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Super Power Crossover for KEF Concerto KEF B139B B110A KEF T27 Zoom


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SKU: Crossover 33c

B139B B110A T27A network, KEF Concerto, Falcon Acoustics Recommended Upgrade. Super Power Low Loss Network version of Crossover 5c

Supplied in Kit Form only. Price is for one crossover/network.

Availability: In stock

Excl. Vat: £32.25 Incl. Vat: £38.70
Product Description


    B139B B110A T27A network, KEF Concerto, Falcon Acoustics Recommended Upgrade,Super Power Low Loss Network version of Crossover 5c.

    Supplied in Kit Form only.  Price is for one crossover/network.


    The No.5 network only will fit in the existing network cut-out. All other types are too deep and in the case of the modified ones too wide. The network edge connector is poor and relies on two tin plated surfaces making good contact. 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 keep 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.

    The No.6 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 a higher power handling version. The 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.


Additional Information

    Additional Information

    System KEF Concerto Super Power Upgrade based on 5c Network
    Author/Publication Falcon Acoustics Recommended Upgrade
    PCB No. 3
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