The second iteration for S18 is making it a 3-Way. Adding four 12" Peerless XXLS subwoofers, they reproduce -6db at 20hz at very serious levels
Waveguide: FaitalPro STH100
Compression driver: B&C DE250
Woofers: FaitalPro 8PR155
Subwoofers: Peerless P830845 XXLS (12" version, two per side)
XO: 1.5kHz LR4 and 120Hz LR4
Sensitivity: 96dB
Follow the discussions at DIYAudio and ASR
DIMENSIONS
Built using 16mm thick MDF, but 18mm would be better.
Input (affects all channels)
Baffle step: Shelving lowpass 200Hz/5dB/1Q
The baffle step can be placement or room dependent so adjust as necessary. I would recommend by turning it off first where the speakers should sound lean, and adjust gain and frequency as necesary.
There are some simulators which you can use to help such as Edge Diffaction program.
Tweeters/Compression drivers
Attenuation: -11dB L-PAD to reduce hiss of this high sensitivity driver
Attenuation/Level: 0dB
Notch 1: 3916 hz/ -4db / 1Q
Notch 2: 16273 hz / -4db /5Q
It is very rare to see electrical slope = acoustic slope so I am very happy. The ±1db of STH100 and DE250 is impressive.
Woofers
Upper XO: 1.5kHZ LR4
Lower XO: 120hHz BW12 (acoustically 120Hz LR4)
The woofers are pretty simple and does not require any PEQ.
The lower XO of Butterworth 12db/Oct forms an acoustic 120Hz LR4)
Only -1dB attenuation is required for the woofer to match the Tweeter, making these speakers a 96dB sensitivity
Subwoofers
Attenuation : -1dB
Upper XO: 120Hz LR4
To form acoustic LR4 at 20Hz, to Linkwitz Transform Biquads are applied:
Warning: these values are valid for 96khz DSP boards such as MiniDSP.
First Biquad:
biquad1,
b0=1.00042618117812,
b1=-1.99813888977116,
b2=0.997733679245083,
a1=1.9981485191522,
a2=-0.998150231042163
Second Biquad:
biquad1,
b0=0.999074688085099,
b1=-1.9981493761702,
b2=0.999074688085099,
a1=1.99814852022621,
a2=-0.998150232114188
Measure raw and LT response of the Subwoofers:
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