Paraflex DDX 12" (1x12") built by Pete in Arizona
PARAFLEX REPORT
I just heard back from my long time local friend Pete ...... He just built a 34hz tuned Paraflex DDX 1x12 (type "A" layout) ........ Pete has had a lot of experience with some very serious high powered PA gear (he used to provide sound for the rave and desert party communities here) and he tells me that he is really impressed with how this cabinet performs (for it's small size and cost) ........... He sent me an email about it .....
I will just copy and paste from his email so you guys can read it yourself (see below):
“The box seems bigger than I imagined, it is lighter due to using the 18mm osb flooring material.
There are no handles on it so it is a little awkward to move around by yourself but not bad really, it is easier with 2 people for sure.
It puts out more sound than I imagined, it is solid to 30hz and smooth up top. I wasn't able to run it with a top yet so it's hard to judge, but I think two of these would work with 1 of the community tops.
The sound is super clean which I love, had the talking into a fan effect of modulating your voice. It filled the garage pretty well, knocking rust loose from the hvac and pictures off the wall.
Awesome design but not a piece of cake to build. I did get it done in 2 days but it is work. Maybe I am just rusty, I could do some things to streamline the build process to make it easier to build multiples. Cutting the wood was easy but assembly is a bitch with all the internal bracing.
I modeled it in Sketch Up as usual, I can give you the plans which include a cut list. Makes things a lot easier.
I was thinking for live sound, the port can be moved to the side. That way you can put 2 together for boundary loading. That would give some directional control and some mid bass punch. Or 3 per side, 2 side opening and 1 front opening in the middle, it would make a nice place to put the top on.
I have the driver coils wired in series and am powering it with a single channel of the Mackie i1400 that Paul donated. So the driver is getting about half its rated power ..
The build reminded me of the old days of driving to a gig with the paint still wet on the subs. “
(note: the driver was only receiving about a third of the rated power really but was surprisingly impressive which i would soon experience for myself.... More about that near the bottom of this post)
Here is the simulated output in Halfspace (single cabinet , and a pair)
So how did this start?
Initially I put together some quick Paraflex 1x12" layout sketches that were optimized for the Skar DDX 12" .... A few different tuning options and footprint shapes .... Pete chose the layout with more of an oblong footprint and lower tuning (target Fb on that one was around 34hz) ...
and as another option:
or
and then here was my suggested bracing sketch
and then Pete converted his chosen layout to a Sketchup 3D drawing and cutsheet (his Sketchup files are also included as attachments to this post)
and a different angle
This build was local so i decided to go meet up with Pete and have a listen
HERE IS MY REPORT:
"Well alright guys , went to visit my friend's industrial shop to hear this Paraflex (DDX 1x12) today .... . This is the cabinet that Pete built ..
On only 350 watts it is impressive!
(he is working on getting a more appropriate amp for the job) ....
It moves a lot of air with accuracy .... Nice impact!
and just enough midbass presence to be used a small PA sub (which is what he is using it for). 
....
It reaches all the way down to 30hz surprisingly well and would probably go lower but we didn't run the sweeps any lower (cabinet tuning is supposed to be 34hz... ..Need to verify with DATS)
........ In fact the way it was pressurizing this large space down around 30hz to 40hz is somewhat astounding ..... I wonder if the room dimensions or boundary gain was giving us a little extra oomph down there .......
We ran sine sweeps from 30hz to 100hz for a while and it is hitting every note
...... We extended the sweep to 200hz just to see how it handled the 100hz to 200hz range and it does play through that range just not quite as loud as below 100hz ...
When we played music through this sub he told me it was FULL RANGE music!! ... No LPF !! .. You couldn't tell that it was a full range signal though , when we listened to the sub by itself it was very well behaved with no noticeable honks , resonances or nastiness in the midbass, just smooth and punchy tight and deep and loud ..... FANTASTIC!
.. .................
Sounds like the design of the Paraflex filters out the higher frequencies but it does so in a way that is graceful (at least with this driver) no lower-mid nastiness or midrange ugliness to be heard whatsoever.. .... No offensive coloration when listening to the sub all by itself driven with a full range signal .. .
This cabinet is everything i had anticipated and more ... "
PARAFLEX REPORT
I just heard back from my long time local friend Pete ...... He just built a 34hz tuned Paraflex DDX 1x12 (type "A" layout) ........ Pete has had a lot of experience with some very serious high powered PA gear (he used to provide sound for the rave and desert party communities here) and he tells me that he is really impressed with how this cabinet performs (for it's small size and cost) ........... He sent me an email about it .....
I will just copy and paste from his email so you guys can read it yourself (see below):
“The box seems bigger than I imagined, it is lighter due to using the 18mm osb flooring material.
There are no handles on it so it is a little awkward to move around by yourself but not bad really, it is easier with 2 people for sure.
It puts out more sound than I imagined, it is solid to 30hz and smooth up top. I wasn't able to run it with a top yet so it's hard to judge, but I think two of these would work with 1 of the community tops.
The sound is super clean which I love, had the talking into a fan effect of modulating your voice. It filled the garage pretty well, knocking rust loose from the hvac and pictures off the wall.
Awesome design but not a piece of cake to build. I did get it done in 2 days but it is work. Maybe I am just rusty, I could do some things to streamline the build process to make it easier to build multiples. Cutting the wood was easy but assembly is a bitch with all the internal bracing.
I modeled it in Sketch Up as usual, I can give you the plans which include a cut list. Makes things a lot easier.
I was thinking for live sound, the port can be moved to the side. That way you can put 2 together for boundary loading. That would give some directional control and some mid bass punch. Or 3 per side, 2 side opening and 1 front opening in the middle, it would make a nice place to put the top on.
I have the driver coils wired in series and am powering it with a single channel of the Mackie i1400 that Paul donated. So the driver is getting about half its rated power ..
The build reminded me of the old days of driving to a gig with the paint still wet on the subs. “
(note: the driver was only receiving about a third of the rated power really but was surprisingly impressive which i would soon experience for myself.... More about that near the bottom of this post)
Here is the simulated output in Halfspace (single cabinet , and a pair)
So how did this start?
Initially I put together some quick Paraflex 1x12" layout sketches that were optimized for the Skar DDX 12" .... A few different tuning options and footprint shapes .... Pete chose the layout with more of an oblong footprint and lower tuning (target Fb on that one was around 34hz) ...
and as another option:
or
and then here was my suggested bracing sketch
and then Pete converted his chosen layout to a Sketchup 3D drawing and cutsheet (his Sketchup files are also included as attachments to this post)
and a different angle
This build was local so i decided to go meet up with Pete and have a listen
HERE IS MY REPORT:
"Well alright guys , went to visit my friend's industrial shop to hear this Paraflex (DDX 1x12) today .... . This is the cabinet that Pete built ..
On only 350 watts it is impressive!
(he is working on getting a more appropriate amp for the job) .... It moves a lot of air with accuracy .... Nice impact!
and just enough midbass presence to be used a small PA sub (which is what he is using it for). .... It reaches all the way down to 30hz surprisingly well and would probably go lower but we didn't run the sweeps any lower (cabinet tuning is supposed to be 34hz... ..Need to verify with DATS)
........ In fact the way it was pressurizing this large space down around 30hz to 40hz is somewhat astounding ..... I wonder if the room dimensions or boundary gain was giving us a little extra oomph down there ....... We ran sine sweeps from 30hz to 100hz for a while and it is hitting every note
...... We extended the sweep to 200hz just to see how it handled the 100hz to 200hz range and it does play through that range just not quite as loud as below 100hz ... When we played music through this sub he told me it was FULL RANGE music!! ... No LPF !! .. You couldn't tell that it was a full range signal though , when we listened to the sub by itself it was very well behaved with no noticeable honks , resonances or nastiness in the midbass, just smooth and punchy tight and deep and loud ..... FANTASTIC!
.. ................. Sounds like the design of the Paraflex filters out the higher frequencies but it does so in a way that is graceful (at least with this driver) no lower-mid nastiness or midrange ugliness to be heard whatsoever.. .... No offensive coloration when listening to the sub all by itself driven with a full range signal .. .
This cabinet is everything i had anticipated and more ... "
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I forgot to include this in the last post so here it is:
Parameters for the Skar DDX 12" measured by J Vansickle of Paragon Concept in North Carolina .... We have been very impressed with this $160 dollar marvel
Yes we can also make some very nice Paraflex cabinets loaded with some of the better Pro Audio 12s, 15s, and 18s but when it comes to low budget drivers it really is hard to beat the DDX 12's bang for the buck dollar-per-decibel value .. .
I also attached Pete's Paraflex Sketchup files to this post (they failed to attach to the previous post because i needed to zip them up first) ..
Parameters for the Skar DDX 12" measured by J Vansickle of Paragon Concept in North Carolina .... We have been very impressed with this $160 dollar marvel
Yes we can also make some very nice Paraflex cabinets loaded with some of the better Pro Audio 12s, 15s, and 18s but when it comes to low budget drivers it really is hard to beat the DDX 12's bang for the buck dollar-per-decibel value .. .
I also attached Pete's Paraflex Sketchup files to this post (they failed to attach to the previous post because i needed to zip them up first) ..
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- read this at ~5am today - very impressive - - I wonder if a little Paraflex could do midbass horn duty and sound maybe better despite not making as pretty graph (?) - - oops - forgot to use lossy Le
https://i.imgur.com/1WwM3TY.jpg
- - I wonder if a little Paraflex could do midbass horn duty and sound maybe better despite not making as pretty graph (?) - - oops - forgot to use lossy Lehttps://i.imgur.com/1WwM3TY.jpg
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- read this at ~5am today - very impressive
https://i.imgur.com/1WwM3TY.jpg
Freddi,
Looks like that Paraflex with the higher tuning might be good out to at least 400hz
Matthew, what useful 1/4 wave Super Planar scenario might be done with an Eminence Kappa12a? - its limited to about 3.2mm excursion
I don't know what I'm doing nor how to draw what's simed Is it even modeled correctly
using TH?
here's a sim - xmax hits at 20 watts/60Hz-ish - that seems like a poor place to run out of steam -but then again its efficient there and not much power would be used in some home setups - -does it need a cabinet tuned higher ?
https://i.imgur.com/ZPjEdjY.jpg
2 cubic foot reflex vs 5.5 cubic foot Paraflex
https://i.imgur.com/AgdISej.jpg
I don't know what I'm doing nor how to draw what's simed
Is it even modeled correctly using TH?
here's a sim - xmax hits at 20 watts/60Hz-ish - that seems like a poor place to run out of steam -but then again its efficient there and not much power would be used in some home setups - -does it need a cabinet tuned higher ?
https://i.imgur.com/ZPjEdjY.jpg
2 cubic foot reflex vs 5.5 cubic foot Paraflex
https://i.imgur.com/AgdISej.jpg
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60hz tuned Super Planar for the Kappa12a
freddi ,
You would want to use "OD" mode (or CH mode if no driver offsets whatsoever) .... I have a 60hz tuned Super Planar model set up for the Kappa12a
Here is the Hornresp export code:
ID=42.00
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Fta=0.00
S1=700.00
S2=700.00
Con=15.50
F12=0.00
S2=700.00
S3=700.00
Con=74.00
F23=0.00
S3=700.00
S4=700.00
Con=0.10
F34=0.00
S4=700.00
S5=700.00
Con=41.20
F45=0.00
Sd=519.50
Bl=15.32
Cms=2.91E-04
Rms=1.57
Mmd=36.17
Le=0.77
Re=5.41
OD=1
Vrc=1.00
Lrc=1.00
Ap=700.00
Lpt=21.80
Vtc=0.00
Atc=0.00
Pmax=700
Xmax=16.0
Path=0.0
Mass=0.00
Fr1=0.00
Fr2=0.00
Fr3=0.00
Fr4=0.00
Tal1=100
Tal2=100
Tal3=100
Tal4=100
Comment=Eminence Kappa 12a
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FILTER
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
100 25 0 0
40.50.50.5
0.50.50.50.5
SSSS
1111
1111
2222
1111
111
000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Matthew, what useful 1/4 wave Super Planar scenario might be done with an Eminence Kappa12a? - its limited to about 3.2mm excursion
I don't know what I'm doing nor how to draw what's simed
using TH?
freddi ,
You would want to use "OD" mode (or CH mode if no driver offsets whatsoever) .... I have a 60hz tuned Super Planar model set up for the Kappa12a
Here is the Hornresp export code:
ID=42.00
Ang=2.0 x Pi
Eg=2.83
Rg=0.00
Fta=0.00
S1=700.00
S2=700.00
Con=15.50
F12=0.00
S2=700.00
S3=700.00
Con=74.00
F23=0.00
S3=700.00
S4=700.00
Con=0.10
F34=0.00
S4=700.00
S5=700.00
Con=41.20
F45=0.00
Sd=519.50
Bl=15.32
Cms=2.91E-04
Rms=1.57
Mmd=36.17
Le=0.77
Re=5.41
OD=1
Vrc=1.00
Lrc=1.00
Ap=700.00
Lpt=21.80
Vtc=0.00
Atc=0.00
Pmax=700
Xmax=16.0
Path=0.0
Mass=0.00
Fr1=0.00
Fr2=0.00
Fr3=0.00
Fr4=0.00
Tal1=100
Tal2=100
Tal3=100
Tal4=100
Comment=Eminence Kappa 12a
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
FILTER
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
0 0.01 0.0 -1 0 0.01 0.0 -1 0 0.01 0.0 -1
100 25 0 0
40.50.50.5
0.50.50.50.5
SSSS
1111
1111
2222
1111
111
000
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
hi LORDSANSUI
that will be interesting - wonder if it could fudge a Karlson better with the new update? MMJ's constricted transflex fudge model for Acoustic Control's 115BK looks close to the real thing (assume can be scaled but don't know)
your Snake 10 should be great for regular front loaded horns
that will be interesting - wonder if it could fudge a Karlson better with the new update? MMJ's constricted transflex fudge model for Acoustic Control's 115BK looks close to the real thing (assume can be scaled but don't know)
your Snake 10 should be great for regular front loaded horns
although off topic, here's some plans for common ported PA planar horn
Poweraudio Romania - MAP of speaker plans - Speakerplans.com Forums - Page 1
Poweraudio Romania - MAP of speaker plans - Speakerplans.com Forums - Page 1
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PARAFLEX REPORT
I just heard back from my long time local friend Pete ...... He just built a 34hz tuned Paraflex DDX 1x12 (type "A" layout) ........ Pete has had a lot of experience with some very serious high powered PA gear (he used to provide sound for the rave and desert party communities here) and he tells me that he is really impressed with how this cabinet performs (for it's small size and cost) ........... He sent me an email about it .....
I will just copy and paste from his email so you guys can read it yourself (see below):
“The box seems bigger than I imagined, it is lighter due to using the 18mm osb flooring material.
There are no handles on it so it is a little awkward to move around by yourself but not bad really, it is easier with 2 people for sure.
It puts out more sound than I imagined, it is solid to 30hz and smooth up top. I wasn't able to run it with a top yet so it's hard to judge, but I think two of these would work with 1 of the community tops.
The sound is super clean which I love, had the talking into a fan effect of modulating your voice. It filled the garage pretty well, knocking rust loose from the hvac and pictures off the wall.
Awesome design but not a piece of cake to build. I did get it done in 2 days but it is work. Maybe I am just rusty, I could do some things to streamline the build process to make it easier to build multiples. Cutting the wood was easy but assembly is a bitch with all the internal bracing.
I modeled it in Sketch Up as usual, I can give you the plans which include a cut list. Makes things a lot easier.
I was thinking for live sound, the port can be moved to the side. That way you can put 2 together for boundary loading. That would give some directional control and some mid bass punch. Or 3 per side, 2 side opening and 1 front opening in the middle, it would make a nice place to put the top on.
I have the driver coils wired in series and am powering it with a single channel of the Mackie i1400 that Paul donated. So the driver is getting about half its rated power ..
The build reminded me of the old days of driving to a gig with the paint still wet on the subs. “
(note: the driver was only receiving about a third of the rated power really but was surprisingly impressive which i would soon experience for myself.... More about that near the bottom of this post)
Here is the simulated output in Halfspace (single cabinet , and a pair)
So how did this start?
Initially I put together some quick Paraflex 1x12" layout sketches that were optimized for the Skar DDX 12" .... A few different tuning options and footprint shapes .... Pete chose the layout with more of an oblong footprint and lower tuning (target Fb on that one was around 34hz) ...
and as another option:
or
and then here was my suggested bracing sketch
and then Pete converted his chosen layout to a Sketchup 3D drawing and cutsheet (his Sketchup files are also included as attachments to this post)
and a different angle
This build was local so i decided to go meet up with Pete and have a listen
HERE IS MY REPORT:
"Well alright guys , went to visit my friend's industrial shop to hear this Paraflex (DDX 1x12) today .... . This is the cabinet that Pete built ..
On only 350 watts it is impressive!
It moves a lot of air with accuracy .... Nice impact!
It reaches all the way down to 30hz surprisingly well and would probably go lower but we didn't run the sweeps any lower (cabinet tuning is supposed to be 34hz... ..Need to verify with DATS)
We ran sine sweeps from 30hz to 100hz for a while and it is hitting every note
When we played music through this sub he told me it was FULL RANGE music!! ... No LPF !! .. You couldn't tell that it was a full range signal though , when we listened to the sub by itself it was very well behaved with no noticeable honks , resonances or nastiness in the midbass, just smooth and punchy tight and deep and loud ..... FANTASTIC!
Sounds like the design of the Paraflex filters out the higher frequencies but it does so in a way that is graceful (at least with this driver) no lower-mid nastiness or midrange ugliness to be heard whatsoever.. .... No offensive coloration when listening to the sub all by itself driven with a full range signal .. .
This cabinet is everything i had anticipated and more ... "
Nice build! I like the frequency response for car audio.
BP1Fan, they do work well in a vehicle or outside in halfspace and also indoors .... So far they just seem to be a versatile all around multipurpose subwoofer design ... .
People who have Paraflex cabinets in their vehicles are loving them
In the beginning all of the Paraflex cabinets that were being built were for Car Audio applications but now we are starting to see some being built with PA drivers for PA applications ....... Jason Geban in New York is currently working on a set of Paraflex (type "A" , 61cm wide) subwoofer cabinets to be loaded with 18sound 18LW2500 drivers ...... Those should produce some exciting results!
Another friend Jory Koolwijk in the Netherlands (maybe USRFObiwan knows him?) just finished a 65cm wide type "A" Paraflex loaded with a B&C 18SW115 driver and he hasn't taken it outdoors for serious measurements yet but his indoor testing has him impressed
Outperforms his large 18TBW100 loaded FLH cabinets everywhere below 95hz it seems (especially in the 30hz to 60hz range) 
..... Initial impressions are very good so far ...... I will dedicate a post to his project once we gather some more data ..
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A car audio enthusiast who heard our TPCH (I don't know what you would call it, since it is not a planar wave design and it is only 6th order) wanted my son to build one for him too.
The driver is a nice 12 inch GAS COMP12D1. It has a low nice Qts of 0,20 and a very strong and durable cone. Perfect for horn and tapped pipe use.
The driver is a nice 12 inch GAS COMP12D1. It has a low nice Qts of 0,20 and a very strong and durable cone. Perfect for horn and tapped pipe use.
The driver is a nice 12 inch GAS COMP12D1. It has a low nice Qts of 0,20 and a very strong and durable cone. Perfect for horn and tapped pipe use.
Johannes,
Do you have the measured parameters (broken-in)? If so please post them .... I will model it in an optimized Paraflex to see how it looks.....If it looks good i will be sure to post the inputs (we can also give it a fold layout if anyone wants) ....
Also, i must ask, what is the pricing on this driver? It would be good to have something i can recommend to friends in Europe ...
- be interesting if close to spec COMP12D1 – GAS Car Audio
I'm hoping for a midbass with low mass 12 (or 15) which is articulate (more so than some flh) on acoustic guitar, cello, percussion
I'm hoping for a midbass with low mass 12 (or 15) which is articulate (more so than some flh) on acoustic guitar, cello, percussion
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No. I only have the few parameters posted on their page.
I have made a guesstimated Hornresp-model that seems to work reasonably well compared to real life outdoor measurements (REW).
This Paraflex is a sound quality orientated build, so the simulated response is optimized to correct for the car cabin gain transfer function.
You can easily make a flatter curve, but it would not suit his VW Polo.
This is already a very optimized custom design.
Cheers,
Johannes
Here is the correct Hornresp simulation data. The previous Hornresp-data was an earlier version.
I have compared both sim and measurements of our old Paraflex (Alpine SWR-8D2) with a simulation of this new build in REW.
I am working within very tight size-constraints so I have been drawing the Paraflex in real size on a scrap piece of plywood to optimize the layout and the performance and to find some way to manage that large magnet. The magnet is always in the way for any and all preferred layouts.
It insane. It is a beast!
B&C 12PS100 looks like a small toy next to it.
Lets take a close look at that driver ..
The driver does look impressive , however it would have been nice for GAS to give us a better list of T/S parameters to work with .... This is a typical car audio industry blunder .. ..... They leave it up to us to measure or figure it out .... The few parameters that car audio brands do provide us are all too often terribly inaccurate anyhow
, best to measure ourselves ...
Johannes, if you were close enough to the part of Denmark where Sebastian Schlager lives i am sure he would gladly measure that driver for you using his Dayton DATS 2 woofer tester ..... I can't think of anyone in Sweden that i know with a tester .. Might be one or two guys in the facebook group from Sweden, i can ask if you like ...
We can calculate out the Sd (cone area) if we measure the diameter of the cone from center of surround roll to the center of the surround roll on the other side in centimeters then we divide that figure by 2 and square the result then multiplying it by Pi (3.14 is good enough) gives us the cone area in centimeters squared, enter this figure into the "Sd" field .. .....
If we plug in our calculated Sd along with the Vas figure and Fs published by GAS we end up with just over 400 grams of moving mass OUCH!! that is a lot of moving mass for a 12" driver 
..... Not ideal but can still be made to work ok if we have enough motor force to propel and control that mass with authority ....
We still need a voicecoil inductance value which they don't provide and unfortunately there is no way to easily calculate that out without measuring , but the 3.1mh figure that Johannes went with is a solid worse case scenario Le:Re ratio for a heavy duty high excursion car audio driver such as this one ......... This Le:Re ratio does put a big dent in the effective motor force but this is typical with this sort of driver ...... As long as we still have enough effective motor force left over to work with after the inductance is accounted for then this can still be a very useful driver ...
Then there is that Qts that GAS provides
.... A Qts of .2 is not likely with Vas of 16 liters (extremely tight suspension for a 12" ) and 400 grams of moving mass .... The motor is strong , but not that strong..... This just doesn't add up so i can see that Johannes did a wise thing and chose a more reasonable value for the Qes and Qts (.45 and .42) .............................................................If the guesstimations that Johaness has made are accurate then that would mean the BL^2/Re with an adjusted BL taking lossy inductance into account (what i am calling the effective motor force score) would be a whopping 92.2 which is pretty good! Right up there with the DDX 12" , Audiopipe BD4 , and the B&C 12TBX100 although those drivers do have less moving mass ........
Anyway , lets not delude ourselves , very fine guesswork it may be but nevertheless this is all just "shooting in the dark" until the GAS driver is actually measured .....
The driver does look impressive , however it would have been nice for GAS to give us a better list of T/S parameters to work with
.... This is a typical car audio industry blunder .. ..... They leave it up to us to measure or figure it out .... The few parameters that car audio brands do provide us are all too often terribly inaccurate anyhow , best to measure ourselves ... Johannes, if you were close enough to the part of Denmark where Sebastian Schlager lives i am sure he would gladly measure that driver for you using his Dayton DATS 2 woofer tester ..... I can't think of anyone in Sweden that i know with a tester .. Might be one or two guys in the facebook group from Sweden, i can ask if you like ...
We can calculate out the Sd (cone area) if we measure the diameter of the cone from center of surround roll to the center of the surround roll on the other side in centimeters then we divide that figure by 2 and square the result then multiplying it by Pi (3.14 is good enough) gives us the cone area in centimeters squared, enter this figure into the "Sd" field .. .....
If we plug in our calculated Sd along with the Vas figure and Fs published by GAS we end up with just over 400 grams of moving mass OUCH!!
that is a lot of moving mass for a 12" driver ..... Not ideal but can still be made to work ok if we have enough motor force to propel and control that mass with authority .... We still need a voicecoil inductance value which they don't provide and unfortunately there is no way to easily calculate that out without measuring , but the 3.1mh figure that Johannes went with is a solid worse case scenario Le:Re ratio for a heavy duty high excursion car audio driver such as this one ......... This Le:Re ratio does put a big dent in the effective motor force but this is typical with this sort of driver ...... As long as we still have enough effective motor force left over to work with after the inductance is accounted for then this can still be a very useful driver
... Then there is that Qts that GAS provides
.... A Qts of .2 is not likely with Vas of 16 liters (extremely tight suspension for a 12" ) and 400 grams of moving mass .... The motor is strong , but not that strong..... This just doesn't add up so i can see that Johannes did a wise thing and chose a more reasonable value for the Qes and Qts (.45 and .42) .............................................................If the guesstimations that Johaness has made are accurate then that would mean the BL^2/Re with an adjusted BL taking lossy inductance into account (what i am calling the effective motor force score) would be a whopping 92.2 which is pretty good! Right up there with the DDX 12" , Audiopipe BD4 , and the B&C 12TBX100 although those drivers do have less moving mass ........ Anyway , lets not delude ourselves , very fine guesswork it may be but nevertheless this is all just "shooting in the dark" until the GAS driver is actually measured .....
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