The Tantaliser - Finished system and measurements

Finally - they are playing!

The Behringer 2496 has been adjusted to give a gain of 10 dB at 25 Hz. A small suck-out at around 63 Hz has been implementet to reduce the room mode (not quite succesfull).

The upper X-over is a 4th order bessel - crossing over at 180 Hz.

The woofer section has been coupled to around 6 ohm with a 2.2 ohm i series to rise the Qt of the system. Internal damping and reinforcemnet in the "U-shaped" baffles have cancelled out some of the booming in the uppper range - around 140 Hz, but this could still be improoved.

The frequency range below 100 Hz is relly good. This should be heard to be beliewed. The bottom range is driven by the B&O ICE-power module delivering close to 250 Watt into the system. Based my previus experience with other amps the woofers will run quite high on only 2-4 Watts.

MLS measurement of the mid/top. X-over is at 2 kHz. There is a 1st order low-pass electric slope on the mid, but this sums with acoustic roll of to approx 18 dB. There is no cap to roll of the bottom, the PHL unit will do this quite OK on its own.

The ribbon use a 2nd order XO - making it a 4th order acoustic roll off.

The two peaks at 7,5 and 16 kHz could be edge reflections. Some kind of felt damping will be tried out.

As it can be seen, the ribbons has absolutely no drop at 20 kHz.

Pink noise in room frequency range - woofer section included. The CLIO has not been level calibrated so dBspl is considerably higher than the 50 dB shown.

The suck-out at 250-400 Hz is the weak spot of the system. Next stage is to put the midrange in a closed box, so it will go lower.

The broad peak around 50-80 Hz is the room. I tried to cancel it out with the Behringer, but some room compensation may be necessary (tube-traps).

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