m501 Microphone Preamplifier

500 series module microphone preamplifier

Presenting the m501, our 500 series module version of the venerable m101 mic preamplifier. Now the signature transparency and detail of our circuit designs is available for your 500 series collection.

While the 500 series market has plenty of colored mic preamplifier options, the natural, musical clarity of the m501 makes it a welcome addition to the field. This circuit is for engineers confident with the quality of the source, mic section and placement, and wish to capture it with as little coloration or distortion as possible.

“It’s not adding the vibe… it captures the vibe.”

-Paul Vnuk J.

The m501 module is a balanced, transformerles design, with 48V phantom, a 75Hz HPF and a 1/4” HI-Z instrument input. Also standard is our exclusive ribbon mic mode, which raises the mic input impedance, bypasses the input decoupling capacitors and deactivates 48V phantom to protect delicate ribbon mics from damage.

Large diaphragm, vintage ribbon or trusty dynamic – the m501 brings out the very best in any microphone and takes the guesswork out of your input chain.

The Grace Design EON and STANDARD Warranties

We back up everything we make with either our unrivaled 20 year EON limited warranty, or the 5 year standard limited warranty. These represent the best coverage in the business and prove our commitment to the quality, serviceability and long term value of Grace Design products.

  • Fast and musical transimpedance architecture
  • Precision audio path with 0.5% precision metal film resistors
  • New 12 position gold plated rotary gain switch
  • High performance output line driver amplifier and HPF amplifier
  • New Ribbon mic mode (also great for dynamic mics) – Relay bypass of phantom power decoupling capacitors, increased input impedance, and 48V lockout
  • Wide 10-75dB gain range
  • Enhanced RFI interference suppression
  • Bombproof laser-etched black anodized frontpanel
  • Sealed gold contact relay for Hi-Z input switching
  • Led indicators for +48V, Ribbon mode, and HPF
  • 20 year EON year warranty on parts and labor
  • Built in the USA
Gain Range (5dB steps)
Mic input10-65dB
Hi-Z input-10-45dB
Output trim control0 to +10dB
THD+N 1kHz, 22Hz-22kHz BW
@ 20dB Gain +20dBu out<0.00085%
@ 40dB Gain +20dBu out<0.0010%
@ 60dB Gain +20dBu out<0.0050%
Intermodulation Distortion
@ 40dB Gain +20dBu out
SMPTE/DIN 4:1 7kHz/50Hz<0.0020
50Ω source<-130dB
150Ω source<-128dB
600Ω source<-124dB
CMRR @60dB Gain, 3.5Vcm
Phase Deviation (HPF off)
50Hz-25kHz @40dB Gain<10
Mic input @ 40dBm Gain -3dB3.8Hz-288kHz
Mic input @ 40dBm Gain -0.5dB8.35Hz-135kHz
Hi-Z input @ 20dB Gain -3dB1.7Hz-180kHz
Hi-Z input @ 20dB Gain -0.5dB4Hz-72kHz
Mic input8.1kΩ
Mic input, Ribbon mode20kΩ
Hi-Z input (unbalanced)2.5MΩ
Hi-Z input (balanced)5MΩ
Balanced Output300Ω
Unbalanced Output150Ω
Green Threshold-10dBu
Red Threshold+16dBu
Maximum Output Level
100k Ohm load, 0.1% THD , 1kHz, API Lunchbox27dBu
Weight and Dimensions
.7 lbsH5.25 x W1.5 x D6.6
316 gH13.34cm x W3.81cm x D16.75cm
Power Consumption
Current required from +16V and -16V power supplies120mA Max
Support Documents

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