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Thread: Pioneer SX-1250

  1. #1
    Senior Member alexkerhead's Avatar
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    Pioneer SX-1250

    I managed to pic up a Pioneer sx-1250 on ebay working in good shape for $225+$60 shipping.
    I know it has 165wpc, but has anyone had any experience with this receiver?

    How do you think it will handle 4x L100s?

  2. #2
    RIP 2013 Rolf's Avatar
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    I know it quite well. A "fair" price, if it is working ok.

    Not 4 L100's. but 2. Remember much of the amps of that time does not like 4 Ohm's.

    Quote Originally Posted by alexkerhead
    I managed to pic up a Pioneer sx-1250 on ebay working in good shape for $225+$60 shipping.
    I know it has 165wpc, but has anyone had any experience with this receiver?

    How do you think it will handle 4x L100s?

  3. #3
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    I also have a SX1250 that I bought new that I stilll use with L100's. It is an excellent workhorse and will be a nice fit with the L100's although I only used it with two. I think it would handle 4 L100's without any problem. I would suggest that you take it apart (pretty easy) and give the switches a nice cleaning as mine got very scratchy over the years and some of the switches started to seize up. It has a decent tuner and you can easily uncouple the amp from the tuner/pre-amp section . Nice price

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    Senior Member alexkerhead's Avatar
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    I noticed the xx50 series has serious control problems like you said.
    I deoxited my mother's sx-1250 a week ago(three hours of work, but I also cleaned inside and out as well), huge pain, but well worth it, at least I have some practice with that unit before I do mine.

  5. #5
    pocketchange
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    Thumbs up Upstairs and Down..

    I have SX1250's for torque and I have NO problem driving 2 pair of speakers.
    For your comfort (and peace of mind) I'd suggest finding a good tech and having the bias checked as there are a few minor age related issues that may have to be delt with. A good idea is to keep an eye on the sinks and if the overload ever kicks on you will need to find a tech. Looking at the big caps would also be a good idea (and give you a chance to see if they are leaking).
    Minor ooze is normal (an age related problem) and keep in mind if the unit is quiet and not humming or getting hot you most likely have a great piece of gear that will continue to give years of enjoyment.
    FYI: The BIG Replacement caps are available..
    PN's from Nickosan (SP) 36DA223F100CD2A (typically $150 for a set of 4)
    Also: check the AudioKarma Forum - Pioneer thread- for info and look for threads from member EchoWars, he knows his stuff.
    You stole this SX for what you paid, specially if it's clean.
    pc

  6. #6
    RIP 2013 Rolf's Avatar
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    Quote Originally Posted by pocketchange
    I have SX1250's for torque and I have NO problem driving 2 pair of speakers.
    You probably don't push it. Do so, and the transistors burn up.

  7. #7
    pocketchange
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    The reference to having the bias being checked is what I was refering to to insure you don't run into the transistor problem. Also keep in mind the transistors on/in the bias control will need to be removed to have their value verified. Unless you have an auditorum or bad hearing the SX1250 has a built in circuit that simply will turn the unit off if thinks get too hot (which I have never had happen when the bias circuit [transistors and such] is working properly).
    Under a load would be having the volumn past the 1 O'Clock posistion. Anything past that and ear muffs are necessary or you will end up with diminshed hearing.
    A trip over to the Pioneer Forum will find a spec. breakdown on some of the features of the SX Series if you are interested...

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    Senior Member spkrman57's Avatar
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    Impedance is the issue here...

    The 123A woofer in them reach down to around 5 ohms, with 2 pairs would have a paralleled total down to 2.5 ohms.

    That would be below the 4 ohm min rating.

    In series would be okay, not saying it would sound good that way or not.

    There are threads on this forum where I read the info. Do a search for 123A and you will find them.

    Regards, Ron
    JBL Pro for home use!

  9. #9
    Senior Member alexkerhead's Avatar
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    I am a amatuer tech, i checked the mV, it runs 10.2 on the left and 11.4 on the right channel, well within safe.
    The caps are registering a bit low on a capacitance meter my friend has, about 19,200uF, and they should do 22,000uF.
    I checked the output power and it is 12watts below the 165watt rms at 8 ohms.

    The output transisotrs will be getting new thermal compound when I replace the capacitors. I am ordering computer grade 22,000uF 100V capacitors from mouser for it.

    If the SX-1250 has too much resistance on it, the speaker protection kicks in to save speakers and the transistors.
    It also has a thermal control circuit, so it shuts off when it gets too hot.

    I have been playing with this unit until I can afford the capacitors, and I must say, this thing blows me away, the bass is solid and controlled, the mids and highs have no distortion at high volume.
    Sound is clean and even.
    At 4ohms it runs about 194wpc(should be 200wpc).

    This unit can handle 4ohm no problem from what I hear.
    It is supposed to be the most reliable monster receiver ever built from reputation at AK. I am an AK member and have asked around there as well.

    This thing is amazing!
    Here are some pics.

    Pics


  10. #10
    RIP 2013 Rolf's Avatar
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    is not good enough. Push it with more than 2 speakers, and it will burn, no matter technical adjustments being done. That is just the way the construction is... So are many others of the time.

    Quote Originally Posted by pocketchange
    The reference to having the bias being checked is what I was refering to to insure you don't run into the transistor problem. Also keep in mind the transistors on/in the bias control will need to be removed to have their value verified. Unless you have an auditorum or bad hearing the SX1250 has a built in circuit that simply will turn the unit off if thinks get too hot (which I have never had happen when the bias circuit [transistors and such] is working properly).
    Under a load would be having the volumn past the 1 O'Clock posistion. Anything past that and ear muffs are necessary or you will end up with diminshed hearing.
    A trip over to the Pioneer Forum will find a spec. breakdown on some of the features of the SX Series if you are interested...

  11. #11
    Senior Member alexkerhead's Avatar
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    Quote Originally Posted by Rolf
    is not good enough. Push it with more than 2 speakers, and it will burn, no matter technical adjustments being done. That is just the way the construction is... So are many others of the time.
    Do you own a sx-1250?

    I am quite sure a bose 1801 or something with bad reliability issues would not handle the load, but Pioneers are quite famous for handling 4ohm loads without a hitch.

    Be content in the fact that each L100 will start bottoming out at around 75watts rms, so therefore the receiver never gets taxed enough to cause damage.
    150wpc is less than rated at 8ohm, at 4ohm is puts out 200wpc, so i have 50watt headroom at 4ohms.
    This allows the transistors not to be pressured heavily.

    Plus, nobody wants their music to bleed their ears, so I only use about 25wpc at loud volume per L100.

    Now 6 L100s would be a problem.

  12. #12
    RIP 2013 Rolf's Avatar
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    Quote Originally Posted by alexkerhead
    Do you own a sx-1250?
    Not anymore, and I do not want it back.

    Quote Originally Posted by alexkerhead
    I am quite sure a bose 1801 or something with bad reliability issues would not handle the load, but Pioneers are quite famous for handling 4ohm loads without a hitch.
    The bose ... well well.

    Quote Originally Posted by alexkerhead
    Be content in the fact that each L100 will start bottoming out at around 75watts rms, so therefore the receiver never gets taxed enough to cause damage.
    150wpc is less than rated at 8ohm, at 4ohm is puts out 200wpc, so i have 50watt headroom at 4ohms.
    This allows the transistors not to be pressured heavily.

    Plus, nobody wants their music to bleed their ears, so I only use about 25wpc at loud volume per L100.

    Now 6 L100s would be a problem.
    I have played the L100 with 200W ... no problem. ... But that is not the issue here, the 1250 is, and it can not ... repeate ... can not drive 4 ohms at high volume levels. ... and that is the truth.

  13. #13
    RIP 2011 Zilch's Avatar
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    123A-1 impedance:

    < 8 Ohms 42 - 775 Hz

    < 6 Ohms 59 - 255 Hz

    Actual Zmin = 5.33 Hz ~110 Hz

    WT2 states Zmin at 0 phase crossing:
    Attached Images Attached Images  

  14. #14
    Senior Member alexkerhead's Avatar
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    Quote Originally Posted by Rolf
    Not anymore, and I do not want it back.
    The bose ... well well.
    I have played the L100 with 200W ... no problem. ... But that is not the issue here, the 1250 is, and it can not ... repeate ... can not drive 4 ohms at high volume levels. ... and that is the truth.
    You actually turned the volume all the way up on a set of L100s on 200watts?
    I call BS.
    You'd blow that L100 with a solid 200 watts in a heartbeat.
    The voice coils simply CANNOT take 200watts.

    I also don't believe you have owned a sx-1250, or else you would not have gotten rid of it. If you did, there was something wrong with it.

    The only totl receivers I have seen that will blow under 4ohms are the suffixed DB sansui totls and the yamaha r-1000/r-2000.

    My L100s cannot take but a little over half the volume this 1250 puts out before the woofers are bottoming. I found that out the hard way when I bumped the volume on accident.
    Also, the 1250 will shut off the speaker relay when too much resistance is present, just so you know, you would have known that if you owned one.



    Thanks for the info zilch, but since the L100s wont take full wattage at any volume, there is no risk of blowing the unit.

  15. #15
    RIP 2011 Zilch's Avatar
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    Quote Originally Posted by alexkerhead
    Be content in the fact that each L100 will start bottoming out at around 75watts rms....
    ...
    Attached Images Attached Images  

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