Accuphase F-25 (1994–1998)
Four-way active crossover with modular design, switchable slopes, and precision level controls
Overview
The Accuphase F-25 is a transistorized electronic frequency dividing network for high-end active speaker systems. Accuphase Laboratory, Inc. (originally Kensonic Laboratory, Inc.) made it. With optional amplifier and filter units it runs two to four ways. The basic setup is one filter amplifier and two line amplifiers, and you expand it by adding DN-25 and LA-25 series units. Input and output are fully balanced. Each band gets a phase switch, left and right levels are independent, and the rear panel has a subwoofer mix selector.
Specifications
| Maximum Input Level | Balanced: 7.0V, Unbalanced: 7.0V (20 Hz–20 kHz, ≤0.01% THD) |
| Total Harmonic Distortion | 0.003% (20 Hz–20 kHz, 2.0 V output) |
| Frequency Response | 20 Hz–20 kHz +0 to -0.2 dB; 0.5 Hz–300 kHz +0 to -3.0 dB |
| Gain | 0 dB |
| Crossover Slope | –12 dB/oct, –18 dB/oct, –24 dB/oct (switchable) |
| Input Impedance | Balanced: 40 kΩ, Unbalanced: 20 kΩ |
| Output Impedance | Balanced: 50 Ω, Unbalanced: 50 Ω |
| Minimum Load Impedance | 600 Ω (Balanced and Unbalanced) |
| S/N Ratio | 100 dB (0.5 V output, IHF-A weighted) |
| Attenuator | 0 dB / 10 dB (via ATT switch on line amplifier) |
| Level Adjustment | 0 to –20 dB (1 dB steps), –∞ |
| Crossover Frequencies | 21 points: 70, 100, 130, 180, 250, 290, 300, 350, 500, 650, 800, 1,000, 1,200, 1,800, 2,500, 3,500, 5,000, 7,000, 8,000, 10,000, 12,500 Hz (via optional boards) |
| Power Supply | 100 VAC, 50/60 Hz |
| Power Consumption | 32 W |
| Dimensions | approximately 475 mm (W) × 170 mm (H) × 394 mm (D) |
| Weight | 15.4 kg |
Design
The F-25 uses a GIC (Generalized Immittance Converter) filter circuit with a Gaussian curve design, chosen for phase and impulse response. An s-Gretta current feedback amplifier keeps the high frequencies stable. Crossover characteristics are set by interchangeable frequency boards. Construction is modular. The F-25V has detachable filter and line amplifier units (DN-25V and LA-25V), but the input board is soldered directly to the XLR terminals - a design noted as difficult to service. The LA-25 and DN-25 units are compatible across F-25 and F-25V models.
Context
The F-25VM came out in February 2001. It is a dedicated variant for bi-amping the JBL M9500 and Project K2S 9500/S 7500 speakers, with fixed 18 dB/oct slopes and the DN-25VM amplifier with FB-25M frequency board. The F-20 is a two-way version of the F-25, so three- or four-way operation means stacking. The F-15L is a three-way alternative with less flexibility, offering only 12 and 18 dB/oct slopes.
Market
The F-25V originally sold for ¥390,000 and the F-25VM for ¥440,000. Optional LA-25V and DN-25V units were ¥60,000 each, and frequency boards were ¥15,000. As of 2026, used units list for $3,500 on US Audio Mart and ¥178,000 on Audio Union. Frequency modules are hard to find, and some sell for over $500. Third parties now make custom boards. One known issue is persistent crackling in one channel, traced to FETs, op-amps, or capacitors. Repairs call for replacing the electrolytics and op-amps. Units have been sold with manuals and rate 8/10 in cosmetic condition.
Market Value
┌──────────────────────────────────────────────────────────────────────────┐ │ ACCUPHASE F-25 Aug 2026 │ ├──────────────────────────────────────────────────────────────────────────┤ │ High $1,995 Latest $390 │ │ Median $104 Trend — │ │ Low $24 Volume ~3/mo │ ├──────────────────────────────────────────────────────────────────────────┤ │ $2,000 ┤ │ │ │ . │ │ │ │ │ $1,143 ┤ │ │ │ │ │ │ │ │ │ . . .│ │ $0 ┤. . . . . .. . . │ │ ├─────────────────────────────────────────────────────────────────│ │ vol │▄ ▄ ▄ ▄ ▄ ▄▄ ▄█ ▄ ▄ ▄ ▄│ │ └─────────────────────────────────────────────────────────────────│ │ 2026-02 2026-04 2026-07│ └──────────────────────────────────────────────────────────────────────────┘
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