Telex ISP-100 manual Metering

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one. The two quantities are then compared and the larger is returned as the signal level.

When the Crest Factor Sensitivity is set to 0.00 the ISP-100 limiter operates as a traditional limiter responding to average signal levels; when the Crest Factor Sensitivity is set to 1.00 the ISP-100 limiter operates as a traditional limiter responding to peak signal levels. Values in-between represent various hybrids of the two. If the limiter is to ignore peaks and respond only to average levels, then the Crest Factor Sensitivity may be set near zero. If the limiter is to respond only to peaks, then the Crest Factor Sensitivity may be set near one.

Good results may be obtained by following these steps:

1.Set the Crest Factor Sensitivity to 0.00. This will cause the ISP-100 limiter to behave like a traditional limiter responding to average signal levels.

2.Set all of the other limiter controls as appropriate for the signal being limited, just as they would be set in a traditional limiter.

3.Adjust the Crest Factor Sensitivity control so that the limiter responds appropriately to short signal peaks. If it were possible to know, in advance, what the crest factor of the input signal was going to be, then the Crest Factor Sensitivity control would ideally be set to 1/(the crest factor of the input signal).

Since this quantity is not generally known, it is best to experiment until satisfactory results are obtained.

Metering

The limiter meter shows the attenuation applied to the signal passing through the limiter at any given moment in time. When the signal is being limited the meter indicates negative values (gain less than 1.0). When the signal is not being limited the meter indicates 0 dB (gain of 1.0). Meter values are raw, no averaging or ballistics are applied.

Notes on Operation of the Limiter:

Bypass

Bypassing a limiter causes the signal to pass through unaltered.

Overshoot

The limiter algorithm used in the ISP-100 allows for a small amount of overshoot on transients, regardless of the settings of the Detection Window and Crest Factor Sensitivity controls. The amount of overshoot is somewhat dependent upon the setting of the Threshold control; the lower the threshold the greater the overshoot. This represents normal operation for the limiter.

Processing Components - Limiter