Hi All,
I tried to estimate volume of Marty Cube subwoofer and simulated in Winisd.
Driver is 18" Lavoce SAF184.03.
The following are the problems I observed.
1. I am getting 112 dB at 22Hz, and 124dB at 100Hz.
So basically 22Hz is 12 dB lower compared to 100Hz.
So 22Hz is below F10 point. Is this ok??
GSG audio is claiming 115dB @ 22hz.
2. For 19Hz tuning, winisd suggesting 67" long port. But looking at the pictures, GSG port length seems to be around 41" long.
Am I missing something?
Please see the attached images for volume estimation and results.
I tried to estimate volume of Marty Cube subwoofer and simulated in Winisd.
Driver is 18" Lavoce SAF184.03.
The following are the problems I observed.
1. I am getting 112 dB at 22Hz, and 124dB at 100Hz.
So basically 22Hz is 12 dB lower compared to 100Hz.
So 22Hz is below F10 point. Is this ok??
GSG audio is claiming 115dB @ 22hz.
2. For 19Hz tuning, winisd suggesting 67" long port. But looking at the pictures, GSG port length seems to be around 41" long.
Am I missing something?
Please see the attached images for volume estimation and results.
Attachments
1: Is the Lavoce the original driver for this cab? If not, then getting a response that's a few dB different than the designer's claims is not unusual. Whether it works for you is up to you to decide - maybe with a bit of room gain or EQ you might find that acceptable.
2: WinISD's port length calculation assumes the back end of the port is in open space inside the box, which is not the case for a slot port.
Slot ports typically tune lower than the basic length would suggest, due to 3 of their 4 walls extending past the other.
One way of calculating a more accurate length is to increase the "End Correction" value in the equation and calculate the new length manually; user Bjorno provided various versions of this. I attach one of them, in this particular case Bjorno showed that 3 different versions of the port length equation all came out with near enough the same length so you can use whichever one you like the look of most.
HTH,
David.
2: WinISD's port length calculation assumes the back end of the port is in open space inside the box, which is not the case for a slot port.
Slot ports typically tune lower than the basic length would suggest, due to 3 of their 4 walls extending past the other.
One way of calculating a more accurate length is to increase the "End Correction" value in the equation and calculate the new length manually; user Bjorno provided various versions of this. I attach one of them, in this particular case Bjorno showed that 3 different versions of the port length equation all came out with near enough the same length so you can use whichever one you like the look of most.
HTH,
David.
Attachments
Well ...I agree little variation is unavoidable.
In this attached image the response looks nearly flat from 100hz to 20hz. (Looks like within 3-4db variation)
But winisd shows gradual slope right from 100hz.
and by the time we reach 20hz it's already 12 db lower. Im thinking that's a little problematic.
In this attached image the response looks nearly flat from 100hz to 20hz. (Looks like within 3-4db variation)
But winisd shows gradual slope right from 100hz.
and by the time we reach 20hz it's already 12 db lower. Im thinking that's a little problematic.
In that image you provided there is no specification of what driver is modelled or whether there is any EQ used, so it is pretty much meaningless.
Hi David....thanks for sharing the attachment regarding port lengths. It is very usefull
Thanks GM ... I tuned it higher to maintain the graph flat.
If can't sacrifice transient response to get low end extension.
As per winisd simulation,
F3 is 33hz @ 120dB
F6 is 30hz @ 118dB
F10 is 26hz @ 114dB
Since this is a slot in reality it may tune 3-4hz lower.
If can't sacrifice transient response to get low end extension.
As per winisd simulation,
F3 is 33hz @ 120dB
F6 is 30hz @ 118dB
F10 is 26hz @ 114dB
Since this is a slot in reality it may tune 3-4hz lower.
😀 Or much lower IME since it's a shelf vent, but then I had no software, advanced calculations such as the late bjorno's to guide me, just basic reflex formulas, so knowing a bit more about horn theory usually designed them as crude ~1/8 WL horns, slanting the top 'shelf'/baffle board a bit to 'dial' them in.
Guys...
check this while using winisd.
If we change END CORRECTION value, WINISD is not showing any change in vent length.
if we put 0.732 or 1.23 or 2.227 the vent length remains same.
check this while using winisd.
If we change END CORRECTION value, WINISD is not showing any change in vent length.
if we put 0.732 or 1.23 or 2.227 the vent length remains same.