Sonic Frontiers SFP-1

The SFP-1 is a hybrid design using a single JFET per channel as an input and followed by a 6922-based triple-series amplifier as a second stage. The output stage uses a second 6922 as a cathode follower to lower the unit's output impedance. The circuit is non-inverting and uses frequency-dependent feedback for equalization. The single compensation network is "fed from a fairly low impedance, thereby avoiding slew-limiting at high frequencies" (from Sonic Frontiers).

Specifications: Frequency response–20 to 20,000Hz; THD– 0.05% at 1.0V input; Gain– 37dB (MM), 57dB (MC); Output impedance:–47k ohms (adjusted internally w/ set of resistors provided); Channel separation– >40dB; Tube complement–Mullard 6922, 12AT7A; S/–- 72dB.

One owner with few hours. No manual. Tube complement (2016 from Parts Connexion) is a matched pair of  NOS 1980s vintage Mullard CV4024 (No Logo), 10,000HR Super Low Noise, 12AT7/ECC81 with <50 hours of use, and upgraded vampire RCA plugs. The amp comes with the original box and OEM packing. Tubes and support by the Parts Connexion (https://partsconnexion.com/).