Test Drive: The NTI EQ3 High Definition Audio Sound Enhancement System

By now you're probably saying to yourself, "Wait a minute. $4,300 for an equalizer with only six bands? I can't cut highs? I can't adjust center frequencies? I can't adjust bandwidths? Hello?" Well, let's take a moment to talk a little about equalization.

Equalization is nothing more than boosting or cutting specific bands of frequencies. Equalizers can be as simple as the bass and treble controls on your home stereo, or they can come in a variety of multi-band graphic and parametric styles. Without getting too technical, let it suffice to say that the very nature of the circuitry of these conventional equalizers is such that the more their effects are applied to a signal, the more phase shifting and distortion is likely to occur. To many, this noise and phase shifting is not noticeable, or it is simply accepted as the very effect the equalizer is supposed to create. To other, more discerning ears, this phase shifting and distortion are unwanted side effects of equalization. Either way, the side effects have been accepted as part of the game, and people have either lived with them or tried other ways to alter the sound of the audio. For example, if you wanted to add some bass to your voice without equalization, you could simply get much closer to many mics and get that effect. Back off, and you'll cut the lows, or, in effect, boost the mids and highs (if you back off and raise the volume). Your ability to really "equalize" your voice without an equalizer is quite limited, but you are not introducing any of the side effects of equalization that you get when you start cranking the knobs on the equalizer.

Well, leave it to the folks at NTI to develop a way to get equalization with virtually no phase shift and no added noise. The technology is rather unique and has caught the ears and attention of quite a list of interested companies, we're told, including Mitsubishi, Sony, TDK, and National Semiconductor, to mention a few.

We asked the technical gurus behind the EQ3, Cliff Maag and an associate who likes to be referred to as Mr. X, exactly what they were doing with the EQ3 to get rid of the phase shift. It turns out that you can't have virtually no phase shift in an equalizer if you're going to have multi-bands with varying center frequencies. And you can't have adjustable bandwidths either. That's why the EQ3 doesn't offer these features. How does it work, guys?

"We get virtually no phase shift by overlapping the broad bands with each other and centering the frequencies at these particular points so that they are equally spaced. The overlap of the lower band negates the phase shift of an upper band. So, where the bands overlap, they cancel their own phase shift. They have to be at these set frequencies, so, when they add, they add in just the right manner to cancel the phase shift."

And when was the last time you saw an equalizer with a frequency response of 5Hz to 330kHz at -3dB? Yes, 330 kilohertz! Why is this, guys?

"This is much like oversampling is to digital recording. If frequencies are rolled off at 20kHz, then there is phase shift in the audible range."

If you're technically inclined, the reported phase shift of the EQ3 is 30 maximum with one control at maximum and others set flat -- 10 Nominal Operating Range. The THD+Noise spec is at 0.005%. Needless to say, the EQ3 is incredibly quiet and clean.

We put the EQ3 through the usual array of radio production tasks. We started by putting a Neumann U-87 microphone on line with the EQ3 for some experiments with the voice. Because of the wide bandwidths, there are some EQ effects you can't get with the EQ3 that you can achieve with other types of equalizers. You're not going to get a "phone EQ" effect out of it. You're not going to be able to do narrow band boosts and cuts. However, you can narrow the bands to a degree. For example, if you want to boost the 650Hz band, but not the entire bandwidth, you can boost the 650Hz band and cut the bands on either side. Because the bands overlap, the effect is a narrowing of the band being boosted. But, don't look for lots of special EQ effects from the EQ3. In fact, don't even think of the EQ3 as an effect box. It's not. It's an equalizer.

Now, for the simple purpose of adding some crispness to the voice at the very high end, we found the Air band alone was ideal for this. For more present crispness and punch, a little boost with the 2.5kHz band was quite nice. A slight boost of the 40Hz band put a nice, clean "boom" in the voice. (Again, bear in mind that frequencies well above 40Hz are getting boosted.) Of course, how it will sound on voices will vary from mic to mic and voice to voice.

Comments (0)

There are no comments posted here yet

Leave your comments

  1. Posting comment as a guest. Your post will be moderated. Your email address will not be shown or linked. (If you have an account, log in for real time posting and other options.)
0 Characters
Attachments (0 / 3)
Share Your Location