Audio Database

Integra M-507
Commentary

Stereo power amplifier using super servo system.

Onkyo's proprietary Super Servo System eliminates harmful ultra-low frequency components and improves low frequency transient response, which is a problem with DC amplifiers.
In addition to the NF circuit, this system consists of a servo loop that combines a low-frequency amplifier and a phase inversion circuit. The servo feedback lowers the output impedance below the cutoff frequency, causing the output circuit to shunt. This reduces the harmful ultra-low frequency components generated in the amplifier (inside the amplifier) and the back electromotive force flowing from the speaker to the amplifier.
This super servo system is different from the system in which a capacitor is inserted in the output circuit or the low-frequency cut is performed by utilizing the characteristics of the output transformer. It is free from problems of S/N and distortion factor due to the capacitor, sound quality degradation due to magnetic saturation distortion of the iron core, and instability due to applying deep NF, and it is free from the problem of S/N and distortion factor due to the capacitor, and it is free from the instability caused by applying deep NF. By this super servo system, the transient response characteristics in the low-frequency range are improved.
In addition, the leakage of DC center voltage due to drift, which was the fate of the DC amplifier, has been reduced to less than 1/20 of conventional levels.

A linear switching method is adopted to suppress switching distortion, which is a problem during B-class and AB-class operation.
In this method, the circuit configuration is similar to that of Class AB using two transistors, and compensation is performed at the junction between two operating characteristics by using a special bias or a special bias, so that one linear operating characteristic is obtained.
In addition, the use of high-ft power transistors reduces switching distortion and enables high-power drive.

Focusing on the rise characteristics of the circuit operation and the slew rate problem, we are trying not only to improve the high frequency by the slew rate but also to achieve a high-speed response over the whole band.

The power supply section is equipped with two large-capacity toroidal core transformers, and the power supply capacitor is newly designed especially for audio use. The capacitor is designed with extremely low characteristics such as the third harmonic level of -150dB at 10 kHz distortion rate, equivalent series resistance (ESR) of 0.01 Ω or less and loss tan δ of 0.25 or less.
In addition, the power supply and distribution lines from the power supply to each block and the ground line are made of copper sheets for low impedance, thereby achieving high stability of the whole system.
In addition, the AC100V power cord adopts a cab-tire type in consideration of the voltage drop at re-output.

To prevent interference and feedback effects between circuits, a non-magnetic aluminum chassis is used for the chassis where the signal system is connected.

A large high-speed peak meter is used.
The temperature of the meter is compensated by a logarithmic compression circuit made into a monolithic IC and a special resistance element to prevent accuracy and deviation of indication error with time.

The speaker output circuit is designed to have low resistance so as not to have excess resistance, and a total of four silver contact relays are used for the switching part.

Model Rating
Type Stereo power amplifier
Amplifier Unit
Effective output (20 Hz to 20 kHz) 210W + 210W (4 Ω)
150W + 150W (8 Ω)
Dynamic Power 200W + 200W (8 ω, 1 kHz)
Total harmonic distortion rate (20 Hz to 20 kHz) 0.007% or Less (Effective Output)
0.006% or Less (at 75W output)
0.006% or Less (at 5W output)
Cross modulation distortion factor (at effective output) 0.01% or Less (SMPTE 70 Hz : 7 khz = 4 : 1)
Powerbandwidth 5 Hz ~ 150 kHz (Measuring Instrument Limit, IHF-3dB, THD0.2%)
Gain 27.5dB
Frequency characteristic Servo Operation Norm : 0.7 Hz to 100 kHz + 0 -1.5 dB
Servo Operation off : DC ~ 100 kHz + 0 -1.5 dB
Subsonic filter characteristics 15 Hz, -6dB/oct.
S/N 110 dB (IHF-A network, input shunt)
Input-output polarity Inphase
Input Sensitivity / Impedance 1.5V/100k Ω
Speaker load impedance 4 Ω ~ 16 Ω
Damping factor 200 (8 Ω, 1 kHz)
Output terminal Route 2
Transient killer operating time Power on:5sec
Power off:100msec
Meter Section
Range switching x1(0dB=150W)
x0.1(0dB=15W)
Indication range -40dB to + 4 dB
Indication accuracy 0 ± 0.5 dB
-10 + / - 1 dB
-20 + / - 1 dB
Response speed 100 μ sec (∞ → 0 dB)
Return speed 1 sec (0 dB → -20dB)
<General>
Semiconductor used Transistor : 72
FET : 2
IC : 8
Diode : 50 pcs
Pwer 100 VAC, 50Hz/60Hz
AC outlet Power switch not linked : 1 system, max600W
Power consumption 280W (Electrical Appliance and Material Control Law)
External dimensions Width 450x Height 191x Depth 420 mm
Weight 28.5kg