboard will be replaced with 1/4" thick dense foam material:
Hey Bill, do you have the article for the infinite box?
No, I just have some handwritten notes that I took a long time ago when reading the articles at a Barnes & Noble. Audioxpress magazine sells back issues, but I just checked and they do not seem to go back that far. What did you want to know about it?
Google search didn’t return anything about infinite box. Got something back from Gemini, but no link or concrete source so not sure if it’s making it up or not and seems to be very generic.
Just your notes and how you are planning to implement it would be good. I got a pair of RD40 from Ron and was thinking of making a deep box 8”-12” depending on the woofer box and stuffing it tightly and making a removable back panel. The true dipole of the ribbon will cause reflection issues in a small room, was looking to see if some of the airiness can be returned while significantly reducing the back propagation. Last case seal the back completely.
Gemini stuff, prompt and response:
Find details about infinite box concept by Koonce and Wright as it pertains to building speaker boxes. It has to do with a periodically load the driver by stuffing the box with alternating layers of different damping materials
Response:
The Koonce and Wright “Infinite Box” concept for speaker enclosures, detailed in an article in the 1980s (likely in Speaker Builder magazine), is a method intended to make a relatively small speaker box behave acoustically like a much larger, theoretically infinite baffle enclosure.
The core of their design relies on periodically loading the driver by filling the cabinet with an engineered array of damping materials.
The “infinite box” effect is achieved through a specific internal structure of the acoustic stuffing:
Alternating Layers: The box is stuffed with alternating layers of different acoustic materials. This typically involves a sequence of materials with high-density damping alternating with materials that provide less damping or more airspace.
Acoustic Resistive Path: This layered arrangement, or periodic structure, is designed to create a very high-resistance path for the back-wave of the speaker driver. The resistance is so high that the air mass within the enclosure effectively appears much larger to the driver.
Simulating an Infinite Baffle: By controlling and resisting the driver’s back-wave, the air mass in the box acts like a very stiff spring on the cone, essentially isolating the driver from the small volume of the enclosure. This acoustic loading mimics the behavior of a true infinite baffle enclosure, where the driver’s back-wave is completely absorbed or vented into an effectively infinite space.
The primary goals of this concept were to:
Achieve Deeper Bass: Allow a driver to achieve the low-frequency performance it would normally only produce in an extremely large or infinite baffle enclosure.
Improve Transient Response: Control the movement of the speaker cone more precisely, potentially leading to cleaner bass and better clarity.
Reduce Cabinet Size: Offer the acoustic benefits of an infinite baffle without requiring a massive, impractical enclosure.
The concept is a variation of a highly damped sealed enclosure or a form of acoustical transmission line loading, where the lining is critical to the system’s performance. It utilizes principles of acoustic transmission line theory where the alternating layers serve to manipulate and absorb specific frequency components of the back-wave.
Seems to me the idea is half way between a simple sealed stuffed box, and aperiodic chambering.
Found your old thread Bill. Interested in where you take this Bill. My build, when it happens will be fully active to help with some of the XO and response issues. But still need to make a pterry functional box.
I think you have the basics down. It is simply a modified form of aperiodic loading. Instead of using a single layer of damping material, as would be done in a standard type aperiodic vent, I would use multiple layers of high density 1" thick fibeglass (like Owens-Corning 703 or 705), alternating each layer with either 1" empty space or a lighter type poly-fil or acousta-stuf type material. Then take a bunch of measurements to see how if affects the baffle step spreading loss and f3. Thus, the mechanical aperiodic loading becomes part of the crossover’s BSC and cutoff frequency calculation.
