Pioneer SX-780

Pioneer SX-780

This is the Pioneer SX-780. It was the last of Pioneer’s 700 series receivers and was very well built. It was produced from 1978 up until 1980 and had a list price of $325.00.

The SX-780 was rated at 45 watts per channel but that was probably under rated. The internals were high quality with Darlington STK-0050 Power Packs in the output stage as well as high quality Nichicon capacitors.

While it had crisp FM reception some feel that its FM selectivity is a little weak. It also has a great phono pre-amp section but could have used some more AUX inputs. Overall a great starter receiver for someone just getting into the vintage audio scene.

Pioneer SX-780 Front

It features:

  • AM/FM stereo receiver
  • A + B speaker outputs
  • 4 RCA inputs: Aux, Tape1, Tape2, Phono
  • 2 RCA outputs: Tape1, Tape 2
  • Chassis grounding post
  • Bass + Treble tone controls
  • Loudness switch
  • 15hz low frequency filter
  • Headphone output
Pioneer SX-780 Back

The Pioneer SX-780’s sell for around $500-700 in very good working condition.

Available on Ebay

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28 thoughts on “Pioneer SX-780

  1. I have one of these that powers on but doesn’t deliver sound through the speaker outputs or the headphones. Is there a common cause for this that you are aware of?

    1. I would check the mono/stereo switch. The signal passes through the switch and if worn out it could be staying open. Do the headphones work? If so I’d suspect the output transformer or power section.

    2. I still have my SX-780 which lost sound from one speaker. I was working as an electronics tech at the time and had to troubleshoot the problem. It turned out to be the Power Pack. I ordered one and after replacing the suspect part and connecting the speakers, I once again had sound from both channels.

  2. CAN I USE THE STEREO/MONO SWITCH FOR LISTENING TO STEREO/MONAURAL, AND FULL FREQUENCY RANGE RECORDING REGARDING VINYL RECORDINGS? IF I’M NOT LISTENING TO A STEREO RECORD, SHOULD I SWITCH TO MONO? THANK YOU FOR YOR HELP.

  3. I’ve read elsewhere that some feel the 750 was higher quality, as evidenced by a superior heat-sinking design as well as other items. Do you know if this is a general assumption: did quality dip with the 780, 880 and 980 series?

  4. So with that phono pre amp.They will hook right up with today’s turntables say a..U turn or a Pro ject. And work correct ?

  5. Rob: Yes, though some turntables today have built-in pre-amps and do not need a receiver like this to produce music. But, with this receiver you will see (hear) much increased sound quality and volume. The amps in these vintage receivers are far, far superior to the cheap built-in amps in many of today’s turntables.

  6. A couple days ago, rescued one of these out of a recycling bin. Spent a couple evenings cleaning the nicotine and dust off the exterior. Straightened the knobs and switches. Was In great cosmetic shape. Guess the nicotine acted as a preservative. Washed and dried the boards with alcohol. Flushed the pots and switches with DeOxit. I hooked it up to a dim bulb tester to bring up the power slowly. No issues. After warmup, adjusted the bias, didn’t need much. Ordered some 8V LEDs because the lamps were burned out. Sonically, seems to be great hooked up to my AR-2AX speakers which are streaming HiRez audio from Tidal.

  7. Just scored one of these for free from my job. I work at an electronics recycling facility and saw it on a shelf and bee-lined over to it. The outer shell is a little beat up, and after getting it home I found the headphone jack doesn’t work. It could be an easy fix, but I’m not too worried about it. I hooked up my LP-120 to it, and some Pioneer floor speakers and it has some serious power behind it. Does anyone have any suggestions for a good tape deck to add?

    1. I have mine paired with a Kenwood KX-3510 cassette deck; which came out in 1989 and is a top quality all metal tape deck. I mean the entire thing is metal, face plate, the body the flywheels etc. And with hx-pro you can’t go wrong. Sounds amazing.

  8. Can anyone provide the value of a Pioneer SX-780 in great shape but not working? I have no way of repairing it at a reasonable price so I would like to sell mine which i purchased in 1979.

    1. If you take this to a reputable repair shop to get it fixed & serviced, you’d likely be able to obtain as much as $500 for it on Ebay. Outward appearances are important to value so if it’s electronically sound, it’ll sell well. My guess is once you have it fixed and serviced, you might want to keep it, esp. if you hook it up to some good speakers and listen to a good piece of music. Their sound is amazing for a ss receiver.

  9. The Sanyo STK 0050 Darlington power packs tend to go bad but you can replace them with new replacement modules already assembled from delta9 electronics on eBay. They work beautifully. Any other aftermarket STKs are going to dissolve or blow up so get these modules. Then the Pioneer really sings with a nice, hefty, authoritative tone. I love it.

  10. I have a nice working sx-780 but given its age I am sure you will see it soon for repairs. I just upgraded speakers to Klipsch 600m. One thing about the 600m is little 6″ woofer. Is there a way to hook up a sub woofer on this old receiver? Not big… i need just a “little more” base… not much.

    Thanks

  11. I have a sx-780 receiver and would like to hook up a CD player. Am wondering about sound quality or do I need some kind of filter ?

    1. Jim, I run my CD player using old-school RCA cables into one of the AUX inputs on the back of my SX780 (or most any vintage receiver) and it sounds great.

  12. Looking for New(ha, ha)or refurbished Pioneer Stereo to record Vinyl to Cassette and CDs.
    Like new. Maybe with a warranty of refurbished.

    Please email me Thank you Mike G

  13. My McIntosh tube blew a thermistor a couple weeks ago so I had to bring it in for a long overdue overhaul. I had an SX-780 that I picked up for $50 from a local classified sitting on the shelf. Considering it would be a good 5 weeks before I got my Mac back, I figured I’d spark up the 780 to get me through the wait. All I can say is WOW! When I picked mine up about a year or so ago, I got it from the original owner and it was in spotless shape. I only powered it on and tested it and then shelved it. Now that I’m putting it through the paces, I can clearly see (and hear) that it is a fantastic amp. It’s definitely making the wait for my Mac a lot more bearable.

  14. I just bought one of these on eBay for $250. It has some burned out dial lamps and the usual dings in the wood, but has been tested, and pronounced “Fully Functional”.

    I’ll run it through my shop and give it a good scrubbing, and it will be my workshop stereo.

    – Jim

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