FYI, both the sims I overlaid are tuned to 'F9'/F-9 db, though obviously screwed up by using the wrong driver where once again I was working multiple folk's Qs off n' on as time permitted. 
The rest is new to me, so learning also.
The rest is new to me, so learning also.
Something's apparently 'up' with them as I've tried every way I know to search there and basically it either returns 'failed' or locks up, including searching myself nor could I find where he might also have posted on the subject.
I will work on a post today / tomorrow.
You basically tune to the 9db down point.
I think keele had the original designs for it.
A Qts .312 worked best because tuning to the speakers fs, that's where the f9 would be.
Shooting from the hip, I think Qts .312 box size as near .4 times the vas.
You basically tune to the 9db down point.
I think keele had the original designs for it.
A Qts .312 worked best because tuning to the speakers fs, that's where the f9 would be.
Shooting from the hip, I think Qts .312 box size as near .4 times the vas.
Yeah Dennis always quoted the Fb=Fs=Faux, Q=2 for Faux for the 0.312 where Vb=0.4*Vas but never much posted on adjusting the whole deal for the other Q values ala Thiele, Keele, Ray Newman et al (can't say I blame him for the time/energy that would've taken).
pretty much, the F9 with these type drivers and Qts will likely be 50 Hz vented.
Huge surprise since the port is 50 Hz
So there is not much room to go.
The port itself is where it ends. So unless your tuned say 10 Hz below Fs
Then you have 10 Hz to add normal every day EQ boost.
You can keep tuning to 50 Hz any EQ boost goes straight into the port.
For actual boost with cone movement you also need the extra volume to allow it to happen.
People loose their marbles over extended bass shelfs.
Basically how you get " extra" bass by tuning below Fs then adding same old EQ to make it " Flat"
To go 10 Hz lower it almost doubles the enclosure volume. And EQ is needed to bring up the shelf.
Problem is it doesnt " look right" in sim looking at the alignment. But your EQ boost wont all be port.
And what you gained with double the box size is 10 Hz lower.
Your actually boosting into more cone movement. Not fluff poofy port boost.
Huge surprise since the port is 50 Hz
So there is not much room to go.
The port itself is where it ends. So unless your tuned say 10 Hz below Fs
Then you have 10 Hz to add normal every day EQ boost.
You can keep tuning to 50 Hz any EQ boost goes straight into the port.
For actual boost with cone movement you also need the extra volume to allow it to happen.
People loose their marbles over extended bass shelfs.
Basically how you get " extra" bass by tuning below Fs then adding same old EQ to make it " Flat"
To go 10 Hz lower it almost doubles the enclosure volume. And EQ is needed to bring up the shelf.
Problem is it doesnt " look right" in sim looking at the alignment. But your EQ boost wont all be port.
And what you gained with double the box size is 10 Hz lower.
Your actually boosting into more cone movement. Not fluff poofy port boost.
Roll the woofer off very early with a HUGE inductor. Classic old school method. Danny explains how it is done in this video on the Brute speaker. Go to 8.20 min. mark for the woofer manipulation explanation:
Make sure to model the resistance of the inductor into your enclosure modeling software.
Dan
true.
6th order vented works for drivers with a strong qts (near .3)
hoffmans iron law.
driver with floppier qts (say .4) = bigger box = lower F3 but 90db 1w/1m or much less
driver with qts .312 = small box = high spl with 1w/1m, but higher F3 values
Running qts .312 tuning to the F9 of 27hz (with no boost), made for a "lean" subwoofer sound.
6th order vented works for drivers with a strong qts (near .3)
hoffmans iron law.
driver with floppier qts (say .4) = bigger box = lower F3 but 90db 1w/1m or much less
driver with qts .312 = small box = high spl with 1w/1m, but higher F3 values
Running qts .312 tuning to the F9 of 27hz (with no boost), made for a "lean" subwoofer sound.
Formulas post 5 not working. Deltapro-12A Fs 51 hz Vas 81.7 L Qt 0.35 maxflatV=20*81.7*0.35=571.9^3.3=1256482136 L
That is not a speaker box size, that is a warehouse volume.
F3=.28*Fs*Qt^-1.4 F3 .28*51*.35=5.0^-1.3=0.123 hz ??
The large vented box Eminence suggests for Deltapro-12A is 3 cuft or 84.9 L versus Vas of 81.7 L They say Fb is 55 hz and F3 is 60 hz. Displacement limited to 150 w with a 50 hz low cut filter.
I want 54 hz f3. I think box size will be 90L. How do I calculate max displacement at 70 w which is the amp I intend to drive it with. Or how many watts can I have for Xmax of 4.55 mm? I do own a Nady crossover appliance that will low cut the mains outputs at 18 db/octave at a frequency I dial in.
I tried all the formulas for sealed box in David Weems Designing Building and Testing Speakers, and I could never get F3 lower than 70 hz for 42 hz Fs. ?? (Deltapro-15A which I own)
Furthermore, what is the Q of a filter? Weems has L & C values for 6 db, 12 db filters, first & second order, but nothing about Q.
That is not a speaker box size, that is a warehouse volume.
F3=.28*Fs*Qt^-1.4 F3 .28*51*.35=5.0^-1.3=0.123 hz ??
The large vented box Eminence suggests for Deltapro-12A is 3 cuft or 84.9 L versus Vas of 81.7 L They say Fb is 55 hz and F3 is 60 hz. Displacement limited to 150 w with a 50 hz low cut filter.
I want 54 hz f3. I think box size will be 90L. How do I calculate max displacement at 70 w which is the amp I intend to drive it with. Or how many watts can I have for Xmax of 4.55 mm? I do own a Nady crossover appliance that will low cut the mains outputs at 18 db/octave at a frequency I dial in.
I tried all the formulas for sealed box in David Weems Designing Building and Testing Speakers, and I could never get F3 lower than 70 hz for 42 hz Fs. ?? (Deltapro-15A which I own)
Furthermore, what is the Q of a filter? Weems has L & C values for 6 db, 12 db filters, first & second order, but nothing about Q.
And who doesn't want a warehouse sized speaker?🙂 I'm game.... my wife might think differently
When I took algebra, the part of the formula that was supposed to be calculated first was supposed to be enclosed in parentheses. Otherwise, left to right. Maximum Flat box formulas now Vb=20*VAS*(Qts^3.3) Fb=0.42*Fs*(Qts^-.96) F3=-.28*Fs*(Qts^-1.4) IMHO.
The more I study this kind of goal,..... the more certain I become it IS just a simple EQ problem 😀
Here's another via Hornresp and its 'Loudspeaker wizard' ... ......close to same thing as markbakks,
100L; port 0.4x Sd, length 19cm
25Hz Low shelf, -20dB, Q=1.26 ......serving as hpf, and providing EQ bump at corner. {credit Perry Marshall for low shelf idea}
PEQ 91Hz, 0.6dB, Q=1.1 ...serving to totally flatten response (not needed)
So 1 filter all that's needed.
f-3 @ 43Hz
Formula free!! 🙂
100L; port 0.4x Sd, length 19cm
25Hz Low shelf, -20dB, Q=1.26 ......serving as hpf, and providing EQ bump at corner. {credit Perry Marshall for low shelf idea}
PEQ 91Hz, 0.6dB, Q=1.1 ...serving to totally flatten response (not needed)
So 1 filter all that's needed.
f-3 @ 43Hz
Formula free!! 🙂
Tune the port to the desired lowest frequency that you expect from the speaker and EQ to taste at and above port tuning. Done.
May cut below the port tuning to prevent overexcursion.
May cut below the port tuning to prevent overexcursion.
I sometimes like to drink, when driving my bass-reflex subs....
So "may cut", is a "must cut" for me 😀
There could be a "Linkwitz transform" for vented boxes ..
https://www.diyaudio.com/community/threads/dsp-assisted-reflex-system.404349/post-7552138
https://www.diyaudio.com/community/threads/dsp-assisted-reflex-system.404349/post-7552138