Posted by Lew on April 20, 2004 at 11:01:54:
In Reply to: M series tone controls posted by avsgroupie on April 19, 2004 at 19:51:03:
I disagree a little with Mr. Fife (and drum). The hi-pass filter operates around 550Hz standard,
so the Brilliance control (which I think is the one referred to by Mr. Fife as the "Hi" control),
operates above that point to attenuate the signal only. In fully open position, there is no boost
effect of the Brilliance control. The "mid" control selects one of four choices for the inductance
that precedes the bass transformer to form a lo-pass filter (which keeps the treble frequencies
out of the bass tranny). These are either no inductor (+3db), 5mH inductor (0db), 10mH
inductor (-3db), and 15mH inductor (-6db). (Please note that I am not completely certain about
the values of the inductances for the -3db and -6db settings, but you will choose by ear
anyway.) The bass control operates to choose among four different primary windings on the
bass transformer which apparently affect efficiency of the bass transduction. I have chosen (i) no
brilliance control at all in the circuit, (ii) 0db for mids, and (iii) 0db for bass. All switches are
removed from the circuitry in my backplates. I suggest you take a month or two to choose your
favored settings for bass and mids and then hard-wire those settings in place so as to bypass
the switches (or jumpers, depending on what model speaker you own). But in any case the
Brilliance control is dispensible. You want to minimize the crap in the signal path and correct the
frequency response of the speakers by dampening or livening your room, as needed.