Hi Martin,
Your optimised SS15 also gives very good results with an 270mm extender in combination with the RCF and Moncacor drivers.
Your optimised SS15 also gives very good results with an 270mm extender in combination with the RCF and Moncacor drivers.
Hi Oliver,
I do it two ways and check the differences; one way is to stretch the concept like usual, and the other way is to use "TH1" in the "Input Parameter" page and recalculate the positions, that Neo Dan pointed out to me. The last one looses the capability to put a horn parameter between S2 and S4. It would be better if you use Akabak, but I hope David will increase the number of horn parameters. Besides, there are more important things you can't model.
Hi Oliver,
Let me put it this way, maybe its not optimised, but it does improve compression figures considerably and gives low freq. extension for the drivers mentioned in my earlier post. It's not tested with the 3015lf (as far as i know) but I think it will be less promising.
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Black is closest in volume.
Black and Grey line are Xoc1 optimised.
Green line is standard SS15 from JBell.
Black and Grey line are Xoc1 optimised.
Green line is standard SS15 from JBell.
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oftopic ,how does one run akabak under win7 x64?
i tryed compatebilety mode and dos envirement.
tnx oliver
i got it running on a vm.
a got an extra section in ,and a hpf.
now i want to put in a eq,but cant figger out how .
sorry 4 the oftopic
In Post # 31 here - http://www.diyaudio.com/forums/subwoofers/189223-crazy-box-design-input-please-3.html - i posted a screeie of a design i did, which included an extended mouth.
Djim posted an extender in Post # 461 here - http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-31.html - His graph clearly shows improvements below 55Hz, & also up to 150Hz 🙂
So based on that, i'm wondering how my design would fail to offer some LF improvement/s ?
TIA
Djim posted an extender in Post # 461 here - http://www.diyaudio.com/forums/subwoofers/190635-th-18-flat-35hz-xoc1s-design-31.html - His graph clearly shows improvements below 55Hz, & also up to 150Hz 🙂
So based on that, i'm wondering how my design would fail to offer some LF improvement/s ?
TIA
Hi Zero D,
Your example is based on a basreflex system and my example is based on a 1/4 wavelength resonator (horn/tapped horn/ pipe). In other words my example is increasing the length of the hornpath.
Your example is based on a basreflex system and my example is based on a 1/4 wavelength resonator (horn/tapped horn/ pipe). In other words my example is increasing the length of the hornpath.
Compression Ratio?
I’m Thinking about the horn throat design for the TH18
My first observation is about the compression ratio (as reported in Hornresp when you hover over the S2 area.)
Most people on DIYaudio try to keep this ratio fairly low. 2:1 or thereabouts.
At this point in a TH you are only looking at half the driver, the other half is past that point in the horn. Does this reduce the supposed compression ratio at the S2 area by at least 50%.?????
Your thoughts please!
Regards Martin. (Xoc1)
I’m Thinking about the horn throat design for the TH18
My first observation is about the compression ratio (as reported in Hornresp when you hover over the S2 area.)
Most people on DIYaudio try to keep this ratio fairly low. 2:1 or thereabouts.
At this point in a TH you are only looking at half the driver, the other half is past that point in the horn. Does this reduce the supposed compression ratio at the S2 area by at least 50%.?????
Your thoughts please!
Regards Martin. (Xoc1)
I do think tapped horns can support higher compression ratio's than front loaded and back loaded horns can.
When sound is seen from the perspective of moving particles (part of the dual theory) as well as behaving as a mass (spring/mass). Air molecules in a front loaded horn, are pushed by one side of the cone. The entire air mass is thus "resting" on one side of the cone and in the example of an outward cone movement are pushed through the throat and simultaniously counteracting/pushing on the cone.
In a tapped horn (and other similar designs 😉 the mass/molecules are pushed by one side of the cone whilst the other side pulls them through the throat (vacuum). That could help to easy the stress on one side of the cone, as it's helped from near the mouth.
Best regards Johan
When sound is seen from the perspective of moving particles (part of the dual theory) as well as behaving as a mass (spring/mass). Air molecules in a front loaded horn, are pushed by one side of the cone. The entire air mass is thus "resting" on one side of the cone and in the example of an outward cone movement are pushed through the throat and simultaniously counteracting/pushing on the cone.
In a tapped horn (and other similar designs 😉 the mass/molecules are pushed by one side of the cone whilst the other side pulls them through the throat (vacuum). That could help to easy the stress on one side of the cone, as it's helped from near the mouth.
Best regards Johan
Hi Johan, that makes sense but only at low frequencies. Is that not what happens when the driver becomes unloaded below the resonant frequency and a hi-pass filter is needed to avoid excessive excursion.
I think that the maximum compression in the TH horn is reached at the point in the horn next to the edge of the driver, not the centre.
As such the Hornresp compression ratio reported is still useful information but does not specifically relate to the actual S2 point in the horn.
Flow analysis sim screenshot attached to illustrate this.
I am trying to concider what is really happening in the TH horn throat.🙂
Regards Martin
