|
|
| Overview of Operation Setting the input level The input selector provides gain in 10 dB stepped increments, from -65 to +14. At the lower extremes, the unit has 2 gain stages and an input transformer. With higher gains the 2nd gain stage is switched out. At even higher gains the input transformer is switched out, and at the highest gains a pad is inserted in the signal path to further lower its amplitude and along with that the 2nd stage gain is set to unity. In the lower gain configurations, the equivalent input noise goes up so the signal to noise ratio suffers. The signal should be close to "0" but with >30 dB of headroom, this is not really an issue nor is it that important. Our only real concern is being able to control the gain with the dynamics that we find audibly pleasant as well as having the output level be within reason. (It is real easy to start pumping out a nominal +26 signal level, and not even notice that you're SMOKING the next piece of gear in line!. Be careful, for you can develop in excess of 100 volts peak to peak signal energy .
Monitoring levels. The LED's around the threshold knob are two audio meters in one. The bright dot is indicating "VU" levels with ANSI ballistics. The solid bar is indicating peak level at 10 dB per division. The input monitor position of this meter looks at the signal level at the output of the 2nd stage as it appears at the gain cell input. (This is the same point as the insert return). The output monitor position is just prior to the mute relay on the output. "0" indication on the meter is calibrated to +4 dbv ref. 600W, or 1.23V. The maximum indicated signal level is +34 dbv, and the minimum is -56.
Set threshold The threshold control is designed to provide a range of -40 to +20, with the "0" point occurring at the "0" LED. Threshold should be set with an exaggerated ratio control, because the gain reduction meter indicates how much limiting is going to occur, not where or when. After the threshold setting has been achieved, then the ratio control should be backed off to the point of auditory satisfaction.
Attack and Release considerations In order to achieve pleasant results in heavy limiting for program material, the attack and release times must be VERY LONG. To recover sustained signal material in the face of heavy background, it is often necessary to resort to very short attack and release times. Between the two is where the majority of the operating life of these controls exist. Stay between 9 O'clock and 3 O'clock in order to keep any concept of fidelity.
Ratio and the concept of open-ness. The robust characteristics of the gain cell make it easy to squash the crap out of a good sounding dynamically alive signal and make everything sound like an AM radio mix. This is not a desirable objective. The design goal of the limiter is to be able to control the dynamics of acoustically originated signals without sucking the life out of them. The higher the ratio, the less dynamic range, and the more control over the signal dynamics you maintain. The lower the ratio, the more dynamic range, and the less control you exercise, but the better it sounds. In the beginning, use the presets, determine which ones you like the sound of the most. The curious can contact their GREG HANKS DESIGN dealer or the factory for technical information about attack and release times along with the ratio for each preset.
Presets. A PCMCIA format plug-in programming card is provided on the rear of the limiter. With this device you can tailor the characteristics of the unit to your satisfaction. The offerings in the "Original" preset card are my impressions of; 1. Fairchild 660 2. LA-2 3. Neve Console Bus limiter 4. SSL Quad limiter 5. RCA BA-6
Manual Control. There are two positions for the presets, primary and trim. The primary position (lower) allows you Trim control of the threshold, with no control over the ratio, attack and release times. The “Trim” position (Upper) allows complete control over the threshold and trim over the ratio, attack and release. Manual control leaves the audio characteristics at your complete mercy.
Output level A trim is provided for output gain make-up that has a range of a few dB of loss to +20 dB of gain, to compensate for whatever attenuation is provided by the gain cell.
Summary The operation is a little different from other limiters that you have used. This unit provides for no gain in the gain control cell. There is no provision for gain change as in most compressors, and this unit only provides for program controlled attenuation of the signal path. As such, when you increase the ratio, the attenuation increases and the signal level decreases. This is to be made up manually. You have to play with the controls to get where you want to go, but after walking around the solo a couple of times with the unit, you should find it to respond as you now expect it to. 
| |
|