Grace 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.

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.

Features:

• 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

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 22HZ-22KHZ BW:

• 50Ω source: <-130dB
• 150Ω source: <-128dB
• 600Ω 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 @ 40dBm Gain -3dB: 3.8Hz-288kHz
• Mic input @ 40dBm 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: 8.1kΩ
• Mic input, Ribbon mode: 20kΩ
• Hi-Z input (unbalanced): 2.5MΩ
• Hi-Z input (balanced): 5MΩ
• Balanced Output: 300Ω
• Unbalanced Output: 150Ω

Peak Led Meter:

• Green Threshold: -10dBu
• Red Threshold: +16dBu

Maximum Output Level:

• 100k Ohm load, 0.1% THD , 1kHz, API Lunchbox: 27dBu

Weight And Dimensions:

• .7 lbs: H5.25 x W1.5 x D6.6
• 316 g: H13.34cm x W3.81cm x D16.75cm

Power Consumption:

• Current required from +16V and -16V power supplies: 120mA Max