One thing I’ve learned from spending time as a reviewer with the Grimm MU2, LS1c Active Loudspeaker System, and as an owner of the MU1 is to expect the unexpected when it comes to sound quality from everything Grimm.
From my review of the MU2:
If you want to hear the best digital music reproduction I’ve heard by an obvious and distinct margin, you’ll need to find a Grimm MU2 to listen through.
I’m also intrigued by their PW1 Phono Preamplifier as I’ve heard similar head-shaking raves and now news of their new PA1 Class AB monoblocks hit my inbox just in time for the Vienna show which I am sadly missing this go around.
I see a hint or tip of the hat to the classic Pass Labs Aleph 3 in the PA1’s design which comes from industrial designer Michiel Uylings who also designed the MU1 and PW1. The PA1 puts out 150 Watts into 8 Ohms and 200W into 4 but this isn’t your father’s Class AB amp.
From Grimm:
One of the most striking design choices in the PA1 is found in the output power stage. It is a traditional ‘class AB’ type of design, but of a highly innovative kind. We created a fully symmetrical circuit, with no less than 96(!) small and fast power transistors to achieve a very high bandwidth. This unique technique became possible by using modern aluminium printed circuit board technology, that offers an extremely tight thermal coupling of all the power transistors. An ingenious output driver circuit, mounted on the very same aluminium printed circuit board, takes care of the quiescent current setting point of the output stage transistors.
The circuit is an evolution of an original design by Henk ten Pierick (†), dating back to 1985. His concept provides an extremely well defined power output stage setting point, through which the output stage impedance remains constant over the full cross-over region, resulting in the lowest possible distortion of dynamic signals. The tight thermal coupling of the output stage transistors with the driver stage ensures that this ideal setting point is maintained even when large (low-frequency) currents are delivered to the loudspeaker. The PA1 name refers to Henk’s genius, we call it the “Pierick Amp”.
Another thing I’ve learned about Grimm is they tend not to make empty promises. You can read more about the PA1’s design here which have a claimed frequency response of 0.1 Hz – 300 kHz.
Simple is as simple does around back does with the exception of a Gain switch (18dB/26dB) to better suit your system.
The Grimm PA1 monoblocks will be on active display at High End Vienna 2026 in sound cabin M01 in Hall X4. Price is TBD.
Company Website: Grimm Audio
Features & Specifications
Balanced design throughout
Extremely low residual cross-over distortion
No coupling capacitors
Extensive protection circuitry
Max. ambient temperature for operation: 40 °C
Line voltage 100-120 VAC or 200-240 VAC
Power Consumption, operation: 65 W ~ 600 W
Power Consumption, low power mode: <5 W
IEC C18 type line voltage connector (without safety earth pin). Class 2 isolation
Fuse 230 V: T2.5AH250V, Littelfuse 021502.5MXP
Connections: XLR input impedance: 33 kΩ, RCA input impedance: 16 kΩ, 4mm ‘banana’ style binding posts
Gain: 26 dB or 18 dB (selectable)
Power: >150 W in 8 Ω
Power: >200 W in 4 Ω
Output impedance: <10 mΩ
Damping Factor: >800 re 8 Ω
SNR: 96 dB (1 W, 8 Ω), 118dB (150 W, 8 Ω)
THD+N: -96 dB (1 W, 8 Ω)
THD: <0.0001 %
Damping Factor: >800 re 8 Ω
Frequency response: 0.1 Hz – 300 kHz
Weight: 15 kg
Dimensions: w x d x h: 250 x 250 x 240 mm
5 year limited warranty
