Small Signal Parameters
D0.33m/12.99in
Fs34.3Hz
Mms126.39g/4.46oz
Qms3.27
Qes0.27
Mmd112.24g/3.96oz
Qts0.25
Re5.37Ω
Vas140.0lt/4.94ft3
BI22.89Tm
Cms0.17mm/N
Rms8.162kg/s
Le (at 1kHz)1.38mH
D0.33m/12.99in
Fs34.3Hz
Mms126.39g/4.46oz
Qms3.27
Qes0.27
Mmd112.24g/3.96oz
Qts0.25
Re5.37Ω
Vas140.0lt/4.94ft3
BI22.89Tm
Cms0.17mm/N
Rms8.162kg/s
Le (at 1kHz)1.38mH
Thanks.
See if you can make the baffles straight. (Volume around 360-390L)
Then use a 15 cm long "parallel" port, port area 760 cm².
This will translate to around 162 mm * 470 mm for the port.
Maybe not the best possible scenario but we got those drivers and this enclosure but it will be an easy fix and sound good.
Use a low cut off with these, relatively steep and around 40(+)hz.
See if you can make the baffles straight. (Volume around 360-390L)
Then use a 15 cm long "parallel" port, port area 760 cm².
This will translate to around 162 mm * 470 mm for the port.
Maybe not the best possible scenario but we got those drivers and this enclosure but it will be an easy fix and sound good.
Use a low cut off with these, relatively steep and around 40(+)hz.
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Many thanks for the design tips.
As a compromise would it be effective to increase the port area by opening up the port by shortening it? and keeping the tapered baffles as I obviously want to minimise the changes....I could perhaps try this first before doing anything more extensive.
Could you tell me if this design is no good then? and what was it trying to achieve, I assume it is a non folded horn design or is it just a flared reflex port?....It seems a shame to just turn it into a normal bass reflex enclosure.
I will use the low cut off you recommend (I always do this anyway to stop excessive cone excursion at very low frequencies)
i would extend the baffling further in two sections towards the outer rear corners that would increase the path length and should give you deeper usable response.
the current path length front to rear is just over two feet and would make for unpredictable low frequency response,no?
i would attempt to make it more of a rear loaded horn.
just what sort of construction are these boxes, any removable baffles?
the current path length front to rear is just over two feet and would make for unpredictable low frequency response,no?
i would attempt to make it more of a rear loaded horn.
just what sort of construction are these boxes, any removable baffles?
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No luck finding info on this box. Not an expert but no amateur either... The design looks (low) midbass-ish to me. Lowish xmax driver too. I bet it sings 70-300hz. That's my vote. Models well with THAM15 but a bit limited by xmax compared to big xmax stuff.
The baffles are not removable but I can get to most of the box internals through the openings for the speakers, so I could add extensions to the ports, I am told though that the present port opening is too small and that would need increasing in surface area, which is no problem to do as it is flared.
OK.
Keep port area the same but lengthen the port.
Maybe around 3-5 cm.
Like already mentioned this one seems to be designed for kick/midbass duty (65-70Hz on up) and the drivers have relatively low xmax for heavy sub duty.
Not really suitable for a sub which should go down to at least 45Hz.
If you want to use it a sub (40Hz on up) you can make those changes but xmax of the drivers might limit the output somewhat at low freqs (below 55Hz).
Although you can play with the low cut-off freq.
If I were you I would get a dsp to run with it, let it be as it is and run 2-way bass. And add another "real" sub "below".
Outdoor a lot of kick is always fun.
For stand-alone it will not suffice as is (without mods).
It will simply go not low enough.
Unless you are rocker, I'd sell and build/buy rather than roll the dice with the mod and I am pretty experienced wooddorker. If RNR, pull the drivers and build. Driver sims better in the SS15 than THAM15. 4 SS15 would be pretty crazy. If not a rocker and dance music there are much better options. I am partial to Art's Keystone.
Well, 600cm² would be technically better because of the reduced air velocity but that would practically double the length of the port - that does not fit anymore.
I've thought about a cancellation but because of the wavelength that's not likely and for a length- or across resonance of the port the hornreflex isn't big enough. I thought about it and such high resonance would only be possible at a high surface area port and since if you rule out the impossible, whatever remains, no matter how improbable, must be the truth another idea sprang to my mind: Is it possible by any chance only one driver is actually running? That would mean the 2nd would act as a passive radiator, which could bring the port frequency that far up by increasing the surface area.
Try modeling one woofer in a 150L box tuned to 60Hz, this may be close to what you have now as there is an excursion peak at roughly 70 Hz. If you can measure impedance one might be able to confirm this guess.
If I were to make something with these drivers, I would probably try 80 Liters each, tuned to 42-45Hz. Maybe 3x 4" diameter ports about 15" (40cm) long. 2nd order low cut below 40Hz.
Total box volume and port quantity would be double this. You'll be close to 126dB@1m, power handling roughly 700W below 100Hz...
If I were to make something with these drivers, I would probably try 80 Liters each, tuned to 42-45Hz. Maybe 3x 4" diameter ports about 15" (40cm) long. 2nd order low cut below 40Hz.
Total box volume and port quantity would be double this. You'll be close to 126dB@1m, power handling roughly 700W below 100Hz...
Attachments
Both drivers are running, as a matter of interest I removed one driver completely and ran the speaker with just one driver...it actually sounded much better it went lower in response and sounded louder!!
I found this info online.....looks like it could be exactly the issue I have....
when a Heavily flared port is pushed into turbulence the effective port length drastically shortens, thus raising the tuning frequency which causes a hump in response and more output in the mid-bass, and worse unloading and risk over over-excursion at low frequencies. This causes a negative spiral of even higher air velocities and more turbulence, distortion and compression. Heavily flared ports are great in more controlled environments but we do not see high SPL live sound as the right place for them.
when a Heavily flared port is pushed into turbulence the effective port length drastically shortens, thus raising the tuning frequency which causes a hump in response and more output in the mid-bass, and worse unloading and risk over over-excursion at low frequencies. This causes a negative spiral of even higher air velocities and more turbulence, distortion and compression. Heavily flared ports are great in more controlled environments but we do not see high SPL live sound as the right place for them.
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