Buzz Audio QSP-20 4 channel studio mic preamplifier

If you are looking for a versatile but cost effective outboard mic preamp for your project studio, then you’ve found it! We think the QSP-20 represents excellent value for money and offers the professional performance of vintage brands without the vintage price tag. Using our proprietory True Class A circuitry and the exceptional Lundhal output transformers, the QSP-20 delivers a big honest open sound and is perhaps the best value Quad Studio Preamplifier available today.

With plenty of low noise gain (70dB) the QSP-20 works really well with low output dynamic and ribbon microphones. The mic input impedance switch can subtley alter the sound from these mic types giving you another flavour. Also included are 4 front panel high impedance 1/4″ jack inputs for your keyboards, bass guitar or anything with a pickup. These inputs use our proprietary “boot strapped” high impedance buffer stage and sound fantastic on bass.

The wide bandwidth of the QSP-20 ensures transient details are preserved, excellent for cymbals, percussives and stringed instruments. The slight increase in distortion at low frequencies from the transformer adds a touch of colour – an ideal combination. The high head room of the QSP means your sounds are captured in all their glory with no nasty clipping. Made with quality components and by real hands, the QSP-20 is a sound investment!


Each channel as a detented 41 position Gain control. Toggle switches select a 20dB input Pad (for both mic and line inputs), Polarity Reverse with a Mute position, High or Low mic Input Impedance and a locking toggle turns the 48Vphantom power on or off. Selection of the 1/4″ front panel jack inputs occurs automatically when a jack is inserted. A peak led will light when the output level reaches +22dBu.


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.

Frequency Response
= 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

= -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.
IEC detachable power cable.