User Manual
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Appendix 3 – Air information
Air is the name we give to the sonic signature of the classic transformer ISA Preamp. Our customers 
first coined this name as a simple description of the effect the ISA preamp added to their sound 
recordings.  The  three  most significant  attributes  of  the  transformer  design  that  create  the  “Air” 
effect are:
• Microphone interaction, created by the unique input impedance of the transformer coupling with 
the microphone output impedance.
• Clarity, created by the low distortion and high linearity of the transformer and preamp design.
• Frequency response tilt created by the transformer resonance resulting in an emphasis in the 
higher frequency content of the sound.
Engaging the Air switches the impedance of the preamp, and enables the “transformer resonance 
effect”, giving your microphone recordings the air and clarity of an ISA transformer-based mic pre 
recording.










