# Mic Preamp ## Description Mic Preamp with Onboard 48 V Phantom Power and Dual Fixed-Gain THAT1512 Channels (0 dB / –20 dB), VR1 Removed, Outputs on J3/J4 #that1512 #phantom48V #fixedgain ## Project Details - **Owner:** ondros - **Created:** 1/24/2024 - **Last Updated:** 1/25/2024 - **Visibility:** Public - **width:** 33 mm - **Role:** Amplification - **System Architecture:** flowchart TD J1["XLR Input (J1)"] PP["48V Phantom Power Subsystem"] J1-->|"Phantom Feed (Pins 2/3)"|PP J1-->|"Signal"|P0["0 dB Path"] P0-->A0["Fixed-Gain Amp A"] A0-->O1["Amplified Output A (J3)"] J1-->|"Signal"|H["H-pad Attenuator (-20 dB)"] H-->P20["-20 dB Path"] P20-->A20["Fixed-Gain Amp B"] A20-->O2["Amplified Output B (J4)"] - **Final Tuning Notes:** TBD – finalize THAT1512 gain‑setting, RF filter, and phantom feed resistor values after selecting target ADC input range, input impedance, and microphone capsule sensitivity / maximum SPL. Adjust: (1) THAT1512 gain resistors for required headroom and noise performance; (2) series RF/RC values for EMI vs. audio bandwidth; (3) any pad/H‑pad values in the –20 dB path to match source/load impedances and preserve CMRR. - **Domain:** Consumer Electronics - **Role Details:** Microphone preamplifier with onboard 48 V phantom power, dual fixed-gain paths (0 dB / -20 dB) and dual amplified outputs without user-adjustable gain control. ## Key Components ### J1 — [NC3FAH1](https://www.flux.ai/jecstronic/nc3fah1~llc.md) - Manufacturer Part Number: NC3FAH1 - License: https://creativecommons.org/licenses/by/4.0/ - Datasheet URL: https://www.mouser.com/datasheet/2/289/st-nc3fah1-1853786.pdf - Manufacturer Name: Neutrik - Part Type: Connector **Pins:** - 1+G [pin 1] - 2 [pin 2] - 3 [pin 3] ### J2 — [Connector 01x04 Horizontal](https://www.flux.ai/jharwinbarrozo/connector-01x04-horizontal~h0.md) - Part Type: Connector **Pins:** - PIN_1 [pin 1] - PIN_2 [pin 2] - PIN_3 [pin 3] - PIN_4 [pin 4] ### J3 — [Connector 01x04 Horizontal](https://www.flux.ai/jharwinbarrozo/connector-01x04-horizontal~h0.md) - Part Type: Connector **Pins:** - PIN_1 [pin 1] - PIN_2 [pin 2] - PIN_3 [pin 3] - PIN_4 [pin 4] ### J4 — [Connector 01x04 Horizontal](https://www.flux.ai/jharwinbarrozo/connector-01x04-horizontal~h0.md) - Part Type: Connector **Pins:** - PIN_1 [pin 1] - PIN_2 [pin 2] - PIN_3 [pin 3] - PIN_4 [pin 4] *The full schematic, PCB layout, bill of materials, and interactive design are available at [https://www.flux.ai/ondros/mic-preamp~ah](https://www.flux.ai/ondros/mic-preamp~ah).* --- *Generated from [https://www.flux.ai/ondros/mic-preamp~ah](https://www.flux.ai/ondros/mic-preamp~ah)*