This tuner also featured automatic wide/narrow IF bandwidth slection. The F-26 was design with a large power supply and two 6000 microfarad power supply capacitors, a muting level control on the rear panel, adjustable stereo/mono signal switchover, adjustable muting control, and gold plated terminals.
The A-27 Integrated Amplifier was the most expensive component in the Series 20 line. Pioneer clearly intended to incorporate much of the circuit design from the M-type amplifiers, but have a greater degree of control than the C-21 pre-amp. It used the "Magni-Wide" DC power amplifier section, but also used a total of three other all-DC-configured amplifier stages: a DC phono equalizer amp, a DC flat amp and DC "head amp" for Moving Coil (MC) type phono cartridges. Like the M-25, the A-27 used RETs in the output stage. It also used automatic Class AB switching, operating in Class A mode until the sudden audio peaks automatically switched to Class B.
The A-27 was rated at 120 watts per channel into 8 ohms, from 5 hz to 30 kHz with no more than 0.012% total harmonic distortion. Between 20 Hz and 20 kHz, toal harmonic distortion was a mere 0.008%--virtually non-existant distortion! Intermodulation distortion was only 0.006%. The A-27 entire frequency response ranged from 5 Hz to 200 kHz.
The other tuner in the Series 20 line was the F-28. It differed in appearance and price (lower) from the F-26, but was still a superb performer. It employed Pioneer's Photo Logic Synthesizer/Quartz Locked system and "Clean Pilot" circuitry. It also used the Parallel Balanced Linear Detector and featured selectable Wide/Narrow IF Bandwidth. The circuitry used a 5-gang variable capacitor for higher tuning accuracy to improve image response, spurious response and IF response ratios, all having 120 dB or better.Its signal to noise ratio in mono was 84 dB and in stereo 81 dB.The F-28 employed 10 FETs, 21 ICs, 63 transistors and 56 Diodes. It measured 16.56 inches wide, 6.12 inches high and 14.21 inches deep. It weighed 19 pounds, 13 ounces and had an M.S. R. P. of $690.00.