Accuphase T-100 (1973 - 1982)

A superior tuner can significantly enrich audio life today for there is an abundance of broadcast reproduction matter which provides great opportunities to expand one's tape library through careful air checking. The ideal tuner should come close to connecting the broadcast studio to the amplifier and eliminate the medium of radio waves. Thus, it should be able to cut the noise, interference and distortion that is picked up with the radio waves during its transmission, to a level which cannot be detected by the ear.This is where the main emphasis was placed indesigning the Accuphase T-100 Tuner. In addition, special attention was paid to performance stability against external variables such as incoming signals levels, changes of temperature, humidity and time, as well as on smooth-working tuning and switching mechanism. In short, the most advanced electronic and mechanical techniques were called upon to develop this outstanding tuner.Two basic functions are required of tuners: the ability to catch and select radio waves as in the case of a receiver's front end, and to amplify and demodulate them, without causing distortion as is so important in audio equipment. The difficulty is that the characteristics of the two requirements are so mutually opposed, that of te one tends to suffer when the other is improved. It is a fact that to solve this problem requires the highest technology and considerable expense.In developing the Accuphase T-100 tuner, we have met this challenge by developing latest radio frequency techniques and by adding required new circitry unsparingly. The result is something we are proud of introducting, and we are sure that you will come to have a special attachment for this tuner too.

ADVANCED DESIGN FM FRONT-END
FM signals picked up by the antenna tuned and amplified by the RF amplifier, then mixed with the local oscillator signal in the converter circuit to from a 10,7 MHz intermediate frequency (IF) signal. This ciruitry constitutes what is known as the front-end, which plays a vital role in determining a tuner's value. This section must be able to amplify weak signals well, handle strong signals without distorting, and have the capability to remove completely all radio frequency noise and interference.The T-100 meets these requirements well by utilizing a linear frequency, 5-gang tuning capacitor, double tuned RF amplifier stages, complete intercircuit shielding, local oscillator buffer circuit, and dual gate FET's in all RF and converter circuits, etc. This is attested by performance ratings for spurious signal rejection of better than 100dB. Image rejection is also better than 90 dB. The T-100 also has a 245mm wide, slide-rule type dial which has linear frequency indications at 250 kHz intervals that is combined with precision tunning mechanism to ensuree smooth, accurate tuning.
15-STAGE LINEAR PHASE FILTER IN FMIF CIRCUIT
The 10,7 MHz IF signal from the front-end enters the IF amplifier circuit where it is amplified and fed to teh detector while adjacent frequency signals are rejected. This rejection(IF sensitivity) is normally the function of transformers or mechanical filters in conventional tuners. The T-100 however employs a newly developed 15 stage LinearPhase Filter combined with an integrated circuit to obtain better rejectionand, at the same time,less distortion. Thus, selectivity was made compatible with sound quality, as attested to by the performance ratings for distortion of less than 0,1% and effective selectivity of more than 70 dB, which significantly surpass the limitations of past tuners.
WIDEBAND FM DETECTOR
In order to demodulate the linear phase amplified IF signal without distortion into an audio signal, the former isfed to a special detector circuit which employs a 1,200 kHz wide discriminator which has three times the width of those normally used. This has contributrd to significant improvement in stereo characteristics.

PHASE LOCKED LOOP STEREO DEMODULATOR

We have avoided all use of coil and capacitor tuned circuits in the stereo dempdulator which separates the audio signal into left and right channel stereo signals. Instead we have used the most advanced phase Locked Loop Stereo Demodulator which automatically locks the phase of the subcarrier generator with that of the incoming pilot signal. This accounts for theexcellent ratings for stereo separation of better than 45 dB (1kHz), and distortion of less than 0,2% on stereo. It also ensures long life and dependable performance.

INDEPENDENT MULTIPATH METER

In addition to teh Signal and Tuning meters, an independent Multipath meter is provided inside the front sub-panel. Multipath signals, like TV ghost signals, cause distortion which harm FM stereo sound quality. To avoid them the FM antenna should be oriented for minimum deflection of the Multipath meter.LOW DISTORTION AM TUNERGood quality broadcasts are also available on AM,although frequency response is narrower, AM has usually been treated as an accessory by most high fidelity manufacturers, and has received very little new design considerations. However as a result of a new type detector circuit, optimum bandwidth reserch and use of expensive MOS and J type FET in the front-end and IF stages, we can offer low distortion noise-free AM msic performance with the T-100.

OTHER FEATURES

The front sub-panel contains a 2-step muting switch, a stereo noise filter control, independent AM an FM level controls, and dial light control. The Multipath meter lamp light automatically when the sub-panel cover is opened.

GUARANTY SPECIFICATIONS
PERFORMANCE GUARANTY:Products of Accuphase guarantee specifications stated;

FM Monophonic Performance:

SENSITIVITY:

2,0 µV, least usable sensitivity; 2,0 µV for 40 dB of quieting; 4,5 µV for 50 dB of quieting

ULTIMATE S/N:

75 dB at 200 µV input

ULTIMATE THD (at 50 µV input, 100% modulation):

100 Hz : will not exceed 0,1%

1,000 Hz : will not exceed 0,1%

10,000 Hz : will not exceed 0,1%

INTERMODULATION DISTORTION:

will not exceed 0,2% (antenna input 1 mV, 100% Mod. 70 Hz: 7 kHz =4 :1)

AUDIO FREQUENCY RESPONSE:

+0, -1 dB 20 Hz to 15,000 Hz

SELECTIVITY: alternate channel: 70 Db

CAPTURE RATIO: 1,5 dB

IMAGE REJECTION: 90 dB (at 100 MHz)

IF REJECTION: 100 dB

SPURIOUS REJECTION: 100 dB

AM REJECTION: 60 dB at 1 mV input

OUTPUT: 2,0 Volts

FM Stereo Performance:

SENSITIVITY:

20 µV for 40 dB of quieting45 µV for 50 dB quieting

ULTIMATE S/N:

70 dB at 2mV input

ULTIMATE THD (at 500 µV input, 100% modulation):

100 Hz: will not exceed 0,2%

1,000 Hz: will not exceed 0,2%

10,000 Hz: will not exceed 0,5%

AUDIO FREQUENCY RESPONSE:

+0, -1 Db 20 hZ TO 15,000 Hz

STEREO SEPARATION:

35 dB at 100 Hz

45 dB at 1,000 Hz

30 dB at 10,000 Hz

STEREO AND MUTING THRESHOLD:

2-step switching at 5 µV and 20 µV

SCA REJECTION: 60 dB

19kHz, 38 kHz REJECTION: 70 db

AM Performance:

SENSITIVITY:

15 µV Distance

150 µV Local

S/N: 50 dB (antenna input level 1 mV, 30% Mod. at 1 kHz)

THD: will not exceed 0,5% ( antenna input level 1 mV, 30% Mod. at 1 kHz)

SELECTIVITY: 30 dB

IMAGE REJECTION: 70 dB

WHISTLE FILTER: -30 dB at 10kHz

OUTPUT: 0,6 Volts (30% Mod.)

GENERAL:

TUNING CAPACITOR:

FM: Frequency Linear 5-gang

AM: 3-gang

OUTPUT IMPEDANCE:

Audio Output FIXED: 200 ohms

Audio Output CONTROLLED: 2,5 K ohms

FM ANTENNA INPUTS:

300 ohms balanced;

75 ohms unbalanced

METERS:

Signal strength Meter

Center Tuning Meter

Multipath meter

POWER REQUIREMENT:

Voltage selector for 100V, 117V, 220V, 240V 50/60 Hz operation

Consumption: 26 Watts

SEMICONDUCTOR COMPLEMENT:

7 FET's, 45 Transistors, 9 IC's, 43 Diodes

DIMENSIONS:

445 mm (171/2 inches) wide, 152 mm (6 inches) high, 355 mm (14 inches) deep

WEIGHT:

14kg (30,8 lbs) net, 18,3 kg (40,6 lbs) in shipping carton