ADK AP-1 Discrete Modular Class A Microphone Preamp Details The ADK AP-1 Discrete Modular Class A Microphone Preamp is ADK's Custom Shop preamp offering... a with a twist. The input transformer of the ADK AP-1 is mounted on a removable circuit board. By conforming to the API 2520/Jensen 990 footprint, other new and vintage op amps can be swapped. ADK will offer optional input transformer daughter boards using transformers such as the Lundahl 1538xl, Jensen JT-110K-HPC and Sowter API 2622 vintage re-creation. ADK will also assist users who want to make custom boards for other transformers. Other features include 1/4-inch DI, impedance loading switch, phantom power, polarity reverse and -20dB pad. ADK AP-1 Discrete Modular Class A Microphone Preamp Features * Hand crafted in USA by top U.S. Engineers * Toroidal power supply - No wall wart here! * Open-ended architecture to vary tone and texture * Dual-topology with ADK "Pop and Swap" technology * Interchangeability - both at the Op-Amp and the transformer * Robust design and tonality are the Paramount Design Criteria * Upgradeable both in the future, and - remarkably - from the past! ADK AP-1 Discrete Modular Class A Microphone Preamp Specifications * Input Impedance: 1.5k ohm * Gain Range: 25-65dB * Noise (EIN): -125dB * Output Impedance: 75 ohms * Max Output Level: +30dB * Frequency Response: 20Hz - 20kHz * Distortion THD: > 0.08% @ 1kHz * Input Connectors: XLR Balanced Mic Input ¼” Unbalance Instrument * Output Connectors: XLR Balanced Line Output Stock Input Transformer Cinemag * Stock Opamp: ADK Class AB JFET Design. Swappable. Compatible Op-Amps available new and on the vintage market from manufacturers such as John Hardy, Millenia Media, API, Seventh Circle Audio, Forsselltech, Melcore. Vint-Op-M/N from ADK. * Power Supply: Internal PSU featuring Torroidal Transformer, pre-regulation circuit at the PSU and localized regulation located for each opamp. * Phantom Power: +48vdc * Op Amp Power Rails: +/-18vdc * AC Power Requirements: 115/230 VAC 50/60Hz set by internal jumpers at the factory. * AP-1 Fuse Requirements: 115VAC: 125ma Slo Bo 230VAC: 63ma Slo Blo * AP-1 Dimensions/Weight: 8.5” x 1.75” x 7” 3 lbs