Digital EQ Fact & Myth.

[bduffy]

I thought i would share my research as of late.

I'm going to make a broad statement that seems to cause some to freakout. Read the whole post before replying.

All properly designed Digital plug-in EQ's are the same.

Don't just take my word for it, listen to the developers.

Read this from algorithmix Algorithmix

The truth is that with a properly designed, fully parametric analytic PEQ, every amplitude and phase characteristic of any other equalizer setup can be recreated. Of course, the contribution of distortions to the specific sound of a particular analog equalizer caused by the respective electronics has to be considered. If the distortions are 'good', they may make certain applications sound better.

So whats this mean?

Emulation plugins for the most part are Hype. But you might find the interface more creative, Or you might like that type of saturation. But in reality you would be better off with using a fully variable saturater & an EQ.
But one thing most emulation plugins do offer is an included compressor. Unlike EQ's compressors come in many shapes and forms. & tools like the URS CSP with it's input stage really can change a compressors quality.

In the end the quality variables are down to internal resolution, oversampling capabilities, & so on. There is no magic in the emulation.

Interesting findings, though perhaps slightly flawed for several reasons:

1) You've quoted Algorithmix and taken it entirely out of context. That paragraph is stating that its possible to recreate any kind of eq with a properly implemented designed analytic eq. That is not the same as saying all digital eq's already out there can and do perfectly recreate each other.

2) Yes, you're right a lot of digital eq plugins out there do share the same algorithms, but not ALL are equal. Comparing just two, or even 4 or 8 of your favourite eq's, one cannot draw the conclusion that every digital eq plugin made can recreate all the others with a little tweaking.

3) You're talking about them all being the same, whilst at the same time pointing out the differences, even with those that use the same kind of algorithms for the curve shapes, with things like saturation/distortion, oversampling, linear phase etc. I could build a car from parts to get me from A-B, but it would take me 6 months to get to my destination instead of 15 minutes if I just had the car already. This ties in with the thread about plugin simplicity. A big part of it is about getting the tool to do what we want in a musical fashion as quickly as possible. If one eq has curves and shapes that are immediately more musical or feel more transparent than another, who wants to spend an hour desperately trying to tweak another eq to match those curves. And if you've only bought that 'other' eq and not the very musical one, you have no reference to match to anyways!.

4) Do freq analysis and phase tests take into account phenomina such as bell ringing on tighter Q's and general transient response when applied to complex material?.

Why is it that when I've compared different linear phase eq's and done null tests on a low shelf , I hear differences in the artifacts left behind throughout the entire frequency range (PlParEQ came out top with no artifacts at all)

In the case of the Eiosis AirEQ I really do notice a difference to its sound to other eq plugins I've tried (and I've tried to match the curves). The way it affects the stereo soundstage is different to say the Sonalksis EQ.

But in the end its not what's under the hood, or the brand name, or the cost that matters. All that matters is that the eq allows you to achieve the desired goal as painlessly and quickly as possible, without trying to tweak constantly to the point you just end up frustrated and it saps your creativity.

So yes, its a fact that 'many' eq plugins employ the same algorithms and could recreate each other. But its a 'myth' that they're all the same and that you can easily recreate any one from another in as fast and productive way

Good post, arksun. So I wonder: how can one test for bell ringing and transient response?

[xoxos]

Arent we underestimating the importance of X here?

i never would

christian you just described my development process. before i knew that mass-springs were a bonafide modeling attempt, i was implementing them from bouncing ball animations i did when i was 12, and doing things differently.. an exponential nonlinearity to k will produce an exponential pitch drop over duration.. when you learn mass-springs by the book, there's no reason to start throwing coefficients into statements willy nilly unless you're in the dark.

take your next c++ students and confuse them about something :p

when it comes to articulation and expression, the world seems to have a fair share of idiosyncratic, unoptimised instances of forms, so i'd expect these characteristics are "desirable" in communication.

an imperfect eq could be analogous to slang or a mispronounced word.. the distortion of language has a discrete semantic "identifying" the speaker. so our choice of eq indicates our mileu :p

[SWAN808]

Arent we underestimating the importance of X here?

X is certainly often important, but i prefer to add that separately.

what do you use to add X?

[Music Engineer]

what do you use to add X?

depends on what the X should be. allpass filtering for transient smearing, if desired (would do something similar like maximum phase response EQ). waveshaping for nonlinear distortion (saturation and stuff).

[Meffy]

what do you use to add X?

A crossfade, what else?

[jwatte]

What do I use to add X? Good question. Ever since I moved, I haven't found a good dealer

When it comes to transient response, if you assume that the analog EQs you are modeling are second-order systems (and almost all of them are, unless they use op amps to go 4th order "active"), then a proper phase and frequency analysis will extract Q and get the same transient response as the modeled EQ.

[hibidy]

what do you use to add X?

A crossfade, what else?

waaaa waaa waaaa waaaaaaaaa

[Zaphod (giancarlo)]

Arent we underestimating the importance of X here?

X is certainly often important, but i prefer to add that separately.

if you are looking for a good emulation, it's not the right way.
Let's make an example: you have a precious valve equaliser, you completed tons of mix with it and you want to replace it in the box.
I think that if you advertising your plugin as a good emulation your plugin should at least
1) have the same amplitude/phase response
2) harmonic distortion behaviour

and if the hardware had not a perfect design (distortion, amplitude response, phase issues or whatever), you should implement all imperfections.
If you fix them, there is no reason for using the same graphic interface.

[vieris]

So i decided to take it a step further.
How close could i get to the waves SSL with ANALOG on.
So instead of using sonar & my usual URS saturation I decided to try it with all native Ableton Live plugins. At 1st i was having a hell of a time trying to match the EQ Phase. That is until i turned off Live's Hi quality EQ mode heh.
Live oversamples with Hi quality on.

Here are the EQ setups.



Frequency Response with saturation.



The left measures frequency differences & the right is phase. Not bad, it's near mono. Pretty cool for completely different tools.

[bduffy]

Jeez. Well done, veiris. How did you figure out how to set the saturation? And Live's EQ is seriously underrated?

[vieris]

Jeez. Well done, veiris. How did you figure out how to set the saturation? And Live's EQ is seriously underrated?

Trial & error. Live's "analog" mode seemed to be the best. Live's EQ is nice. I like how you can see the high frequency filter curve actually change when the Nyquist point moves when switching on "hi quality". from 22k to 48k

[bduffy]

Jeez. Well done, veiris. How did you figure out how to set the saturation? And Live's EQ is seriously underrated?

Trial & error. Live's "analog" mode seemed to be the best. Live's EQ is nice. I like how you can see the high frequency filter curve actually change when the nyquest point moves when switching on "hi quality". from 22k to 48k

You're a patient (and skilled) man! I've tried matching EQs before, but not that close!

That's neat with the Nyquist-thing. So what's your ultimate verdict based on others' input? Are all well-made digital EQs the same?

[bduffy]

You know, I was just playing around with some EQs, and I was surprised by how close I could get them! I've been suspecting for a long time that there may be no need to ever buy a $300 EQ, and this all makes me wonder if it's just a matter of curves and slopes...

[vieris]

You know, I was just playing around with some EQs, and I was surprised by how close I could get them! I've been suspecting for a long time that there may be no need to ever buy a $300 EQ, and this all makes me wonder if it's just a matter of curves and slopes...

For digital parametric EQ's I don't think it's worth it. But hey it's all about the compressors anyways right? Still got those to drool over.

[bduffy]

You know, I was just playing around with some EQs, and I was surprised by how close I could get them! I've been suspecting for a long time that there may be no need to ever buy a $300 EQ, and this all makes me wonder if it's just a matter of curves and slopes...

For digital parametric EQ's I don't think it's worth it. But hey it's all about the compressors anyways right? Still got those to drool over.

Indeed! Lord knows, I'm using EQ less and less these days...