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 $500-900 in very good working condition.

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47 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.


  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.

      1. Hi, Altho this is almost 3 yrs old, I picked up an sx650 and liked it so much that I grabbed its older brothers, an SX750 and 2 SX780’s. I am very pleased. I’ll probably sell the 780’s and put the$$ to an

  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.


    1. They really sound fine, I have 2 780s I want to sell, I had them hooked to my Cerwin V SL-12s dayum loads of bass. or my Magnavox 3 ways floor spkrs. these 780’s ARE nice receivers.
      yeah u lose 5 watts from the SX750 but I’m telling you a good pair of speakers will sing like
      Caruso. The sounded sweet w JBL A180’s too. 774-225-4753

  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.

    2. I use a K&N on my Harleys so they are good filters! But for a cd player on a 780 nope no need.
      I have used a 37$ player from best buy w my sx780 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.

    1. Yes, you can hook up a powered subwoofer that has speaker level inputs. Connect that to the b channel on the back of the receiver. It won’t draw much power from the amp as the sub will be providing its own power. I run this config on my SX-780 all the time using a variety of speakers with no problem.

  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

  15. Bought my SX-780 new in 1978 and have used it (hard) ever since. Replaced a power transistor about 5 years in but this it still works as perfectly as I could want. Lots of horsepower, drives 4 big speakers and works 8 hours a day, longer on weekends. Cost me $400 in Canada. Best buy of my life.

  16. I had the signal path on mine recapped–it took 34–but wow, it sounds wonderful. Coupled with new modules for the failing STK-0050 Darlington Power Packs brings this nice piece of equipment to a new and better second life.

  17. Bought one refurbished and the treble is really low. Not sure if this is typical of the 780. Sounds that way through headphones and speakers. I turn the bass knob from min to max and there is a significant change in the sound (it does BOOM) but when I do the same with the treble knob there is not much change in the sound. I’m kind of unsatisfied and I hope something is not wrong. I am a drummer and I love to hear cymbals and hi-hats and other subtle stuff going on on the high end. Anyone have the same experience or should I take it back for service? Can that even be corrected?

    1. If lacking treble something is wrong – the 780’s are very “bright”. A service should correct it. I have a SX-1250, a SX-1010 and my little SX-780 hangs with them better than one would expect – great little receiver.

      1. The bass and treble on these receivers are quite nice, a wide bandspread is what I call it.
        The sx650 was the first receiver I got at a thrift shop, being so impressed I got an SX750 and 2 780s. The sx650 works my Cerwin-Vega SL-12’s damn well, at half the volume, those speakers put out a lot of music.

      2. It is one of the reasons I like the sx jobs, very good tone in both the treble and bass.
        I started with an sx 650 I bought from a church thrift shop and that was the springboard to get me to an sx750, 2 780s, and an sx850 These are very good receivers so you will want one very good pair of speakers like JBLA180s or Cerwin Vega SL-12s.

  18. I have had a pioneer pl-560 for years, but it has been running through a late off-brand 80 receiver. I am looking at a 737 or a 780 to pair with it. I would like an opinion from a more experienced person about what they would choose between the two. Thanks

  19. Just picked up the SX780. Near perfect condition, just had one very small scratch on the side. Paid $300.00 for it. I have it hooked up to my 2000 Klipsch Synergy 10.5 tower speakers. It sounds amazing ,the speakers were being powered by a Yamaha studio AX550 receiver, I believe it’s a 2002 model. This set up sounds so much better and don’t have to turn it up past 2-3 . I do think the FM tuner on it is week though. Can’t pick up 2 of the 3 stations in my area. Is there a solution to that issue ?

  20. I don’t have an SX780, but an SX650, I have to say, I am very impressed with it and wish I started with the 650 way back when I wanted some good tunes. That being said, I will be looking for an SX780 later this year. Currently owning three Kenwoods a KR6030 and two KR6600’s The 6600s seem to have a bit more spread in the bass and treble controls.
    I have heard as others may have, that the SX750 has a warmer sound to it as compared to the 780. Either way, I’d say getting my hands on an SX 780 would be very nice.

    1. Well it is later and I have two Sx780s and an sx750 all damn nice, I am going to sell the 2 780s and go for an SX850. These are fine receivers and look and work much better than anything in the later 80s and onwards. Even the Kenwoods that I like so much went down the dirt hi-way in the late 80s much smaller, all black with pushbutton tuning, and a 1-inch sq. window w an led readout. Exit stage left, um outa here.

  21. I have my sx-780 paired to Klipsch KG-4’s. I listen to music through this system but also use it for TV sound. I’m would like to add in the Klipsch R-52C Center Channel to add a little more definition. But obviously the sx-780 is a stereo receiver, not 5.1. It does have A/B channels to send stereo signal to another pair of speakers.
    Is there a way to use the stereo B output to power the Center Channel speaker?
    How would I wire that into essentially mono output – without burning up the power output stage of the amp?

  22. pulled my sx-780 out of a pile at the scrap yard, THE SCRAPYARD, anyway, after saving thing this beautiful piece of my historic childhood I went to work cleaning and loving her. but she says nothing, always full of energy, but nothing to say. headphones, inputs, even the FM/AM is silent/ I’m good with technology. I had an IBM personal system 2 (the first PS2, lol) and the commodore 64 at the ripe age of 6 or 7, and a tolerant family as i ripped them apart and put them back together, nothing was safe. this was my dad’s, (he owned the same unit back in the day) and was the first stereo i tore apart believe it or not, maybe why i can’t let it die. but this is infuriating. i have power, the power packs have power, everywhere i check i have power, but the source light stays on, whether or not a signal is running to it, even when i switch to tape monitor. I’ve checked the grounds and all the wiring. i feel like I’m going crazy. any help here?

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