Lo-D HA-500F

Commentary

Pre-main amplifier equipped with vertical power FET.

A vertical power FET, which has attracted attention as a new element, is used as an amplifying element.
Since this device does not have the carrier-storage effect of general transistors, it has a high switching speed and can stably apply NFB to high frequencies. It can also obtain N-channel and P-channel complimentary service devices. It also has high input and low output impedance characteristics and smooth pinch-off characteristics that are expected as an audio amplifier. It also has a negative temperature coefficient and is less likely to cause thermal runaway.

In the HA-500F, this vertical power FET is adopted in the power section, and it is a push-pull pure complimentary service OCL circuit configuration with vertical power FETs of N channel and P channel.
The constant current circuit increases the gain of the A-class stage, and the development of a new drive circuit achieves stable operation and excellent characteristics.

In the equalizer stage, the first stage is a differential amplifier using a high voltage and low noise transistor, the second stage is an FET to increase the gain of the first stage, and the third stage is an emitter follower using a bipolar transistor and is driven by ± 2 power supply.
This results in a large dynamic margin, and the RIAA deviation is also improved by high precision elements and sufficient NF.

In the first stage of the tone control section, an FET with less noise is adopted when the signal source impedance is high, and an input circuit without deterioration of SN ratio due to volume position is constructed.

The volume switch uses a 22-contact switch-type attenuator with less left-right interlocking error.
It is also possible to fine-tune the level using an additive 3-stage gain selector.

Equipped with speaker B level adjustment, convenient for comparing and listening to different speakers.

Equipped with a loudness switch and a tone defeat switch.

The wood case was sold separately as an option.

Model Rating

Type	Pre-main amplifier
Power Amplifier Unit
Circuit system	Vertical Power FET Pure complimentary service OCL
Effective power	20 Hz to 20 kHz, both channel drive : 50W + 50W (8 Ω) 1 kHz, both channel drive : 55W + 55W (4 Ω) 55W + 55W (8 Ω) 1 kHz, single-channel drive : 60W/60W (4 Ω) 60W/60W (8 Ω)
Total harmonic distortion factor	0.3% (Effective Output) 0.008% (1 kHz at 1/2 effective output)
Intermodulation distortion factor (70 hz : 7 khz = 4 : 1)	0.3% (Effective Output) 0.1% (at 1W output)
Output bandwidth	5 Hz to 37 kHz
Frequency characteristic	10 Hz ~ 20 kHz + 0.5 -1dB
Input Sensitivity / Impedance	1V/55k Ω
Output terminal	A, B : 4 Ω ~ 16 Ω A + B : 8 Ω ~ 16 Ω Headphone terminal : 4 Ω ~ 16 Ω
Damping factor	50 or More (1 kHz, 8 Ω)
S/N (IHF, A Network)	100 dB or more
Preamplifier Section
Circuit system	Equalizer amplifier : 1-stage and 3-stage differential directly connected, with FET Control Amplifier : NF Type, First Stage FET Used
Input Sensitivity / Impedance	Phono1 : 2mV/50k Ω Phono2 : 2 ~ 5mV/50k Ω (Low-High Switching) Tuner, Aux, Tape PB1, 2 : 100mV/50k Ω Mic : 2mV/25k Ω
Phono maximum allowable input	Phono1 : 280 mV (RMS, 1 kHz) Phono2 : 280 to 700 mV (RMS, 1 kHz)
Output Level / Impedance	Tape rec1, 2 : 100mV/1k Ω Pre out: 1V/4.7k Ω (Rating) 6V/4.7k Ω (maximum)
Frequency characteristic	Phono (RIAA deviation) : 30 Hz to 15 kHz ± 0.3 dB
Tone control	Bass : ± 10 dB (100 Hz) Treble : ± 10 dB (10 kHz)
Filter	Low : 40 Hz, 6dB/oct.
Loudness control (Volume -30dB)	+ 13 dB (100 Hz), + 7 dB (10 kHz)
S/N (IHF, A-Network, input short)	Phono:75dB Tuner, Aux, Tape PB : 90 dB
Attenuator	-5, -10, -20dB (can add)
<General>
Semiconductor used	Transistor : 42 FET : 8 Diode : 37 pcs
Power supply voltage	100 VAC, 50Hz/60Hz
AC outlet	Power switch interlock : 1 system Power switch not linked : 1 system
Rated power consumption (Electrical Appliance and Material Control Law)	170W
External dimensions	Body : Width 435x Height 144x Depth 388 mm Wood Case : Width 467x Height 179x Depth 400 mm
Weight	12kg
Sold Separately	Wood Case LA-200 (¥ 6,500)