Tone Controls

A few comments about analog and digital EQ.

There are any number of outstanding sounding analog EQ units (Avalon, GML. Manley, Millennia, etc.) on the market. Although clearly aimed at the pro audio market, they are easily incorporated into a component based high end system. The Manley unit is of particular interest in that its a tube design.

Digital EQ offers enormous potential for audiophiles. It can be both precise and unobtrusive even at extreme settings. I use a 5 band parametric unit by Drawmer. The bottom three bands are used to correct for the room's bass response and the two other bands are used as tone controls to shape the treble. As with analog circuitry, there are large sonic differences between digital EQs products.

If you use either analog or digital EQ, don't equalize your system for flat response at the listner position. It will sound way too bright. Aim for a smooth response with a downward sloping response from the upper mid-range on up. Also, don't try to EQ out the narrow band, sharp response dips in the bass region that are inherent in nearly all rooms. Even the Sigtech or TACT processers don't try to remove these sonic "sink holes". Trying to get rid of them will create boomy bass at every other listner position in the room as well as robbing you system of dynamic headroom.

Onhwy61, your comments are well-considered and very helpful. Would like to know what sonic differences you have discovered between digital EQ products. --What is striking with the z-systems TTC is the large sonic variations achievable through line filtering and power cord substitutions--just as with most digital equipment. --Once I achieved a flat response at the listener position, I noticed the brightness you mentioned and developed a second EQ setting with slow downward sloping response from 8-9kHz onwards. The STAX earspeakers required this downwward hi-freq. slope from the very start, because of their etch (a cause of much fatigue and even pain, and even the desire to sell them). --To perfectly EQ the narrow-band irregularities in the bass response of a room loudspeaker would require too many bands of EQ, so that none would be left for other purposes, and yes the dynamic headroom significantly decreases. --Some consideration always needs to be given to maximum smoothing effect with the number EQs one has at hand (of course, one can always run two units in series...). --Given your description of your EQ settings, it seems that you do not EQ any mid-range: lucky you, as every speaker in my possession has irregularities in both low and upper mid-range freq. response (e.g. 1.4kHz-3.0kHz; and 5.0kHz-7.0kHz). Perhaps the happiest result of digital EQ on two-way monitors was to hear significant low frequency from them, and a linear mid-range corrected for obtrusive crossover irregularities.

Slawney, I purposely left the mid-range untouched and used it as a reference for setting both bass and treble levels. I'm still learning how the use effectively use EQ, but I've noticed that even with EQ, standard audiophile practices still have to be observed. The EQ works best when the speakers are well positioned in the room. I could not compensate for poor placement with EQ. I tried and I was able to get better measurements, but it never sounded right.

As a room bass equalizer, the Drawmer works fairly well, but my system is such that I do not use it on SACDs or analog sources. As with most things in life, there are trade-offs.