Single sheet TH challenge

[maxo]

Originally Posted by Djim

Hi Maxo,

Time has moved on. If you want a 18Sound for the SS15, check out the 15W750 and the 15W930.

wow 1200w RMS and 500w RMS

who sells those in usa...
( i dont think i have budget for that powerfull xpensive drivers )

so i will stick with the most budget ones

[Djim]

Not sure what the US price will be for the 15W930 but I think somewhere around 225. Btw it is no accident that the specs look like a ninety 200AK . Therefore it is also a splendid replacement for classic bass enclosures of EAW and Nexo (reflex and horns) for instance.

[Matthew Morgan J]

Originally Posted by epa

the le value rizez as freq drops,for subs you can easely double le value.

Epa
Well now, that is interesting ...
The LE figure on hornresponse is based on a 1khz standard right? Same with woofer inductor values as well as crossover inductor values, correct?
However strange it may be i suppose the system works if we stick to the same standards.....
I have to wonder if hornresponse takes this phenomenon into account and actually runs it's internal calculations using double the inductance figure listed in the LE field, in the bass range ...
If not i suppose it would explain why the peaks and saddles of a tapped horn can sometimes be moreso exaggerated in the hornresponse simulations as opposed to real world measurements ... If this is the case then perhaps we could always just increase the LE figure a bit in simulation to get a better idea of what the real world response will actually be like ..... Just a thought .....

If Mr McBean is around maybe he can enlighten us on this inductance issue ....

[Matthew Morgan J]

Originally Posted by wg_ski

And I'm wondering how the heck you can get a 4" VC driver to have such a low BL.....

Wg_Ski thats very observant ! I took a second glance at the specs for this 15W1600 driver today and saw the 13.5 BL rating and it simply doesn't compute......More than just suspicious , the numbers simply don't work ..... The VAS listed on PE is also very different from what is stated on the PDF file ....
I have contacted PE and asked them to put a WT3 on this driver to see what they get ...
When i first tried to sim this driver i had assumed it had a BL factor of around 20 which is what you would need to get the QTS they have listed with a VAS of 63Liters and MMS of 105... If the specs turn out to be remotely close to the ones i used in my sim then it actually works incredibly well in a small single sheet sized straight tapered 40hz TH, great extension without sacrificing too much sensitivity , it could end up being an off-brand pleasant surprise! ...I will post my inputs if the specs i used turn out to be truly correct .... Who knows what the specs will really be though, PE will get back to me soon enough im sure ..

[David McBean]

Originally Posted by Matthew Morgan J

I have to wonder if hornresponse takes this phenomenon into account and actually runs it's internal calculations using double the inductance figure listed in the LE field, in the bass range ...

Hi Matthew,

Hornresp assumes a constant inductance Le at all frequencies. The reactance of the inductance increases with frequency.

Kind regards,

David

[epa]

right david
we'v been down that road already
mathew i always double the le value in hr for subs under 100hz.

[Matthew Morgan J]

Awesome! Thank you David and Epa
That clears some things up for me ... I will remember to always bump up the LE for subwoofer sims to get more realistic graphs

I absolutely LOVE your software David! Hornresponse is not only helpful but has become essential to me! I cannot imagine just how dreadful horn designing must have been back in the dark ages before you crafted your masterpiece

[maxo]

Originally Posted by Matthew Morgan J

Awesome! Thank you David and Epa
That clears some things up for me ... I will remember to always bump up the LE for subwoofer sims to get more realistic graphs

I absolutely LOVE your software David! Hornresponse is not only helpful but has become essential to me! I cannot imagine just how dreadful horn designing must have been back in the dark ages before you crafted your masterpiece

That leads me to think
how manufacturers made and design their subs
10 yrs or 20 yrs before this tools

[epa]

akabak is around for a while.
i stil have a quickbasic formula for horn caculations i used about 20 years (or so) ago.
but there was a lot of trial and eror.
i think david saved a lot of trees with his program.

[Djim]

Hi all,

The inductance plot shown in post#1863 is probably of a driver in a closed box. Therefore the plot shows a relative stable character that rises from 1Khz going down. In Tapped Horns the inductance is much more complex.

I think what David McBean was trying to communicate is that inductance is a complex interaction between lots of parameters; an electric component (impedance), an acoustic component (air load) and mechanical components (moving mass and its mechanical resistance). What makes it even more complex is that some of these components are also time/frequency related (phase). The relation between all these parameters is called the 'impedance phase angle' to which the inductance responds (inductance reactance). HornResp calculates perfectly the inductance for every frequency.

When one changes the Le value it changes the 'impedance phase angle' over the entire response! That often leads to wrong plots/assumptions. Therefore increasing the Le value to compensate 'something' is only valid if 'something' is well understood. Maybe even more important, if the limitations of such compensation is understood.