How to run a second power amp with a receiver?

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

  1. z-adamson

    z-adamson AK Subscriber Subscriber

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    I have an Onkyo TX8500.

    I wish to run the amp within the receiver in addition to a separate power amp.

    The preamp within the TX8500 running both amps.

    What is the most practical way to do this?
     

     

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  2. kvining

    kvining Active Member

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    Can't do it without another pre-amp unless your power amp has both input and output RCA jacks, like this HK PA-2000:

    http://2.bp.blogspot.com/-tTH30ny_ZeQ/Ux0eNmifQVI/AAAAAAAAkNU/N1L2bjy_ElY/s1600/rearlrg.jpg

    Most power amps just have input and the only output is the speakers, like this Rotel, so you need a separate pre-amp for it, otherwise you have to disconnect the power amp section from the receiver and use the receiver as a pre-amp only since you have no way to get signal back into the receiver's Main In:

    http://www.nrpavs.co.nz/archive_1_16/Sold_1_16_htm/Images/Rotel_RB-890_b2_700x346_pixels.gif

    If you are lucky enough to own a power amp with output jacks, then you pull the jumpers from the pre-amp main and run pre-amp to power amp and RCA out from the power amp back to the receiver's Main In, that will allow you to control the power amp from the receiver, volume and tone controls will have the same effect on the speakers wired to the receiver and those wired to the power amp. Great way for lazy people with remote controls.

    If your power amp has only inputs, you need to run them off the tape rec out jacks to a pre-amp and then to the power amp, and control has to be done from the separate pre-amp. Integrated amps are a lot simpler, just run the tape out to the AUX and you're in business, that's my preferred way of adding power because you can just keep daisy chaining them, and I like having separate controls for each set of speakers myself.

    If I were in your shoes this is the one I'd be looking for, you'll have your neighbors calling the cops in no time with one of these added to that receiver:

    http://audio-database.com/ONKYO/amp/integraa-820rs-e.html
     
    Last edited: Mar 12, 2018
  3. orsen

    orsen just another old cheapskate that likes audio Subscriber

    i take it your adding speakers

    your amp has pre outs
    you need rca y cables 2 of them
    they need to be 2 male 1 female
    pull the jumpers from your onkyo
    replace with the 2 male ends of a y plug
    do this for both channels
    now you have 2 female ends left
    plug those into the inputs of your power amp

    only problem is if your power amp does not have level controls you may find one is louder than the other
     
  4. xero-D-hero

    xero-D-hero Super Member

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    What orsen said x2...

    That Onkyo has the pre-out/main-in.
    So all you need to do is pull the jumpers and split the signal and run one leg from the pre-out to the power amp.
    And then the other leg gets routed back into the main-in.

    That's assuming the power amp being used does'nt have a pre-out loop that lets you just loop the signal right back to the receiver.
    An example of an amp that has a line level output like that would be the Onkyo M-282 WRAT.
    There are others but it's not a very common feature so most doing this just use some sorta splitter and loop one leg back to the main-in.

    And as mentioned it helps if the power amp has input level control(s).

    HTH

    Bret P.
     
  5. E-Stat

    E-Stat Addicted Member

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    Note the pre-out/main in jacks on the back of your Onk.
    onk.jpg

    Remove the jumpers, purchase a couple of Y-Adapters like this from Parts Express and attach male ends to "pre out". With two sets of standard ICs, connect one set back to "main in" on receiver and other set to new power amp inputs. Note that the input impedance value will drop significantly from the perspective of the receiver's preamp which may roll off the top.
     
  6. kvining

    kvining Active Member

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    Yeah the Y cable thing works, but I've always thought it degraded the sound quality. You've got to be degrading the signal by splitting it into weaker channels like that.
     

     

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  7. 62caddy

    62caddy Trust but verify Subscriber

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    It could. Depends on the what the preamplifier's output impedance and the resulting impedance from the combination of inputs from both the outboard amplifier & Onkyo's inputs.
     
  8. cademan

    cademan Addicted Member

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    If you use a Y at the pre out/main in jacks, it is exactly like leaving the jumpers in place except you have an extra out to go to an amp of your choice. It does not degrade the sound. Don't know that I ever heard that it did unless you are running more than 10 amplifiers off of one single output where it divides the load so many times.

    My system consists of five power amps driven by a mixer and preamp using Y's to connect all five. No degradation whatsoever.
     
  9. quiet

    quiet AK Subscriber Subscriber

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    Does each of the five amps then drive a single pair of speakers? I can see where that would provide plenty of diverse sound pressure.
     
  10. cademan

    cademan Addicted Member

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  11. quiet

    quiet AK Subscriber Subscriber

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    Nice .Very nice.
     

     

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  12. cademan

    cademan Addicted Member

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    Teaser!
    SOUND 3.JPG
     
  13. orsen

    orsen just another old cheapskate that likes audio Subscriber

    there is a check to be made to all of this
    speakers powered by different amps can be out of phase with eachother unless all amps are the same model
     
  14. 62caddy

    62caddy Trust but verify Subscriber

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    Unfortunately, receiver manufacturers rarely publish specs for preamplifier outputs. Nor are input load specs published for all power amplifiers either which can vary widely from one amplifier to the next. The effects of improper loading between components is no different than it is for phono cartridges - namely irregular frequency response.

    Without knowing what the values are for the specific units, it is impossible to answer in the absolute whether there will be any negative sonic effects or not.
     
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  15. quiet

    quiet AK Subscriber Subscriber

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    I see a cloud coming.
     
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  16. tarior

    tarior Dirty pool, old man? Subscriber

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    Just about any receiver/integrated that came equipped with preamp outputs will have more than enough oomph to drive 10 outboard power amplifiers (unless they are real oddballs with very low input impedance and/or need a very high voltage drive) without fear of damage or signal degradation.
    Just grab some "Y" cords and go for it.
     

     

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  17. whoaru99

    whoaru99 Epic Member

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    Possible, but typically not to any material degree.
     
  18. 62caddy

    62caddy Trust but verify Subscriber

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    A McIntosh C26 dedicated preamplifier, for example, is rated to operate into a 47,000 ohm load. A McIntosh MC7300 power amplifier input is rated at 20,000 ohm. Therefore these two units are incompatible right at the outset, nevermind 10!

    Too many blanket statements here.
     
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  19. whoaru99

    whoaru99 Epic Member

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    Yeah, two of this style is about as easy as it gets. Replace the two jumpers with two of these, then use RCA cables from the female plug of each Y to the respective external amp input.

    21Q9GYK0TZL._SY400_.jpg
     
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  20. E-Stat

    E-Stat Addicted Member

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    I think you got the genders wrong in your photo. :)
     
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