Posted by Lew on November 21, 2005 at 10:34:09:
In Reply to: Re: Re: Biamping? posted by sonic on November 20, 2005 at 20:53:06:
The bass and treble transformers are preceded in the signal chain by 6db/octave lo-pass and hi-
pass filters, respectively. The cross-over point is set at ca 500Hz. For the bass transformer, the
filter consists of an inductor in series with the signal. The factory allows for selection of any one
of three inductors or no inductor, to allow for varying degrees of midrange "fill". The choice of
inductance is effected by a switch on the top of the backplate. Good quality iron-core inductors
are used by the factory, but an improvement can be had by choosing a single value and subbing
an air-core inductor. This also gets rid of any sonic degradation caused by the switch network
itself. For the treble transformer, the hi-pass filter consists of an RC network. The factory uses
sand cast resistors and Solens metallized polypropylene caps. There is much that can be done to
upgrade this set-up as well; search the Archives. In addition, the treble network includes the
Brilliance control, which is a variable resistor in series with the signal such that it can attenuate
the treble response. Most of us have found that removing the control, or subbing for it a high-
quality, high-power fixed-value resistor of the value deemed to give the best hf response, is the
best way to go. The "mixer" box is now the subject of a factory-authorized upgrade, and brand
new speakers may have this mod already installed.