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A THAT1512 microphone preamp. This is a very simple board with a THAT1512 based preamp for replacing the one in the Buchla 208 for a much lower noise floor and higher gain. Wire between the preamp jack and T.P.1 on card 10. Lower R6 on card 10 to compensate for the gain increase.
The board is 45 × 24 mm with a single M3 mounting hole. Gain is set by the 1K trimmer (RV1, a Bourns 3362P): about 15 dB at full resistance up to about 59 dB at zero, where the 5.6 Ω R6 sets the top of the range.
Pin 1 is the square pad.
| Pin | 1 | 2 | 3 | 4 | 5 | 6 | 7 |
|---|---|---|---|---|---|---|---|
| i+ | i− | g | −v | +v | g | out |
rev3 (2026) — same outline, header pinout and mounting hole as rev2, so it is a drop-in replacement.
rev2 (2022) — the board fitted in the 208, tagged rev2. Its raytraced render is uAmp_3D_render.png.
| Ref | Value | Part number | Notes |
|---|---|---|---|
| U1 | THAT1512 | THAT1512P08-U | DIP-8 |
| RV1 | 1 kΩ trimmer | Bourns 3362P-1-102LF |
| C1, C2 | 470 pF | Murata RDE5C2A471J0M1H03A | C0G, 5 mm pitch |
| C3 | 47 pF | Murata RDE5C2A470J0M1H03A | C0G, 5 mm pitch |
| C4, C5 | 100 nF | Murata RDER71H104K0M1H03A | X7R, 5 mm pitch |
| C6 | 6800 µF 6.3 V | Nichicon UVZ0J682MHD | 12.5 × 25 mm, 5 mm pitch. Polarized is correct here: both gain pins sit at the same DC level. Bipolar 6800 µF only comes as 18 × 35.5 mm, which does not fit |
| C7, C8 | 10 µF 50 V | Panasonic EEU-FR1H100 | 5 mm diameter, 2 mm pitch |
| R1, R2 | 1 kΩ 0.1 % | Vishay CMF551K0000BEEK |
| R3 | 100 Ω | Vishay MBA02040C1000FC100 | mounted vertically |
| R4, R5 | 10 Ω | Vishay MBA02040C1009FC100 | mounted vertically |
| R6 | 5.6 Ω | Vishay MBB02070C5608FCT00 | mounted vertically |
| J1 | 1×7 pin header | 2.54 mm |
THAT Corporation put the 1510 and 1512 on end-of-life status on 1 September 2026 (memo). The Analog Devices SSM2019BNZ (DIP-8) has the same pinout and fits U1 with no board change.
Its gain is 1 + 10 kΩ/Rg where the THAT1512's is 0.5 + 5 kΩ/Rg, so with the rev3 values the range moves up about 6 dB, to 21–65 dB. Two value changes bring it back to about 15.5–59 dB:
| Ref | With THAT1512 | With SSM2019 |
|---|---|---|
| R6 | 5.6 Ω | 11 Ω |
| RV1 | 1 kΩ (3362P-1-102LF) | 2 kΩ (3362P-1-202LF) |
Nothing else changes; C6 then rolls off near 2 Hz at full gain instead of 4 Hz.
By the datasheets the SSM2019 matches the THAT1512's 1 nV/√Hz input noise at 60 dB and is a little noisier below 40 dB (7 against 4.6 nV/√Hz at 20 dB). Its bandwidth at 60 dB is 200 kHz against 1.6 MHz, and its distortion there is about twice as high (0.017 % against 0.008 %, measured under different conditions). It drives 5000 pF where the THAT1512 is limited to 300 pF.
The TI INA217 shares the pinout and the SSM2019's gain equation, but TI no longer lists it in DIP-8.
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