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The third module that completes the ToolMod BM stereo mastering set is the limiter TM215; a unit that is optimized for the regulation of signal peaks in the range of several dB’s. The feed forward controlled limiter offeres in addition to the threshold control that covers the range from –10 to + 20 dB adjustable time constants for the individual alignment of the control characteristics with the shortest attack time of 20 micro second. Even a signal frequency of 20 kHz is being processed within the first half wave. The gain reduction of the limiter is displayed on a bar graph meter with five LED’s. An output gain control with +/- 10 dB control range makes it possible to align the output level precisely to the optimum input level of the a/d converter that is driven by the peak limiter.

Test Results

In face of the former tests of the different adt-audio module systems and consoles, we were quite optimistic to confirm the well-known high performance level with this gear too. We were not disappointed – quite the contrary. All line inputs were able to handle a maximum level of more then + 30 dBu, which is the limit of our Audio Precision test system; the maximum output level was about + 31 dBu for both units. The two TM101 mic pre’s in the ToolMod MS unit were already tested in the first ToolMod session, so we just made a quick check to confirm the old results. The Diagram no. 1 shows frequency and phase response of a microphone input at 40 dB gain that confirms the excellent phase response of the preamp at very low frequencies. These results were even better than the results of the first test session. The old values for the noise performance could be easily confirmed. The output noise of the TM101 at 40 dB gain is –86.9 dBu RMS, unweighted (22Hz – 22 kHz), this is a more than excellent input referred noise of –126.9 dB. With the line input at unity gain, all modules including the eq switched on and set to unity gain, the output noise was –87.1 dBu RMS, unweighted (22Hz to 22kHz), which results in a total dynamic range of about 118 dB. The values of the ToolMod BM are almost the same.
With compressor, eq and limiter switched on and set to unity gain, the output noise was –86.9 dBu RMS, unweighted (22Hz to 22kHz), the CCIR-468-3, quasi-peak value was –76.3 dBqp. Therefore, the dynamic range of the BM is also about 118 dB. The output noise of the single modules was –90.9 dB RMS, unweighted (22Hz to 22kHz) for the EQ, and –91.4 dBu RMS for the compressor and the limiter. Diagram no. 4 shows the excellent spectral noise density of the ToolMod BM (all modules on, at unity gain), which is entirely free of hum.

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