The 'Other' Type of Equalizer?

[thehallofshields]

I'm looking to find a Diy project for a specific kind of EQ that is becoming popular on the boutique market.

The kind like in the Metal Zone, where you have a Boost/Cut control and also a Center Frequency control. Commercial products I've seen also include a Frequency Band Width, and a Master Volume.

Sometimes I've seen these called Parametric EQ's, but sometimes I've seen those Bass-Mids-Treble setups called Parametric EQ's.

Can anyone straighten this out for me?

[thehallofshields]

Hah. I just saw SFV Parametric EQ on the first page. What are the chances?

[blackieNYC]

"Parametric" just means that the 3 parameters are adjustable- Q or bandwidth, center drew, and boost/cut.  Simple Parametric at Geofex is great.
Although I have a metal zone I no longer use, and I was considering modifying it to not distort, which you might consider if you in fact own one. Distortion Defeat switch - adding/ removing clipping diodes, substituting resistors for gain changes, I would expect. 

[thehallofshields]

I don't own an MT2 but when I missed a friends I became jealous of the Filter.

I think for guitar its more useful than a Graphic EQ, which I do have.

[thehallofshields]

So I've often seen Tone-Stacks Pedals called Parametric EQ. Is this a misuse of the term?

[thehallofshields]

And I just discovered another thread "Any easy sweepable filter?" On the main page.

It looks like this is a hot topic for beginners right now.

[induction]

So I've often seen Tone-Stacks Pedals called Parametric EQ. Is this a misuse of the term?

yes

[PRR]

> Tone-Stacks Pedals called Parametric EQ. Is this a misuse of the term?

Google is your friend.

Wikipedia is often a good overview of a topic.

http://en.wikipedia.org/wiki/Equalization_%28audio%29
http://en.wikipedia.org/wiki/Equalization_(audio)#Parametric_equalizer
http://en.wikipedia.org/wiki/Equalization_%28audio%29#History

"Daniel N. Flickinger introduced the first parametric equalizer in early 1971. Flickinger's patent (USPTO #3752928) from early in 1971 shows the circuit topology that would come to dominate audio equalization until the present day...."

Three knobs: boost/cut, frequency, Q.

A single section of parametric EQ can only adjust one frequency-band. Unless you have one specific problem, you generally need other EQ tools in addition: multiple parametric sections ($$$!!), bass/treb shelving, graphic, etc.

While a parametric can do heavy work, it is not easy for a beginner (or a performer who also has to perform) to get it to do 'musical' work. For mastering I got away from this concept and used infinitely adjustable digital filters.

[Quackzed]

the metal zone uses gyrators, 3 of em iirc... for eq... theres a calculator at musique, and a good article at geofex...
http://www.muzique.com/lab/gyrator.htm

http://www.geofex.com/article_folders/eqs/paramet.htm

[Mark Hammer]

Generally, where the resonant frequency of the boost/cut is sweepable, but there is no control over bandwidth, people refer to these as "semi-parametric" or "quasi-parametric".

As meatloaf said "Two out of three ain't bad".

[thehallofshields]

Thanks guys. I read RG's article and that put everything into perspective. I was just thrown off by guitarists misuse of the term.

[aion]

The Pearl OD-05 overdrive has exactly what you're talking about before the clipping sedition. Awesome circuit but pretty unexplored in the DIY scene. I just released a PCB for it last week:

https://aionelectronics.com/product/fractal-pearl-od05-overdrive/