I put this speaker into a winisd simulation, but at a port of 40 hertz it tells me that the port should be one meter long.
The recommended box for according to the simulation is 25L, which seem to be too small.
I try with 80L , but still not good result .
Thank you !
The recommended box for according to the simulation is 25L, which seem to be too small.
I try with 80L , but still not good result .
Thank you !
Don't use the standard sim in WinISD, the values used are a wild guess. I got this driver quiet good in a 75L with two slot ports of 15x15cm and 90cm long. This on the condition you use the box as subwoofer (below 125hz), otherwise you will have port resonances (appearing at 250Hz). that will be excited. The port needs to be that big to avoid flapping (high air velocity in the port that makes unwanted noise.). You need to keep the air velocity below 23m/s to avoid that on high power and below 17m/s for hifi to avoid that you hear it.
This is the response i have (with a 4th order filter at 125Hz like you should use it).
This is the response i have (with a 4th order filter at 125Hz like you should use it).
B&C even suggest 90 liters, tuned to 40 Hz on their website, but I guess the suggestion by @waxx is more sensible.
such a rather small enclosure tuned low with very high output is an ideal application for a flared port.
If you have a possibility to 3d-print a port you could try my flared port optimizer tool here:
https://www.diyaudio.com/community/...rbers-and-port-geometries.388264/post-7943524
the following inputs ...
... lead to a 50,3 cm long (round) port:
definition of geometry parameters:
Such a port should behave similar or probably better than a longer straight port.
for more background about the development of this tool have a look at the index in post #1.
3d-printing such a big port probably requires splitting it up into 4 or more parts. Alternatively you could translate the port surface development into a curved wall slot port.
Let me know if I can assist!
EDIT: curved wall slot port example here or here!
such a rather small enclosure tuned low with very high output is an ideal application for a flared port.
If you have a possibility to 3d-print a port you could try my flared port optimizer tool here:
https://www.diyaudio.com/community/...rbers-and-port-geometries.388264/post-7943524
the following inputs ...
- 75 liter enclosure
- 40 Hz tuning frequency
- 120 dB max port output
... lead to a 50,3 cm long (round) port:
definition of geometry parameters:
Such a port should behave similar or probably better than a longer straight port.
for more background about the development of this tool have a look at the index in post #1.
3d-printing such a big port probably requires splitting it up into 4 or more parts. Alternatively you could translate the port surface development into a curved wall slot port.
Let me know if I can assist!
EDIT: curved wall slot port example here or here!
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The 150L 35Hz Fb suggestion B&C puts on the driver's spec sheet is a good starting point:
That said, for home use, I'd prefer a larger box with a lower tuning, like the S18BN subwoofer design:
The trade off of low frequency sensitivity, extended LF response and box size are always a consideration.
Art
Damn, so used to 18SW missed it was a 15SW, should be wearing reading glasses 😳 ...
That said, the 40Hz Fb 90L box has a upward bump above Fb:
That's OK for the driver's usual PA use, but for home use I'd still go with a Fb at or below the driver's 35 Hz Fs, and a larger box closer to it's 110L Vas if more LF sensitivity was desired.
The OP didn't state what the box was going to be used for, or desired frequency response range, so I've already said more than enough 😉
Art
