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Pioneer SX-939

AM/FM Stereo Receiver (1974-76)

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Pioneer SX-939


The Pioneer SX-939 is a highly versatile, big powered FM/MW stereo receiver.

The unit features a parallel push pull OCL power amplifier with less than 0.3% total harmonic distortion, a completely new PLL MPX circuit, frequency linear 4-gang variable capacitor and a newly developed IC AM.

It also has a twin control system and duplication switch, and Dolby adapter in/out terminals with switch.


Tuning range: FM, MW

Power output: 70 watts per channel into 8Ω (stereo)

Frequency response: 10Hz to 40kHz

Total harmonic distortion: 0.3%

Damping factor: 45

Input sensitivity: 2mV (mic), 2.5mV (MM), 150mV (DIN), 150mV (line)

Signal to noise ratio: 65dB (mic), 70dB (MM), 95dB (line)

Output: 150mV (line), 30mV (DIN), 1V (Pre out)

Speaker load impedance: 4Ω (minimum)

Semiconductors: 3 x FET, 4 x IC, 57 x transistors, 39 x diodes

Dimensions: 520 x 175 x 420mm

Weight: 18.5kg

Accessories: FM T-type antenna


instruction/owners manual   English -

service manual   English -

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Reviewed Jan 22nd, 2016 by Stildawg

Had my SX 939 for a year now. It sounds great and has a warm sound to it. It does get loud when needed and I can't say enough about it. It looks really cool to, I had it re capped and new LEDs. It is a pain to recap there are a ton of capacitors.

Reviewed Apr 09th, 2014 by starbender

I always wanted x2x - x3x series receiver. Finally got SX-939. Build quality is impressive. These series has nice warm-mellow sound. Tried three different speaker. Especially bass response is unbeatable. If you are looking for a tube-like sound and eye candy looks, this is the one!



re: SX-939 vs. 737

I have a SX-737 I bought new in 1975 along with the 939 I was gifted 3 years ago. The 939 was almost a basket case. Had to replace the Front panel, Power switch, and the board with the -20db cut. Unit has been recapped with Nichicon UPW and UKL's, and Panasonic ECQ's for the films or to replace 2.2uf Sky Blue Sanyo caps.

Putting the 737 and 939 together and using an A/B switch, The 737 gives up nothing except for SPL. Twice the wattage on the 939. I don't care for the DUAL TONE Controls, and the function switches need constant (semi-annual) cleanings just like the 1010(which shares the Front panel and most of the boards). Other than that the 939 is a really good under the radar receiver.

If you want a 1010 and can't afford one, get a 939! The only thing you give up is about 30Watts in power, but 99% of your listening is below 3watts anyway, unless you have a death wish and crank it to 11 all the time.

As for me I've never had a receiver over 60W (FISHER 700-T is 65W) until I bought a 1010 and wasn't really impressed with it except for the sheer size of it. I did a complete rebuild and sold it for 5 times what I paid for it. All of my receivers are 20-50 watts except for the above FISHER, and will rattle the windows with 98db speakers.

Again. If you want a 1010 and the prices scare the crap out of you, go for the 939. Internally it's basically identical except for the amplifier board. It sounds the same as the 1010, but with less wattage. But for me the 737 is the biggest bang for the buck in the x3x series. In either case you win.

re: SX-939 vs. 737

Indeed, most people that use normal listening levels only use less than 5 watts.
But alas, some people are power-hungry, or simply trying to make up for other shortcomings :)
As for me, my Technics receiver is 60/60 watts, and I'll never use all that power - I like my Advent Maestro speakers too much to stress them out, and I like my neighbors too, so I don't intend to piss them off.

re: SX-939 vs. 737

I would consider using 5 watts to be "normal" listening level if I had guests that were in a mood to debate the economic insanity that The US Fed is unleashing to slow the total collapse of our worthless fiat currency. But if I want to seriously listen to music, a minimum of 100 watts per channel is necessary to provide headroom and keep the distortion low. I love my Carver Platinum series Amazing Loudspeakers, but they are hungry for power and I just bought a Phase Linear 700 to find out what their potential sonic output is. And as far as my neighbor goes... I don't always listen to Metallica- but when I do>so will he!! And it will be in the afternoon, not late at night, so he'll have to deal with it. :-) Also, I appreciate your concern, BUT I have absolutely no shortcomings in 'other areas'..... I just enjoy music at high volume levels to re-create the magic of the bands live performance.Different strokes for different folks keeps the world interesting.

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