CAMBRIDGE R50 KEF B139B KEF B110A KEF T27A Coles 4001G network, C Rogers Monitor, Super Power Low Loss Network version with Falcon Acoustics MF and HF 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 slightly different 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.33 and 33C networks are modern higher power handling versions.
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.
|System||Cambridge R50, HiFi Answers Monitor, Coles 4001G Super Tweeter with Falcon Acoustics MF & HF Upgrade Super Power Version|
|Author/Publication||C Rogers HiFi Answers August 1973/Falcon Acoustics|
Bought to replace R50 crossovers from 1986 by Jon
I was intending to recap my old units. Really glad I didn't. Apart from the redesigned and far superior biwirable pcb, the hf and mid modification give the speaker a presence and accuracy previously missing, without becoming harsh or shouty. Excellent! (Posted on 21/07/2021)