The Threshold can be adjusted in the range from -10 dB to + 20 dB. This covers all common input levels of a/d converters and analog tape recorders. The 0 dB position is internally calibrated.
In order to allow precise optimization of the Release Time, the control range is extended down to a value far below the optimum value of approximately 0.3 sec for pump free operation. Although a release time setting of less than 0.3 sec is not possible with low frequency signals, the range below can be used with audio signals with no considerable low frequency components. Such short release times result in a very high density of the audio signal. The minimum release time is 50 ms; the longest release time is 3 sec. A long release time will cause pumping, but offers the choice to adjust a wide range of conventional settings, as they are used with broadcasting.
Only the shortest possible Attack Time of
20 µs is important when using the TM215 as peak limiter with stereo mastering
applications; however, short attack times can cause attack distortion effects
in the low frequency range. Attack distortion due to the physical effect of disrupting
the wave form of the signal when the limiter kicks in with a short attack time,
can limit the maximum possible gain reduction. Setting the attack to the highest
value that is possible to catch all peaks in the mid and high range can reduce
this effect. However, longer attack times might cause short peaks to pass thru
the limiter. Such peaks can overload the input of the A/D converter that is usually
driven from the limiter output The attack time control range reaches up to 7
ms to offer the choice of using the TM215 for other applications. A longer attack
time is well suited for using the module as additional, hard, compressor that
adds some density
An additional Output Gain Control with +/- 10 dB range and precisely calibrated 0 dB position at the center detent affects only the output level but not the settings of the limiter. After adjusting the limiter, the gain control is used to adapt the output level to the A/D converter connected downstream of the limiter.
The Gain Reduction Display is a LED bar graph with 5 LEDs and 10 dB display range.