Nakamichi TA-1/1A/1E receiver

 

Nakamichi High Definition Tuner Amplifier

Features:

Discrete Power Stage with High Curent Capability

Multiple Isolated-Ground Power Supplies

Quartz PLL Tuner with 10 Presets and Auto-Seek Tuning

Nakamichi-Concept Tone and Loudness Controls

High Accuracy Phone Equalizer with Built-in Subsonic Filter

Speaker Selector for A / B or A + B System

Protection Circuitry

 

Discrete-Configuration / High-Current Power Amplifier

If you were to look into the average basic receiver, chances are you'd find IC power amplifiers. That's not surprising because IC power amps are convenient, inexpensive and produce adequate sound for the not-too-discriminating listener. For better or for worse, Nakamichi engineers are a pretty discriminating lot and, after auditioning the various IC power amps on the markeet, decided to design their own "discrete" power amplifier. By "discrete" we mean a custom-designed circuit using carefully selected individual components that can be fine tuned for optimum performance. It's a more expensive way to go, but it permits us to create a uniquely musical design that guarantees "Nakamichi Sound" at an entry-level price.

The discrete output transistors used in the TA-1 have a higher current capability than those in the average 35-watt power IC. With an ability to deliver peak currents of 10 amperas, the TA-1 output devices drive difficult loudspeakers easily and that means purer, more natural sound. Then, too, by designing our own circuit, we ensure adequate output-stage and loudspeaker protection without audible side effects. That means the TA-1 will play safely and more loudly than a comparably rated receiver that uses power ICs. Finally, by custom designing the output stage, we are able to increase the gain over that of an IC, incorporate the tone controls as part of the power amp and thus eliminate need for a line amplifier - another step in simplifying the signal path.

 

Nakamichi Concept preamp and Tone Controls

You'll find the Nakamichi TA-1 substantially different from the ordinary in its phono preamp and tone controls too. For example, the preamp has a subsonic filter built into the phono equalizer - not as an appendage to the line amplifier. This means that, not only can you play warped records without overloading your speakers, you can make clean copies of them without overloading your tape recorder - an advantage many designs do not provide. And, thanks to Nakamichi precision components, equalization accuracy is within ±1 dB from 30 Hz to 20 kHz including the effects of the filter.

TA-1 tone controls were designed to be useful, not flashy. Compared with those in other receivers TA-1 controls have a carefully limited range and are most effective at frequency extremes, not in the midband. This means you can create a subtle boost or cut in the extreme bass or treble without altering the character of the music. Similary, the TA-1 loudness contour comes into increasing prominence as volume is reduced and therefore tracks the characteristics of human hearing at low listening levels in a more natural way.

 

Multiple Power Supplies with Isolated-Ground Topology

Even though the TA-1 is Nakamichi's "entry-levl" receiver, it has been designed with separate transformer windings and power supplies for the audio and control circuits to prevent control-circuit noise from contaminating musical purity. In addition, the tuner's power source is regulated independently of the power-amp and preamp sources and that for the preamp features Nakamichi's unique "Isolated-Ground" topology to ensure a noise-free ground reference for the critical low-level stages. Circuit grounds are kept separate for each channel both in the power amp and in the preamp for best channel separation and absolute musical purity.

 

Quartz PLL Synthesized Tuner

The TA-1's  tuner complements the excellent sound of its preamp and power amp. A quartz PLL synthesized "front-end", with twin varicap diode, provides accurate drift-free reception, 10 station presets and a choice of manual or auto-seek tuning modes. As with every Nakamichi tuner, the TA-1 uses an unusually high reference frequancy to provide better Signal-to-Noise ratio and lower distortion.

 

Specifications

Power Amp Section

Continuous Average Output Power:  35 watts per channel into 8 Ω (both channels driven, 20-20,000 Hz at no greater than 0,1% T.H.D.)

Dynamic Output Power:

52 watts / channel at 8 Ω

65 watts / channel at 4 Ω

Power Bandwidth:  10 - 40,000 Hz

Frequency Response:  20 - 20,000 Hz ±1 dB; 10 - 50,000 Hz +1 -3 dB

Signal-to-Noise Ratio (A-weighted, Input Shorted):  better than 98 dB re Rated Power

Total Harmonic Distortion:  less than 0,1%

Peak Output Current Capability:  10 A per channel

Preamplifier Section

Sensitivity (for rated output)

Phono MM :  2,5 mV

CD/Tape :  150 mV

Input Impedance

Phono MM :  47 k Ω

CD/Tape :  20 k Ω

Phono Max. Input level (1 kHz):  150 mV

Phono T.H.D. (1 kHz, 1 V at Rec Out):  less than 0,01%

Phono Signal-to-Noise Ratio (IHF-A-202):  better than 76 dB

RIAA Deviation:  30 - 20,000 Hz ±1 dB

Record Output Level/Impedance:  150 mV/2,2 k Ω

Bass Control :  ±10 dB at 20 Hz

Treble Control :  ±10 dB at 20 kHz

Loudness (Volume at -30 dB):  +10 dB at 20 Hz ; +6 dB at 20 kHz

FM Tuner Section

Frequency Range:  87,5 - 108,0 MHz (in 100 kHz steps)

IHF Usable Sensitivity [Mono]:  12,0 dBf/2,2 µV

-50 dB Quieting Sensitivity:

Mono :  15,7 dBf/3,3 µV

Stereo :  38,5 dBf/46,1 µV

Signal-to-Noise Ratio at 65 dBf

Mono :  better than 79 dB

Stereo ;  better than74 dB

Muting Threshold:  30 dBf/17,3 µV

Frequency Response:  30 - 15,000 Hz ±1,5 dB

Total Harmonic Distortion at 1 kHz

Mono :  less than 0,15%

Stereo :  less than 0,20%

Capture Ratio:  2,0 dB

Alternate Channel Selectivity:  55 dB (±400 kHz)

Stereo Separation at 1 kHz:  better than 45 dB

Spurious Response Rejection:  better than 80 dB

Image Rejection:  better than 47 dB

IF rejection:  better than 80 dB

AM Suppression:  better than 60 dB

AM Tuner Section

Frequency Range:  520 - 1710 kHz (in 10 kHz steps)

Sensitivity:  53 dB µ/m

Signal-to-Noise Ratio:  better than 52 dB at 90 dB µ/m

Total Harmonic Distortion:  less than 0,5% at 90 dB µ/m

Selectivity:  better than 20 dB (±10 kHz)

General Section

Power Requirements:  120, 220, 240 V (or 110/120/220/240 V) AC 50/60 Hz

Power Consumption:  220 W max

Dimensions (W x H x D):  430 x 100 x 265 mm (16-15/16" x 3-15/16" x 10-7/16")

Weight:  6 kg (13 lb 4 oz)