PHILIPS RH545
¥ 480,000 (1 unit, around 1979)
Commentary
Active speaker system of Studio Monitor Series.
In order to obtain sound without distortion or coloring, the Studio Monitor Series uses the MFB (Motional Feedback) method.
In the MFB method, the acceleration of the cone paper is detected and voltage converted by the piezoelectric element (PXE) installed at the top of the cone paper of the woofer. By comparing this voltage and the input signal with a comparator, the reproduced sound wave can be made identical to the original waveform, and distortion components are canceled.
At RH545, the input signal is divided into high, mid, and low frequencies by a precision electronic filter. The high and mid frequencies are driven by the respective amplifiers, while the low frequency uses an MFB loop composed of a bass amplifier, woofer, and comparator for undistorted bass reproduction.
It has a 30 cm cone woofer in the low range, a 5 cm dome squaker in the middle range, and a 2.5 cm dome tweeter in the high range.
Equipped with a low-pass filter and continuously variable Bass control to enable sound field correction depending on the installation location.
The Treble control allows you to switch the turnover frequency between two levels.
Equipped with an automatic power ON/OFF mechanism driven by relay.
It turns ON automatically when 2 mv or more is input, and turns OFF automatically when there is no signal for 2 minutes or more.
You can check the operation status of the power ON/OFF and Treble filter by the indicator.
It has an electronic protection circuit to protect the speakers from overload.
The enclosure is made of wood with a black ash finish.
A balanced input terminal (cannon jack) of studio specification is used.
Since parallel connection is possible for each channel, power up for multiple use is possible.
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Model Rating
| Method | Built-in Amplifier / 3-way / 3-speaker / Bookshelf Type | ||||
| Speaker Unit | |||||
| Units Used | For Low Range : 30 cm Cone Type (AD12100/MFB4) For Middle Area : 5 cm Dome Type (AD0210/Sq8) For High Range : 2.5 cm Dome Type (AD0161/T8) |
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| Total output | Continuous Sine Wave 100W | ||||
| Frequency characteristic | 20 Hz to 20 kHz | ||||
| Crossover frequency | 500 Hz, 3 kHz | ||||
| Enclosure volume | 70 liters (50 liters acoustic part) | ||||
| Input / output terminal | Input / output (unbalanced type) Input (balanced) Service outlet |
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| Input sensitivity |
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| Electronic ON/OFF switch | ON (for 1 second or more at 1.5 mv or more input) Off (2 minutes or more without signal) |
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| Low pass filter | 1:-5dB(200Hz) 2:-5dB(60Hz) 3 : -3dB (55 Hz to 160 Hz) |
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| Bass Control | ± 10 dB at 60 Hz Turnover frequency : 350 Hz |
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| Treble Controls | Continuously Variable 0 ~ 20dB/oct. Turnover Frequency : 7kHz/10kHz |
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| MFB Amplifier Unit | |||||
| Output | Continuous Sine Wave 50W | ||||
| Harmonic distortion factor | 1% or Less (50W, 100 Hz) 0.1% or Less (40W, 100 hz) |
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| Output bandwidth | 5 Hz to 5 kHz | ||||
| Amplifier Section for Middle Band | |||||
| Output | Continuous Sine Wave 35W | ||||
| Harmonic distortion factor | 1% or Less (35W, 1 kHz) 0.1% or Less (25W, 1 kHz) |
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| Output bandwidth | 40 Hz to 30 kHz | ||||
| Amplifier Section for High Frequency | |||||
| Output | Continuous Sine Wave 15W | ||||
| Harmonic distortion factor | 1% or Less (15W, 5 khz) 0.1% or Less (10W, 5 khz) |
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| Output bandwidth | 100 Hz to 50 kHz | ||||
| <Others> | |||||
| Semiconductor used | Transistor : 85 Diode : 39 |
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| Power supply voltage | AC110V/127V/220V/240V | ||||
| Power consumption | Up to 200W | ||||
| External dimensions | Width 436x Height 650x Depth 320 mm | ||||
| Weight | 31.0kg | ||||