MOX - active crossover

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MOX_EQ

Hi all,

This is a simple parametric equalizer made with an inductor and a set of capacitors. It is a simplified version of a more complex parametric equalizer shown below...
 

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MOX_EQ

The simplified equalizer uses standard parts, which are easily available. Certain characteristics of the simplified version are slightly worse in comparison with the characteristics of the complex one, but this does not adversely affect performance of the equalizer in an active crossover (for which it has been designed).

The filter has been tested and works satisfactorily.
 

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Parametric EQ stuff

Hello moamps,

First of all, great looking design on the EQ.

I have some questions.

How can it be a parametric EQ when you clearly have dependencies between Q and fo?

A parametric EQ section is a circuit that lets you change the three defining parameters (fo gain and Q) individually, without any influence on the other two parameters.

\Jens
 
Re: Parametric EQ stuff

JensRasmussen said:
I have some questions.
How can it be a parametric EQ when you clearly have dependencies between Q and fo?

Hi Jens,

from
http://www.rane.com/note101.html
"Constant-Q Graphic Equalizers"

"It should be obvious by now, that parametric equalizers must be based upon totally different topology than are graphic equalizers, since all three parameters are independently adjustable.
Well, some are and some are not.
Some parametrics (I will be kind and not name them) offer adjustment of amplitude, center frequency and bandwidth that are not independent. But since you can adjust each, they get away with it. Those parametrics that offer truly independent adjustment (and there are many) are indeed based on different topology. The heart of these designs is a bandpass section called a state-variable filter."

It's parametric EQ.

Regards
 
More EQ stuff

Hello,

Without wanting to start a fight on definitions (or any other kind of fight BTW) I find that the term "parametric" means that parameters are independent of each other. Any of the three available controls can be altered without affecting the other two. For example, a change in boost will not effect the Q or center frequency of the filter.

However there is something called Quasi-parametric Equalizers

The quasi-parametric EQ allows control over the Q, center frequency and gain of a filter (just as a true parametric) however these components of the filter may be interactive. For example, changing the center frequency and the gain of a filter will also change its Q.

The advantage of these units are the substantially lower cost than true parametrics. With the exception of infinite-depth notches, the same response curves can be achieved on quasi-parametrics as their more sophisticated counterparts. Of course, these curves will be harder to achieve since all adjustments affect the others.

:)

\Jens
 
Re: More EQ stuff

JensRasmussen said:
Without wanting to start a fight on definitions (or any other kind of fight BTW) I find that the term "parametric" means that parameters are independent of each other.


Hi,

"Parametric" means ONLY that you can adjust all 3 parameters; Q, Fo and gain. IMHO.

The advantage of these units are the substantially lower cost than true parametrics.

Not allways. (two antilog pots (or VCA's) and few ICopams can be cheaper than one good inductor). Also, I was compare some "true" parametrics (dbx series 900, etc.) and simple "fake", and for me "fake" sounds better.

Regards
 
Good job, Jens!
I've seen that your layout uses dual in line sockets (single opamp?) instead of moamps' SIL for the discrete opamp.
This gives the opportunity to use standard opamps, but is left unclear if those who still want to use discrete opamps will have to make their own adapters or if you or tiroth are going to make a suitable layout in order to produce such pcbs also while we are at it.
In the wiki there was also a mention to regulators (Jung type): are you planning to make boards for them also or should we go with the group buys currently in progress?

Cheers

Andrea
 
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