PHILIPS LHH A200

Commentary

A pre-main amplifier with expressive power while inheriting the technology of LHH A700.

Uses low NFB high-speed voltage amplification stage.
The LHH A200 consists of a wide-band, small-capacity bipolar transistor for the voltage amplification stage. As a result, the bare characteristics (open-loop frequency characteristics) before applying NFB has been dramatically improved to 500 kHz (-3dB) compared with the conventional one. At the same time, by minimizing NFB, dynamic characteristics have been greatly improved and flat phase characteristics have been obtained.

MOS-FET, a high-speed switching element, is used for the power stage and driver stage, which are current amplification stages. It has a single-push-pull configuration with an emphasis on linearity. The low-impedance drive realizes an ultra high-speed overall amplifier with a slew rate of 200 V / μ.
In addition, the LHH A200 has a non-feedback current amplifier stage that is less affected by the back electromotive force from the speakers than the first stage. This provides excellent stability against not only low loads but also capacitance loads. The output coil, which was a necessary evil in ordinary NFB amplifiers, is eliminated, and dynamic characteristics are further improved.

The volume uses a current drive type low impedance volume.
In this system, the signal current does not pass through the carbon resistor or slider contact, so the deterioration of sound quality is minimized.

The power supply section is equipped with a 260 VA high-capacity EI core transformer. This transformer has ± separate windings and separate rectification to improve stability against fluctuations.
In addition, a number of custom electrolytic capacitors with low-magnification foils are connected in parallel to the smoothing capacitor to achieve low impedance and high speed.
An OFC bus bar with a diameter of 2.0 mm is used for the power supply ground.

A 1.6 mm thick steel plate is used for the top cover and a 2.0 mm thick copper plated steel plate is used for the bottom chassis to increase rigidity.
The heat sink uses a chimney type with excellent vibration resistance, which is connected to the top cover and bottom chassis to increase chassis rigidity.
3-point support system sintered alloy heavy legs (point grounding, interview site selectable) are used for the legs.

Uses carefully selected high-grade parts.
± 1% metal film resistor, high voltage acoustic electrolytic capacitor, Silbird dip mica capacitor, etc. are adopted.
In addition, high-reliability parts such as brass machined RCA pin jacks, a vise speaker terminal for banana plugs, and a gold-plated contact relay are used.

There were aluminum side panels and brass point bases as options sold separately.

Model Rating

Type	Power buffer amplifier
Rated output	40W + 40W (8 Ω, 20 Hz to 20 kHz) 80W + 80W (4 ohm, 1 khz)
Input Sensitivity / Impedance	450mV/10k Ω
Frequency response (at 1W output)	5 Hz ~ 350 kHz + 0 -1dB
Output bandwidth	7 Hz ~ 110 kHz (20W/8 Ω, when both channels are driven)
Total harmonic distortion factor	0.2% (20 Hz to 20 kHz at 8 Ω rated output)
Signal-to-noise ratio	105 dB (A-curve correction)
Slew rate	200 V / μ sec or more
Power consumption	160W
External dimensions	Width 437x Height 110x Depth 384 mm
Weight	13kg
Sold Separately	Side Panel AS200 (Set of 2 Panels, ¥ 18,000) Point Base PB3 (3-piece 1 set, ¥ 5,000)