VINTAGE > Tuners > Accuphase T-1000

Accuphase T-1000

Beschrijving / Description

A top-of-the-line FM stereo tuner developed by combining advanced high-frequency technology with the latest digital technology.

The front-end section uses a double-tuned antenna circuit to prevent cross-modulation at high input power. For high-frequency amplification, a cascode FET with less feedback is used. An attenuator circuit is also installed at the input gate to cope with excess large input power in areas near the transmitting tower.

The local oscillator is equipped with DDS (Direct Digital Synthesis).
In this DDS, the output of a crystal oscillator is first divided by a frequency divider to create a sampling frequency, which is the timing for reading out sine wave data. Sine wave data is then read out at this sampling frequency, and sine wave analog waveform is generated by a D/A converter.
Since it does not use a feedback system like a PLL circuit, it can generate an output signal with exactly the same frequency purity as a crystal oscillator. It does not inject unnecessary frequency modulation components into the IF stage, and realizes a front end with an excellent SN ratio.

The detection section is equipped with an advanced DGL (Differential Gain Linear) detection circuit unique to AccuPhase.
The input section uses a 2.5 MHz wide-band amplifier and a high-speed comparator to eliminate beat interference, and the delay circuit uses 24 high-speed C-MOS IC to increase stability.
The operation of this circuit is focused on the delay time of the output of the high-speed logic IC. The delay circuit is configured by delaying the phase angle by 114 degrees so that the distortion is minimized and the SN ratio is maximized by 24 ICs. This delay signal and the input signal are added to the exclusive OR circuit. The potential between the two signals is selected to open and close the circuit. At this time, the amplitude and density wave generated by the modulation is digitally detected and the music signal is extracted.
In this system, the linear region of the delay circuit is as wide as 2.5 MHz, and moreover, since there is no adjustment, stable and excellent linear differential gain characteristics can be obtained.

The stereo demodulation section uses ACCUPHASE's unique DSDC (Direct Synthesis-Double Cancellation) stereo demodulation circuit.
DS-DC consists of two technologies : direct synthesis of pilot signal and double cancellation of crosstalk.
In general tuners, a PLL circuit is used to extract the pilot signal and extract the frequency and phase components from the input signal. Therefore, if the pilot signal becomes small at the time of extraction, noise affects the separation. In DS-DC, the waveform of the pilot signal included in the input signal is identified as it is, and it is directly produced by the DSP operation, so it is resistant to noise and can ensure separation even if the pilot signal level is small.
In addition, after separating the input signal into left and right signals, the phase component is taken into consideration and the crosstalk is canceled twice, so that the left and right separation can be further improved.
All of these functions are performed by software operations on a digital signal processor (DSP), enabling excellent stereo demodulation.

Equipped with the FREQ. TRIM function, which is effective when interference occurs.
By switching this function to ON, it is possible to change the step of the receiving frequencies (at 10 Hz intervals) while maintaining the bandwidth for the center of the filter. Therefore, when Radio noises with adjacent broadcasting stations is intense, it is possible to receive signals with less interference by avoiding interference.
Turning the FREQ. TRIM button ON changes the reception frequency display from three digits to four digits.

It uses 16 station memories that can store and call up all function settings simultaneously.
The acPHASE's unique pulse tuning method allows manual tuning.

There are two analog outputs, balanced and unbalanced.
It also has a digital coaxial output terminal.

It is equipped with functions such as a Filter switch to reduce the noise of a stereo station with weak radio waves, a Mute off switch to turn off the muting circuit, and a Mono switch to forcibly make the output of the stereo broadcast transmission monaural.

When the tuning knob is turned or all function buttons are operated, an electronic beep is added.

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Specificaties / Specifications

Type FM stereo tuner
MonAural Characteristics
Practical sensitivity 11dBf(IHF)
S/N 50 dB sensitivity 17dBf(IHF)
S/N (80 dBf input, A-correction) 90dB
Total harmonic distortion factor
(80 dBf input, +/- 75 kHz shift) 20Hz:0.02%
IM Distortion Factor (80 dBf input, +/- 75 kHz shift) 0.01%
Frequency characteristic 10 Hz - 15000 Hz + 0 -2.0 dB
Two signal selectivity (IHF) 400kHz:70dB
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
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) 20Hz:0.04%
IM Distortion Factor (80 dBf input, +/- 75 kHz shift) 0.03%
Frequency characteristic 10 Hz - 15000 Hz + 0 -2.0 dB
Stereo separation factor 100Hz:50dB
Stereo switching input sensitivity 28dBf
Antenna 75 ohm unbalanced (F-type connector)
Standing-wave ratio 1.5
Tuning system DDS synthesizer system
16-station random memory tuning
Detection system Advanced DGL system
Stereo demodulation system DS-DC system
Digital Output (EIAJ CP-1201) Coaxial : 0.5Vp-p/75 ohm
Sampling frequency : 48 kHz
Output impedance Balanced : 200 ohm (100 ohm / 100 ohm, balanced XLR type)
Unbalanced : 200 ohms (unbalanced)
Meter Signal strength
Power supply voltage 100 VAC, 50Hz/60Hz
Power consumption 17W
Maximum external dimensions Width 465x Height 140x Depth 402 mm
Weight 11.8kg
Attachment Remote Commander RC-33

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