Technical Data

This page contains some information and explanations about the general technical data of the Integrator series. All data information represents minimum values. In some cases the real values are substantially higher than these minimum values that represent worst-case scenarios.


Electronically balanced inputs and outputs are standard on the Integrator modules. However the microphone inputs are transformer balanced and floating for all the microphone amplifiers apart from the I47 transformerless unit. For almost all other inputs a transformer balanced version is available.

Electronically balanced inputs:

Nominal Level + 6 dBu
Maximum Level >+ 30 dBu - Gain
Input Impedance > 10 kOhm
Input CMRR > 50 dB
(some inputs, e. g., DI-Amps, have different data - see module specific data sheet)

Balanced and floating Line Inputs:

Nominal Level + 6 dBu
Maximum Level >+ 30 dBu - Gain
Input Impedance > 5 kOhm
Input CMRR > 60 dB according to IRT
typical value 70 dB bei 15 kHz
Haufe of Lundahl made

Balanced and floating
Microphone Inputs:

Maximum Level >+ 30 dBu - Gain
Input Impedance >> 1 kOhm
Input CMRR > 70 dB according to IRT
Haufe made transformers


Electronically balanced outputs are standard on the Integrator modules. For almost all outputs a transformer balanced version is available.

Electronically balanced Outputs:

Nominal Level + 6 dBu
Maximum Legel >+30 dBu - Attenuation Load Resistance > 600 Ohm
Source Resistance < 40 Ohm
CMRR according to IEC > 40 dB

Balanced and floating Outputs:

Nominal Level + 6 dBu
Maximum Level >+ 30 dBu
(with kges 1 % and 40 Hz)
Load Resistance > 300 Ohm
Source Impedance < 40 Ohm
CMRR according to IEC > 40 dB
CMRR according to IRT > 60 dB
Transformers Haufe or Lundahl made


Within the transmission band crosstalk is typically:

Between independing Signals >95 dB
Between Multi-Channel Devices
(Stereo or 5·1) >70 dB
in MS-Direction Mixers > 40 dB


Nominal Level + 6 dBu

Any other nominal level can be choosen. Unless otherwise stated, data refers to: 0 dB = 1.55 V = + 6 dBu.


Nominal Tolerenz ± 0.5 dB

This tolerance applies to calibrated scales points, like 0 dB points of faders, center detends of rotary gain controls and as well as other level adjusting controls like stepper switches.


Headroom >+ 30 dBu

The headroom for all devices is >+30 dBu at inputs and outputs - depnding ont the setting of gain or attenuation. The value of + 30 dBu applies to a harmonic distortion of kges >1% in the transmission band and is typically 0.3 % at + 30 dBu and 40 Hz for modules with transformers. The typicall clipping level of the modules is +27.5 dBu with unloaded ouputs. The observance of the value assumes the correct setting of the power supply voltages. *1

Transmission Band

In accordance with the IRT 3/5 rules the frequency range of 40 Hz to 15 kHz is defined. These values do not refer to the frequency range of the devices but to the standardized values for the measurement of vertain data. So CMRR values are measured at inputs and outputs usually at 15 kHz. The measurement of distortion is at 40 Hz.

Dynamic Range, Signal to Noise Ratios and Noise Level

Processing Devices:

Almost all processing devices have a dynamic range of more than 116 dB. This means that the maximum output voltage is >+30 dBu and the noise level is below - 90 dBu (RMS/22Hz-22kHz). For detail see module specific data sheet.

Master Outputs

all Faders switched to master, closed Master fader at 0 dB. 1 Frame full installed

Dynamic Range > 118 dB
Noise Level < - 92 dBu
(RMS, 22Hz-22kHz)
Twice the number of channels results in a noise performance, that is 3 dB worse.

Cut Off Levels

up to 15 kHz
closed Faders > 100 dB
Cut Switches > 110 dB
Rotary Faders > 76 dB
  Microphone Preamplifier

With more than 70 dB of gain the noise figure is > 1.5 dB (200 Ohm source, less than -117 dBqp input referred).

With 45 dB of gain the noise figure is < 2.5 dB (200 Ohm source, less than -116 dBqp input referred)

Harmonic Distortion:

kges < 0.1 %

Within input and output levels up to +24 dBu within the transmission band the maximum harmonic distortion with the nominal load resistance ammounts to 0.1 %.

For devices equipped with transformers the distortion coefficient k3 rises at 40 Hz up to a level of + 30 dBu at maximally 1 % . The typical value for the THD at 40 Hz and + 30 dBu is 0.3 %. The Haufe und Lundahl tranformers have saturation levels of >> + 28 dBu at40 Hz.

With regulation amplifiers the harmonic distortion is determined by the setting of the release and attack parameters.

Frequency Response

For any modules at nominal level, without any processing stages that affect or modify the frequency response:

20 Hz bis 20 kHz ± 0.25

The normally integrated RF- and subsonic filters attenuate frequencies above 100 kHz and below 10 Hz. In the standard version the attenuation at 200 kHz is - 4 dB and the attenuation at 5 Hz is - 2 dB. Above 100 kHz and below 10 Hz the signal level rises by resonance effects not above 0 dB values. Modules that are produced according to the IRT rules are kept within the specified frequency range of 15 Hz to 40 kHz. The filters can be tuned differently for custom versions.

For microphone amplifiers a more effective filtering is employed because of the high sensitivity of the microphones and cables to subsonic disturbances and RF irradation. The following data is valid for all gains from 0 to 80 dB.

40 Hz to 15 kHz ± 0.5 dB
20 Hz to 20 kHz + 0.5 / - 1.5 dB
Attenuation at 5 Hz > 6 dB
Attenuation at 200 kHz > 10 dB

Modules produced according to the IRT directives have a blocking attenuation of > 20 dB at 40 kHz and > 12 dB at 15 Hz.

Phase Response

Equal matched audio chains have less than 5° phase difference in the transmission band. The phase response is determined, first of all, by the layout of the RF and subsonic filters. 2)

  1) Measurements of the Haufe and Lundahl input and output transformers display 'real' headroom values of more than + 28 dBu at 40 Hz and more than + 30 dBu at 30 Hz. The typical harmonic distortion of these transformers with a signal level of + 24 dBu at 40 Hz is in the region of 0.1% and with + 30 dBu in the region of 0.3 %.

2) Phase response changes caused by the high frequency and low frequency filter circuits. All standard Integrator modules are designed so that a good compromise exists between sturgeon protection and phase linearity. We have conducted many listening tests between the two types but have never been able to differentiate between them. The phase response of the devices is located in the region of +5° to -20° in the frequency range. The phase rotation of the signal is positive in the low frequency and has negative rotation values in the high frequency spectrum of the signal. A decrease of the sturgeon protection qualities automatically reduces the phase displacements and vice versa. Custom tuning of the damping characteristics of the modules is possible.