ToolMod Pro Audio
Stereo Limiter

Extremely fast Stereo Peak Limiter TM215

The TM215 is a Stereo Peak Limiter that can catch short peaks without audible side effects. The module operates neutral without colorization and will not alter the sound under regulation. It is fast enough to react within the first period of a 20 kHz sine wave signal. Adjustment of the output level without changing the limiter setting is possible by the output gain control.
  • very fast Stereo Peak Limiter
  • Attack 20Ás to 7ms
  • Release 50ms to 3s
  • Threshold -10 to +20 dB
  • Output Gain ▒ 10 dB
  • Headroom + 30 dBu
  • Dynamic Range
    124 dBA/122 dBRMS
Stereo Limiter Stereo Limiter TM215
The Stereo Mastering Peak Limiter TM215b with useful additional Features is an alternative to the TM215.

The Stereo Limiter TM215 has been optimized for the use as output limiter of an analog stereo signal chain. The attack time of this feedforward VCA limiter with a special peak detector circuitry is extremely fast and reacts within the first period of a 20 kHz sine wave. This property is a very important qualification of a limiter that drives the A/D converter at the end of a mastering chain. In combination with a compressor that is optimized for high loudness gain, which requires a longer attack time, the stereo limiter takes care of an effective control of the signal peaks that will pass the compressor without causing any regulation.

The TM215 stereo limiter does not alter the sound or the frequency response

The possible gain reduction of the stereo limiter is more than 20 dB; however, the feasible gain reduction without unacceptable side effects is a lot lower and limited by the short release time setting that is necessary to prevent pumping and by the problem of attack distortion in the low frequency range, which is better covered by the TM215b Stereo Mastering Peak Limiter, which is the better choice when dealing with problematic signals.

When optimizing the release time in a way that pumping barely disapears the physically depending effect of low frequency distortion due to regulation within the cycle duration of the audio signal determines the maximum gain reduction. Depending on the portion of low frequency components at high levels in the output signal, a gain reduction of 3 to 6 dB is realistic und possible with minor or even inaudible side effects.

  • Threshold
  • Release
  • Attack
  • Gain
  • Display
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.

The TM215 Stereo Limiter is a 2U ToolMod module that can be used in all ToolMod frames. As usual, horizontal and vertical versions are available.
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Price: € 495.00
excl. of VAT and Shipping
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Test Reports
-h: horizontal
-v: vertical
technical Specifications
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Picture h-Version
Picture v-Version
ToolMod Manual
...the limiter proved to be extremely fast and free from loss in the high frequency range...

- Quote from Test Report
read Test

The TM222 Stereo Mastering Compressor is the best possible supplement to the TM215 Stereo Limiter. The combination of both devices forms a very effective dynamics processing tool for mastering.


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