OPERATING / SERVICE MANUAL GE 14/GE 27
GRAPHIC EQUALIZERS
QUICK START
The GE 27 and GE 14 are extremely accurate instruments capable of precise equalization down to a fraction of a dB. However, equalizing a sound system by ear is very difficult to do with any degree of accuracy, even with years of training.
To obtain the best performance from your equalizer it is strongly recommended that you use some type of realtime analyzer. Any equalizer used in conjunction with a well designed analyzer system will be significantly more effective in reducing feedback and providing consistent, optimum sound quality in varying acoustical environments.
If you don’t have an analyzer (such as the Rane RA 27), then you will have to resort to Section 2408, paragraph 84-B of the Performing Musicians Code, which reads:
“Fiddle with it until it sounds good.”
This fiddling process can be both time-consuming and frustrating with a 1/3 or 2/3 octave equalizer––you can end up chasing your own tail until all the sliders wind up at full boost, unless you have a basic procedure to follow. If you haven’t one of your own, here’s a procedure you might try.
Point to remember: All things are relative. This applies especially well to tonal perception. What sounds like too little bass could really be too much midrange, and so on.
The idea is to start with some frequency area and use it as a reference for further comparison; then leave this area pretty much alone and make your adjustments elsewhere. Otherwise you might wind up hopelessly trapped in Murphy’s EQ Syndrome, which roughly reads:
“O.K., we need more low end here; now add a little presence at 10k or so; hmmm, mid range is off a little, so I’ll bump up 800 and 1k; now I need more punch, so up with 80, 100 and 125; darn, presence is still not there, so more of the 5k and 6.3k, vocals seem a little buried—needs more 1.25k and 1k...” and so on until all the sliders are near full boost and you have a high-dollar volume control.
To avoid this, choose an area in which you know your speakers perform well, such as around 1kHz. Leave this area at roughly center position on the sliders and then compare bass, mid bass, mid highs and highs to the 1kHz area. Then if, for example, the overall sound appears to be “boomy”, muddy, or lacking in midrange, turn down the mid bass and/or mid highs––don’t turn up the 1kHz midrange area instead, or you’ll be headed right into the vicious circle.
Once you are familiar with your own system, you will develop your own procedure. The golden rule is: “Whatever Works, Works.”
FRONT PANEL DESCRIPTION
1.POWER Switch: It comes as no surprise that this switch turns the GE 27/GE 14 on and off. An LED is located to the right of this switch that illuminates when the unit is turned on. Each output of the GE 27/GE 14 is fitted with a relay which provides delayed turn-on and instant turn-off to avoid switching transients.
2.LEVEL Control: This sets the overall Level through the GE 27, or the Level of each Channel through the GE 14. Use this control to turn down the Input if the overload LED ever lights. The approximate unity gain position of the knob, with all sliders centered is “7.5”. Full clockwise position of the knob yields 6-8dB of line gain with sliders centered.
3.BYPASS Switch: This is a passive or “hard-wired” type Bypass, which means that the Equalizer is completely Bypassed when this switch is in. The Input jack is connected directly to the Output jack internally, with no active elements in series. The red LED right next to the BYPASS switch lights whenever it is engaged.
4.OVERLOAD Indicator: This red LED lights whenever signal through the GE 27/GE 14 reaches 4dB below clipping. Occasional flashing of this LED is usually safe, but consistent blinking means there is danger of clipping.
5.SIGNAL PRESENT Indicator: This green LED lights with any Input of -20dBu or greater. This indicator assists in signal tracing should the need arise (and it will, sooner or later, so help us Murphy).
6.Filter Slider Controls: These 45mm sliders control the amount of boost or cut at the indicated frequency. All filters are constant-Q for constant bandwidth at any level of boost or cut, on ISO centers, and calibrated in 3dB increments on the front panel.
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