Aretha is a Baxandall tone control preamplifier in a classic cathode follower circuit with a tube output buffer. The tone controls allow the user to adjust for not-so-perfect recordings and to compensate for room acoustics. With the tone controls in the cut/center position, there is no influence to the signal. See below graph for tone control range.
Care was taken in this design to keep the circuit as straightforward as possible to avoid manipulating the signal more than is strictly necessary. The result is this outstanding tone control preamplifier.
A lot of time and care was taken in the design of the power supply, as any shortcomings here will show themselves in the resulting tone of this preamplifier. To that end, we chose a solid state power supply, a regulated B+ high voltage and a regulated DC filament supply, one for each channel. This results in an ultra quiet power supply that is extremely stabl, with NO variations despite any variations there may be from your household 120VAC power outlet.
Low-noise toroidal transformer housed in a fully shielded aluminum enslosure contribute to the ultra low noise environment..
A 120V/240VAC 60/50Hz selector switch on the rear panel allows Aretha to be used anywhere in the world.
Only high quality components are used in the construction of Aretha. Low-noise Vishay +/-1% variation metal film resistors are used throughout the signal circuit with high quality Panasonic metal oxide resistors in the power supply circuit. WIMA film and Nichicon electrolytic capacitors are used throughout. Coupling capacitors are Mundorf MCap EVO series for the main preamp, and Solen film capacitors in the phono preamp. Gold pin ceramic tube sockets are used in both preamps.
The printed circuit boards are designed in house , manufactured to FR4-TG standards, and are double-layer with full ground planes on both sides to ensure complete screening of the circuits.
RCA sockets are gold plated and mounted directly onto their dedicated printed circuit board, which also carries the selector switch keeping wiring within the preamp to an absolute minimum. The selector switch is connected via a stainless steel shaft and supported by a miniature ball bearing running through the front panel to the selector knob.
Tubes are factory new - a quad set of matched Tung Sol 6SL7's and Gold pin 6922's.
Main preamplifier gain with tone controls centered - 15dB
Frequency response is 20Hz to 30KHz, +/-0.1dB
1.5V out @ max volume
Tone controls, boost and cut of 15dB
Phono preamplifier gain - 45dB - for MM cartridge only. For MC cartridge, see our SUT (Step Up Transformer)
Phono preamp frequency response is accurate to within +/- 0.1 dB of the RIAA curve from 10Hz to 40 KHz
Chassis size: 14.5"W x 12"D x 8"H