The bbe (rack) also had a 'low' end enhance ... I thought that the 'low contour' control was of the 'sub-harmonic generating' kind .. adding harmonics at 1/2 of the 'low end dominant freqs' or something like that.
The top end 'process' sure does a lot of boost/cut - I'm pretty sure the harmonic distortion from that would not be unchanged.
But - I haven't measured, only 'used' it for a long time back in the mid 90s. It seemed quite novel then, and I used it alot for years ... it was the best I had access to at the time .... eventually bin-ed it after it went awol.
It must have done 10 years service as my 'lounge hifi' enhancer, however ;D
I do like these kinds of processors ... my progression was bbe enhancer then spl vitalizer then several finalizers
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I also had a yamaha fx750 which was a 90s guitar processor ... it did have a multiband distortion block. It was quite interesting as a distortion effect, a bit more refined than most at that time.
I like the principle ... nowadays I use that kind of thing as a plugin.
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One of the most versatile distortion processors of all time, imho, is the one in the Roland VG-8 guitar processor.
It's polyphonic, requiring the GT-6 'divided pickup' [and a worthy 'donor' guitar']. It is 'mult-band' to the max, for guitars.
Once you get going with the 'models' and 'resonators' and stuff, it gets very 'out there', but polished sounding and studio friendly.
I use mine with an Art Compressor/Limiter/Gate - the Roland VG-8 has a ferocious dynamic range when going from preset to preset ... the Art box adds the sorely needed analog functionality.
Here is Australia, it was made famous by a local artist mr Ed. Kuepper, who used it for many years live performance.
He was, and still is a force to be reckoned with in the guitar world .. from 1975's 'Im Stranded' (emi uk release) to the present day.
A real 'delta blues' man at his most introspective and all round serious, working man guitar/comp/singer guy.
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And speaking of generating upper harmonics .. the FInalizer has a 'digital radiance' function block in it ... it adds/subtracts 'harmonics' in the digital domain (of course). It's quite subtle .. certainly doesn't damage the sound
I am doing some more measurements of the Finalizer with REW ... there's literally an ocean of audio in that 1RU to get busy with.