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Pioneer SX-680

AM/FM Stereo Receiver (1978)

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Pioneer SX-680


Tuning range: FM, MW

Power output: 30 watts per channel into 8Ω (stereo)

Frequency response: 5Hz to 100kHz

Total harmonic distortion: 0.1%

Damping factor: 25

Input sensitivity: 2.5mV (MM), 150mV (line)

Signal to noise ratio: 75dB (MM), 90dB (line)

Output: 150mV (line)

Speaker load impedance: 4Ω (minimum)

Dimensions: 435 x 144.5 x 314mm

Weight: 8.9kg

Accessories: FM T-type antenna



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Reviewed Jul 19th, 2019 by jamminjerome

This was an awesome receiver back in the day. Used it with Yamaha NS-10M's. those 30 watts a side sounded like 250 watts through these speakers.

Reviewed Jun 10th, 2019 by fatmouseinhome

I got this piece from a fire home. It took quite a bit of cleaning, both external and internal. But I got it for free, so what is sweat equity worth. After all the cleaning I finally had some time to sit and listen to this piece. First thing I found, and should not be surprised, is how good the tuner is in this receiver. Great separation, and reception for FM and clean AM. I used this receiver with 3 different types of speakers. I also had a BSR vintage turntable hook up to it. Also a Harman Kardon BT10 Bluetooth receiver streaming Tital music. The sound with the turntable was in my opinion out standing. good volume (no Pre-amp) great tone, flat response, (all settings flat) no loudness. The receiver has great headroom to let the sound really come through as recorded. The first set of speakers I listened through were Hafler 2 way 6 book shelf speaker. and this receiver powered them perfectly. The second set were Hafler 3 way 2x 6 woofer, 1 tweeter. The sound was again outstanding, but I noticed that the receiver was working much harder with these speakers. But they are a very power hungry speaker rated 25 to 250 / 125 nominal. But it still sounded great just would not recommend pushing the volume much past half, or the receiver will start to clip and start running hot. The third set I ran were a set of Advent Legacy II with a 10 woofer and 1.5 dome tweeter. These are era correct for this receiver and matched perfectly. The sound was full and loud, and again lots of headroom using all three sources. the receiver did get warm at higher volume, but nothing close to hot, nor did it shut down at any point. I would recommend if you have the chance to pick one of these up for a reasonable price, it would make a perfect office, bedroom, den, etc. system with a quality turntable. you will get GOOD sound, at moderate to loud volume levels. Simple, Clean, powerful, Cheap. for a good clean fully functioning example, expect to pay around $200 to $275 ??

Reviewed Apr 02nd, 2019 by Knilas

All that you could ever want in a vintage tuner

Reviewed Nov 29th, 2016 by MikeofBournemouth

This old timer has a reasonably good all round sound. I believe people prefer the older models. My son borrowed it for just over 5 years, its come back with its Left Power meter FSD and hum out of the left speaker. I'm guessing STK failure? Anyone disagree?
Kind Regards

Reviewed Nov 28th, 2015 by RTM

This was my first Hi-Fi receiver and it provided just enough of a glimpse of that line's quality to understand what it's big brothers could do if you had the scratch to pay the price of entry. It's a great starter receiver.

Reviewed Nov 26th, 2014 by César Concha Zevallos

it is very good

Reviewed Mar 09th, 2014 by joe4fun

This is a nice little receiver which has a big sound for its size and specs (30wpc). Nice black power meters, and accurate controls. These things are little workhorses. The only thing it could have used besides some toggles for bass and treble boost might be additional connections on the back to support more gear. I use mine as a workshop music source and I can vouch for this unit- Also great FM Tuner, which does not drift.



re: SX-680

I have a Pioneer SX-680 I purchased in 1976 I believe. I now have it stored in garage. Does not currently operate. The poweramp went out once in the past but was replaced and it contiuned to work for awhile. Wondering what to do with it. I also believe that the tuner does not move with the dial.

re: SX-680 barely audible left channel both A and B

Hi, I am new to the "engine" I hope I can help some time, but at this point I am just beginning. I have found a Pioneer SX 608 on a sidewalk heap waiting to be hauled away! OK, but the excitement faded as soon as I found one side with barely a faint sound coming out. I faded left to right and back on the balance, but neither speaker set A nor B left channel puts out much more than a faint sound. No crackling on any knobs as I am turning what-so-ever so I think that is a good sign? I opened the box up and blew the dust out. I found no fuses blown. I found nothing loose or solder joints that might be cold as far as I can see. no cracks in the boards. I don't have a old set of earphones and no adapter so I can't check the headphone out yet. the right channel is quite crisp, I can't wait to listen in stereo! Can any one start me on the way to checking for solutions? I have no electronic checking equipment, I am a user, but I have some knowledge about what the inside should look like and I know some of the parts (fuses, transformer, and a few other obvious parts.) I did notice a small dribbling of some reddish liquid inside dried up near the right rear of the transformer, but it is limited (looks like grenadine!) OH yeah, I noticed that I feel a kinda hum or vibration-like feel as if there is some sort of charge to the outside of case on the metal parts? I am not sure if I explained that feeling, but i remember having an old record player and it was a similar feel, as if there is some sort of poor wiring and a prickly feel to any metal or external/exposed screws on the unit. Where do I begin? Thanks so much, if you can direct me.

karodimitrov's picture

re: SX-680 barely audible left channel both A and B

Hi.In your case(without equipment)try this:open amp. there are two equal channels with STK-0039.(remove undercover,turn power "ON")-be careful.Begin from "Volume Control" resistor(must see it on main board plate).Touch with thin metal jumper middle points of resistor-one is "left",another-"right"channel.Hum...if equal for 2 ch.-OK.If not-check visually capacitors for swellings or leaks.And then-
voltmeter...:)))Hope understand my English!:)))Luck!
P.S. By this way you can check all circuit-to end of amp,skipping preamp. and switches(works for them too)-but be careful-hum can be too loud,and keep away from high voltage.

Dead Pioneer SX-680

HELP!! Just bought a Pioneer SX-680 off of eBay, plugged it in, NO sound
coming out of it, even thru the headphone jack. No static even. Unit looks
very clean, undamaged, doesn't even look like it's ever been serviced. All
fuses look good, tuner section appears to be fine. Bad power transformer

SX-680 problem

Because this unit didn't have the usual pre out to power amp in RCA's on the back, You can try cleaning the switches and pots, like the tape monitor switch, etc. I have seen these units not pass signal, because of dirty switches and pots, not even hum would pass to the outputs. I have seen this problem on the cleanest looking units through our shop. The dirt is more like a fine film and makes those old switches inoperable. If the fuses on the back are good, it is likely not the output I.C.'s.

sx680 pegging right power meter

just got this receiver off e-bay, has a blown right channel, gonna change the stk 0039 output ic and see if that fixes 'er up......thanx for the service lit. that helps a lot! miklsee

fatagnus's picture

Pioneer SX-680 Good Grief~

Got mine as a rescue project from someone moving out to smaller spaces. It had so many dust kittys I just washed it down inside with MCM cleaner/degreaser. It didn't play right for about an hour or two - think it was drunk. Then it just snapped to attention - guess the liquid finally dried off the tuning caps. I am so impressed with the FM sensitivity - it is pulling in stations my Marantz can only dream of... I get several stereo receptions from Baltimore here in Washington DC - which in the old days wouldn't be remarkable. Also, it has plenty of power and I cannot believe the THD specs - 0.1% - this unit sounds better than indicated. Of course I didn't crank it and always listen critically <;^) Does anyone know what dBf is in reference to? I found that in the specification sheet on the FM tuner section. Would it be dB in reference to the noise floor? Which itself would vary among each unit. Thanks to this website and responsive members and readers. Greatly appreciated.

Pioneer Manual

My beloved receiver came out of the attic to thrill my son. Who woulda thought when I bought this at age 16 that my son would be showing it off to his friends! Seems he popped a channel though, so Dad to the rescue. Wish me luck fixing it!!

Hi there: I just obtained a

Hi there: I just obtained a 680 as well with a whisper if anything coming out of the right channel and was wondering what is the cause of this situation, Power amps?

Thank you

Thank you to who ever uploaded this manual.

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