Denon DH-710F

The Denon DH-710F (also sometimes grouped with DH-710 series variants like DH-710S) is a late 1970s flagship high-performance stereo reel-to-reel tape deck, introduced in 1976 and produced through the early 1980s (manufactured in Japan by Nippon Columbia/Denon). It was a professional-grade open-reel machine developed for audiophiles and semi-pro users, often described as a "full-fledged high-performance deck" with broadcast-level engineering. The DH-710F is particularly celebrated for its two-capstan direct-drive system, three-motor configuration, Sendust alloy heads, and exceptional tape handling—praised by audio legends like Tim de Paravicini as one of his favorite "road/travel" machines for its reliability and sound quality.

This was a 2-track (half-track) stereo recorder with quarter-track playback capability in many units (versatile for both professional and consumer tapes), featuring a separate drive mechanism and electronics unit in some configurations (two-box design: transport deck + amplifier/preamp unit). It prioritized studio-grade performance, low wow/flutter, wide bandwidth, and gentle tape handling over consumer gimmicks like auto-reverse.

Key Technical Specifications

• Recording/Playback System — 2-track (half-track) stereo recording and playback; 4-track (quarter-track) playback compatibility (in some configs); 2-channel stereo/mono compatible; sound-on-sound/multiplay overdub facilities; no auto-reverse.

• Tape Speeds — Two professional speeds:7½ ips (19 cm/s)
  15 ips (38 cm/s)
  

• Reel Size — Up to 10.5 inches (Type 26/No. 10 NAB hubs; professional large reels for extended playtime).

• Frequency Response (approximate, within ±2 dB tolerances; varies by tape/condition):At 38 cm/s (15 ips): 30 Hz – 30,000 Hz
  At 19 cm/s (7½ ips): 20 Hz – 20,000 Hz Outstanding extension for the era—hi-fi capable with excellent high-frequency performance.
  

• Wow & Flutter — <0.02% WRMS at 15 ips; ~0.03–0.05% at 7½ ips (ultra-low thanks to three-motor direct-drive, two-capstan transport, and electronic AC servo tension control).

• Signal-to-Noise Ratio — >66 dB at maximum recording level (514 pWb/mm); >58 dB at standard level (200 pWb/mm) (very high for transistor design with low-noise tape).

• Total Harmonic Distortion — <0.5% at 1 kHz (with Scotch 206 tape or similar; low saturation in recording amp).

• Heads — 3 heads (some listings note 4-head configs with additional quarter-track playback): separate record, playback, and erase (newly-developed Sendust alloy heads by Denon; 2.1 mm track width for excellent S/N; ferrite erase in some).

• Drive System — Three motors (1 × 6-pole outer-rotor AC servo capstan motor + 2 × 6-pole AC servo reel motors); two-capstan direct-drive system (main capstan + sub-capstan blocks external vibrations for stable tape-to-head contact); electronic AC servo tension control (eliminates start-up load fluctuations; one-way air damper prevents excessive tension); fast wind/rewind (~2 minutes for No. 10 reel with 740 m tape); precise dynamic braking.

• Electronics — Fully transistorized; printed circuit board amplifier; NAB equalization; maximum recording amp output >+30 dB @ 1 kHz (to match professional gear; low saturation distortion).

• Inputs —Microphone (low-level).
  Line/radio/phono (standard line level).
  DIN-style connectors (some pro/export versions with XLR I/O).
  

• Outputs —Line out (~1 V).
  Headphones (monitor).
  External amp/speakers.
  DIN-style.
  

• Features —Twin illuminated VU meters (needle type; active for record/playback).
  Electronic logic transport (smooth push-button).
  Off-tape monitoring (source/tape switch).
  Input mixing.
  Pause function.
  Remote control terminal (optional DIN).
  Vertical/horizontal operation; massive chassis.
  

• Power — AC mains (100 V Japan standard; multi-voltage variants); consumption 130 W.

• Build & Dimensions — Massive two-piece tabletop case (deck + electronics unit; often wood/teak or metal finish):Deck: 505 × 420 × 310 mm
  Electronics unit: 490 × 180 × 330 mm
  Weight: ~27 kg (deck) + ~8.5 kg (electronics) — very heavy and robust.
  

• Manufacturing — Japan (Denon/Nippon Columbia).

Performance & Legacy Context

The DH-710F was a "marvellous" machine in tape handling—thanks to its three-motor direct-drive, two-capstan system, and electronic AC servo tension (smooth start-up, minimal fluctuations, gentle on tapes). It delivered ultra-low wow/flutter (<0.02% WRMS at 15 ips), high S/N (>66 dB max), wide frequency response (30 Hz–30 kHz at 15 ips), and low distortion—often described as "studio-grade" for home use. The Sendust heads and generous recording amp headroom ensured clean, professional results, with the ability to play both ½-track and ¼-track tapes in some configs (like Technics RS-1500 or Otari MX-5050). Tim de Paravicini favored it as his road/travel machine for its reliability and sound.

Common issues today: Belt/idler degradation (goo/melting—kits needed), dried electrolytic capacitors, transistor aging, dirty heads (3-head alignment critical), worn idler tires/clutches, and occasional servo/tension faults. Restorations are rewarding—many units achieve superb performance post-service. Service/user manuals available (HiFi Engine, Audio Database—schematics, alignment).

Compared to siblings:

• DH-610S — Similar flagship (often considered close or variant; some prefer DH-710F for refinements).

• DH-510 — Related but sometimes seen as slightly less advanced.

• DH-710F — Balanced high-end with pro specs (15 ips, NAB 10.5" focus, two-capstan).