Accuphase F-15L
¥ 230,000 (released in June 1987)
Commentary
As part of the introduction of balanced transmission promoted by Acuphase, the channel divider has been improved in detail by adding balanced input / output circuits based on F-15.
It is equipped with an input / output circuit for balanced transmission. For signal transmission between devices, opposite phase target signals at the same voltage are generated and transmitted by a 3-core cable.
The multi-channel divider consists of an active filter and a buffer amplifier. The F-15L uses seven buffer amplifiers to prevent interference between the front and back of the circuit.
In the F-15L, all unit amplifiers have the same configuration with a gain of 1. The number of active filter amplifiers that produce crossover characteristics is 2 to 5. When combined with a CR element, the desired characteristics are produced.
The unit amplifier is a push-pull circuit. The input is a source follower of low noise and high gmFET complimentary service, and the complimentary service is push-pull by a wide-band transistor.
The characteristics of this circuit are that there is no loop feedback, elements are selected carefully, and excellent characteristics can be obtained by push-pull method and local feedback method, so that low distortion rate is ensured over a wide band.
In the output unit amplifier, DC servo is applied to prevent the generation of DC component and to stabilize it.
The basic structure of the circuit is the same as that of the unit amplifier. The output unit amplifier has an additional servo amplifier and its time constant is determined by C and R.
As a result of this measure, all unit amplifiers operate as DC amplifiers without coupling capacitors, and are designed with an emphasis on sound quality.
The front panel is equipped with independent left / right low / mid / high level control. The level control of each sound range is not dependent on the power amplifier and can be concentrated on the panel surface of the F-15L.
The attenuator is a precision 1-dB step type and additionally has a 0.5 dB shift switch, enabling 0.5 dB step control by combination.
The adjustment range is 0 dB to -20.5 dB and 41 points of - ∞.
You can change the crossover frequency by changing the crossover board for each frequency.
Elements that have a significant impact on sound quality are composed mainly of precision metal film resistors and high-quality silbird mica capacitors to minimize deterioration and coloring of sound quality.
The crossover board was sold separately because the cost varies depending on the frequency.
In addition, since it is the same as the crossover board for F-5 and F-15, it can be reused.
Two types of cutoff attenuation slope, 12dB/oct. and 18dB/oct. can be selected with the selector switch.
It is compatible with the 3D method and a switch for this is mounted on the rear panel.
If the crossover board is replaced under operating conditions, the speaker may be damaged due to shock noise.
To protect the speakers, the F-15L has a built-in protection circuit that cuts off the output by muting just before the board is released from the socket electrode.
When using the 2-way (bi-amp-type), you can make it 2-way by inserting the included 2-way board into the socket of the medium / high sound board.
When using it as 4-way or 5-way, it is possible to add another F-15L.
A special rosewood cabinet was sold separately.
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Model Rating
| Type | Multi-channel divider | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Gain | 0dB | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Maximum Input (Distortion Factor 0.01% or Less, 20 Hz to 20 kHz) | Unbalanced:8.0V Balanced:8.0V |
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| Total harmonic distortion factor | 0.003% (20 Hz ~ 20 kHz, Output 2.0 V) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Frequency characteristic | 20 Hz ~ 20 kHz + 0 -0.2 dB 0.17 Hz to 1000 kHz + 0 -3.0 dB Single Channel Equivalent Bandwidth |
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| Crossover frequency | Change by replacement of crossover board Standard frequency : 21 points |
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| Crossover characteristic | -3.0 dB + / - 5% | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Slope characteristic | -12dB/oct, -18dB/oct switching type | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Input impedance | Unbalanced : 20k Ω Balanced : 40k Ω |
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| Output impedance | Unbalanced : 100 Ω (both Low/Mid/High) Balanced : 50 Ω (both Low/Mid/High) |
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| Minimum load impedance | Unbalanced : 1k Ω Balanced : 600 Ω |
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| S/N | 100 dB (output 0.5 V, A-corrected) | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Level adjustment | 0 dB ~ -20.5 dB, 0.5 dB step | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Semiconductor used | Transistor : 100 units FET : 56 IC : 22 Diode : 58 pcs |
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| Power supply voltage | AC100V/117V/220V/240V, 50Hz/60Hz | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Power consumption | 20W | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| External dimensions | Width 445x Height 109x Depth 373 mm | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Weight | 9.1kg | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Sold Separately | Dedicated Wood Cabinet A-12 (¥ 16,000) Crossover board
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