Audio Database

The

Accuphase F-15L
230,000 yen(June, 1987 release)

Description
 
Channel dividers which added the balance input-and-output circuit and have improved over details as part of the formation of balance transmission which the Accuphase was promoting based on F-15.

The input-and-output circuit for balance transmission is carried, the object form signal of negative phase is made from the same voltage for the signal transmission between apparatus, and it transmits by 3 core cable.

The multichannel divider consists of combination of an active filter and buffer amplifier, and seven buffer amplifier has protected the interference before and behind a circuit in F-15L.
Moreover, in F-15L, all the unit amplifier is the amplifier of the identical configuration by the gain 1, and the active filter amplifier which makes the crossover characteristic is 2-5, and has made the expected characteristic with combination with CR element.

Unit amplifier has composition of the complimentary push pull according [ the source follower of low noise high gmFET complimentary and an output ] to a broadband transistor in an input in the push pull circuit.
The feature of this circuit does not have a loop return, the element was selected carefully, it is being able to acquire the characteristic which was excellent with the push pull system and the local feedback system, and the low distortion is secured over a large zone.

With output unit amplifier, in order to prevent generating of direct-current ingredient and to attain stabilization, direct-current servo is given.
The basic structure of a circuit is the same as unit amplifier, with output unit amplifier, servo amplifier is added further and the damping time constant is decided by C and R.
With this cure, all the unit amplifier operates as direct-current amplifier without a coupling condenser, and serves as a design focused on sound quality.

The level control of mid [ a right-and-left independent type low / ] / high is carried in the front panel, it cannot be dependent on power amplifier and the level control of each compass can be intensively performed in respect of the panel of F-15L.
The Attenuator is a precision 1dB step type, and also since it carries the 0.5dB shift switch, control of a 0.5dB step is possible for it by combination.
An adjustable range is 41 points of 0dB--20.5dB and -infinity.

A change of crossover frequency is made by substituting the crossover board only for each frequency.
For the element which has big influence on sound quality, it constituted centering on precision metal tunic resistance and a good silvered mica condenser, and degradation and coloration of sound quality are prevented for it to the minimum.
Since a crossover board changed cost with frequency, it had become option treatment.
Moreover, since it is the same as that of the crossover board F-5 and for F-15, it can divert.

The cutoff attenuation slope can choose two kinds, 12 dB/oct and 18 dB/oct, with a changeover switch.

3D system is supported and the switch for it is carried in the rear panel.

If a crossover board is substituted by an operating state, a speaker may be damaged for a shocking noise.
In F-15L, in order to protect a speaker, just before a board separates from a socket electrode, muting carries out differential, and the protection circuit which intercepts an output is built in.

When using in two ways (by amplifier system), 2 way-ization can be performed by inserting attached 2 way board in inside and a loud-sound board socket.
When using as four ways or five ways, it is possible by adding one more set of F-15L.

The rosewood cabinet for exclusive use was an option.

Rear
Board
Crossover

Rating of a mode
Form Multichannel divider
Profit 0dB
The maximum input (distortion 0.01% or less, 20Hz - 20kHz) Unbalanced:8.0V
Balanced:8.0V
THD 0.003% (20Hz - 20kHz, output 2.0V)
Frequency response 20Hz-20kHz+0 -0.2 dB
0.17Hz-1000kHz+0 -3.0 dB
(Single channel equivalent zone)
Crossover frequency It changes by substitution of a crossover board.
Standard frequency: 21 points
Crossover characteristic - 3.0dB±5d%
Slope characteristic - 12 dB/oct and -18 dB/oct Change type
Input impedance Unbalanced: 20kohm
Balanced: 40kohm
Output load impedance Unbalanced: 100ohms (Low/Mid/High)
Balanced: 50ohms (Low/Mid/High)
Minimum load impedance Unbalanced: 1kohm
Balanced: 600ohms
S/N 100dB (Output 0.5V, A-compensation)
Level adjustment 0dB--20.5dB, a 0.5dB step
The semiconductor used Transistor: 100 pieces
FET: 56 pieces
IC: 22 pieces
Diode: 58 pieces
Power supply voltage AC100V/117V/220V/240V, 50Hz/60Hz
Power consumption 20W
Dimensions Width 445x height 109x depth of 373mm
Weight 9.1kg
Option Exclusive wood cabinet A-12 (\16,000)
Crossover board

Part number Crossover frequency Price
CB-70 70Hz 15,000 yen
CB-100 100Hz 15,000 yen
CB-130 130Hz 15,000 yen
CB-180 180Hz 15,000 yen
CB-250 250Hz 15,000 yen
CB-290 290Hz 15,000 yen
CB-300 300Hz 15,000 yen
CB-350 350Hz 15,000 yen
CB-500 500Hz 13,000 yen
CB-650 650Hz 13,000 yen
CB-800 800Hz 13,000 yen
CB-1000 1kHz 13,000 yen
CB-1200 1.2Hz 11,000 yen
CB-1800 1.8kHz 11,000 yen
CB-2500 2.5kHz 11,000 yen
CB-3500 3.5kHz 11,000 yen
CB-5000 5.0kHz 11,000 yen
CB-7000 7.0kHz 11,000 yen
CB-8000 8.0kHz 11,000 yen
CB-10000 10kHz 11,000 yen
CB-12500 12.5kHz 11,000 yen