Steve: What's the difference between analog and digital EQ?

I've never heard a good sounding digital EQ. The new Sony Oxford plug in system is supposed to be great sounding, but then again it's trying hard to imitate an analog EQ sound. Since I work in the analog domain, I don't need the thing to imitate anything, I just use the real deal.

My buddy at Sony sent me this about digital EQ; it's just so hard for digital EQ's to sound pleasing:


There are many ways in which errors can crop up in digital EQ and there has been much research and publication of the subject. Many different architectures (algorithms) have been proposed to optimize the situation and they all have advantages and disadvantages depending on the type of EQ and processor intended. In all cases these different algorithms are compromises that trade-off one undesirable effect against another.

Another issue that has differentiated the sound of digital EQs from their analogue counterparts is HF response cramping. This phenomenon occurs when EQ curves approach the HF area closest to the half sampling frequency (Nyquist frequency) and manifests itself as an increase in the steepness of the EQ curve at the upper most part of the response.

The effect of the cramping is to reduce the HF content of the EQ curve, restricting the openness of the sound and adding to the effect of harshness due to the predominance of mid frequency action within the unbalanced EQ curve.

Since this effect is related the closeness to the intended response to the Nyquist frequency, the problem is greatly reduced if the system is run at 2FS (88.2KHz or 96KHz) and this may be part of the reason why over sampled systems are often preferred. But since over sampling the entire system will halve the processing capability of the hardware, this solution is costly in a workstation environment where processing power is at a premium. Some digital EQ designs address this problem by up sampling before the EQ and then down sampling at the output to match the system-sampling rate. But although this is more cost effective than running the whole system at 2FS, the up sampling and down sampling processes are themselves a possible cause of error and quality loss.

By employing novel coefficient generation techniques, the Sony Oxford EQ plug-in produces a fully de-cramped and symmetrical EQ response without resorting to inefficient or error prone over sampling techniques. In fact the method also allows the EQ to simulate the responses of an analogue EQ with the centre frequencies above the Nyquist frequency (i.e. 26KHz for the GML option), all at normal base band sampling rates without any change to the performance of the rest of the system.

 

Does digital EQ 'suck the life' out of music? Or is that just digital compression?

I've always wanted to ask you (and other members) if anyone has noticed any 'breath of life' in a digitally recorded piece of music. I have not but I don't critically listen to everything through my 'main' system. Maybe another thread....

 

Just my second question, CB. I don't expect Steve to answer it. I was just musing....

 

Breath of life in a full digital recording? Sure, why not? It just has to be done carefully. It can sound quite wonderful!

 

Possibly, but you must realize that some day your playback system might improve dramatically and you will be hearing things a lot differently. You might not love your creations as much. A little (very little) processing goes a long way.....A little top end air on your system might sound nice now, but it might make you run out of the room on a high resolution system. Think ahead! I learned that bitter lesson on my first mastering project.

 

Very wise!

I learned the hard way when I had my first mastering "creation" played back on a really good system and not just the stereo in my office.

My ears were literally ringing and all of my smart EQ moves were so overdone and overblown that I cringed. My first thought was:

"Oh Lord, I almost built this dreadful sound right into my release".

Some mastering engineers have never learned that lesson...

 

On important projects I need to hear what the original engineer heard while mixing the album. The only way to judge what his or her intentions were. The best way to do this is to listen to the mix on the same speakers that were used in mixing. It does not mean that they are great speakers, it just gives me a handle on what they were trying to achieve.

I have six different playback systems that I evaluate sound on.

I never use headphones for two reasons. One, the levels are different when they hit your ears, making mixing inaccurate for me. And two, because research shows that music is mainly listened to on speakers. No engineer mixes or masters on headphones, and any that do will have balances and tonality that will be way, way off for the majority of listeners.

 

I must say this, lest I be accused of being anti-phone.

I've spent many years enjoying music through headphones, I have the same pair of light green Koss cans that I had when I was in school in the 1970's. Same damn pair! They still sound amazing. I used to love listening to FM radio with them and hearing the DJ's talk trying to ID what microphones they were using (before radio started sounding really crappy). Since I wanted to be a DJ (was actually for a while), I got used to functioning with cans on my head.

After a while though I discovered that having the music so close to my brain made me a bit crazy like!

If you listen through headphones, don't turn them up too loud. They can really damage your hearing.

 

This is the old Neumann mastering console at Location Recording Service in Burbank, California, where most of the DCC Gold Discs and LP's were mastered. Take a look on the console if you have good resolution on your screen. Lots of little twiddly knobs on the thing. I hardly ever used ANY of them to do anything with. I used the Sontec EQ unit on my left and I sometimes used the Neumann EQ to tailor the EMT stereo echo plates to sound less trebly (like the echo sound in "All Things Must Pass") and more like Gold Star or Capitol chamber echo. But, mostly, none of that stuff was used by me. It was always hard, but I did it! So many neat knobs and buttons, packed with German design know-how.

My point is that even with all of that stuff to play with, I resisted the temptation to do so, just so I could keep the music as pure as possible, warts and all. I think this shot was taken the day I started work on Cream's "Wheels Of Fire".