Can I Amplify an 85WPC Receiver?

Discussion in 'Music Forums' started by IraGress, Jul 16, 2017.

  1. IraGress

    IraGress Active Member

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    I know this is probably a stupid question, but this is where I learn, thanks to all of you.
    I'm selling all my gear and upgrading.
    I want a Pioneer SX-1050 or 1250 (120wpc & 180wpc), but the best I can afford right now is the 85wpc SX-950.
    What would happen if I hooked a 950 up to an SA-7500 ll 45 watt amplifier?
    Does it add 45 watts to 85 watts to make a 130wpc system, or will the entire setup just incinerate, go supernova, and crack the fabric of time and space?
     

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  2. whoaru99

    whoaru99 Epic Member

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    You could connect them together at line level so the same source signal goes to both and have 85wpc for one pair of speakers and 45wpc for another pair of speakers (a separate pair of speakers connected to each amp).

    But, the power of each receiver/amp is not additive, per se, to the other.
     
  3. C6Bill

    C6Bill AK Subscriber Subscriber

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    85 WPC is nothing to sneeze at, just use an efficient speaker and you'll have plenty of volume. Then get the bigger SX later.


    EDIT: Typo
     
    Last edited: Jul 16, 2017
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  4. IraGress

    IraGress Active Member

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    But it actually says 85wpc x 2. I thought that meant each pair of speakers had 85watts.
    But this receiver has THREE pairs of speaker jacks, a, b, and C.
    And just to make matters even more confusing, the manuals say 85wpc x 2 (or 85wpc + 85wpc) but the back of the unit says 370 watts!
    I'm so confused.
    Nobody ever discusses this, presumably because I'm the only person confused by it, so I can never find any written explanations for it.
     
  5. RichPA

    RichPA Don't drive angry Super Mod Subscriber

    When you use multiple pairs of speakers, the power is divided among them. The combination of speakers may result in a load lower than that for which power is rated (e.g., 2 8-ohm speakers connected in parallel will present a load of 4 ohms), so power may be somewhat higher than rated, as long as you're not exceeding the the current ability of the receiver. The 370 watts on the back is the AC power drawn, and not the power output.
     
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  6. dyche01

    dyche01 "Buy high. Sell low" Subscriber

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    The 370 Watts is the power that the entire unit sucks out of the wall, not the power that it delivers to the speakers.

    And I agree with a previous post: 85 Watts is plenty of power for most speakers. My two best systems are 40 and 20 Watts per channel respectively.

    EDIT: RichPA slipped in ahead me with the power info.
     
  7. IraGress

    IraGress Active Member

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    Looks good in print, but it'll never fly.
    The 950s are around $500 now, but jump up just one to the 1050s and you're in the thousands, virtually the only difference being an additional 40w, so that ain't happnin'.
    And I put my Sony STR-V4 in the closet because it's 55w wasn't cutting it for me.
    I replaced it with a 100wpc Pioneer SA-1050, and it doesn't seem any better, honestly. In fact, I think the 55w Sony is a little louder and richer.
    I just don't want to screw around the next time I buy a receiver. I want to be able to blow the roof off the sucker.
    By the way, how do you tell how efficient a speaker is?
     
  8. IraGress

    IraGress Active Member

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    So. When the speakers are doubled, the power is halved, which lowers the load (which is possibly the ohms?), which makes the power higher.
    Clearly, I'm going to need a tutor.
    And I'm not even touching the question of how 370w of energy goes in while significantly less comes out, or where the excess goes.
    But hey, sincerely, thanks to everybody for trying.
    Maybe it will all sink in one day.
     
  9. whoaru99

    whoaru99 Epic Member

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    The reason you don't see/hear much difference is because the power differences you're describing are little more than incremental.

    For example, doubling the power from 50 watts to 100 watts is a 3dB increase. Problem is, 3dB is only a small change in volume.

    If you want to double the volume, all other things equal, you need 10x more power (10dB increase).

    So, unless you are prepared to go a lot bigger in amplifier or with speakers a lot more sensitive than you have. These steps you describe are not going to get you much in terms of volume.
     
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  10. whoaru99

    whoaru99 Epic Member

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    Amplifiers are not 100% efficient. For a typical Class AB amp you're looking at maybe 50%. The difference goes up as heat.
     
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  11. IraGress

    IraGress Active Member

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    Well hell. I've finally learned something, and that's basically, "I can't get there from here."
    My volume level has gone about as high as my wallet can take it.
    Meh. Good to know I suppose. I can stop spinning my wheels anyway.
    But wait a minute. What is gained by buying the monster-watt receivers? Nobody's paying and extra $1500 for a 3db increase. What are the 120wpc receivers doing that my 55wpc can't?
    Thanks again for the info, to you and everyone in here.
     
  12. C6Bill

    C6Bill AK Subscriber Subscriber

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    What are you using for speakers and what size room ? I assume classic rock is what you are playing ?


    Give this a listen, this will give you a good idea about speaker efficiency.

     
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  13. onwardjames

    onwardjames Hoardimus Maximus Subscriber

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    To the OP, if you're wanting ear bleeding levels, might consider investing in a high efficiency speaker instead of scrapping that 950. CV, Klipsch, all sorts of speakers where that 950 would be running me right out of the room.

    Lots of reading to do for you. Sounds like you're getting overwhelmed. Step back, take a breath, and listen to the good advice here. Best of luck, and enjoy the ride.
     
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  14. KingBubba

    KingBubba "Too Much Stuff" Subscriber

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    I have run my SX-1250 alongside 60 -80 watt receivers and could not find any difference when cranked to the 12 o'clock position. Your 950 is going to slam you to the ground and not let you get up unless you are using very inefficient speakers. Your original idea is called bridging. I am not sure that bridging is possible with consumer grade equipment. Maybe others here could clear that up for you.
     
  15. hjames

    hjames Nabbed ... Subscriber

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    Another possibility I did with my Harman Kardon receivers before I went full component ...
    I would run the Preamp-Out ports (pair of RCA connectors on the back) into discreet Power amps -
    JBL/UREI amps for a while, then Adcom GFA-555 (series 1), and finally settled on a B&K ST-202Plus amp (roughly 200w/ch)
    but a nice warm sound like a good tube amp. I still have the B&K amp in place to this day.
    It may cost a bit more going with discreet components, but you have a lot more versatility swapping pieces around until you get what works for you.
    And frankly, you generally have better power supplies and more honest wattage/power figures on standalone amps than you do on receivers.
     
    Last edited: Jul 17, 2017
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  16. Ken Boyd

    Ken Boyd AK Subscriber Subscriber

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    Your better off not blowing off the roof, because you would be blowing out your hearing as well. Focus on the quality of sound rather than the volume of sound.
     
  17. petehall347

    petehall347 the brandy coffee man

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    go for new speakers . at least 96db .. go over 100db and up if you are brave . hope you have good neighbours
     
  18. I LIKE MUSIC

    I LIKE MUSIC Super Member

    And a good audiologist.
     
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  19. zebra03

    zebra03 All Audio - NO BS

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    :thumbsup:Kudos to all the posters !
     
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  20. faber12

    faber12 AK Subscriber Subscriber

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    You need some big Cerwin-vegas, and a pro amp pushing about 500 watts per channel I think.
     
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