Hi Amir

Thanks for this review.

Nice to see that here.

For such a device, an important question is: what kind of graphic EQ correction does this one bring ?

Is that a constant Q ? Or a vary-Q ?

A simple frequency response test at 4 levels on the same graph would bring the answer (and measure the amount of correction): for, say, 1kHz, level at 0, 1/2 max, max, 1/2 min, min.

Another big difference between graphical EQs is: if I push, say, 1kHz to max, then cut 1.25kHz to min and 1.6kHz to max, what is my level at 1.25kHz ?

Some EQ will have level at the middle frequency to 0dB, which may be confusing.

(More explanations between constant Q and vary-Q

here)

(

**EDIT:** Another interesting explanation

here
and

here an example of an asymmetric EQ)

**EDIT:**

An example of "Q check" measurement
Here, the RME ADI-2 Pro fs R. I tried different boost/cut levels with a "Peak" EQ, 1kHz, Q=9.9, at level -12dB, -6dB, 0dB, +6dB and +12dB

As I've fixed the RME's Q, we see very well the effect of a "Constant Q" EQ: The correction bandwidth is larger if you increase Boost/Cut

Some EQ are more or less keeping the bandwidth constant (and therefore vary the Q with level) or do even more complex tricks (like the Proportional Q in Klark Teknik EQs)

View attachment 219666
Here is what we could get if the EQ is trying to keep the +/-3dB bandwidth constant

Q is now 5.3 at +/- 6dB and 9.9 at +/-12dB

View attachment 219668
Some EQ are even asymmetric, using a different profile for boost and for cut.

(picture from Presonus)

View attachment 219852
So this simple measurement gives us a lot of information...

I've also performed the comparison of the second test I listed:

Alternate max boost/cut on adjacent faders:

Here, still with the RME, I've set 3 EQ to 1kHz -12dB, 1.25kHz +12dB and 1.6kHz -12dB

First with a Q of 9.9 (Max)

View attachment 219671
then with a much lower Q of 2.0

View attachment 219672
The different is stunning, isn't it ?

(NB: It would be more "readable" with frequencies centered around 1kHz, so 800Hz, 1kHz and 1.25kHz)