TRIO KA-990
¥ 79,800 (released in 1982)
Commentary
Pre-main amplifier that uses DLD (dynamic linear drive) circuit.
The DLD circuit consists of two amplifiers at the output, a low-power amplifier and a high-power amplifier. Most of the signal is processed by a low-level amplifier with a distortion factor of 0.001% or less. This low-level amplifier can handle up to 50W. Since this amplifier is driven by a power supply that can handle more than 100W, the impedance of the power supply can be reduced, and excellent characteristics are obtained without being affected by the load fluctuation of the speaker.
The high-power amplifier generates little heat and generates almost no internal loss because it is used only for a very short moment when the peak signal passes through.
In addition, a Σ drive system is adopted to improve the performance at the input terminal of the speaker.
This method suppresses distortion of the waveform at the input terminal of the speaker and drives the speaker with a faithful waveform.
We reconsidered the layout of each block and arranged each stage according to the signal flow. In the power amplifier, a large radiator is used to shield the B - and A-class stages, and a dedicated shield plate is used for the equalizer stage to reduce mutual interference.
The power transformer is also shielded to prevent adverse effects on the circuit such as power flux.
The equalizer amplifier uses ICL high GmFET differential inputs and ICs.
In particular, the grounding section, which has a significant impact on sound quality, uses 26 single wires with a diameter of 0.26 mm, with a cross-sectional area six times that of conventional wires.
Gain switching is adopted for MM and MC switching.
The tone control is a trio type NF-CR type with a dedicated IC.
.JPG)
Model Rating
| Type | DLD Integrated Amplifier |
| Rated Output (Both Channel Operation) | 105W + 105W (20 Hz ~ 20 kHz, 8 Ω) |
| Total harmonic distortion factor (20 Hz to 20 kHz, 8 Ω) |
Phono → SP terminal : 0.007% (at rated output) Tuner, AUX, Tape → SP terminal : 0.005% (at rated output, 1/2 rated output) |
| Intermodulation distortion factor (60 hz : 7 khz = 4 : 1) | 0.005% (Tuner, AUX, Tape → SP terminal, at rated output, 8 Ω) |
| Frequency characteristic | DC ~ 200kHz-3dB (Tuner, AUX, Tape → SP terminal) |
| Damping factor (100 Hz) | 1000 |
| Input Sensitivity / Impedance | Phono MM → SP Terminal : 2.5mV/47k Ω Phono MC → SP Terminal : 0.2mV/100 Ω Tuner, AUX, Tape → SP terminal : 150mV/47k Ω |
| Signal-to-noise ratio (IHF-A) | Phono MM → SP terminal : 88 dB Phono MC → SP terminal : 70 dB (at 250 μ V input) Tuner, AUX, Tape → SP terminal : 107 db |
| Tone control | Bass : 100 Hz ± 10 dB (400 Hz) Treble : 10 kHz ± 10 dB (3 kHz) |
| Loudness control | 100Hz +10dB(Volume-30dB) |
| Subsonic filter (-3dB) | 6dB/oct(18Hz) |
| Rise time | 1.7 μ s (Tuner, Aux, Tape → SP terminal) |
| Slew rate | ± 100 V / μ s (Tuner, Aux, Tape → SP terminal) |
| Output Bandwidth (0.02% distortion, 8 Ω) | Tuner, AUX, Tape → SP connector : 5 hz to 50 khz |
| Phono maximum allowable input (Phono → Tape Rec, 1 kHz, THD0.005%) | MM:240mV MC:18mV |
| Phono RIAA deviation | ± 0.3 dB (Phono → Tape Rec, 20 Hz to 20 kHz) |
| Output Level / Impedance | Tape Rec Pin : 150mV/330 Ω |
| Pwer | 100 VAC, 50Hz/60Hz |
| Rated power consumption (Electrical Appliance and Material Control Law) | 260W |
| Power outlet | Interlock : 2 systems 100W Non-linked : 1 system 400W |
| Maximum external dimensions | Width 440x Height 143x Depth 383 mm |
| Weight | 10.7kg |