Question on using outboard EQ

[SoundKlang]

When EQing a mix with an outboad EQ I heard remarkable changes coming from sub-millimeter parameter changes. For example, a little less lofreq-gain with a little less lofreq Q, a bit more hifreq gain and a bit more midfreq gain with a little more midfreq Q. And in the result the Bass was more defined, the overall image shows more spatiality, same peak gain but more loudness and so on. Really tiny, not recallable knob tweaking.

I think I am missing some knowledge here. Why do such little changes make that much difference? Phase shift ('delay' times), harmonics of certain instruments, psycho acoustics?

Is there a straight-forward approach for EQing to get optimum results regarding bass frequencies, spatiality/transparence, natural sound, loudness, 'glue' and so on?

Or is there no way around the iterative approach of recording - comparing - different settings - recording - comparing - different settings ... ?

Curious to read about your experiences, hints, books, ...

[fl]

While a student at McGill, I was part of a master class with Bob Ludwig. I remember him taking one student's mix, running it through our GML parametric EQ, and just barely moving one frequency band's gain control off the centre position, and whup! the mix magically came together. Somehow, the combination of choosing just the right frequency, with that circuit, with the absolute minimum of gain change made all the difference, and of course it took someone with Bob's years of experience to know the precise frequency to choose.

A lot of hardware units will exhibit some form of "mystery processing" beyond what the front panel controls promise, and indeed we prize some processors for their unique colours and subtle shades of subjective enhancement. With that in mind, the results you describe are not all that surprising, even though they may be startling. What unit were you using?

What causes it? Any number of things, and it's only through experience with a particular unit that you can begin to predict results with any reliability. It sounds like now you have a new tool in your arsenal that can enhance bass clarity, for that particular piece of music, with that playback chain, listening environment, state of aural health and head position...

There are any number of books available on the subjects of signal processing, and psycho-acoustics. The AES has a wonderful archive of research papers and collections on various subjects, including what we're discussing here. One of the seminal studies into psycho-acoustics was done by Diana Deutsch back in the '70s and reprinted in the "Auditory Illusions and Audio" issue of the AES Journal, Vol. 31, No. 9. If you're not already a member of the AES, I'd encourage you to consider it, particularly if you live in a community with an active local chapter.

Perhaps the most exhaustive book on the subject is Jens Blauert's "Spatial Hearing" published by MIT Press. At a more introductory level, a book I've come to like very much for its clarity and no-nonsense approach to audio engineering is Alex Case's "Sound FX", published by Focal Press. The title is perhaps misleading, as it's more concerned with signal processing, than with sounds used for soundtracks, but it's a well written book, particularly the chapter on Compression.

[SoundKlang]

Frank, thank you for your answer. So such results are not explainable by an ideal equalizer, which could allow for a theoretical approach. Such results depend on a certain circuit design and there is no other approach than work with it and learn? Okay, that's good enough for me.

I am using a more or less (truth is: more) modified Meyersound CP-10.

[fl]

I think it goes beyond even that - two different examples of the same piece of gear can sound different (try to find two identical sounding UREI 1176s), because there may be circuit revisions that are not immediately apparent, and because electronic components can change their values over time (capacitors in particular) which can change how everything else reacts.

Famously, Brian Eno told of how he owns several synthesizers that are all broken in one way or another, in ways that makes them much more interesting sonically. Whenever he gets these things serviced, he has to take special care that whatever it is that he likes that is broken, stays broken.

Software versions of various circuit designs will often have their roots in their actual electronic forbears, so these might be closer to an "ideal" realization of that design, but even that assumption is stretching things, since the code equivalencies of component behaviours are often based on assumptions which may or may not be accurate. In short, I don't think there is any such thing as an "ideal" anything, only whether or not something is suitable and gives expected and/or desired results. I think it can be a blind alley to search for an absolute, especially when dealing with something as personally subjective as responding to music and other aural stimuli through ears which are as variable as the humans to which they are attached.

[SoundKlang]

Okay, for the fun of it let's go a little offroad.

Regarding software simulations of analog gear my individual conclusion is that (FWIW) they are really great flight simulators. Reliable and instant-recall tools for refining the idea of the direction to go. But you still stay at home and get not anywhere else. At some point it is necessary to leave the instant-recall and make decisions. For example a Revox A77, even in the beginning when it was in bad shape, immediately had what I was missing in tape emulations.

But analog gear is not generally 'better' than software simulations. For example too much tape hiss, or not enough transparency. I think for one part that's the result of trying to offer as many features as possible for the lowest possible price. For the other part I think it is the result of manufacturers needing to design circuits in a certain way to achieve certain technical specifications, not purely to achieve sound. Because sound is not measurable one can easily be back to sesame street's 'I say wonderful, I say yucch"' (https://www.youtube.com/watch?v=2aAB1sK10Cg). That makes no good sales argument. And what about 'I love trash' (https://www.youtube.com/watch?v=rxgWHzMvXOY)?

But it is also not all in wonderland. Technical specifications and measurements like harmonic distortion and step response can at minimum give a hint of what to expect. Price vs amount of functionality must not, but can be another indicator. And, literally everything (units, cables, ground, power distribution and so on) influences the sound result in a repeateable manner. Maybe comparable to how you choose certain microphones, microphone configurations and positions. It is not like 'If I choose this, I will reliably get that ideal result'. It is more like 'The result will be more in the direction of this or that'. And in the end all those decisions and small differences create the final result.

And then we are looking for a no-harmonic-distortion tube device and operate it mostly at levels saturating the tubes ...

But I was referring to 'an ideal equalizer' not as an actual physical device, but as the theoretical behaviour of equalization. If affecting loudness, spatiality etc. by euqalization could be linked to theoretical behaviour of euqalization, then there could be some research results explaining what is happening. In the following this could lead to a straight-forward approach in using real-world (as opposed to theoretically ideal) equalizers.

[SoundKlang]

Update:
(Foreword - please consider, we may prefer different sound ideals and/or methods of working and have different musical and theoretical backgrounds leading us to different conclusions.)

I noticed the effects described above for the first time while using an outboard EQ. For this reason the title of the topic refers to "outboard EQ". Meanwhile, I am not sure if these effects are depending on the type of EQ alone (analog or digital algorithm).

When improving an acoustic guitar recording I got comparable results from two different plugins. I spent some time to match the settings of each band of the two plugins by ear, because same numbers for the Q and gain settings clearly showed different results. Then the effect of the equalization was comparable, though one of the plugins seemed to introduce a bit of harshness/distortion which resulted in a brighter but slightly more obscured sound while the other plugin was doing its work less obviously but slightly more transparent.

I do not question that some piece of gear (or digital algorithm) can have an unique quality which can not be fully explained by theory.

On the other hand, if similar settings on two or more different pieces of gear or (in this case) digital algorithms produce a comparable effect, I wonder if there is a more general principle at work.

I also want to add, the more transparent and less obvious sounding plugin was Pyramix's Eq-X. Took me some time, but now I can appreciate it's quality for acoustic sources and transparent EQing.

[SoundKlang]

Another update:
In the reply from Nov 08, 2014 I mentioned cables. Some people clearly hear a difference using different cables. For example, replacing a Mogami Gold with a Vovox cable of comparable length makes a difference. Naming these only because they are well known and not saying one is "better" than the other, just different.

I was researching that for some time before arriving at my ideal cable. Now, if the use of some kind of processing (i.e. outboard EQ) is not generally ruled out, I would not use different cables to shape the sound, but use the individually best sounding cable and if necessary eq and compression to shape the sound - from the viewpopint of multitrack mixes that is, not pure microphone recordings of complete performances.