Grace Design M501
500 Series Single-Channel Preamp/DI Module

Grace Design's m501, is the 500 series module version of the venerable m101 mic preamplifier. Now the signature transparency and detail of Grace's circuit designs is available for your 500 series frame.

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.

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 an 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.

Features:

• Fast and musical transimpedance architecture
• Updated 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
• Wider 10-75dB gain range
• Enhanced RFI interference suppression
• Three output connectors: XLR balanced, TRS balanced and ¼” unbalanced
• Bombproof laser-etched black anodized frontpanel
• Sealed gold contact relay for Hi-Z input switching
• Built in power supply / no wall-wart!
• Led indicators for +48V, Ribbon mode, and HPF
• Five year warranty on parts and labor
• Made in the USA

Specifications:

GAIN RANGE (5dB steps)
Mic input 10-65dB
Hi-Z input -10-45dB
Output trim control 0 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

NOISE - REFERRED TO INPUT @ 60dB Gain
50 ohm source <-130dB
150 ohm source <-128dB
600 ohm  source <-124dB

CMRR, @60dB Gain, 3.5Vcm
100Hz  >55dB
1kHz  >75dB
10kHz  >65dB

PHASE DEVIATION (HPF off)
50Hz-25kHz @40dB Gain  <10

FREQUENCY RESPONSE
Mic input @ 40dB Gain -3dB 3.8Hz-288kHz
Mic input @ 40dB Gain -0.5dB 8.35Hz-135kHz
Hi-Z input @ 20dB Gain -3dB 1.7Hz-180kHz
Hi-Z input @ 20dB Gain -0.5dB 4Hz-72kHz

IMPEDANCE
Mic input 8.1k ohms
Mic input, Ribbon mode 20k ohms
Hi-Z input (unbalanced) 2.5M ohms
Hi-Z input (balanced) 5M ohms
Balanced Output  300 ohms
Unbalanced Output 150 ohms

PEAK LED METER
Green threshold  -12dBu
Red threshold  +16dBu
MAXIMUM OUTPUT LEVEL
100k Ohm load, 0.1% THD , 1kHz, API Lunchbox 27dBu

WEIGHT and DIMENSIONS
0.7 lb H5.25 x W1.5 x D6.6
316g H13.34cm x W3.81cm x D16.75cm

POWER CONSUMPTION
Current required from +16V and -16V power supplies 120mA Max