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Author: Wayne Harris Click HERE to view more articles by Wayne Harris. Originally appeared in the Volume 3, Number 1 issue of Made in the USA magazine. © All rights reserved. |
Welcome to Wayne's World!
Vacation time at last! I'm writing this on my way to the Cayman Islands for 9 days of surf, scuba & sunshine! With each passing minute it becomes harder and harder to stay focused on my last responsibility before I can truly relax. Writing this column, as I peer out the window of the first class cabin, it occurs to me that I haven't told you about my newest product, the OEQ2. And, if I'm going to continue taking trips like this, I'm going to need some of you guys...all of you...to go out and buy one.
The OEQ2 is what I like to call a paragraphic equalizer. It is loaded with features that make it ideally suited for high performance applications. In this issue, I'd like to go over each of these features in detail.
The power supply provides the fundamental voltages required for circuit operation. In simplest terms, a power supply converts the standard automotive 12 volts DC into the bipolar voltages required for audio applications. What makes the OEQ2 Power Supply unique is that it utilizes a Self-Oscillating High Voltage topology. This type of design provides a full 1,000,000 ohms of "Power Ground / Signal Ground" isolation. Input ground isolation is the single most effective way to prevent alternator whine from entering an auto sound installation.
The OEQ2 has a switch that lets the user select between Balanced Line inputs and RCA inputs. Both circuits utilize "differential amplification" to help prevent noise problems from creeping into the audio system. A circuit that incorporates differential amplification will only amplify the difference between two conductors or wires. In car audio, most components are connected together with RCA patch cables. Under ideal circumstances, the difference between the hot center conductor and the outer shield is the musical signal. Cars are anything but ideal, however. Electrical noise is generated by the alternator, fan motors, windshield wipers, brake lights, etc. These noises can be inductively coupled into the RCA patch cables. When this occurs, the noise spikes appear on both the center conductor and its outer shield. Since differential amplification only amplifies the difference between the two conductors, the noise spikes are NOT amplified, and they are consequently eliminated from the system.
In addition, the OEQ2 features independent left and right input sensitivity controls as well as calibrated bargraph level indicators. These indicators are extremely useful when setting system levels. They are also used to indicate a poor audio ground connection. (In any system, there should be one, and only one point where audio ground and power ground are common. This point should be established by the source unit.) A poor audio ground makes your system more susceptible to noise.
Equalizers are used to correct or compensate for the acoustical deficiencies inherent in most auto sound installations. EQs are also commonly used to "tailor" the sound of a system to the listener's own personal listening preference. Common graphic equalizer topologies include 7, 10, 14, 30 or more "bands." Each band is centered at a specific frequency. The user can then correct for problems at that frequency by boosting or cutting that specific band. As you might have guessed, correcting problems that occur BETWEEN bands can be very difficult, if not impossible to achieve. The OEQ2 takes a somewhat different approach. It, too, has 10 discrete bands that can be boost or cut. But we didn't stop there! The OEQ2 also lets you "warp" each band by +/- ½ octave. This allows the user to center each band directly over the problem area. Corrections can then be made much more easily. Other EQ features include a BYPASS/ENGAGE switch and independent adjustments for both left and right channels.
The OEQ2 has two sets of RCA outputs as well as a balanced line output connector. All outputs can be driven simultaneously. The maximum output voltage of the OEQ2 is a whopping 8 volts RMS. The differential output voltage of the Balanced Line Driver is greater than 16 volts RMS! Output voltages are controlled via independent left and right output level attenuators. (Attenuators provide the best signal-to-noise performance because there is no unnecessary gain circuitry following the EQ circuit.) The output impedance of the OEQ2 is incredibly low at only 51 ohms. This means you can drive a LOT of amplifiers without any problem.
As you can see, the OEQ2 is packed with features that distinguish it as a true high performance component. Visit your dealer NOW so I can visit Cayman more often. Finally, check out my new Web site at http://www.termpro.com. It's totally cool and has areas dedicated to Term-Pro, dB Drag Racing, Research and Development, etc.
Until next time, party on!!