Pioneer SX-304B
¥ 38,000 (around 1965)
Commentary
AM/FM multi integrated stereo amplifier equipped with automatic switching mechanism of FM mono and stereo.
A meter-type tuning instruction by a tuning meter is adopted in the tuner section instead of the conventional magic eye to suppress tuning deviation at the time of tuning.
The FM tuner uses a 6AQ8 cathode injection self-excited front-end to achieve stable high-frequency amplification.
In addition, 3 stages of intermediate frequency amplification including 1 stage of limiter are adopted, and the signal with suppressed noise is sent to the latter stage.
A wide-band ratio detection method suitable for stereo reception is adopted.
The tuner section is equipped with a newly designed stereo / mono automatic switching mechanism. You can automatically receive FM stereo by setting the selector knob to FM-Auto.
The neon tube stereo indicator lights up during stereo reception.
Switching system is adopted for the multi-circuit.
An SCA filter is added to this multi-circuit.
Equipped with FM-AFC (Automatic Frequency Adjustment) circuit.
Equipped with a tuning indicator.
A push-pull circuit using 6BM8 is adopted for the output stage of the amplifier section.
The power supply employs a voltage doubler rectification system using a silicon diode.
Equipped with tone control and loudness control.
A newly designed lever switch has been adopted for the front panel switches to ensure reliable operation with a light touch.
It is equipped with a wide range of input / output terminals such as MAG terminal with RIAA curve equalizer, input terminal for ceramic, aux, tape and line out, output terminal for Tape Rec, headphone, and DIN tape recorder / reconnector jack.
Ease of use is improved by integrating the input switching of the tape source into the selector switch.
Model Rating
| Type | Stereo receiver |
| Tuner Section | |
| Circuit system | 6AQ8 Cathode Injection Self-excited Front End One limiter out of three intermediate frequency amplification stages Wide-band ratio detection system |
| Receiving band | FM : 76 MHz to 90 MHz AM : 535 kHz to 1605 kHz |
| Intermediate frequency | FM:10.7MHz AM:455kHz |
| Practical sensitivity | FM : 2 μ V (IHF) AM : 50 μ V (IHF) |
| Image ratio | FM:40dB(82MHz) AM:50dB(1,000kHz) |
| Antenna | FM : 300 Ω Balanced Type (T-shaped Simple Antenna Included) AM : With Lead Wire Antenna |
| Tuning instruction | AM/FM common tuning meter |
| <FM Multi Section> | |
| Circuit system | Switching type stereo demodulation method with mono-stereo automatic switching circuit |
| Separation | 35 dB or More (1 kHz) |
| Accessory circuit | AFC ON-OFF SCA Filters |
| Amplifier Unit | |
| Circuit system | 6BM8 Push-Pull |
| Effective power | 11W + 11W (1 kHz, 1% or less distortion factor) |
| Music power | 34W (IHF, 1% or less distortion factor) |
| Frequency characteristic | 30 Hz to 20 kHz ± 3 dB |
| SN ratio (Vol-max, tone under a control point, IHF) | MAG:60dB Aux-High:75dB |
| Input sensitivity (input voltage required for effective output) | MAG:3mV CER/Aux-low:40mV Aux-high:430mV | Tape(Playback):350mV
| Output terminal | Speaker : 8 Ω ~ 16 Ω (switchable) Jacks for stereo headphones Tape-rec DIN Standard Tape Recorder Reconnector |
| Residual noise | 2mV |
| Equalizer | Phono MAG:RIAA |
| Tone control | CR type 2-channel link |
| Loudness control | ON-OFF enabled |
| <General> | |
| Vacuum tubes and diodes used | 12AX7x2 6BM8x4 6BA6x2 6AU6x1 6BE6x1 6AQ8x1 6EA8x2 OA70x3 OA79x6 SD1Ax2 1S351x1 |
| Power supply voltage | 100 VAC / 117 V (Switching Type), 50Hz/60Hz |
| Power consumption | 115W maximum |
| External dimensions | Width 402x Height 139x Depth 336 mm |
| Weight | 10.5kg |