A New Idea
In Microphone Preamps
problem arose one day while recording a really loud vocalist singing through a
U47 microphone. The problem was assumed to be the clipping of the microphone
since every mic preamp in the studio also was clipping in this signal chain.
further measurement it was determined that the U47 output was not clipping, it
was outputing a signal of -15 dBm. Too much output for most mic preamps.
solution was the A9033. This microphone preamp was designed for this situation.
However, the added benefit of passive voltage gain possibly makes this the most
transparent and open sounding microphone preamp ever.
discrete transistor design
voltage gain from transformers
open and uncolored
- Will not
clip with known mics
- Switchable phantom power
- Single-space 500 series rack format
Input Impedance: 1.2KΩ,
Impedance: less than 50Ω
- Max. Output
Level: +32dBu, transformer balanced
- Gain: 5 to
20 dB in 3 dB steps
Response: +/- 1 dB from 7Hz to 85kHz
Level: better than 86dB below +4dBu, 0-30kHz
- Passive transformer
for phantom power