AKAI GX-F91

Commentary

This is a cassette deck with Dolby CNR, with advanced original technology in addition to Akai's various basic technologies.

The head part can adopt a 3-head system using AKAI's unique Super GX head.
This head uses a low-noise crystal ferrite core that boasts high magnetic permeability and high saturation magnetic flux density. The head gap is set to 4 μ for recording and 1 μ for playback. This ensures excellent sound quality performance such as frequency characteristics, distortion factor, and dynamic range.
It also shows excellent performance in mechanical secondary characteristics such as no azimuth slippage, wear resistance, and low dust adhesion.

Equipped with Dolby C Type NR as a noise reduction system. The C Type is approximately twice as effective as the B Type in reducing noise in the 1 kHz to 10 kHz band and has a maximum noise reduction effect of 20 dB.
In addition, the C-type employs a sliding band method in which the starting frequencies are shifted according to input levels and frequencies in order to suppress the bleeding phenomenon (absorption of noise). It is also equipped with a spectral skewing circuit that improves high-frequency linearity and an anti-frequency saturation circuit that reduces recording saturation in high-frequency ranges.
The GX-F91 uses a double-process system with dedicated Dolby circuits for encoding and decoding, so that the noise reduction effect of the Dolby B/C can be confirmed during recording monitoring.

The amplifier circuit uses a direct-coupled complimentary service DC-amplifier.
All amplifier blocks except for the Dolby circuit are of a differential 2-stage A class SEPP configuration using dual FET and dual transistor. Moreover, the recording and playback amplifier is directly coupled to the head. In addition, a DC servo circuit is mounted to improve stability by preventing DC drift. When the Dolby is off, the amplifier block is completely independent of the Dolby block.
The power supply for each circuit is independent, the pattern thickness of the printed circuit board is 70 μ s, twice that of conventional ones, and oxygen-free copper wire is used for the shield wire for the head.

A precision mechanism is adopted for the mechanism part to realize accurate tape travel.
First, we use a quartz-locked PLL servo DD motor for the capstan drive motor on the take-up side, which boasts high-precision rotation and high torque. Phase control by crystal oscillation realizes stable tape travel without temperature drift or aging. In addition, we use a closed-loop double-capstan transport mechanism, in which two capstan blocks disturbance components from the reel and provides constant tension to the tape, thereby reducing minute vibration of the tape during travel.
By slightly changing the diameter of the capstan on the take-up side and the supply side, the generation of harmful resonance is suppressed. In addition, each capstan is coated with reverse electric hard chrome plating so that the tape can be securely gripped for many years. In addition, unique tape guides are used on the left and right sides of the head to prevent deflection, uneven crimping, and tape edge curl.

A newly developed quick and quiet mechanism has been adopted, and all mechanism operations are performed quickly and quietly.
This mechanism is a compact system control mechanism in which a dedicated motor controlled by a microcomputer controls the setting of each mode. As a result, the mechanical noise is minimized, the head block is lifted up to the conventional pose position even in the stop state, and the play operation starts in 0.2 seconds. Quick response is also realized.
In addition, the durability of the mechanism is greatly improved.

Uses a direct lead-in & power eject system.
The direct lead-in system automatically starts loading by simply setting the cassette half in the ejected state and pressing the desired operation button. At the same time, it removes slack from the tape and operates quietly and quickly according to instructions.
In the power eject system, the eject mechanism is controlled by a microcomputer, and if you press the eject button even during play, all the mechanisms are automatically assisted and ejected.

A high-torque DC motor is used for the reel drive mechanism.

Equipped with an output volume that can adjust the output level and headphone level independently.

Line input / output terminal with gold plating is adopted.

Equipped with a dedicated tuning microcomputer and an automatic computer tuning system with an efficient program.
The tuning is performed at a set point of 64 steps (one step 3%). First, coarse adjustment is performed by recording and reproducing a 1 kHz signal. Next, the bias is applied in 16 steps at every 4 steps from the shallow side. Coarse adjustment is performed twice and the average is taken. The bias is applied in ± 16 steps at each step from the shallow side to the average value. Fine adjustment recording is performed by applying the bias in ± 16 steps at each step from the shallow side to the average value. This is also performed twice and the average value is taken. The value four steps over the average value is taken as the optimum bias value.
Next, the L/R-independent recording equalizer is adjusted at three frequencies, 5 kHz, 7 kHz and 15 kHz (13 kHz for normal tapes) to flatten the frequency response based on the reference level of 1 kHz.
This process takes approximately 16 seconds, and upon completion, it is rewound and set to recording standby. In addition, once tuned, data can be stored up to four times per tape position, for a total of 12 times. This recording uses non-volatile memory and does not lose data even when the power is turned off.

Equipped with an auto-tuning bias system.
AKAI's original variable bias mechanism has been added to the tape tuning mechanism. By fine-adjusting the bias to change the MOL curve of the tape, sound can be created in accordance with the sound quality (frequency distribution) of the recording source. For a source that wants to gain a mid-range dynamic range, the bias can be set deep to gain mid-range MML. Conversely, if the bias is set shallow, wide-band recording that extends to the ultra-high frequency range can be achieved.
Regardless of how the bias is set, the frequency response is automatically adjusted to be flat by auto tape tuning.

Equipped with a REC cancel mechanism.
Press this button to immediately stop recording, rewind to between songs, record silence for about 4 seconds, and set to recording standby.

Equipped with an intro-scan function.
If you press the FF and PLAY buttons simultaneously, the head of the song is skipped for 10 seconds from the next song to the end of the tape.

Equipped with IPLS (Automatic Heading) function.
When the auto system switch is in IPLS mode and the FF or RWD button is pressed, the head of the next or current track is automatically found and play starts.

It is equipped with a memory autoplay mechanism. If the counter memory mode is set, it will rewind to the' 0000' position and start playing automatically by simply pressing the RWD and PLAY buttons simultaneously.

Equipped with an auto fader function, you can fade in and fade out with one touch operation in recording mode.
In recording standby mode, press the Fade button to automatically fade in to the set recording level in 5 seconds and start recording. Press the Fade button during recording to automatically fade out, record silence for 4 seconds, and set to recording standby mode.

It is equipped with an auto monitor function that monitors the source side during recording standby and switches to the tape monitor side as soon as recording starts. Since the monitor switching is performed instantaneously, you can check the recorded music from your head and prevent recording errors caused by operation of the monitor switch.
The monitor function can also be operated manually.

The auto-mute function is installed. During recording, a four second silent recording is performed with one touch operation, and then the recording standby mode is activated.

Equipped with an auto tape selector, it automatically detects the tape position just by loading the cassette half, and the bias and equalizer are set to the reference value of the aperture.

The FL Bar Meter has 2-color 24-segment display, allowing 3-way display of VU/PeakI/PeakII. In addition, the scale can be switched between VU and Peak for reliable reading.
The VU is convenient for monitoring the level of the entire recording source, the PeakI shows the peak value of the input, but the recovery action is relaxed to make it easier to see the peak fluctuation, and the PeakII has the peak hold with the recovery time earlier than the PeakI, so that the distribution of peak components is easy to understand and severe level check is possible.

Equipped with a dynamic range compensation (D-COMP) mechanism.
This function corrects the meter reading in the high frequency range to match the MOL characteristics of the tape. This makes it easy to set the level without on the meter reading alone.
In addition to the tape position indicator linked with the auto tape selector, an indicator is also provided on the meter to indicate the warning zone of the maximum recording input level.

Equipped with a 4-digit electronic counter, the elapsed time and tape travel amount can be switched and displayed.

The ceiling door is a feather touch type and uses a power drive system that opens and closes by button operation.

Equipped with a timer start mechanism, you can record messages and play an alarm clock.

There are 2 color variations of silver and black.

Remote control (sold separately) enables remote recording, playback, and auto-fade recording.

Model Rating

Type	Stereo cassette deck
Track system	Light motor vehicle set stereo
Wow and flutter	0.025%WRMS(JIS) ± 0.05% Wpeak (EIAJ)
Frequency characteristic	20 Hz ~ 18 kHz ± 3 dB (Normal Tape) 20 Hz ~ 19 kHz ± 3 dB (CrO2 Tape) 20 Hz ~ 21 kHz ± 3 dB (Metal Tape)
Distortion Factor (1 kHz, 0 VU)	0.7% (Metal Tape)
Signal-to-noise ratio (metal tape)	60 dB (3% THD level WTD) 56dB(EIAJ) Dolby B on : 5 dB improvement at 1 kHz, 10 dB improvement at 5 kHz or higher Dolby C on : 15 dB at 500 Hz, 20 dB at 1-10 kHz
Heads	One Super GX recording head 1 Super GX Playhead Erase Head x1
Motor	For Capstan : Quartz Lock PLL Servo DD Motor For Reel : DC Motor
Quick winding time	Approximately 90 Seconds (Using C-60 Tape)
Input level	Line : 70mV/47k Ω
Output level	Line : 410mV/2k Ω or less Headphone : 1.3mW/8 ohm
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	39W
Maximum External Dimensions (EIAJ)	Width 440x Height 100x Depth 363 mm
Weight	Approx. 9.8 kg
Attachment	Connection code x2
Sold Separately	Wired Remote Controller RC-31 (¥ 6,000) Wireless Remote Control RC-91 (¥ 18,000)