O.T.Parametric equalizer

[LICORNE]

Any one knows exactly who invented the parametric EQ. I think it must have been post tubes equipment.

[Old Guy]

Wikipedia sez-
Daniel N. Flickinger introduced the first parametric equalizer in early 1971. His design leveraged the high performance op-amp of his own design, the 535 series (USPTO #3727896) to achieve filtering circuits that were before impossible. Flickinger's patent (USPTO #3752928) from early in 1971 shows the circuit topology (Figure 2.) that would come to dominate audio equalization until the present day, as well as the theoretical underpinnings of the elegant circuit.

Patent US3752928 - Amplifier system utilizing regenerative and degenerative feedback to shape ... - Google Patents

[mah]

Prior art? http://www.massenburg.com/wp-content.../GM_ParaEQ.pdf

OG, you may be interested in the references to Dolby.


A forum discussion: http://www.gearslutz.com/board/so-mu...metric-eq.html

[Old Guy]

Serious error in the Gearslutz forum. Massenburg's device was only quasi-parametric, in that it only offers partial control, frequencies not sweepable, only selectable fixed points. Not a full parametric.

Parametric has FULL control of frequency, width, and cut/boost. Frequencies and width were variable before Massenburg. Just as we can build different frequencies and slopes in passive crossovers, the same could be done in line level passive filters. It took the opamp to make these parameters continuously variable. Massenburg may have had the concept, but not the execution.

[LICORNE]

Wow!! Interresting discussion. It looks like an evolution from fixed to variable band width in the late 60's to early 70's.

[Old Guy]

Wow!! Interresting discussion. It looks like an evolution from fixed to variable band width in the late 60's to early 70's.

More like 1930's till present, and they are still evolving.

[mah]

Massenberg claims he penned the term Parametric Equalizer for the device described in his May, 1972 paper - http://www.massenburg.com/wp-content.../12/ParaEQ.pdf This paper describes a Parametric Equaliser which is a device which offers vernier control of frequency and amplitude, and coherent control of "Q" or shape ................................by use of all active RC circuitry................... .

Flickinger does not include the term Parametric Equalizer in his 1971 patent application claims.

Just two statements - not an argument.

- - - Updated - - -

Some Rane publications of interest:

http://www.rane.com/note122.html

http://www.rane.com/note115.html

[Old Guy]

Massenberg claims he penned the term Parametric Equalizer

I don't consider it worth debating, honestly- he may have, even though by standard definition his device is not fully parametric.

I CAN tell you that way back then a great deal is undocumented. The line array's evolution began in the 1940's at least, maybe before. Yet some wag probably claims the idea.

[mah]

I have no problem calling Flickinger's device a parametric equaliser, even if the term did not exist at the time of its invention, and I am too old to give full credence to Massenberg's own claim without further corroboration. Thus my 'not an argument' rider to my above posting.

Inventions, inventors and ownership claims can become very slippery indeed when you try to pin them down.

[Old Guy]

Inventions, inventors and ownership claims can become very slippery indeed when you try to pin them down.

Yes there are legends about almost every invention, at least some provable...we sometimes find out that different claimants to an invention had contact...further muddying the waters...