Like most of our microphone preamplifiers, the QSP-20 does not use a transformer at the input. Instead we couple direct to the Class A (BE41) amplifier modules with hi-quality WIMA capacitors. This approach presents a much less reactive load to the microphone and allows it breathe better. In other words, the QSP is like an extension to the microphone and this means you can clearly hear the differences between all microphone types and brands. The HI Z - LO Z switch allows you change the load the microphone sees, and this can produce subtle tonal changes depending on the type of microphone.
Another advantage of the direct coupled input is noise - or lack of it. You will discover the QSP has an extremely low noise floor making it useful for low output microphones such as ribbons. The low noise plus the high output headroom results in a preamp with 92dB dynamic range at full gain of 70dB.
In addition to the four mic inputs, you also have four high impedance instrument inputs on the front panel. These inputs can be used for keyboards and instruments with unbalanced pickups.
Both the mic and line inputs benefit from the sound of the Lundahl* output transformer which exhibits an incredible frequency response right out to 200kHz, whilst adding a subtle amount of harmonic at the lower frequencies. Transients are preserved and the bottom end sounds full and these attributes make the QSP an excellent preamplifier for recording drums and other percussive instruments.
Modern music recording
Acoustic music recording
Mobile recording set ups
Toasty discrete Class A amplifiers
Flashy Lundahl* audio output transformers
Up to 70dB of gain
+28dBu output headroom
Culmination of 20 years design experience
Robust chassis construction
On board linear power supplies - no wall warts!
Easy to use control layouts
Min Gain Mic = +22dB (-2dB with pad in)
Max Gain Mic = +70dB
Min Gain Instrument = +12dB (-3dB with pad in)
Max Gain Instrument = +60dB
Maximum Output Level = +29dBu into 3k ohm load.
Mic = 10Hz to 200kHz @ 20dB gain (-3dB).
Instrument = 10Hz to 120kHz @ 20dB gain (-3dB).
Total Harmonic Distortion
(measured at -20dBu input, gain adjusted for +10dBu output level)
Mic = 0.15% @ 100Hz, 0.01% @ 1kHz, 0.005% @ 10kHz
Instrument = 0.15% @ 100Hz, 0.015% @ 1kHz, 0.015% @10kHz
EIN Mic = -131dB A wtg, 150ohm source Z.
Signal to Noise Ratio Instrument = -76dB A wtg, input shorted.
CMNR Mic = -78dB @ 100Hz, -100dB @ 1kHz, -100dB @ 10kHz.
Input Impedance Mic = 4k ohms/1k2 ohms switchable.
Input Impedance Instrument = 1MEG ohms.
115V or 230V ac mains, switchable on rear panel.