Help with box volume and Fb/F3 values

[raelman]

Hello.

I do have a Audiotechnology woofer 10C77-25-10-SD-KAP.

I will filter in active, and the driver will be driven by an Hypex Ncore Nc500MP (500W @4 Ohm, 270W @8 Ohm). Woofers paranmeters as follows:

Fs 23,00 Hz
Vas 145,28 l
Qts 0,27
Qes 0,29
Xmax 7,50 mm
Sd, cone area 334,00 cm2
Power input 113,56 W
Re, spkr res 5,40 R

I am in doubt about volume for the box, F3 and Fb values. The box is almost built and I will use a 10cm diameter and 19,7cm long bass port.
My main problem is that I cant install any longer port than 20cm.33

The values I get from software calculations (speaker box designer) are the following to match por lenght:

OPTION 1:
Vb 42,50 l
Fb 45,00 Hz
F3 42,00 Hz
Port length 20,06 cm

OPTION 2:
Vb 52,50 l
Fb 41,00 Hz
F3 38,00 Hz
Port length 19,38 cm

OPTION 3:
Vb 57,50 l
Fb 39,00 Hz
F3 36,50 Hz
Port length 19,62 cm

I can modify box volume (although desired volume is 42,50 liters) , or I could install a smalled diameter port as follows, but its supposed that reducing port diamater my bass port will sound:

OPTION 4: Port diameter 6,40cm
Vb 42,50 l
Fb 32,40 Hz
F3 39,00 Hz
Port length 16,92 cm.

What do you think I should do regarding to volumes and diameters? (My preferred options are 1 and 4)

 

[TMM]

Where are you getting those T/S parameters? Did you measure them yourself? Audio technologies website has different values:
Sandwich cone

10cm dia and 19.7cm length is too short in my opinion. It results in a peaking response (green trace below). If the aim is to run the system without a subwoofer then I would tune it a little lower with a slight shelf to the response, around 32Hz (orange trace below) as this will give you better extension and power handling - this is basically your Option 4. I get 17.4cm length for a 6.4cm port as per the T/S parameters on AT's website.

If the aim is to cross the woofer to a dedicated subwoofer then running sealed might work out better for you (yellow trace). 15Litres sealed gives F3 of 77Hz @ Q=0.7. Run a 12dB/octave highpass @ 77Hz on the woofer and 24dB/octave lowpass @ 77Hz on the subwoofer. This is a very small box for a 10" woofer though, you might run into 'box spring distortion'.

 

[hugo stiglitz]

Don't reduce the diameter of the BR port to 6,50cm!.. unless you want to hear air noise!

Here you go:
55L cabinet net volume
port dia: 10cm
port length: 25cm
-3dB @ 36Hz

if the cabinet is not deep enough to let you use 25cm of tube, use an elbow

thank me later

 

[raelman]

The parameters were measured by AT since this driver is a custom order.

My main problem is to make a longer port than 20cm

Thanks.

 

[hugo stiglitz]

My main problem is to make a longer port than 20cm

you know what an elbow is?!

 

[raelman]

And the aim is to run without subwoofer in a 3 way system
Thanks for your help

 

[raelman]

I know what an elbow is, but due to bracing, it’s very difficult for me to install the elbow without any case modifying in depth. I could do it, but it will be really difficult in this point.
My mistake, I know it.