CROSSOVER No.33Mc Mk2. KEF CONCERTO R40 FALCON ACOUSTICS MF & HF UPGRADE SUPER POWER VERSION

B139B B110A T27A network, KEF Concerto, Falcon Acoustics with Falcon MH and HF upgrade. Recommended Upgrade.

New Mk2 Multilayer PCB for improved results. Full BiWire capability.

Networks are supplied pre-assembled only. Price is for one crossover/network.

FALCON ACOUSTICS MF& HF UPGRADE

This exclusive Falcon improvement designed by Malcom Jones improves the performance of this network for the original B139/B110/T27 units by (A) increasing the roll off of the B110A (SP1003) at high frequencies from 12 to 18db per octave and (B) incorporating a simplified version of the acoustic Butterworth section for the T27.

UPGRADING THE KEF CONCERTO NETWORK

It is best to put the network inside the cabinet on the bottom at the back or on the back at the bottom and rewire with a decent cable. We recommend 76/0.2 mm.

If you want to preserve an authentic look keep the original SP1004 network and wires as they are, but not connected inside. Just leave the existing bits as they are, but disconnect all the wires inside the cabinet (to units and input) and rewire the new network with good wire to the input and units. Unless you want rear panel authenticity, fit a new input panel or terminals. It will sound better without the connector and with thicker wire.

This network was originally designed (in a 4-way version) for a prototype Ferrograph system. The network was subsequently offered to Cambridge Audio where Bert Webb was designing the R50 transmission system. Bert made a few simplifications and added a super tweeter.

The No.33Mc network is a modern higher power handling version.

This design never went into KEF production as the Concerto was coming to the end of production. The sound was flatter and smoother than the DN12 SP1004. Note there are 2 versions of the DN12 SP1004. The first had a 60 μF and a 2mH inductor in the MF low frequency roll-off, whilst the later had a 30 μF and a 4mH. This gave a higher impedance at the LF/MF crossover. This became important when transistor amplifiers standardised on 8 Ohm output.