RaneGain
General Description
The RaneGain test set is a handy tool kit based on techniques first developed by Pat Brown of Syn-Aud-Con for use in quickly setting sound system gain controls. Using the RaneGain pair makes setting level controls a snap.
Comprised of a precision 400 Hz sine wave generator and a matching piezo transducer, the test set makes use of the Fourier principle that all periodic waves can be broken down into a sum of pure sine waves. If a pure 400 Hz tone is the source in a system, and the system is turned up until clipping, then what comes out is the 400 Hz fundamental, plus a whole string of predominately odd-order harmonics. Spectrum analysis of the output will show the 400 Hz fundamental, plus strong harmonics at the odd harmonic intervals of 1.2 kHz, 2 kHz, 2.8 kHz, 3.6 kHz, 4.4 kHz and so on. The RaneGain Transducer is a piezo tweeter designed to reproduce mid-to-high audio frequencies, so while it doesn't reproduce the 400 Hz fundamental worth a hoot, the harmonics make it scream.
Application Information
The RaneGain test set provides a 400 Hz test tone and matching transducer for setting gain controls in a typical sound system. Consult "Setting Sound System Level Controls" for detailed set-up procedures. For those in a hurry, here is a brief and simplified summary:
Simplified RaneGain Setting Procedure
Verify correct hook-up and system operation, then turn off all power amps, and set all level controls to zero or minimum.
Connect the RaneGain Generator to any mic/mixer input with phantom power ... important, the generator requires phantom power to operate ... and connect the RaneGain Transducer to the output of the mixer or mic preamp. Turn up the gain of the preamp/mixer until a buzz is heard from the transducer. This indicates the maximum output level. Turn the gain down until the transducer just stops buzzing. Now you have established the largest possible signal output before clipping. Use this signal to set the remainder of the system level controls as follows:
Set all outboard processors for flat frequency response, i.e., EQ controls centered, compressor/limiters set not to operate, etc. Move the RaneGain Transducer to the output of the next unit in line from the preamp/mixer. Using the level previously established adjust this level control until the transducer starts buzzing, then back off just enough until it stops. This is the proper set point for the level control to allow the maximum unclipped signal to pass.
Further Information
