25/04/2026
(Shivansh Electronics) Shivansh Electronicsβ’οΈ β’ Eastern India's Premier Audio Destination
[Founder: Mr. Gopal Das Deb (Gopal Das Deb)]
Authorised Distributor β MOTU (Mark of the Unicorn) Audio Interfaces | Eastern India
π https://shivanshelectronics.in
π +91 98316 62458 β’ +91 91477 00677 β’ +91 89818 07755
ποΈ The MOTU M2 β Where Engineering Meets Performance
π Document 2 of 5 | Microphone Preamplifier Design
-129 dBu EIN β’ 1.9 dB Above the Laws of Physics β’ Studio-grade audio at βΉ28,000
Whether you're recording, producing, or mixing β the MOTU M2 delivers transparent, ultra-low-noise conversion that professionals trust. As the Authorised Distributor of MOTU (Mark of the Unicorn) Audio Interfaces in Eastern India, we bring you genuine products with full warranty support β right here in Kolkata.
This is Document 2 of our five-part technical series on the MOTU M2. If Document 1 established what the ESS Sabre32 DAC does on the output side, Document 2 addresses what happens at the very first point of entry β the microphone preamplifier. Noise introduced here cannot be removed by any downstream process. Ever.
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WHAT WE COVER IN DOCUMENT 2:
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β’ The THAT 6263 Preamp IC
The M2 uses the THAT Corporation 6263 β a digitally controlled programmable gain preamplifier that integrates the gain stage, variable control, and ADC driver into a single 7Γ7mm package. By replacing analog potentiometers with a digital step controller and zero-crossing detection, the M2 eliminates zipper noise on gain changes and delivers precise channel matching that analog circuits cannot sustain over time.
β’ Johnson-Nyquist Thermal Noise β The Physics Minimum
The absolute quietest any preamplifier can ever be is determined by physics, not engineering. For a 150Ξ© source resistance (standard dynamic microphone) across a 20kHz bandwidth at room temperature (293K):
V_noise = β(4kTRΞf) = 22.04 nV RMS = -130.9 dBu
This is the thermal noise floor of the microphone's own impedance. No amplifier β at any price β can go below this number.
β’ -129 dBu EIN β 1.9 dB Above the Theoretical Limit
The MOTU M2 achieves -129 dBu Equivalent Input Noise on both channels. The gap to the theoretical minimum is just 1.9 dB β meaning the M2's own preamp noise contribution is only 16.3 nV RMS, which is less than the 22.04 nV generated by the microphone's impedance itself. The preamp is quieter than the source physics.
β’ Competitive EIN at This Price Point
β MOTU M2 ($199): -129 dBu | Gap: 1.9 dB β Reference
β Focusrite Scarlett 2i2 ($199): -128 dBu | Gap: 2.9 dB
β SSL 2 MKII ($249): -130 dBu | Gap: 0.9 dB (closest to theory, at higher cost)
β Audient iD4 MKII ($229): -127 dBu | Gap: 3.9 dB
β Behringer UMC202HD ($59): -120 dBu | Gap: 10.9 dB
The M2 achieves the second-best EIN in its class β at the lowest price point in the comparison.
β’ 60 dB Gain Range β What It Covers and Where It Ends
60 dB accommodates condensers (20β35 dB needed), dynamic microphones like the SM58 (40β55 dB), and broadcast dynamics at close range (55β60 dB). The one honest edge case: the Shure SM7B at quiet speech levels requires ~68 dB β 8 dB beyond the M2's range. Solution: Triton Audio FetHead (+27 dB, $79). M2 + FetHead = $278 total, 87 dB of clean gain, Sabre32 conversion intact.
β’ Per-Channel Phantom Power & USB Power Budget
The M2 provides individual 48V phantom power switching per channel β not a global switch. This allows a condenser on Channel 1 with phantom ON and a ribbon on Channel 2 with phantom OFF simultaneously. Phantom power draws 552 mW from USB at typical load. Total worst-case M2 power draw: 2,355 mW β within the USB 2.0 limit of 2,500 mW with 145 mW to spare.
β’ Combo Jack & Hi-Z β Both Channels, Not Just One
A critical distinction: the M2 is the only interface in the MOTU M-Series where BOTH channels offer switchable 1 MΞ© Hi-Z instrument input. The M4 restricts Hi-Z to channels 3β4. This means the M2 can simultaneously record two guitars DI β a significant advantage for guitarists tracking direct.
β’ Preamp Transparency β Measured, Not Claimed
Frequency response: Β±0.1 dB (20 Hzβ20 kHz)
THD+N:
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