Unorthodox 2x18 slot loaded PA sub

Only God knows! ;) Me, I'm still 'scratching my head' as to how Pi, etc., math constants? were found or the incredible accuracy of ancient complex structures, etc., were designed built without falling back on space aliens.
I’ve been up and down and back-and-forth and all over the place collecting information on these things after a point where something clicked or I saw the light at the end of a tunnel so speak. it wasn’t a choice and I didn’t understand I have a clue what I was looking for I just knew something kept standing out in in that?

I never took The odd harmonic intervals very seriously except for the one that you can get from Martin’s page at the 0.349. Which I used all the time just do plain old full range driver TLs for fun.

But when I would play with other enclosure designs higher orders and offset stubs, post stuff on diy audio.com (most of which I didn’t describe well, it typically sounded weird and I wasn’t getting anywhere with that for the most part, it’s too hard to describe what I was trying to say and people couldt understand) it was slowly but surely trying to find this pattern of things that was sort of revealing itself but didn’t make any sense or never was going to until Horn response a couple months ago changed to the PH mode thankfully🙏🏻🙏🏻

It’s not just pi, It’s that 3+1÷7 and that would also be similar to anything that requires something to change on the circle or at the circle itself is not even possible to exist and that brings you to 365.25?? In that conundrum what does that even represent or what is that all about …. It’s a corkscrew it’s never return to the same spot I never ever will be it’s always advancing in time and in actual space while spinning around the sun and 360 we are all moving with it forward to the galaxy and well for whatever reason that might be 365.25 it is absolutely connected to numbers that work out no matter what into that affect and then it becomes a non-harmonic interval as well. Or everything becomes much clearer once you make your pipes incorporate 360 cm as the total length and break that up into 12 parts using horn response i.e. 30 cm parts which are the speed of light or the number 341728 square rooOr everything becomes much clearer once you make your pipes incorporate 360 cm as the total length and break that up into 12 parts using horn response i.e. 30 cm parts which are the speed of light or the number 3, or sq root 1728 or The radius of the sun squared in miles not metric what are the dimensions of the sun as pie or as they are described by 8÷254!!?? End it starts to get weird why are there numbers inside this description of a centimeter conversion to an inch and who defined that who made up to centimeters where did that begin?

0890D2FA-F432-4EBF-A1BD-40CF3785601B.png


it’s more like an argument with pie it’s trying to fit 300 into 360 (and pies in the circumference of a circle and a volume of a circle equations which will point out something if you inject them with information as the radius to start with and compare it in contrast and try to figure out how this is all connected why is jumping through the dimensions of math and shapes but also using angles and phase at the same time ??or pointing that out so to speak?? If you look at a couple of things it comes together and it’s not crazy hard it just doesn’t make sense until the end. So I understand why people would get frustrated and not even look at it! It just leave you and all but halfway there to nothing except more wondering??


Well I I kept going for whatever reason….

and It ended up in the centimeter conversion changes or anything using 1÷254 and the 0.250 of quarter wave, 0.254.
Than the radius of the sun as a quarter wave product of a sine wave and the fact that that squared is the speed of light in miles per second or (432)^2 is 186624.

what nobody ever looks at all the decimal points in all of these numbers because they go on forever but nobody cares to notice they all speak things or they don’t and they repeat things if they are saying anything except dayshift by one digit and keep going even though it looks to be repetitive:

if you make a list of numbers after first looking at 8÷254 to set up something to observe in the conversion of centimeters to inches..

Then you can navigate things a little bit with some confidence or some curiosity that motivates you further cause it’s a long road to lots of numbers and without any kind of motivation or clue you get derailed quick and never go back unfortunately no one tellThen you can navigate things a little bit with some confidence or some curiosity that motivates you further cause it’s a long road to lots of numbers and without any kind of motivation or clue you get derailed quick and never go back unfortunately no one ever does
 

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until Horn response a couple months ago changed to the PH mode

??? Searched the HELP file to no avail. :(

Thanks for the uploads! I remember Tom referring to some pyramid measurements, but have yet to do a search, so got any links?

You're right, the rest is not making much sense beyond due to the basic physics of our known space there has to be some common denominators and between the 'geniuses' on The BIG BANG THEORY TV show and what passes for my common sense 'says' there must be some asymmetry to it also.
 
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these two blueprint like pictures aren’t in standard units whatever and a lot of it doesn’t make sense because it’s ancient numbers or forgotten ones unit of measure and it’s converting those to something modern that’s going to help out but only if it’s a centimeter or 1÷254 which is the conversion of centimeters and then parts of a circle meaning pie but the pie with the number parts and (not the symbolic one ) this is PI 22÷7 . and what that ends up being in the radians or degrees as centimeters is circumference.


clear as mud?🤪🔊🤷🏻
 

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Only horn response can come up with the numbers for offsetting a pipe or a driver or stub that will contribute it precisely to a number that’s needed and nothing else will do that so we build speakers we understand what steps do we understand how things are gonna be perfect or they’re not in regards to that and the closer you get to perfect in the decimal points of it because of your arrive at numbers that matter for a very important reason
 
GM it is what’s wrong with Paraflex that needs to be fixed (The misalignment in both lengths offsets and cross-sectional area at a certain point )but then reveals the numbers to use to understand Egyptian pyramid and it would seem more so than anyone has in the history of civilization at this point?
 
No clue. Guess I need to refresh my memory on it and if it's the original it seemed to be a worse, 'enhanced', K15 sans K-slot, so never paid much attention to the thread and by the time I browsed the FB site it had so many variations on a theme that I didn't have time/enthusiasm to play 'catch-up' or even a way for a 'newbie' to make an intelligent choice for the intended app.
 
HI Guys!
Thank you very much for those big informations!
I want to go in deep with fluid dynamics because is very interesting and I think I will test 2 ports on sidewalls.
Now I bring you my (poor?!) results with round ports.

4 Ports,14cm diameter each, 45 cm lenght.
I tested in outdoor enviroment but with mic maybe too close to the enclosure ( 3meters max).
FREQUENCY PPSL.png
I like linearity of the response but I would eliminate the dip at 45hz and 170hz even if I will use steep LPF at 100-120hz.
I hope that 45hz is due to air leaking from the enclosure joints (only screws at the moment)
the 170 I think is a modal resonance of the internal lenght of the enclosure so I will use damping material if necessary.
This plot is mic inside a vent:

INSIDE VENT (4 VENTS) PPSL.png
Still same dip at 45hz and very broad response from the port.

Initially I couldn't see by eyes which was the real tuning fr so I built a quick impedance test jig
I built also two sealed front panels :
IMPEDENZA PPSL.png
I've never made impedance tests but I think that BR impedance dip is in the same frequency of the bigger peak casued by the lenght of the plenum.
The BR tends to lower the highest peak.
Can be a problem?

Thank you very much
Ale
 

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I tested in outdoor enviroment but with mic maybe too close to the enclosure ( 3meters max).
Ale, 3 meters should be plenty. Was the mic on the ground?
I hope that 45hz is due to air leaking from the enclosure joints (only screws at the moment)
Leaks around the drivers also could be part of the problem.
the 170 I think is a modal resonance of the internal lenght of the enclosure so I will use damping material if necessary.
I doubt a narrow dip like that would result from an internal resonance.

Locate and fix the leaks, then re-test.

Cheers,
Art
 
Ale, 3 meters should be plenty. Was the mic on the ground?

Leaks around the drivers also could be part of the problem.

I doubt a narrow dip like that would result from an internal resonance.

Locate and fix the leaks, then re-test.

Cheers,
Art
Hi

yes mic on the ground in a garden with 2 small buildings at 10meters at least.
Today I found big leaks from the "utility" doors using sin waves.
I'm glueing everything together except for the front baffles and internal braces.
do this kind of bracing interferes with the plenum or brings some resonances?
PPSL PLENUM BRACING.png

Thank you
Ale
 
I'd start off with playing a 45Hz tone and see where the air is escaping. There's clearly something weird happening there.


On a different note, is there any concern about the compression ratio that the cones will see? - The slot looks quite narrow.

Chris
Hi
I made some noise like you suggested and after I decided to seal everything definitely, was a shame the air mass leaking :rolleyes:.

about compression ratio: I've read a big part of the ppsl thread and every plenum were as little as you can mount 1 driver with the magnet in the plenum.
For my goal dimension I developed the exit area in height.
Thank you
Ale
 
I dunno if its relevant but I used this test dummy for a variety of things one of which was the different types of bracing and running air over them see if anything happened. Far left has a solid brace and the other two are staggered holes as you can see.

two of them are dead silent no matter how much I cranked on the shop vac , or how I tipped or split the flow around them or between the two . and slow or high or pinched the end.

The solid bracing which doesn’t go all the way to the very end (but is a dead end ) to be fair could quite easily induce a howl or some sort of consistant resonance.

A lot of things can contribute to that whixh arent realistic to the speaker environmebt ?
No back-and-forth(oscillate) except the closed end which is kind of like an oscillation since the shop vac isn’t…. And the other two are flowing all the way out as im only stickingthe shop vac directly in the driver hole or vent here.

Sharp edges no roundoff bits in the router, nothing, (but silent to air flow)..
 

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HI
Finally I assembled with glue the box except the front panels.
For the moment I used one 200mm pvc pipe 42cm long per side, Unfortunately 42cm is the max lenght I can achieve because of the cone baskets position.
I included the plenum bracing like Art and Booger suggested (bracing perpendicular to the plenum sides and chamfered holes)
and now impedance and fr measurements are very clean.
Here the measurements ( outdoor, 3 meters, no spl calibrated, no smoothing):

RED: total response
BLUE : mic inside plenum
GREEN: mic inside one port.

PPSL OUTDOOR 3METERS GLUED.png

Here impedance check ( using headphone out of the soundcard and resistors jig):
PPSL IMPEDANCE GLUED.png

I tried to learn how to check tuning fr of a reflex cab looking at the impedance and its phase and it seems tuning is at 39hz and I could cut the pipes
for my 44hz goal. Putting also a piece of paper in front of a vent and looking at the minimum cone excursion I obtain 39hz'ish region.
But the final response and mic inside a port it seems the tuning is higher and the peak is very broad.
Now I'm not sure how to interpret those data.

One thing I learned first-hand: reflex is not just a hole in a box :D

Thank you guys
Ale
 
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HI
Finally I assembled with glue the box except the front panels.
For the moment I used one 200mm pvc pipe 42cm long per side, Unfortunately 42cm is the max lenght I can achieve because of the cone baskets position.
I included the plenum bracing like Art and Booger suggested (bracing perpendicular to the plenum sides and chamfered holes)
and now impedance and fr measurements are very clean.
Here the measurements ( outdoor, 3 meters, no spl calibrated, no smoothing):

RED: total response
BLUE : mic inside plenum
GREEN: mic inside one port.

View attachment 1039193

Here impedance check ( using headphone out of the soundcard and resistors jig):
View attachment 1039194

I tried to learn how to check tuning fr of a reflex cab looking at the impedance and its phase and it seems tuning is at 39hz and I could cut the pipes
for my 44hz goal. Putting also a piece of paper in front of a vent and looking at the minimum cone excursion I obtain 39hz'ish region.
But the final response and mic inside a port it seems the tuning is higher and the peak is very broad.
Now I'm not sure how to interpret those data.

One thing I learned first-hand: reflex is not just a hole in a box :D

Thank you guys
Ale
Hi
Meanwhile I measured one speaker impedance in free air out of the box and the fs peak of the driver Is at 42hz, despite of 30hz showed in the manufacturer datasheet.
Do I Need some warming up for the suspensions?
Can this be the detail that moves the reflex Port peak higher in frequency than the dip of the nearfield (plenum) cone meausurement?
Thank you
Ale
 
Hi
Meanwhile I measured one speaker impedance in free air out of the box and the fs peak of the driver Is at 42hz, despite of 30hz showed in the manufacturer datasheet.
Do I Need some warming up for the suspensions?
The suspension may need breaking in, run it past Xmax for a while below Fs.
The Fs also will appear lower at higher drive levels, might take 4 volts or more to read correctly.
Can this be the detail that moves the reflex Port peak higher in frequency than the dip of the nearfield (plenum) cone meausurement?
Both excursion and impedance minima should be at Fb, regardless of Fs.
Is your plenum actually the 79cm depth indicated in the Hornresp inputs in post #1?
 
The suspension may need breaking in, run it past Xmax for a while below Fs.
The Fs also will appear lower at higher drive levels, might take 4 volts or more to read correctly.

Both excursion and impedance minima should be at Fb, regardless of Fs.
Is your plenum actually the 79cm depth indicated in the Hornresp inputs in post #1?
Ok. I Will use an amp in the impedance jig and do also free air noise if with amp Notting changes.

The plenum depth is 89 simulated and 88.2 in real world.
Ale
 
Despite my ingnorance understanding the difference between impedance and fr plot,
the horn resp imported response overlaps the real world :D

PPSL SIM VS REAL.png

this is without flare and ports extensions, so not a scenario I would use, but only for testing.
scenario 1: no 2°flare with extension ports
scenario 2: with 2°flare without extension ports
(scenario 3: with both).

Thank you
Ale
 
Despite my ingnorance understanding the difference between impedance and fr plot,
the horn resp imported response overlaps the real world :D
+/-3dB, close enough for rock & roll ;^).

The deep notch at 180Hz is interesting, looks like the plenum and port output may be 180 degree out of phase at that frequency, usually that sort of dip would show up in the simulation. That said, Hornresp is assuming one port, but there are four, so the port's "pipe resonance" will not be the same.

Some interesting discussion in this thread:
https://techtalk.parts-express.com/...5-port-resonance-what-should-i-be-looking-for

If the ports are capped off (covered/stuffed), does that dip still show up in the response?