AEA TRP500 is a single-channel microphone preamplifier in API 500 format, built on a DC-coupled JFET circuit with 100 kΩ input impedance (phantom off) and up to 85 dB of gain. As AEA's first third-generation preamp in modular format, the TRP500 brings the topology and sonic character of the classic TRP into a 500-series slot — no input transformer, minimal signal path, and self-noise below –128 dBu typical with a 40 Ω source.
100 kΩ and DC Coupling — Full Bandwidth Without Restriction
The 100 kΩ input impedance (phantom off) is the highest value in the AEA lineup and among the highest available in 500-series format preamps optimized for ribbons. With phantom engaged, impedance drops to 11.9 kΩ due to the phantom feed resistors — still several times higher than the 1.5–2.5 kΩ of standard mic preamps, maintaining the impedance advantage with condenser and vintage high-impedance dynamic sources. DC coupling extends the low-frequency response below 10 Hz and speeds recovery to linear operation after transient overloads — subsonic content and impulse peaks don't generate LF tails in the signal path. At 85 dB gain, bandwidth measures –1 dB below 20 Hz and above 100 kHz; at 30 dB gain, ±0.6 dB below 10 Hz through 200 kHz. EIN below –128 dBu (unweighted, 40 Ω source), typically –130 dBu.
HPF, Phantom and 500-Series Power Isolation
A first-order high-pass filter (6 dB/oct) with –3 dB selectable at 115 Hz or 230 Hz handles proximity effect and mechanical rumble before the signal enters any downstream EQ. The twelve-position gain switch (+7 to +65 dB) combined with a continuous output trim (0 to +20 dB) delivers 7–85 dB total range with repeatable session-to-session settings. THD+N is 0.0017% at 30 dB gain. The 500-series format means power comes from the lunchbox chassis, keeping the switching supply outside the audio circuit entirely — at 85 dB of gain, any power supply noise inside the preamp enclosure would be directly audible. Maximum input before 1% THD is 21.5 dBu at minimum gain, requiring a clean-power 500-series chassis for optimal headroom.
KEY FEATURES
- API 500 Series format, 1 slot
- Single-channel DC-coupled JFET preamp, 85 dB gain
- Input impedance: 100 kΩ (phantom off) / 11.9 kΩ (phantom on)
- Gain range: 7–85 dB (12-position switch +7 to +65 dB + output trim 0–+20 dB)
- EIN: <–128 dBu (22 Hz–22 kHz, unweighted, 40 Ω source); typically –130 dBu
- THD+N: 0.0017% (1 kHz, 30 dB gain, +4 dBu output)
- Bandwidth (85 dB): –1 dB below 20 Hz and >100 kHz; –2.5 dB below 10 Hz and >200 kHz
- Bandwidth (30 dB): +0/–0.6 dB below 10 Hz through 200 kHz
- Max input level: 21.5 dBu (1% THD, minimum gain)
- HPF: –3 dB at 115 Hz or 230 Hz, 6 dB/oct (switchable)
- +48 V phantom power (switchable)
- Polarity reverse: yes
- Power: API 500 chassis (±16 V rails), 130 mA draw
- Handmade in Pasadena, California, USA
TECHNICAL SPECIFICATIONS
- Format: API 500 Series, 1 slot
- Input type: DC-coupled JFET, transformerless
- Input impedance: 100 kΩ (phantom off) / 11.9 kΩ (phantom on)
- Gain range: 7 dB – 85 dB
- EIN: <–128 dBu (22 Hz–22 kHz, unweighted, 40 Ω); typically –130 dBu
- THD+N: 0.0017% (1 kHz, 30 dB gain, +4 dBu output)
- Max input level: 21.5 dBu (1% THD)
- HPF: –3 dB @ 115 Hz or 230 Hz, 6 dB/oct
- Phantom power: +48 V (switchable)
- Polarity reverse: yes
- Current draw: 130 mA (±16 V rails)
- Made in: USA (Pasadena, CA)
