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In recent months we've had through our shop 2 Pioneer SX-1980s, an SX-1250, a SPEC-1 and SPEC-2, a Sansui 9090, and a Yamaha C-800.
I've never cared much for the most common Pioneer SX-n50 and -n80 receivers such as the SX-780. I think there is much better-sounding vintage gear.
When we got in the first SX-1980 and fixed it, I wasn't expecting much. To my great surprise the power amp section is very good. Dynamically correct, unexpectedly detailed for a high-power vintage amp. Pioneer tuners are usually good, so the excellence of the tuner section wasn't a surprise. The second SX-1980 sounded identical after repair and with the caveat that several months passed between the two units, so the fidelity of my aural memory may be an issue.
The next piece we got in was an SX-1250. After repair I hooked it up and was amazed. This is a VERY good sounding amp, better than the SX-1980. It produced bass out of my little B&W DM-303s that I didn't think they were capable of, and that no other amp has produced. And it wasn't just a bunch of overblown muddy bass; it was good tight (upper) bass. This amp sounded better in bass than any other amp in this comparison; only the little Yamaha in class A beat it overall. I think the SX-1250 may be the sweet spot in 1970's Pioneer gear. I'd like to get another.
We then got in a SPEC-1 and SPEC-2. After repair (extensive repair for the SPEC-2) both units worked up to spec and sounded decent. The SPEC-2 just didn't do anything for me. It sounds ok, and it was obviously operating correctly and at least as well as when it left the factory (we upgraded a couple of underdesigned power supply regulators) but I just didn't much care for it.
The Yamaha C-800 has a front panel switch that changes operation from 50 watts per channel in class AB ("Normal") to 15 watts per channel in class A. The switch should not be in the front, and should be integrated with the power switch. Operating the switch changes the rail voltages, which can easily blow the amp if done with the amp on if switched from Normal to Class A. That is exactly what happened to our unit prior to our getting it, and it required extensive repair. In class AB it sounds decent and typical for a Japanese amp of that power rating and vintage. I also hooked it up through an electronic crossover so it only had to handle frequencies above 80 Hz and used a power sub for the rest. WOW! I could play to any loudness I desired and it sounded very, very good. I like class A. It's amazing how loud 15 watts per channel can be if it doesn't have to handle bass. As an aside, that's one big reason I'm in favor of electronic crossovers and separate amps for bass and the mids/highs. It's also amazing how much heat 30 watts is--this guy gets pretty darn warm in class A.
The Sansui 9090 confirmed, a bit to my surprise, my memory of 35 years ago. My first roommate in the Air Force had a brand new Sansui 9090DB (onboard Dolby, the 9090 doesn't have onboard Dolby). I remember thinking that the phono preamp could be used as a noise generator. It was noisier than the stock phono preamp on my Fisher 500B, and the noisiest solid state preamp I've ever heard. Conversations with Sansui enthusiasts led me to question whether my roommates' unit was a nonrepresentative sample. We cleaned the 9090 and replaced some lamps and hooked it up. The result was exactly what I remembered from so long ago. OK sound overall with a terribly noisy phono preamp. Either I've had two bad samples separated by 35 years or they used a lousy phono preamp. Other than the phono preamp the amp sounds typical of a 1970s Japanese receiver--ok, grainy, slightly fatiguing. This is a nice looking amp with nothing to commend it aurally.
Overall, the winner in this small sample is the SX-1250, with the Yamaha C-800 an interesting amp that could be a nice part of a budget audiophile system (in Class A used for mids and highs). The loser is the Sansui. your mileage may vary.
Follow Ups:
Lee, after fixing about a half dozen sansui's I've come to the conclusion I like (SOME) of them but would never own one. Much to my horror after looking inside these units I was amazed that ANY of them are even still around! Great designs but holy cow - did they skimp on parts!!! I mean unrated voltage parts, and even the cheapest of all - ceramic caps with underated voltage. How cheap CAN they get!
And I found the as the price of the Sansui went up the sound quality went down. The cheaper units sounded better than the expensive ones.
As for Pioneer I would classify that as personal taste. They do sound good if that's your thing. I found the Pioneer SX-750 to be quite good. I would go as far as to say it would be a runner for one of the top ten best receivers in that wattage range. I also found the more expensive separates Pioneer made to be AWFUL!!!! Ear bleeders I called them.
Marantz - also a taste had it's sweet spots. Excellent 30 wpc and below and excellent 100wpc and above. Seemed in between those units were fair. with the exception of the 2270.
As for the Yamaha's, I has a CA610 that was wonderful. It did everything well. No flaws but also nothing stood out - if that makes any sense. If there was any mistake I made in audio, selling my Yamaha was it!!!!
charles
Thanks for the interesting data points. More good stuff to keep an eye out for!
Interesting observations. You'd probably like the SX-1010 as well. It's the top model in the SX-n3n series, which preceeded the SX-n50 series.
A lot of guys have raved about Sansui; but I share your views.
I do have a question. When the Yamaha is switched to class A operation; does the Damping Factor change? Actually, what I'm asking is if the source impedance changes; but if it's in the manuals, it would be expressed as DF.
On the Marantz sound. At one point, I owned a Pioneer SX-626 and a Marantz 2230. Similar power, and both have capacitively coupled outputs. In comparisons, they sounded exactly the same and a little on the warm side. The SX-727 and 828 were direct coupled and more neutral.
Jerry
I don't know about the damping factor. I do know it sounds awfully good in class A.
My brother's we often compared his with my Kenwood KA-7300 integrated. Both were excellent mid 70's product.
Three most important things in Audio reproduction: Keep the noise levels low, the power high and the room diffuse.
I have a Yamaha M-80 that has the class A option. It is, as you said, great sounding in Class A, and runs very hot. It is decent, but not remarkable in Class A/B, but it has a lot of power. I like the idea of having an amp with dual personalities. Sometimes I just want to shake the walls, but most of the time, I want great sound at a reasonable sound lever.I was considering rebuilding it. What did you do to repair the CA-800?
Dave
Edits: 07/09/12
Replaced the filter caps and a hell of a lot of transistors, resistors, capacitors, etc., that had been stressed or failed due to hot switching. man o man is that a bad design to put the switch on front.
I wonder if that is the case with my M-80. I did not have a problem since I mostly left it in Class A. I will try to research it.
Dave
A couple years ago I started getting into vintage hifi, almost randomly. I have a thoroughly modern, high end stereo, but bought a vintage Marantz receiver to use as a headphone amp, and kind of got bitten by the bug a bit.
I now have a fully recapped Pioneer SX-1980, Sansui 9090DB, and Marantz 2285. There is no doubt that to my ears, the Pioneer is the best sounding, in that it is the most neutral. I do not mean neutral as a euphemism for bright - it may be ever so slightly warm, but I hear it as editorializing very, very little, and possessing a superb tuner and phono stage (complete with variable MM loading options). I pair it with Infinity Kappa 6's and Pioneer HPM-100's, and dig it with both.
The Marantz I also really, really enjoy, but it is undeniably warm. Very pretty sounding, almost hard to believe its not tube. But not think, opaque, or slow. It's currently paired with Spendor LS3/5As in my office, and sounds lovely. Again, very goof FM and phono, though clearly below the 1980 on both.
the Sansui for me also comes in last. It's also a bit warm, but a bit thick and murky sounding compared to the other two. Not tragically, but it just isn't as good. same goes for the tuner and the phono. Again, all three were completely recapped except for the main filter caps.
Also, JMO!
Rob
"Let there be songs, to fill the air"
Lee,
I'm curious as to what specific repairs you had to do to the SX-1250. Any pitfalls to report? I would appreciate any comments as I have one in the queue.
John
Don't remember all of it. Replaced the big electrolytics and a couple of the smaller ones, cleaned, set bias, replaced the zeners, etc. I don't know that there were any pitfalls, but there was a lot of work.
nt
It's been many years now but I was really excited to find a 9090 -- until I heard it. It was the most lifeless sounding vintage piece ever...until the 'loudness' button was engaged. Then it came to life.
Later came a few others including a G87000 something, and it too was unsatisfying, so I wrote off the brand.
The 50-series Pioneers were as you described, muscular but perhaps a bit 'hard' sounding. I found them best with boxy east coast speakers, but too rough for revealing speakers like horns or 'stats. The bass was great though!
... an amplifier that, in Class A, need make no apologies for itself. And fifteen watts is plenty for speakers with triple-digit sensitivity (trust me on this).
Given the SX-1250 comments, and the fact I have a SX-1050 quite literally gathering dust downstairs (well, actually, I have a cloth draped over it)... wonder how it might fare...
all the best,
mrh
I had a SX-1980 once - bought it in an estate sale, and it looked almost new. The sound never did impress me that much - I don't know, it just didn't do anything for me.
I agree with you on the SX-1250, in fact, I think the SX-x50 series of Pioneers were their best of the late 70's. The SX-x80 series were pretty bad in my opinion. Still, the best sounding one I've ever had was the SX-1010, which came out in the mid '70's I think.
Sansui has never really impressed me either, and I never ran across one that was working perfectly.....always something wrong with it.
After years of auditioning all sizes types of receivers I'm of the opinion that any solid state receiver or amp over about 50 watts per channel is overkill.
Your comment about 50 watts rang a bell. Years ago, Bob Carver commented that amps under 60 w/ch were all pretty good and that he had never seen "sticking" behavior in them. Problems begin to occur when output devices are paralleled and that occurs above 60 w/ch. on the older stuff.
Jerry
Got a 'sui 9090 a few years back. Recapped that pup, & upgraded internal speaker wiring to 16 gauge. It was warm in spades, but those 110 watts per channel didn't sound any louder than a Marantz MR-235's 35 wpcs. Just when 9090 started to sound sweet around one-third volume, that damn protection circuit would kick in. It wiped out a feces-load of tweets, including two Utility Advent tweets. Bass-bottomed out a hemp-coned Celestion V-30 too, which was wired in Hafler centre-channel configuration. However, with Ibanez Les Paul Custom copy plugged into microphone imput, it wiped out a 12" Electro Voice Force without even flickering protection light. Much prefer 'sui 5000X instead. Luis of stereoadvisor said 9090s were designed to sound warm-n-lush, whilst 5000Xs were more "neutral" in sonic delivery. Even with cap-coupled output. Still have mad love for Pioneer SX-780. Emulates Marantz sound when speaker protection relay is bypassed. Brown Soun's John Harrison demonstrates his hemp coned home theatre speakers with Pioneer SX-5590 (European black-faced SX-1250). 73s para Sactown !!!
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