ONKYO Integra A-817XX
¥ 79,800 (released in 1986)
Commentary
This pre-main amplifier is equipped with a real-phase <digital> amplifier and a W stabilizer system to improve the quality of playback sound by increasing the linearity during low sound.
In order to prevent dynamic distortion that occurs when the linearity of the power stage temporarily deteriorates when the signal level changes inside the amplifier, and acoustic distortion that occurs when the amplifier vibrates due to sound pressure from the speakers, we have adopted a new real phase <digital> amplifier configuration using the newly developed W stabilizer method.
In the New Real Phase <Digital> amplifier, dynamic distortion is solved by a DD (Dynamic Distortion) stabilizer circuit, and acoustic distortion is solved by a new structure called X stabilizer.
The DD stabilizer circuit detects dynamic distortion at the power stage and cancels this distortion component by subtracting it from the signal at the driver stage.
In addition, the X stabilizer was created from the idea of attaching a strong base to the chassis of the amplifier itself. The X-shaped structure made of high-rigidity PbSb special alloy reduces chassis vibration.
A real-phase <digital> amplifier configuration is adopted in which an in-phase transformer is added to the input terminal and power supply, which are input paths of disturbance signals from the outside.
A signal-in-phase transformer (S. I. T) is installed at the input terminal and a power-in-phase transformer (P. I. T) is installed at the power supply section to guard the amplifier circuit, preventing the penetration of external noise and achieving high-purity transmission.
A charge noise filter is also added to the power supply to eliminate normal mode noise that enters from the AC line.
The power-in-phase transformer inserted into the power supply circuit not only eliminates common-mode noise but also eliminates the phase shift of the charging current of the power supply and transmits correct phase information.
The power-in-phase transformer combines charging currents with opposite phases on the + side and - side to generate a charging current with a certain peak, and removes out-of-phase information from the charging current. This improves the driving performance of the speaker and the braking performance in the low-frequency range.
In order to achieve high-purity transmission, we have taken various circuit measures, such as eliminating the contact point of the Tape Monitor switch and adopting the Rec Selector method, removing the Tone amplifier from the signal path and adopting the Direct Tone method using the center tap of the volume, and removing the Muting switch from the signal path and placing it in the Direct Tone circuit.
It is equipped with a CD Direct switch. When this switch is pressed, the signal is sent directly to the dedicated 4-channel volume without passing through any contact points, which enables high-purity transmission.
In order to cope with the low impedance of speakers, a powerful power supply with a margin and a power transistor connected in parallel are adopted. Even if the load temporarily changes to low impedance such as 2 Ω, stable driving is possible.
In addition to the Treble/Bass, the tone control is equipped with a Contrabass that boosts the band below approximately 100 Hz.
This allows you to boost the low range without affecting the middle range of vocals.
In addition, it employs a new circuit that provides a boost of up to 20 dB when muting is on. If you use the Contrabass with muting on in the middle of the night, for example, you can enjoy rich bass playback even at a low volume.
Each of the Tape1rec, Tape2rec and Video Mode has an off position. When recording is not performed, the off position allows the recording system to be separated from the signal system, ensuring high-purity transmission.
In order to prevent the video signal line from adversely affecting the audio signal line, a remote switching method using a relay is adopted for video signal switching. The layout is separated from the audio circuit by processing the video signal in close proximity to the pin jack.
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Model Rating
| Type | Stereo pre-main amplifier |
| Rated output (20 Hz to 20 kHz, CD → sp out, both channels driven) |
115W + 115W (6 Ω) 100W + 100W (8 Ω) |
| Dynamic Power | 275W + 275W (2 Ω) 220W + 220W (4 Ω) 142W + 142W (8 Ω) |
| Total harmonic distortion rate (20 Hz to 20 kHz) | CD → sp out : 0.004% (8 Ω at rated output) Phono MM → rec out : 0.003% (at 3 v output) Phono MC → rec out : 0.015% (at 3 v output) |
| Intermodulation distortion factor (20 Hz to 20 kHz) | CD → sp out : 0.004% (at rated output) |
| Powerbandwidth | 5 Hz to 100 kHz (IHF-3dB, THD 0.2%, 8 Ω) |
| Damping factor | 100 (1 kHz, 8 Ω) |
| Frequency characteristic | Phono → rec out (RIAA deviation) : 20 Hz to 20 kHz ± 0.2 dB CD → sp out : 2 Hz to 100 kHz + 0 -3dB |
| Input Sensitivity / Impedance | Phono MM : 2.5mV/47k Ω Phono MC : 180 μ V/220 Ω CDDirect, tuner, tape play : 150mV/47k Ω Video, VCR play (audio) : 150mV/47k Ω Video, VCR play (video) : 1Vp-p/75 Ω |
| Phono maximum allowable input (1kHz/10kHz, 0.005%) |
phono MM:210mV/1000mV phono MC:15mV/75mV |
| Rated output voltage / impedance | Tape rec1, 2 : 150mV/560 Ω VCRrec (voice) : 150mV/560 Ω Pre out : 1V/600 Ω VCR rec, video mon out : 1Vp-p/75 Ω |
| S/N ratio (IHF-A filter input short) | phono MM:87dB phono MC:70dB CD, tuner, tape play : 100 dB Video, VCR play (audio) : 100 dB |
| Tone Control (Vol-16dB) | Bass : + / - 10 dB Treble : + / - 8 dB Contrabass (when muting off/on) : + 10 dB / + 20 dB |
| Muting (below volume center) | -15dB |
| Pwer | 100 VAC, 50Hz/60Hz |
| Power consumption (Electrical Appliance and Material Control Law standard) | 210W |
| AC outlet | Switched : 1 system, 100W Unswitched : 2 lines, 100W total |
| External dimensions | Width 435x Height 163x Depth 385 mm |
| Weight | 17.5kg |