• The move to the new server is done. There are some software and database maintenance updates in process. This has us passing the hat around to help out. We appreciate any donations. Seriously, even a dollar helps. The payment page may be found here - https://www.audiokarma.org/support.html

SX-850 vs SX-950 Differences

ukfan4sure!

ukfan4sure!

Expert Smoke Releaser
I have both an SX-850 and an SX-950. In casual observation, I can find little physical differences in the two units, other than 15KuF vs 22KuF power capacitors, and 2 vs 3 speaker hookups.

Is it the ratings on the output transisitors that make the difference between 65 and 85 WPC?

I have a 950 schematic, but not the 850.

Thanks.
 
Register to hide this ad
The SX-850 owner's manual and service manual can both be found here:

http://www.kallhovde.com/pioneer/Pioneer/Main scan page.html

From a quick look at an old brochure:

http://www.kallhovde.com/pioneer/pio-76-77-b.pdf

it looks like the only difference is a slight increase in power for the SX-950 and the third speaker connection for the SX-950, which you have mentioned. I have not, however, compared schematics or done any kind of detailed examination, but it appears as though they are nearly equal.
 
Pyrrho said:
From a quick look at an old brochure:

http://www.kallhovde.com/pioneer/pio-76-77-b.pdf

it looks like the only difference is a slight increase in power for the SX-950 and the third speaker connection for the SX-950, which you have mentioned. I have not, however, compared schematics or done any kind of detailed examination, but it appears as though they are nearly equal.
Click to expand...

It's interesting in the description of the 950 and the 1050, they mention a "separable pre-amp" for each, but do not mention that in the 850 description. Yet, it also has that feature.
 
From looking at the brochure again (the chart toward the end of the brochure), I see that I missed something. According to it, the AM tuner selectivity is different in the two models. You might want to look at the owner's manuals for both and compare the more detailed specifications listed in them.

One of the things that struck me about the brochure is that they claim the two weigh the same. They also list the same dimensions.

I have never thought about this before, but it is making me think that the SX-850 was likely a better value when they were new, unless the prices were very, very close.
 
The power supply would have to be different to achieve 85 WPC vs. 65WPC. Most likely a different transformer and rail voltages at the output transistors.
 
EastPoint said:
They have basically identical boards for power supply, protection, amp, preamp, and phono.
Click to expand...

OK, so the 950 has the AWE 066 tuner board, and AWH 050 Power Amp board. The 850 has the AWE 071 Tuner and the AWH 059 Power Amp board. So, the tuner in the 950 is better and the power amp board has higher voltages. The transformer for the 950 is an ATT-265 and the SX-850 is an ATT-302. The output transistors are different between the two also.

And of course, the speaker switch assy boards are different; with the 950 having 3 vs the 850's 2. Input fuses are 6a (950) vs 5a (850).

Both share Power supply, Protection, Tone amp, Flat amp, and Phono boards.
 
I also have an example of each. The basic differences are the output transistor ratings and power transformers. The SX-950 runs the rails at about ±5V more than the SX-850, and the outputs are sized accordingly with 8A devices (collector current) versus 6A devices.
 
The SX-950 also has a different FM front end, with an extra ceramic filter (4 instead of 3 for the SX-850) and another J-FET instead of bipolars used in the SX-850. Frankly, I can't tell any difference between the SX-850, SX-950, and SX-1250 for tuner sensitivity, even though the SX-1250 has five gangs in the FM section of the VC versus four for the SX-850 and SX-950.
 
Watthour said:
The SX-950 also has a different FM front end, with an extra ceramic filter (4 instead of 3 for the SX-850) and another J-FET instead of bipolars used in the SX-850. Frankly, I can't tell any difference between the SX-850, SX-950, and SX-1250 for tuner sensitivity, even though the SX-1250 has five gangs in the FM section of the VC versus four for the SX-850 and SX-950.
Click to expand...

With differences in tuner performance, that will not tend to be noticed when they all are decent and the signal from the station is good. Differences in tuner performance tend to show up in situations of a poor, weak signal from a radio station. (Or, for some aspects of tuner performance, an overly strong signal.) And then to properly compare, one would have to be using the same antenna, in precisely the same location, which most people are not going to do when comparing things. In most locations, the tuners in all three will be fine and be of little, if any, practical difference. It is only in situations where one is trying to pick up a troublesome station where the differences will be prominent. Of course, if the signal from the station is too poor, then none of them will pick it up decently, so it really is a narrow range of signal quality where there will be a significant difference between the three tuners under consideration.

In most cases, the tuner in the SX-450 will be satisfactory. Having owned an SX-450 for a while, I can certainly see it as a viable option (though I kept my SX-1250; I also had, for a while, an SX-750, which I also sold).

One can try to find differences in performance by doing things to make the differences more prominent. For example, one can turn the volume way up to try to hear the noise floor during moments of silence on a broadcast, though one will be having it very loud when there isn't silence. But doing that might make one notice differences in signal to noise ratio, assuming that the station is broadcasting a quality signal where they have taken care to keep the noise floor low (if they have not kept the noise floor low, then you will hear broadcast noise in all of them). But with normal listening, all of these have a decent signal to noise ratio and one is unlikely to notice the differences without trying to make them noticeable.

With the crazy prices on vintage gear these days, if I had an SX-850, I would not be looking for a higher model. If you need more power, adding a separate power amp would be the way to go.
 
Pyrrho said:
With differences in tuner performance, that will not tend to be noticed when they all are decent and the signal from the station is good. Differences in tuner performance tend to show up in situations of a poor, weak signal from a radio station. (Or, for some aspects of tuner performance, an overly strong signal.) And then to properly compare, one would have to be using the same antenna, in precisely the same location, which most people are not going to do when comparing things. In most locations, the tuners in all three will be fine and be of little, if any, practical difference. It is only in situations where one is trying to pick up a troublesome station where the differences will be prominent. Of course, if the signal from the station is too poor, then none of them will pick it up decently, so it really is a narrow range of signal quality where there will be a significant difference between the three tuners under consideration.

In most cases, the tuner in the SX-450 will be satisfactory. Having owned an SX-450 for a while, I can certainly see it as a viable option (though I kept my SX-1250; I also had, for a while, an SX-750, which I also sold).

One can try to find differences in performance by doing things to make the differences more prominent. For example, one can turn the volume way up to try to hear the noise floor during moments of silence on a broadcast, though one will be having it very loud when there isn't silence. But doing that might make one notice differences in signal to noise ratio, assuming that the station is broadcasting a quality signal where they have taken care to keep the noise floor low (if they have not kept the noise floor low, then you will hear broadcast noise in all of them). But with normal listening, all of these have a decent signal to noise ratio and one is unlikely to notice the differences without trying to make them noticeable.

With the crazy prices on vintage gear these days, if I had an SX-850, I would not be looking for a higher model. If you need more power, adding a separate power amp would be the way to go.
Click to expand...

Why didn't you just say the tuner is "better on a good day, under ideal circumstances, with all things being equal"? :)

I'm not looking for any more power, both of these sort of just fell in my lap, so to say.

The 950 was my Christmas present to my son years ago, in the days when $200 was the average price. He told me later it was cutting out on him after a while and he shelved it for a surround sound system. When he moved from his apartment, I told him I'd take it and fix it. He sort of shrugged as if to say, "OK, if you want to..". So, it sat for a while and I didn't think I was going to get around to fixing it, so I asked him if he wanted me to sell it for him. Again, he shrugged and said, "I don't care really, Dad. You can have it if you want it.". I think he liked his TV's surround system better.

The 850 came to me recently on a "jump in the car and get moving" Facebook ad. I've been restoring it. In fact, I've rebuilt the entire unit as of today, except for the tuner and amp board. I guess you could say it's all new on the bottom side, at least.

It feels really good to see this number on the old Fluke:

IMG_4822.jpg
 
With an SX-850 and SX-950 within about 6" of each other, I think it's a fairly equal comparison.

EquipmentWall.jpg
 
Pull out a 2 Sx-950. I was working on both just to see if I could get them up and running , I noticed that one had 3-speaker Pb's and other one had 2 but since I was working w them and everything looked the same but the speaker output terminals were a different setup one is set up, up/down the other one across. But a week later I said that's not right so I looked again and one was a SX-850 Lol. And I was thinking both have the same Output transistors. So I will be look at the transformer output and see what the voltage is,,, if yes possibly installing bigger Caps and make it a SX-950. I will also would have to check the output board and see if their any differences.
 
markthefixer said:
There are differences, I thought the same thing, once way back... big enough differences that the 850 will never upgrade to a 950.

Starts with the main transformer, and diverges further from there on....
Click to expand...
I just checked the voltage and the transformer which look the same but the SX-950 has more Voltage so A new transformer would be need w new caps and brackets (if your upgrading to new caps would not be no big deal) and the output board? anyway is it worth it maybe not,,,,, I have to much to do now Lol
I received the parts you fixed for the CT-F9191 Thanks everything works!:beerchug: I need to fix the tension for the unwind spring for the cassette when I put it together I forgot to hook it up and I had low wow and flutter. I hooked it up up and wow and flutter went through the roof, My Bracket is straight and not bent, Like the one I was listed on E-bay. I really like this deck it is really well built , don't know if I will keep it. also have the a bunch of Ct-F and I just received my CT-F1250 :rockon:
 
Hello does any one know the values for the transformer output voltages in the sx-950 ? The transformer of the one I have is grilled and I want ro replace it with a new one.
Many thanks !
 
Hello new member.
You did not say what’s wrong with the original, open,shorted primary? Secondary windings?
The voltages written on the big schematic can be used to figure out the secondary voltages.Take the DC voltages and multiply by 0.707 to get approximate ACVrms.
 
Thanks very much for your answers ! I mean the voltages coming directly out of the transformer - so, across 16/19 (Red), 25/26 (Orange), and 27/28 (Green). The fuses arenot the fault part. As for the transformer I can't very well see, I opened its metal casing, there is burn sign where smoke was coming out.
 

Attachments

  • DSC_3277.JPG
    DSC_3277.JPG
    44 KB · Views: 9
Godement said:
Thanks very much for your answers ! I mean the voltages coming directly out of the transformer - so, across 16/19 (Red), 25/26 (Orange), and 27/28 (Green). The fuses arenot the fault part. As for the transformer I can't very well see, I opened its metal casing, there is burn sign where smoke was coming out.
Click to expand...
If you're trying to find which winding is bad just measure the power supply voltages to eliminate the good ones.

If you're seeing how the 850 & 950 xfrmrs compare, the red windings are different. The 950 puts out ±49.5 volts after rectification. The 850 only ±45v.

If the transformer is bad there's one for sale on that big auction site.

No affiliation.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom