Lo-D HA-610

Commentary

A pre-main amplifier that realizes low distortion and loose output by gathering Lordi's technological achievements.

The power amplifier uses carefully selected transistors for Hi-Fi and consists of a constant-current drive emitter-grounded inverted pure complimentary service OCL circuit.
The inverted Darlington circuit is a circuit that can obtain not only power gain but also voltage gain at the power amplifier stage. It also has a large naked gain and provides stable feedback. In addition, since the drive voltage of the driver stage is low, it is possible to use semiconductors that are excellent for noise figures.
In addition, the two stage differential constant-current drive suppresses crossover distortion at the time of very small output by constant-current drive of the driver stage, and enables more beautiful reproduction of pianissimo. At the same time, stable drive is possible by differential amplification.

The equalizer stage of the preamplifier section has a 3-stage configuration consisting of differential input, FET and bipolar transistor.
The circuit is driven by ± 2 power supplies and has a dynamic margin of 280 mV, while accurate elements and sufficient feedback keep the RIAA deviation to ± 0.3 dB.
This equalizer uses carefully selected Hitachi LTP transistors to achieve high S/N.

The flat amplifier part of the control amplifier uses a 2-stage direct connection type by combining FET-PNP, and low distortion and high stability are realized by applying NFB at both AC and DC simultaneously.
In addition, because the tone control circuit is driven with low impedance, an ideal tone control circuit with no waviness in frequency characteristics is realized. In addition, it is equipped with a turnover frequency switching function, which is designed for a wide range of program source compensation.
It also has a defeat mechanism that can remove the tone control circuit.

The volume uses a 22-contact switch-type attenuator.
An FET with high input impedance is used for the first stage of the control amplifier to enable accurate level adjustment with little left / right linkage error. In addition, since there is little change in NF (noise figure) due to fluctuation of signal source impedance, deterioration of SN ratio due to volume position is suppressed.

Equipped with an additive 3-stage gain selector.
Since they can be used independently and also as an addition type, they can be used in a wide range from -5dB to -35dB, and can be used in combination with a switch-type attenuator for precise fine adjustment.
This gain selector can also be used as an audio muting.

Equipped with speaker B level adjustment function.
Comparing Speakers of Different Efficiency You cannot make an accurate comparison without adjusting the levels of the speakers. The HA-610 allows you to adjust the level of the B speaker system to -15dB, so you can make an accurate comparison by adjusting the level settings.

Equipped with Phono2 level fine adjustment function.
More accurate comparison and trial listening can be performed by matching the output level of the cartridge.

An electronic protection circuit is used.
It contains Lordi's unique and stable circuits, such as a DC voltage detection circuit that works when a DC voltage is generated at the speaker terminals, and a safety operation area detection and protection circuit that stops the operation of the amplifier to prevent the transistor from being damaged when the speaker terminals are short-circuited.

Equipped with two tape input / output terminals.

Equipped with high filter and low filter.

Equipped with a mode switch and a loudness switch.

The wood case was sold separately as an option.

Model Rating

Type	Pre-main amplifier
Power Amplifier Unit
Circuit system	Inverted Darlington pure complimentary service OCL
Effective power	20 Hz to 20 kHz, both channel drive : 70W + 70W (4 Ω) 60W + 60W (8 Ω) 1 kHz, both channel drive : 90W + 90W (4 Ω) 70W + 70W (8 Ω) 1 kHz, single-channel drive : 100W/100W (4 Ω) 75W/75W (8 Ω)
Dynamic Power (IHF)	180W (8 Ω)
Total harmonic distortion factor	0.3% (Effective Output) 0.006% (1 kHz at 1/2 effective output)
Intermodulation distortion factor (70 hz : 7 khz = 4 : 1)	0.05% (at effective output) 0.05% (at 1W output)
Output Bandwidth (IHF)	7 Hz to 50 kHz
Frequency characteristic	7 Hz ~ 70 kHz + 0 -1dB
Input Sensitivity / Impedance	0.8V/70k Ω
Output terminal	A, B : 4 Ω ~ 16 Ω A + B : 8 Ω ~ 16 Ω Headphone terminal : 4 Ω ~ 16 Ω
Damping factor	60 or More (1 kHz, 8 Ω)
S/N (IHF, A-Network, input short)	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 : 1.6 ~ 6mV/50k Ω (continuously variable) Tuner, Aux1/2, Tape PB1/2 : 100mV/50k Ω
Phono maximum allowable input	Phono1 : 280 mV (RMS, 1 kHz) Phono2 : 200 to 750 mV (RMS, 1 kHz)
Output Level / Impedance	Tape rec1/2: 100mV/1k Ω Tape rec2 (DIN terminal) : 30mV/80k Ω Pre out: 0.8V/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 (50 Hz, 100 Hz) Turnover frequency : 150 Hz, 300 Hz Treble: ± 10 db (10 kHz, 20 kHz) Turnover frequency : 3 kHz, 6 kHz
Filter	Low : 20 Hz, 12dB/oct. High : 8 kHz, 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 : 55 FET : 4 pcs Diode : 29 units
Power supply voltage	100 VAC, 50Hz/60Hz
AC outlet	Power switch interlock : 1 system Power switch not linked : 2 systems
Rated power consumption (Electrical Appliance and Material Control Law)	150W
External dimensions	Body : Width 435x Height 144x Depth 388 mm Wood Case : Width 467x Height 179x Depth 400 mm
Weight	12.0kg
Sold Separately	Wood Case LA-200 (¥ 6,500)