KVR Audio

Music Engineer · Post by **Music Engineer** » Mon Dec 01, 2008 7:39 pm

Shy wrote:I can't hear JPEG files.

reading a frequency response is to the audio engineer what reading a score is to the musician...a bit

Christian Budde · Post by **Christian Budde** » Mon Dec 01, 2008 8:37 pm

vieris wrote:No need.

Matched frequency response
+
Matched phase response

= nothing to hear.

Invert one channel and there really is nothing to hear.

This might be true from simple view point. Unfortunately it isn't if you go further into detail. First of all -30 dB isn't what I would call "nothing". It is in fact if it is properly masked. However, you could also imagine a scenario, where one EQ mutes the input entirely and the other one applies some effect and attenuates the audio by about -30 dB. The screenshots would look exactly like the ones you posted.
All this does not say anything yet about the tested EQs being equal. Furthermore some criterics (harmonic distortion) also depends on the type of input. The effect if quite low, if not negliable for low levels, while it is salient for higher levels. So far I could see, I couldn't get any idea of the excitation signal.
Also that kind of test will fail badly if there is only the slightest delay between the subtracted channels.

While I can believe that indeed several of the mentioned EQs can produce identical results as claimed, those screenshots do not prove anything. You have to prove that the shots are equal at least for any input signal. If you could prove that the tested EQs are are LTI systems, the plots would be satisfiing, but on the other hands -30 dB are not very good and indicate for other effects (not entirely matched phase, distortion).

Kind regards,

Christian

vieris · Post by **vieris** » Mon Dec 01, 2008 9:07 pm

What -30 are you referencing? The test has pink noise going into 2 different eq's panned hard left & right. I then match the freq/phase response while passing signal. The pics show equal level. I don't have a channel inverted in the pics. I was showing matched performance. The plots show equal freq & phase. If i invert a channel i get a complete null.

Aleksey Vaneev · Post by **Aleksey Vaneev** » Mon Dec 01, 2008 10:09 pm

vieris, Christian is right here. Take Voxengo GlissEQ for example, I'm pretty sure with an average-static input signal (white noise) it will provide a similar sound to many other EQ plug-ins. But apply it to a real song and it will sound different to many other EQs, since it has a dynamical response. The same applies to saturation. Saturation is heard on transients mainly when it further multiplies a wide spectral content. On stable sounds and especially white noise it won't reveal anything special.

The thing you are seemingly missing is that EQ *should not* have an exagerrated phase response for a given frequency response. Its sound mathematics and physics - minimum phase. If it was different, the EQ would sound like sh*t, unpredictable. You can't really get anything else than minimum-phase response with conventional analog electronics or otherwise you'd need a lot more components just to create a special phase response. bmanic is right as well, EQ/compression processing is about convenience, sound comes together with it.

Zaphod (giancarlo) · Post by **Zaphod (giancarlo)** » Mon Dec 01, 2008 10:20 pm

Christian & Aleksey

+1

vieris · Post by **vieris** » Mon Dec 01, 2008 10:27 pm

So by getting a complete null while playing any content doesn't = same to you?

The EQ's i have tested havent had "x" factor. No harmonics or saturation. Everything i have tested so far seems identical.

Aleksey Vaneev · Post by **Aleksey Vaneev** » Mon Dec 01, 2008 10:53 pm

vieris wrote:So by getting a complete null while playing any content doesn't = same to you?

First of all, from your tests "null" applies to frequency and phase response, that are average measures. Secondly, making a comparison using a stationary signal will only reveal how EQs deal with such exact stationary signal, this comparison won't cover "second order" reactions that make a difference e.g. between American Deluxe and Mexican Standard Strat electric guitar (at least how I understand this). Both these guitars produce mostly identical stationary tone I believe.

vieris · Post by **vieris** » Mon Dec 01, 2008 11:00 pm

Aleksey Vaneev wrote:
vieris wrote:So by getting a complete null while playing any content doesn't = same to you?
First of all, from your tests "null" applies to frequency and phase response, that are average measures. Secondly, making a comparison using a stationary signal will only reveal how EQs deal with such exact stationary signal, this comparison won't cover "second order" reactions that make a difference e.g. between American Deluxe and Mexican Standard Strat electric guitar (at least how I understand this). Both these guitars produce mostly identical stationary tone I believe.

It's pink noise. Far from stationary. The same is true if i play music as i keep on saying. Hard to trick a nulled file..

mustgroove · Post by **mustgroove** » Tue Dec 02, 2008 12:09 am

I'd just like to add something to this thread, in regards to the "x factor" of harmonics/distortion... Plugins which add harmonics/distortion to the signal tend to be referred to as more "vintage" or "analogue" on KVR and other places, so I wanted to test some UAD EQs to see whether they have this behaviour.

They don't. The 88RS, 1071, 1081, Helios and Pultec EQs don't add any distortion whatsoever (measured with Christian's VSTPluginAnalyser). Yet 10 minutes with these plugins instantly made my mix sound 10 times better.

There is clearly some kind of mojo going on with the UAD EQs that doesn't involve the addition of harmonics. The UAD compressors, on the other hand, do add quite a bit of harmonics/distortion to the signal. But speaking about the EQs alone, there is none to be seen... do they therefore have less "character"? Hell no, they blow away every other plugin EQ I've ever heard.

Vitaly · Post by **Vitaly** » Tue Dec 02, 2008 6:50 am

mustgroove wrote:The 88RS, 1071, 1081, Helios and Pultec EQs don't add any distortion whatsoever (measured with Christian's VSTPluginAnalyser).

Oh thanks for that info! That 'x-factor' was the only thing making me curious about UAD-2. Now I can forget it and keep using EQs from BTE Audio without any doubt.

mustgroove Could you do me a favour? Could you publish here a screen shot of Harmonic Distortion of 1176 when GR meter is at -10dB and Ratio is 4:1. It would be much appreciated, thanks.

vieris I myself am coming closer and closer to the same conclusion you've come. Yet I prefer using my favorite EQs from BTE Audio because I get used to their sound. What I mean is I know what will happen if I turn THAT knob. So when I need THAT effect I go for THAT EQ. I guess I could get the same sound if I play around with full parametric EQ for some time but it would be much longer. Bottom line is, if two EQs sound the same to you, then they are the same and thanks for sharing your tests!

It is funny how people use real life examples (cars, colors, guitars...) to justify the difference between software models. C'mon guys, don't confuse the actual physical and electrical laws with formulas.

Cheers,
Vitaly.

birrbits · Post by **birrbits** » Tue Dec 02, 2008 7:21 am

vieris wrote: It's pink noise. Far from stationary. The same is true if i play music as i keep on saying. Hard to trick a nulled file..

results of a sinusoidal sweep would probably be more revealing than pink noise..

Christian Budde · Post by **Christian Budde** » Tue Dec 02, 2008 7:25 am

vieris wrote:So by getting a complete null while playing any content doesn't = same to you?

What I am wondering here is what you mean with 'complete null'. I could not see a prove for that. Again, I do not want to mistrust you, when you claim, that several EQs can produce a near equal output, but from a programming point of view there should be at least some, probably very tiny difference. You only need to have the internal topology not to be equal, or if one uses SSE or just have the initial states initialized differentially. Not to mention the denormal prevention, which is for sure different in every plugin.
You might get a "null", that will be equal to no difference played with any DA converter (if the difference is somewhat larger than -100 dB). It might be inaudible, sure, but I doubt it is zero.

Don't get me wrong, I do not want to critisize your work exploring all these EQs, but you need to improve your measurements. In that business you have to be more than accurate, especially if you want to convince other people. Believe me or not, but several years ago I was on the same path, doing the same tests. Last year I have written my diploma thesis about measuring nonlinearities (e.g. harmonic distortion) and I can tell you there is so much more to evaluate, once you know what to look for.

Honestly I wish you good luck and success for your research.

Christian

PS: The only problem with these kind of research is the fact, that you can not save the planet with that, you can only make it worse by wasting energy. But then I shouldn't write these lines either...

Compyfox · Post by **Compyfox** » Tue Dec 02, 2008 7:26 am

So in short:

Get ElectriQ Poshifopit or the full version and you're happy till death does you part?

Hm... no wonder why I only use "three" EQs lately only:
- Steinberg Q (4band, more "broad" and "oldschool")
- ddmf FreeEQ (10band)
- AixCoustic ElectriQ Poshifopit (mostly for mastering with "warm" filters, and I'm not limited to a "certain ammount" of bands)

Or am I doing anything wrong here? I mean, if every digital EQ is the same, then to me it's:
Steinberg Q and ddmf FreeEQ -> Digital EQ with same settings (which is not the case, since Q acts a bit iffy)
AixCoustic ElectriQ poshifopit -> EQ + X

Christian Budde · Post by **Christian Budde** » Tue Dec 02, 2008 7:44 am

Vitaly wrote:mustgroove Could you do me a favour? Could you publish here a screen shot of Harmonic Distortion of 1176 when GR meter is at -10dB and Ratio is 4:1. It would be much appreciated, thanks.

I'm not sure why you need this, but if you are trying to recreate the 1176 by this plot only you will surely fail. You do not cover any dynamic behaviour with that nor the frequency dependent harmonic distortion. You need at least to plot a series of THD plots for every single frequency (just to be sure it's equal over the whole range). Also the THD depend on the attack/release time. So there is no single plot for -10 dB with the ratio 4:1 if you do not specify the attack/release. Also I can already tell you, that the emulation is far away from the original, but that's another story...

birrbits wrote:results of a sinusoidal sweep would probably be more revealing than pink noise..

Again, this wouldn't capture the dynamic behaviour. In case of a so called 'logarithmic sweep', you could at least evaluate the harmonic distortion for the fixed input level, but only if you apply a deconvolution with windowing all the HIRs.

Compyfox wrote:Get ElectriQ Poshifopit or the full version and you're happy till death does you part?

I want to say, that with my posts I do not want to do any advertisement for my EQ in the first place. Sure it is my idea of a perfect EQ and it has everything I can think of, but everyone has his own taste. This is especially true for the 'X' part. Especially with the full version the user has more than 200 different filter types, but even with so much possibilities some users prefer other EQs depending on the material. Especially the 'X' can be so rich of options...

Christian

mustgroove · Post by **mustgroove** » Tue Dec 02, 2008 7:47 am

Vitaly wrote:
mustgroove wrote:The 88RS, 1071, 1081, Helios and Pultec EQs don't add any distortion whatsoever (measured with Christian's VSTPluginAnalyser).
Oh thanks for that info! That 'x-factor' was the only thing making me curious about UAD-2. Now I can forget it and keep using EQs from BTE Audio without any doubt.

mustgroove Could you do me a favour? Could you publish here a screen shot of Harmonic Distortion of 1176 when GR meter is at -10dB and Ratio is 4:1. It would be much appreciated, thanks.

vieris I myself am coming closer and closer to the same conclusion you've come. Yet I prefer using my favorite EQs from BTE Audio because I get used to their sound. What I mean is I know what will happen if I turn THAT knob. So when I need THAT effect I go for THAT EQ. I guess I could get the same sound if I play around with full parametric EQ for some time but it would be much longer. Bottom line is, if two EQs sound the same to you, then they are the same and thanks for sharing your tests!

It is funny how people use real life examples (cars, colors, guitars...) to justify the difference between software models. C'mon guys, don't confuse the actual physical and electrical laws with formulas.

Cheers,
Vitaly.

Don't get me wrong, the UAD plugins definitely have an x factor of some kind, they give an instant "wow" whenever you use them... all I've discovered is that it isn't distortion or harmonics or anything of that kind.

The whole distortion/harmonics and "warming" thing needs to be rethought IMHO. I think that whole theory arose at the dawn of the digital audio era, when some people were scratching their heads as to why all this digital gear didn't sound as "good" as the old analogue stuff... But to me it seems like just a theory - these UAD EQs kick total ass over everything else I've ever used... and none of them have any harmonic distortion to speak of. Clearly something else is going on.

Digital EQ Fact & Myth.