Useful Arts SFP-60 Dual-Channel Tube Microphone Preamplifier
The Useful Arts SFP-60 Tube Preamp is an all tube two channel mic prel, full-featured and designed to make microphone signals stand out in a mix - without the need for additional processing.
The Useful Arts SFP-60 Tube Preamp has a clear, present and edgy sound, and is specifically designed to make vocals sound forward and intimate. We accomplish this by using tubes for what they are best at – accentuating harmonics that make sound more clear and pleasing to the ear and brain in the real world. Different tubes have different properties. Properly used, pentodes add third-order harmonic content that contributes the the “clarity” and “bite” associated with the sounds of the great early radio recordings. Triodes contribute more second-order harmonic components, which add a richness, or “thickness” to the sound without sounding dark. (Note: These are subjective impressions. People can and do debate these adjectives for a lifetime). The SFP-60 input tube is an EF-806 pentode, and the final 2 gain stages are high-current ECC82 triodes. 12AX7s, which are wonderful in guitar amps and form the basis of many mass-marketed tube mic preamp circuits, are nowhere to be found in the SFP-60.
Useful Arts SFP-60 Tube Preamp Features
- Absolutely no signal passes through these switches, because we hate the noise that develops over time in even the most expensive switches. Instead, the front panel switches control sealed, gold-plated relays to ensure years of operation without pops and clicks.
- The input and output levels of the triode stages of the SFP-60 are separately controllable by detented attenuators, and combined with the color control, the SFP-60 provides just over 55dB of useable gain.
- The rear panel is simple: Gold-plated XLR connectors for the transformer-balanced inputs and outputs, a ground post, and a voltage selector for 115/230 volt operation.
- The faceplate is milled from .190”-thick aircraft-grade aluminum for maximum rigidity, and anodized in a very dark green finish. All markings on the front panel are laser-engraved, ensuring that the unit’s appearance will not deteriorate with age.
- The only active devices in the signal path are the three tube gain stages, consisting of 1 EF806 and 1 ECC82 per channel. We use new-manufacture JJ tubes for long life and easy replacement.
- Each channel features an output level VU meter, which is op-amp buffered to ensure that the signal is not loaded by the meter.
- The audio power supply features a toroidal dual-primary transformer and linear regulation for lowest noise.
- Construction is fully modular, with gold plated connectors used throughout the audio path.
Useful Arts SFP-60 Tube Preamp Specifications
- Each gain stage is single-ended, inherently class A.
- Audio Magnetics (Input and Output Transformers, Plate Inductor) custom wound by Cinemag
- Output Transformer with 50% nickel core
- Frequency response is flat within 2dB from 20Hz-30KHz:
- Each channel of the SFP-60 features 5 switches:
- Input selector (Rear XLR/Front Instrument Input)
- High Pass Filter
- Input Pad
- Phase Reverse
- Phantom Power
Useful Arts SFP-60 Tube Preamp Includes
- SFP-60 Tube Preamp
- Power Cable
- Warranty Information