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Clarification on SX model lines

Rubber Ducky

Rubber Ducky

Member
Hi, newb here. I apologize if this has been answered somewhere before, but I've recently started getting back into vintage gear (especially Pioneer) and it would help if I could understand what the differences are between the SX receiver lines:

x50
x80
x2x
x3x
3x00

Is it just features? black or silver faces, black meters, blue vs white lighting, etc.

I recently bought an SX-780 that I'll be using primarily for headphone listening. About 20 years ago I had a SX-3800 and a couple of fluoroscan-equipped tape decks (CTF900, IIRC) and a PL-500 tt. Love the Pioneer gear.
 
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I can comment on the 3 Pioneer receivers I have
1. SX-1000TW
2. SX-636
3. SX-950

I listed in them by age and 'warmth' of sound.
I like them all.
The 1000TW and 636 are both very strong in the low frequencies.
The 950 is more neutral, but still strong low down. It's a nice balance.
My 950 and 1000TW are both refurbished (caps and transistors). The 636 untouched, so the comparison may not be valid.

I have never had an x80-series receiver, but it is newer still than the x50s. It probably is biased a bit further toward neutrality in tone than the x50s.
I think that some of the x80s have integrated circuit amplifiers that are difficult to find if they fail.
I love their black-faced meters, though. They are very similar to but flashier than the x50s.

My first stereo was an SX-550, so I have a soft spot for the 50 series.
 
A little googling and I managed to find this site, which was somewhat helpful - http://classicreceivers.com/

So it seems the x80 line superceded the x50 line, but the x80 line has output transistors that are difficult to find. Also the x80 line has black meters whereas the x50 line had white meters. Other than that just minor differences. The 3700, 3800 and 3900 ushered in the 80's with fluoroscan meters and digital tuner displays. The monster receivers were the SX-1010 thru SX-1980. The 1980 goes for stupid money these days! There's one on ebay right now for $5,800 and another for $4,700. Fully restored, of course.
 
model series in ROUGH chronological order:
1971: x2x SX-424, SX-525, SX-626, SX-727, SX-828,
1974: x3x SX-434, SX-535, SX-636, SX-737, SX-838, SX-939, SX-1010
1975: some x3x blackface: SX-5530, SX-7730, SX-9930 (the "black face" versions of the SX-535, SX-737,& SX939 respectively)
1976: x50 SX-450, SX-550, SX-650, SX-750, SX-850, SX-950, SX-1050, sx-1250
1976: x50 SX-5560, SX-5570, SX-5580 (also "black face" versions of the SX-750, SX-950, & SX-1050, respectively)
1978: x80 XX-XXX, SX-580, SX-680, SX-780, SX-880, SX-980, SX-1080, SX-1280, SX-1980
1980: 3x00 SX-3400, SX-3500, SX-3600, SX-3700, SX-3800, SX-3900
1980: SX-D5000, SX-D7000

sometimes the higher powered models came out a year earlier.

Basically as technology advanced, the next model series was introduced, from mostly transistors through integrated circuits.


edit 10-27-2019:
Moth R. Superior said:
also:
1975: SX-5530, SX-7730, SX-9930 (the "black face" versions of the SX-535, SX-737,& SX939 respectively)
1976: SX-5560, SX-5570, SX-5580 (also "black face" versions of the SX-750, SX-950, & SX-1050, respectively)
These versions only being available over seas for servicemen
(it was just such a complete and thorough list, I just had to contribute)
Click to expand...

credit to Moth R Superior for the blackface information.
 
Last edited:
The x80 series output transistors can be substituted by modern replacements, with some mechanical retrofitting.
 
The most notable diferences were the subtle cosmetics and as you mentioned the final stage outputs. The x50's utilized the typical T03 semis whilst the x80s had the integrated STKs which are rare as hens teeth. As mark mentioned, there a some guys here who have an STK replacement upgrade, so all is not lost if you have an x80 series.
I have an SX 690 (same as a 680) and an SX-780. I'm confident.
 
Thanks for the info on the STKs! It's good to know I have options if and when mine blow up, other than buying another receiver.
 
Aren't the outputs on the x50 series (850, 950, 1050, 1250) also readily available should replacements be needed?
 
learning the gutz of these machines now - never thought i would need this intel until you are looking at a restoration. one thing I do remember about the differences in the years was the x50 were solid state? and AC amps? and when the x80 series came along, the amps were DC, and in that change, the THD went from .1 to .01. I naturally, at the time, wished I had waited a year. But later, in college, neighbor with his 1280 had problems, and my x950 was still humming along. So I had an impression that the x50 were more durable. these dates were early 80s when he had those issues, not more than a few years after it was brand new.

cheers,
g
 
markthefixer said:
model series in ROUGH chronological order:
1971: x2x SX-424, SX-525, SX-626, SX-727, SX-828,
1974: x3x SX-434, SX-535, SX-636, SX-737, SX-838, SX-939, SX-1010
1976: x50 SX-450, SX-550, SX-650, SX-750, SX-850, SX-950, SX-1050, sx-1250
1978: x80 XX-XXX, SX-580, SX-680, SX-780, SX-880, SX-980, SX-1080, SX-1280, SX-1980
1980: 3x00 SX-3400, SX-3500, SX-3600, SX-3700, SX-3800, SX-3900
1980: SX-D5000, SX-D7000

sometimes the higher powered models came out a year earlier.

Basically as technology advanced, the next model series was introduced, from mostly transistors through integrated circuits.
Click to expand...

also:
1975: SX-5530, SX-7730, SX-9930 (the "black face" versions of the SX-535, SX-737,& SX939 respectively)
1976: SX-5560, SX-5570, SX-5580 (also "black face" versions of the SX-750, SX-950, & SX-1050, respectively)
These versions only being available over seas for servicemen
(it was just such a complete and thorough list, I just had to contribute)
 
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