Accuphase T-109

Commentary

An FM stereo tuner for music fans who want the best sound quality, aiming for the ultimate grade of tuner.

In tuning for channel selection, the desired station can be tuned with high precision by a crystal oscillator. There is almost no deviation due to time or temperature change, and it is locked at the point of minimum distortion and maximum sensitivity.
In addition, since it is electronically tuned, no modulation distortion or noise due to external vibration occurs.

The front-end uses a double-tuned antenna circuit that passes through a selection circuit before being amplified by the antenna circuit to prevent cross modulation caused by direct amplification at the time of Tsutomu Dainyu.
For high-frequency amplification, we use an FET with a cascode amplifier (a circuit with improved frequency characteristics by connecting two amplifiers in cascade) with less feedback. The input gate is equipped with an attenuator using a PIN diode. The attenuator is turned on and off by a microcomputer depending on the antenna input level to cope with excessive input in the area close to the transmitting tower.
The mixer employs a balanced mixer circuit using a push-pull FET to suppress harmonic distortion and eliminate interference signals.

Based on the DGL (Fifferential Gain Linear) circuit with high performance, high reliability and no adjustment, we have newly installed an advanced DGL detection circuit with a significant improvement. At the input of this circuit, a 2.4 MHz wide-band amplifier and a high-speed comparator are used to eliminate beat interference, and 24 high-speed C-MOS ICs are used for the delay circuit to increase stability.
The operation principle is that the delay circuit focuses on the delay time of the output of the high-speed logic IC and is composed of 24 ICs delaying the phase angle by 114 degrees so as to maximize the distortion minimum and SN ratio. This delay signal and the input signal are added to an exclusive OR circuit, and the potential between the two signals is selected to open and close the circuit. At this time, the compression wave generated by the modulation is digitally detected and the audio signal is extracted.
In this system, the linear region of the delay circuit is as wide as ± 2.4 MHz, and moreover, since there is no adjustment, stable and excellent linear differential gain characteristics can be obtained.

The IF stage adopts two stage switching of Normal and Narrow.
By switching to NARROW when there is intense interference with adjacent broadcasting stations, it is possible to receive sharp signals with an emphasis on selectivity.

In the stereo demodulation section, the internal oscillation circuit is locked (fixed) by the PLL circuit to obtain an accurate 38 kHz switching signal.
The T-109 combines the internal oscillation circuit of the PLL with a ceramic resonator and a variable positive and negative reactance circuit that can be controlled by the control voltage, so that accurate switching signals can be obtained in a narrower lock frequency range than before.
This circuit has features such as non-adjustment of the stereo demodulation circuit and securing long-term stability, almost no change in the degree of separation due to temperature change and fluctuation of line voltage, etc., and little beat interference at high frequencies because the lock frequency range is narrow.

It is equipped with 16 station memory, and if it is stored in advance, it can be called up instantly by button.
In addition, functions such as Selectivity, Meter, Filter, Muting, and Mono can be stored in memory according to radio wave conditions.
Accuphase's original microcomputer is used for these functions, and the clock frequency is divided from the PLL frequency of the electronic tuning circuit by the bowl clock method to suppress beat interference.

In addition to memory tuning, a manual tuner using a rotary knob of pulse tuning type is mounted.
A disk with radial slits attached to the shaft of a rotary knob generates a pulse by passing through a phase detector (non-contact by light), and this pulse is input to a microcomputer to control the PLL tuning frequency.
When you turn the knob, a beep sounds to indicate a change in frequency.

A balance circuit is mounted on the audio output to eliminate noise components from signal cables and ground lines, enabling noise-free high-quality transmission.

The meter can be used to check the antenna input signal level and multipath with a changeover switch.
Multipath is peculiar to FM broadcasting and is a distortion caused by multiple reflected waves (ghost). Since this can be prevented by the orientation of the antenna, the meter selects the broadcasting station to minimize multipath and adjusts the antenna orientation.
The antenna input signal can the antenna input signal can be checked by the deflection of the meter. The larger the deflection of the needle, the better the SN ratio.

Included functions include a noise filter to reduce weak stereo station noise, a muting switch to remove inter-station noise, a mono switch to force monaural, and output level control.

The included remote commander allows you to control the channel selection and various functions.

Model Rating

Type	FM stereo tuner
MonAural Characteristics
Receiving frequency	76.0 mhz to 90.0 mhz
Practical sensitivity	11dBf(IHF)
S/N 50 dB sensitivity	17dBf(IHF)
Standing-wave ratio	1.5
S/N (80 dBf input, A-correction)	90dB
Total harmonic distortion factor (80 dBf input ± 75 kHz shift, Normal)	20Hz:0.02% 1kHz:0.02% 10kHz:0.02%
IM distortion factor	0.01% (80 dBf input, ± 75 kHz shift)
Frequency characteristic	10 Hz ~ 16000 Hz + 0 -1.0 dB
Two signal selectivity (IHF)	Disturbance wave Normal Narrow 400kHz 70dB 100 dB or more 300kHz 30dB 100dB 200kHz 10dB 40dB
Capture ratio	1.5dB
RF intermodulation	80dB
Spurious interference ratio	120dB
Image ratio	100dB
AM suppression ratio (65 dBf input)	80dB
Subcarrier suppression ratio	70dB
SCA interference ratio	80dB
Output voltage (± 75 kHz deviation)	1.0V
Stereo Characteristics
Sensitivity	S/N 40 dB sensitivity : 29 dBf (IHF) S/N 50 dB sensitivity : 37 dBf (IHF)
S/N (80 dBf input, A-correction)	85dB
Total harmonic distortion factor (80 dBf input ± 75 kHz shift, Normal)	20Hz:0.04% 1kHz:0.04% 10kHz:0.04%
IM distortion factor	0.03% (80 dBf input, ± 75 kHz shift)
Frequency characteristic	10 Hz ~ 16000 Hz + 0 -1.0 dB
Stereo separation factor	100Hz:50dB 1kHz:50dB 10kHz:40dB
Stereo switching input voltage	20dBf
<General>
Antenna	75 Ω unbalance
Tuning system	Quartz synthesizer system 16-station random memory tuning
Detection system	Advanced DGL system
Output impedance	Balanced (Balanced XLR type) : 200 Ω (100 Ω / 100 Ω) Unbalanced Fixed output : 200 Ω Controlled (variable output) : 1.25k Ω (maximum)
Meter	Signal strength, multi-path switching
Power supply voltage	100 VAC, 50Hz/60Hz
Power consumption	15W
Maximum external dimensions	Width 475x Height 140x Depth 402 mm
Weight	9.5kg
Attachment : Remote Commander RC-12
Remote control system	Infrared pulse system
Pwer	DC3V
Dry battery	Use 2 pieces of SUM-3 type (IEC name R6)
Maximum external dimensions	64 mm wide x 149 mm high x 18 mm deep
Weight	145g (including battery)