Additional information will be included in the next update to hopefully make things a bit clearer:
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|Options
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Sets the throat chamber and rear chamber resonance masking and default result window options.
The 'Not masked' chamber resonance option assumes that the throat and rear chambers are cylindrical segments capable of generating end reflection resonances, whereas the 'Masked' option assumes that the chambers are simple acoustic compliances with no reflections.
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Yup, that looks like it. I rejigged the PR parameters a bit and now I'm getting something a lot closer to what was predicted by the LDC calculations.
Of note is that the stated advantage of the APR, that the null is driven a lot further down in frequency, basically eliminating the "notch" caused by a typical PR, is correct. In this example, it looks like the notch is driven down to somewhere around 13 Hz, and there's no sign of it in the system's FR.
Since there are tools in HR to suggest a starting point for encloures für TL and BP4, how about adding this for sealed and BR?
I found these formulas reliable:
BR:
Vb=15*Vas(Qts^2.87)
Fb=0.42*Fs(Qts^-0.9)
Port calculation was already discussed somewhere above, but for the record, here a simple( and probably not reliable) formula:
Choose R, e.g. R=3 In
Lv=(1.463*(10^7)*(R)^2/(Fb^2)(Vb))-(1.463)*R
Sealed enclosure:
X=(0.70/Qts)^2-1
Vb=Vas/X
I got these formulas from https://diyaudiocorner.tripod.com/formula.htm
I found these formulas reliable:
BR:
Vb=15*Vas(Qts^2.87)
Fb=0.42*Fs(Qts^-0.9)
Port calculation was already discussed somewhere above, but for the record, here a simple( and probably not reliable) formula:
Choose R, e.g. R=3 In
Lv=(1.463*(10^7)*(R)^2/(Fb^2)(Vb))-(1.463)*R
Sealed enclosure:
X=(0.70/Qts)^2-1
Vb=Vas/X
I got these formulas from https://diyaudiocorner.tripod.com/formula.htm
There are already many existing design tools out there for closed box and bass reflex loudspeakers...
Besides, there is something radically wrong with the Lv formula you quote.
Given:
R = 10 cm (3.150 inches)
Fb = 50 Hz
Vb = 10 litres (610.237 cubic inches)
Lv = (1.463*(10^7)*(R)^2/(Fb^2)(Vb))-(1.463)*R
Where Lv is in inches.
Then:
Lv = (1.463*(10^7)(3.15)^2/(50^2)(610.237))-(1.463)*3.15
Lv = 35434303.84 inches
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An option for a starting point is to use the method proposed by King using LDC formulae kind of ‘unifying’ sealed, vented and TL enclosures sizing described in http://www.quarter-wave.com/TLs/TL_Alignments.pdf . Manual calculation could be error prone though. If I understand correctly, this is used for the Hornresp TLdesign tool with the additional Brian Steele option. Noting sealed and vented enclosures can be initiated in the input wizard and fine tuned in the loudspeaker wizard, would there be anything gained by aligning the input wizard to King/LDC method?
Sure, but it's incredibly handy e.g. in the bp4 simluation to get a very good FR for any driver just by the push of a button.
Sorry, i only did use the Vb and Fb part from the formula to start a simluation, since HR does anyway the better job for the port's diameter and length. Probably a typo in the formula ...
For the formula to work, Vb should be in cu.ft., not cu.in.
In any case, that formula, a well-known one btw, even mentioned in the LDC, produces results that don't match Hornresp sims. See this post for a reminder
- https://www.diyaudio.com/community/threads/hornresp.119854/page-688#post-7423148
Greets!
Using the latest 0924 updated offset driver/vent Input Wizard, when I save a different QL than the default '7' in the Loudspeaker Wizard it displays correctly on the Input Parameters, but when I save the file it defaults back to '7'.
Hi GM,
That's because the QL feature was added quite late in the piece, and by then there were no spare fields left in the data record to be able to permanently store the QL setting value.
Unfortunately it would be too much trouble now to change the data record format just to include an additional field for the QL value
.Kind regards,
David
For the formula to work, Vb should be in cu.ft., not cu.in.
If so, then the information given on the site rertrobaer referred to, is incorrect
.Does that mean that the proposed features are not really worth pursuing?
Attachments
It might be, but use the equation given for the optimum Vb, and then use approach that you use in Hornresp for setting the vent size and length in the 4th order BP wizard. Don't use the given equation to calculate the length of the vent as we know it gets inaccurate as the volume of the vent gets larger.
CORRECTION:
R should have been shown as 8 cm not 10 cm.
8 cm = 8 / 2.54 = 3.150 inches