Pioneer RT 901

The Pioneer RT‑901 is a 10.5‑inch, 2‑speed, 3‑motor, 3‑head stereo reel‑to‑reel deck using a closed‑loop dual‑capstan transport, aimed at high‑end home use and sharing its basic platform with the auto‑reverse RT‑909.

Transport, format, and mechanics

• Tape format: ¼‑inch, 4‑track, 2‑channel stereo (standard consumer quarter‑track stereo record/play).​

• Heads: 3 total – erase, record, and playback (forward direction only), allowing proper off‑tape monitoring during recording.

• Motors: 3 – one FG‑servo DC dual‑capstan drive motor plus two 6‑pole induction reel motors, giving a true closed‑loop transport with independent reel tension control.

• Tape speeds: 3¾ and 7½ ips (9.5 and 19 cm/s), NAB equalization at both speeds.​

• Max reel size: 10.5‑inch NAB reels; rack‑mountable front panel, essentially the non‑auto‑reverse counterpart to the RT‑909.

• Rewind speed: about 120 seconds for a full 10.5‑inch, 720 m reel.​

Audio performance

• Frequency response:
  7½ ips: 20 Hz–28 kHz (±3 dB).
  3¾ ips: 20 Hz–18 kHz (±3 dB).​

• Wow and flutter: 0.04% at 7½ ips, 0.08% at 3¾ ips, reflecting the dual‑capstan servo drive’s stability.

• Signal‑to‑noise ratio: 60 dB at 7½ ips, 55 dB at 3¾ ips (no noise reduction).

• Distortion: ≤ 1% at 7½ ips.

• Stereo separation / crosstalk: better than 50 dB.

• Bias/erase: 125 kHz bias; erase ratio > 60 dB.

Heads, electronics, and I/O

• Head composition: permalloy stereo heads (erase and record/play), optimised for longevity and HF performance.​

• Electronics: fully solid‑state, with NAB EQ; roughly 4 FETs, 43 ICs, 121 transistors, 125 diodes, and 2 photo‑interrupters used in logic/transport control.

• Inputs (per channel):
  Mic: 0.316 mV nominal, 80 mV max, 27 kΩ, via 6 mm jacks.
  Line: 50 mV nominal, 25 V max, 50 kΩ, via RCA.

• Outputs:
  Line: 450 mV nominal, 900 mV max, 2.6 kΩ (RCA).
  Headphones: 50–100 mV into 8–250 Ω.

Physical data and production

• Dimensions (W×H×D): about 19 × 13½ × 12½ inches (≈ 480 × 340 × 318 mm).

• Weight: ~47 lb (≈ 21.5 kg).

• Supply voltages: switchable 110–120 V / 220–240 V AC, solidly in the “super high fidelity” consumer category.​

• Production: circa 1979–1984 in Japan; the RT‑901 is the single‑direction, simpler, slightly less complex logic sibling to the RT‑909, sharing most transport architecture but omitting auto‑reverse and the extra playback head.

In practical audiophile terms

The RT‑901 combines a 10.5‑inch, closed‑loop dual‑capstan, three‑motor transport with true 3‑head monitoring, low wow & flutter, and strong S/N, making it a very capable high‑end home deck and a solid light‑studio machine for 7½ ips work. Its lack of auto‑reverse simplifies the tape path and logic versus the RT‑909, which many enthusiasts regard as an advantage for reliability while preserving essentially the same sonic potential.