Re: Tone Controls
It is interesting that the continuously variable slope filter was a feature of Quad preamps from late 1950 through to the last Quad 44 in 1989, so 39 years and covering two valved, one discrete transistor and one IC preamp.
The two frequency two fixed slope HF filter lasted a little longer in the 34, which finished in 1995.
By 1989 most listening was done from CD, and sales of vinyl were plummeting. So I guess that the need for sophisticated switched frequency variable slope HF filters were no longer needed - if indeed they ever were.
Craig
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