Bee-Happy 550 – Free american vintage EQ emulation

Hello,
I’d like to share my first creation in the VST world.
It’s meant to be an emulation of a famous EQ (sure you can guess…)
I just passed two weeks to check, tweak, compare, try and read forums and since I am totally unable to write (or even read) one line of code, this release is a kind of patchwork (see the credits). I just made my brain on fire to find some creative way to put this together and to fix common issues with EQ designing (Nyquist freq warping, phase issues,…)
So I hope you’ll enjoy this even if it’s not this revolutionary 😉

*SPECS*

– Carefully matched EQ curves with gain-dependant variable Q.
– No oversampling but (quite) corrected curves near nyquist frequency (only for 44.1 & 48 kHz samplerates).
– Soft clip (odd harmonics) & tube (even & odd) distortion section.
– No warped phase behavior in the high range.
– Double precision with a SNR of 125dB.

*CREDITS*

Big thanks to these guys (which are « real » developers !! 😉

– « tor » for his double precision version of biquad filters.
Check his website for great free VST gems: http://www.audioteknikk.net

– Christian-W. Budde for his awesome « VST Plugin Analyzer »: http://www.savioursofsoul.de/Christian/

EDIT:

– About weird phase behaviour in the Hi range:

This is a common problem with oversampling in Synthmaker, generally you get this:

This result in hi-freq roll off (even leaving all parameters at zero) when you insert the plugin in a track of a multitrack recording, really disturbing 😦

So, choosing not to use oversampling avoid this kind of effect. But this creates another issue: warped frequency curve while approaching nyquist frequency.

-About the corrected curve near nyquist:

What is done here is an automatic correction of the Q depending on the frequency, it starts operating after 10000 Hz, and only for samplerates under 48000 Hz.

If you’re working at higher samplerates, there is no need of this correction because the Nyquist frequency is much higher.

If you watch carefully, you can see that the curve is not totally corrected, but the left part of the bell nearly match the original curve.

(I am currently working on way to develop a better correction)

Below is a comparison between not corrected Q without oversampling and the correction included in the plugin (also without oversampling):

Not corrected:

Corrected:

 

Below, is the harmonic distortion depending on settings:

Clean:

Soft Clip:

Tube: