TRIO KA-7100D

Commentary

Integrated amplifier with 2 power supply configuration on right and left.

The power amplifier consists of a DC amplifier without a capacitor in either the signal system or the NF loop. Therefore, there is no phase rotation so that signals of all frequencies can pass through as they are.
The circuit configuration consists of three differential stages using an FET at the first stage and a direct-coupled ICL-OCL DC amplifier at all stages. The FET at the first stage is a dual FET with high input impedance, which eliminates the input capacitor and improves sound quality.
In addition, the Class A amplifier stage is a 3-stage amplifier with a large bare gain, so a sufficient amount of NF can be applied. In addition, the CMRR (common-mode signal rejection ratio) is designed to be large. Moreover, the load circuit of the pre-driver stage is made constant current and the bias of the power transistor is used as a stabilizing power supply, so that low distortion factor is maintained over a wide band. Moreover, stable characteristics that are not affected by power supply fluctuations due to sudden large input are realized.

The protection circuit is equipped with a double protection circuit using limiter protection and relay unique to TRIO.

The equalizer circuit uses a 2-stage direct-coupled ICL type equalizer with 1 stage differential and class A amplification of constant current load.
The first stage is an FET differential amplified ICL system, which realizes excellent phase characteristics and transient characteristics by eliminating a capacitor from the input, and low distortion factor over a wide band by adopting class A amplification with constant current load circuit.
The equalizer uses a 1% resistor and 2% capacitor with an RIAA deviation of ± 0.2 dB, and a high signal-to-noise ratio is achieved by selecting the optimum constant using carefully selected low-noise elements.

For tone control, the first stage FET ± 2 power supply 3-stage direct connection configuration is adopted.
This tone control is designed with a low distortion factor so that an in-phase component always appears in the output, including tone jump.
The tone jump switch allows direct connection between a flat amplifier and a power amplifier.

The power supply section uses a large 190 va power transformer with windings separated from the secondary side to the left and right sides, and consists of four 6800 μ F filter μ F filter capacitors and has a left and right independent configuration.
The power supply for the preamp is a full-scale regulator using transistors to reduce interference from the power section to the preamp section.

The internal layout has a heat sink in the center to increase the strength of the case, shield the small signal of the class A amplifier from the power supply, and shield the large AC current flowing to the speaker system.
The equalizer uses a direct connection directly connected to the input terminal to prevent stray capacitance from adversely affecting the low-level signal from the player.

A 7-pin balanced code with L/R on the ground is used for the part from equalizer to tone in.
In addition, in order to remove unstable elements from the entire circuit, we have adopted a configuration that does not even use a single shield wire, thereby improving sound quality and achieving stability.

Tape dubbing circuit with through circuit is adopted.

It uses a -20dB attenuator and a 32-contact attenuator volume.

Uses a two step switching type loudness control.

The carrying handle in the picture was sold as an optional item sold separately.

Model Rating

Type	Integrated amplifier
Overall Characteristics
Total harmonic distortion factor (Tuner/Tape → SP terminal)	0.02% (250 mW ~ 60W, 20 Hz ~ 20 kHz, 8 Ω) 0.004% (at 60W output, 1 kHz, 8 Ω)
Intermodulation distortion factor (Tuner/Tpae → SP terminal)	0.01% (250 mW ~ 60W)
Frequency characteristics (Tuner/Tape → SP terminal)	10 Hz ~ 100 kHz + 0 -1.8 dB
SN ratio (IHF-A curve)	Phono → SP Terminal : 80 dB (2.5 mV input) Tuner/Tape to SP terminal : 110 dB
Output bandwidth	5 hz to 45 khz (Tuner/Tape to SP connector, IHF)
Power Amplifier Unit
Effective power	60W + 60W (20 Hz to 20 kHz, both channel operation, 8 Ω)
Frequency characteristic	DC ~ 100 kHz + 0 -1.5 dB
SN ratio (IHF-A curve)	120dB
Damping factor (8 Ω)	50
Optimum load impedance	4 Ω ~ 16 Ω
Preamplifier Section
Input Sensitivity / Impedance	Phono : 2.5mV/50k Ω Tuner, Aux, Tape play : 150mV/50k Ω
Output Level / Impedance	Tape rec pin : 150mV/450 Ω
Maximum Allowable Input (1 kHz, Distortion 0.02%)	Phono:200mVrms
Phono RIAA deviation	+ / - 0.2 dB
Tone control	Bass : ± 7.5 dB (100 Hz) Treble : ± 7.5 dB (10 kHz)
Filter	Subsonic : 20 Hz, 6dB/oct. High : 8 kHz, 6dB/oct.
Loudness control (at -30dB output)	100 Hz : + 3 dB, + 6 dB
<General>
Power outlet	Switched : 2 lines Unswitched : 1 line
Power supply voltage	100 VAC, 50Hz/60Hz
Rated power consumption (Electrical Appliance and Material Control Law)	150W
External dimensions	Width 430x Height 149x Depth 379 mm
Weight	11.5kg
Sold Separately	Carrying Handle D-7 (1 set, ¥ 3,000)