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ADM 1540 Equalizer

So I was given a free pair of (what seem to look old) ADM 1540 equalizers today and I'm very unfamiliar with the product. I am not finding much info online. The ones I'm seeing online have the actual number "1540" engraved next to "ADM" but mine do not. I attached a photo. Any info on worth or the year it was made would be great. I've attached a photo.

*** bonus points. Where could I get these fixed up?

Why are frequencies on equalizers unequally spaced?

I've been wondering this awhile now. On the generic Pro Tools graphic equalizer, the frequencies are unequally spaced. For example, there is a large gap between 100hz and 200hz. But between 200hz and 300hz, the gap is about half as wide. Can someone explain the reasoning for this?


Hardware device or computer plugin used to alter the frequency balance of an audio source. An equalizer has the ability to boost or cut specific frequency ranges based around a center frequency and can be used either creatively, to drastically alter a source, or in a corrective manner, such as in a mastering situation, to even out anomalies in a mix. Equalizers come in various forms, including parametric and graphic, active or passive.
(See Filter, Graphic, Parametric)

Graphic Equalizer

The term nowadays refers to a type of equalizer where 15 or more, narrow frequency bands are controlled using sliders, either boosting or cutting the individual bands. The term graphic came about because the arrangement of the sliders provides a visual representation of the EQ curve. Graphic equalizers can still be found that use rotary controls instead of faders.

Parametric Equalizer

To pan, or panning refers to the act of moving the perceived location of a sound source within a stereo soundstage. Generally works by reducing or making louder the particular sound source in either the left or right channel of a stereo output. Although slightly more sophisticated electronics are used to control this movement accurately, the net result is the same. If a source is panned hard left, then it will appear at only the left speaker, and likewise with the right side.

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