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How to run a second power amp with a receiver?

Discussion in 'General Audio Discussion' started by z-adamson, Mar 12, 2018.

  1. the skipper

    the skipper Amateur Curmudgeon Subscriber

    Messages:
    2,743
    Location:
    Aggieland
    Actually, no. The two males replace the jumper and another interconnect goes from the dangling female to the external amp.
     
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  2. orsen

    orsen just another old cheapskate that likes audio

    photo is correct
    the 2 males replace the original jumper pin
    the female allows for an rca cable from one amp to the other
     
    doctor fuse likes this.
  3. orsen

    orsen just another old cheapskate that likes audio

    beat me to it
     
    doctor fuse likes this.
  4. 62caddy

    62caddy Trust but verify Subscriber

    Messages:
    9,553
    Location:
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    Or simply get a pair or 1M > 2M and forget about additional cables...
     
  5. E-Stat

    E-Stat AK Subscriber Subscriber

    Messages:
    6,710
    Sit corrected. Since the grounds are shared, that should indeed work even if the outputs are not on the same "leg".
     
  6. cademan

    cademan Addicted Member

    Messages:
    9,045
    :thumbsup:

    Easiest way to phase speakers with mismatched equipment is to connect the first pair of speakers normally then phase the next pair to the first pair, and so on. It only took me about ten minutes to phase all the speakers and believe you me, you can certainly hear that something is off if only one speaker is not phased correctly with the others. It kills the bass. :mad:
     

     

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  7. cademan

    cademan Addicted Member

    Messages:
    9,045
    These are the one's I use. I have a box of many different Y configurations. You need them if you wanna build big.
     
  8. z-adamson

    z-adamson Super Member

    Messages:
    1,656
    Here is the scoop...

    Input impedance of second amp......47000 ohms
    Input impedance of Onkyo TX8500 amp.......???
    Output impedance of Onkyo TX8500 preamp......???

    Should I go for it?

    What is the worst that can happen? Could I compromise reliability of the preamp / receiver?
     
  9. tarior

    tarior Dirty pool, old man? Subscriber

    Messages:
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    Location:
    Kelso, Washington
    The worst that can happen is that it will sound bad, and you'll be out $5 for the "Y" cords.
     
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  10. cademan

    cademan Addicted Member

    Messages:
    9,045
    Sure. Why not!

    Not even close!

    Do it, listen to it, and report back. I'll bet you will be pleased.........for now. :D
     
  11. z-adamson

    z-adamson Super Member

    Messages:
    1,656
    My thought was that the engineers at Onkyo probably did not intend for this and maybe the impedance specs of the preamp / amp within the TX8500 are such that this will pose a problem. This is the reason for not doing this. On the other hand, maybe the components are spec'd for this and it will work out just dandy.
     

     

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  12. E-Stat

    E-Stat AK Subscriber Subscriber

    Messages:
    6,710
    Seek and ye shall find...

    Amp input 50k ohms
    Pre out 3k ohms.

    3k pre driving ~24k amplifier load. Not ideal, but it's cheap to give it a try!
     
  13. cademan

    cademan Addicted Member

    Messages:
    9,045
    The engineers did intend for this or else they would not have had these options on any of their units.

    People have been doing things like this for a long long time using multiple pieces of equipment.

    In my house, I have a Pioneer SA-8500II and 9500II plus a Sherwood S-6040-CP along with a Pioneer SX-1010 all using Y adapters because each one has pre out and main in options except the sherwood as it is just a straight power amp. Its meant to mix and match at your hearts content.
     
  14. z-adamson

    z-adamson Super Member

    Messages:
    1,656
    OK, so what is the relationship exactly between the impedance at the pre and impedance at the amp? I understand by running the amps in parallel, the impedance is cut in half. But how does the preamp impedance come into play?

    Additionally, this is not ideal as you say, but what will happen exactly? Less bass? Highs start to distort?
     
  15. cademan

    cademan Addicted Member

    Messages:
    9,045
    You probably won't even notice anything! I keep telling you that nothing bad will happen. No smoke, no pops, no fizz, etc.

    The most that will happen is that you may or may not like the sound.
     
  16. z-adamson

    z-adamson Super Member

    Messages:
    1,656
    Understood.

    For my own understanding, I would still like to know what is going on.....as in the relationship between pre impedance and amp impedance and how exactly the sound could be effected theoretically.
     

     

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  17. cademan

    cademan Addicted Member

    Messages:
    9,045
    So you want to do the math? Be my guest. :D

    I have done the math and I understand it but I think its irrelevant in your case but if you are interested, then there is nothing wrong with that. :thumbsup:

    EDIT: I think at this point that we are just waiting to see what you think about the sound. :rockon:
     
    Last edited: Mar 12, 2018
  18. E-Stat

    E-Stat AK Subscriber Subscriber

    Messages:
    6,710
    Not so much that highs distort as they might roll off and dynamics may suffer. Nothing horrible on the horizon. Give it a try.

    My garage system runs a Music Hall DAC 25.3's balanced outputs with a uniform 4k output impedance into a 47k Hypex amp. Works great for me.
     
  19. z-adamson

    z-adamson Super Member

    Messages:
    1,656
    I got the Y cables coming!
     
  20. z-adamson

    z-adamson Super Member

    Messages:
    1,656
    Looks like the rule is that the amp impedance should be 10 times the preamp impedance and this situation puts me just shy of that.
     

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