Receiver/Speaker Wattage Relationship

Discussion in 'GENERAL AV Discussions' started by titzlaroo, Mar 19, 2006.

  1. titzlaroo Audioholic Intern

    titzlaroo
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    I'm looking to purchase my first stereo settup. Right now I'm reading reviews on receivers and book shelf or floor standing speakers. I'm having trouble finding any literature on receiver to speaker wattage relationships. For instance, if I purchase speakers rated to 200 watts should I have a receiver rated at, above, or below that wattage to get the best sound? I need all the help I can get in this area. Any info. or links would be appreciated, as well as any other helpful advice for a newbie.

    thanks
  2. kay Audioholic

    kay
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    Power ratings on speakers do not equal louder speakers; a higher rated speaker should be able to handle a louder signal however (if you could supply it with enough clean power). A highly rated speaker will be able to sing at party-levels for a long time without overheating its critical components. Whether you really want that is another story - most people really don't need it.

    Power ratings on receivers & amps need to be carefully interpreted - not all ratings are the same. Look at what bandwidth they're rated at and the THD figure. Some manufacturers publish specs with for fixed frequency signal with high THD (distortion) which makes them look good. Watch out for this.

    Keep in mind that for every 3dB increase in SPL, you need to double the power. So to make a small audible difference over a 100w/ch amp, you might have to go to 150-200w/ch - which equals a beeeg price difference. On the other hand, the difference from 80 to 140 watts which is where most receivers lie won't really be noticeable; other things will influence the sound much more. Signal-to-noise ratio, damping factor, quality of power supply, supported formats, inputs & outputs are all very important considerations. I would go as far as to say that any amp/receiver from a decent brand in the mid-range upwards will give you what you need. If the receiver has pre-outs, you can always add a dedicated power-amp later.

    Typical listening volumes (even loudish ones) only require power in the region of 10-20w/channel. Any receiver can provide that, but you need the headroom to accomodate peaks in the signal (explosions, dramatic moments in music etc.).

    Bottom line: No, if you buy a speaker that says it handles 200w, you don't need a 200w amp to make it sound good. Look at its efficiency rather: that tells you how many watts it takes to produce X amount of SPL (i.e. loudness). Higher efficiency = less load on the amp = generally better.

    Hope this helps :)

    Go out and listen to different set-ups. The speakers & room acoustics make the most difference. Read the Audioholics "Get an AV Education" section for more - you will find everything there is to know there ;) (ok, not quite, but everything you really need and then some...)
    kay,
  3. titzlaroo Audioholic Intern

    titzlaroo
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    So, I should have no problem buying 200w speakers and supplying only 140w/ch. Assuming that it is a good pair of speakers and a good receiver.
  4. mtrycrafts Audioholic Slumlord

    mtrycrafts
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    Room size, listening habits, very loud or moderate, speaker sensitivity, speaker impedance would come into play. Some silliness such as damping factor is not an issue with solid state amps.

    Usually, you don't need the same power.
  5. jonnythan Audioholic Ninja

    jonnythan
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    Speakers don't supply power. They have maximum power ratings which refer to the maximum amount of power you should feed to them.

    So, your receiver should put out less maximum power than the speakers can handle. If the speakers say "100 watts RMS" that means you should use a receiver that doesn't put out significantly more than 100 watts RMS. There's more to it than that, and you can usually get away just fine with a "130w/channel" receiver and "100 watt" speakers.
  6. Buckeyefan 1 Audioholic Ninja

    Buckeyefan 1
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    I'm assuming you're looking at the Yamaha 5890 or 5990. There's a good example of manufacturers not using full bandwidth or proper thd stats.

    Look on page 119 of the Yamaha 5990 manual, and you'll see at the top, this unit is actually rated at 120 watts up to two channels, at .04 thd, 8 ohms and a bandwidth of 20-20,000Hz. This is not the 140 watt rating you'll see on the main advertisement page for the unit.

    http://www.yamaha.com/yec/customer/manuals/PDFs/HTR-5990_e(U).pdf

    When a manufacturer rates a speaker able to handle 200 watts rms per channel (per speaker), it's telling you the load may be tough for an average receiver at reference levels. This gets even worse when that power rating goes up to 400 or 500 watts rms.

    You need to pay attention to the spl rating of the speaker, as well as the nominal impedance (4 ohm, 6 ohm, and 8 ohm). The lower the spl, the tougher it is on the receiver to reach the same volume. There's a world of difference in efficiency in a 94dB speaker compared to a 88db speaker with the same impedance rating. It's the same with a 4 ohm versus an 8 ohm speaker, with the same spl ratings.

    When you purchase a high end receiver (say a Denon 4806), picking out speakers normally isn't an issue. Many say to purchase the speakers first, then buy the receiver based on the speakers specifications.

    What receiver/speakers are you considering?
  7. MDS Audioholic Spartan

    MDS
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    The max power rating of a speaker doesn't tell you anything without considering the sensitivity of the speaker or its nominal impedance. A high max power rating doesn't mean that the sensitivity or impedance is necessarily low. I have decade old JBL speakers with a sensitivity of 93 dB, 8 ohm impedance, and 150 watt max rating. They are easily driven to reference level with a lowly Onkyo 502 receiver.
    MDS,
  8. Buckeyefan 1 Audioholic Ninja

    Buckeyefan 1
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    Who said max? I said rms. What are your JBL speakers rated at rms?

    (I know the argument of rms vs average sine wave output power - let's not get into that right now. It's a good topic for another thread. ;) )
  9. MDS Audioholic Spartan

    MDS
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    The original poster was talking about max power rating and I conveniently overlooked the rms in your post. :) But I still disagree. The RMS rating is what it can handle on a continuous basis, not what it needs in order to reach reference SPLs.

    I don't recall the RMS rating of the JBLs, but I would guess 100 wpc. The high sensitivity and stable 8 ohm impedance is what allows them to reach reference levels with moderate power, not so much that they can handle more power than I give them. That and the fact that the room is 16' x 18' which is not gigantic.
    MDS,
  10. Buckeyefan 1 Audioholic Ninja

    Buckeyefan 1
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    He didn't say max or rms. It's hard to tell what he was referring to without him giving us the model no. I'm guilty of assuming it's rms, but I stand by the rms explanation.

    That depends on quite a few things. At reference levels, what thd are we talking? Anything above 1% could be audible. What I said was:
    A speaker rated at 200 watts rms is quite a bit. I said "the load may be tough..."

    Small rooms, high spl's, 8 ohms, etc... will help in the output of an AVR - no doubt. All great reason to save a few bucks on an AVR. But take a good look at the rms power handling of Klipsch speakers, including the Reference speakers. How many handle 200 watts rms other than the RF-7? ;)
    Last edited: Mar 20, 2006
  11. MDS Audioholic Spartan

    MDS
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    I don't know how many speakers handle 200 watts rms, but Klipsch is definitely not hard to drive as they are some of the most efficient speakers available. Are you saying that when Klipsch reference speakers are rated at 200 wpc rms they are tellling you they may be hard to drive?
    MDS,
  12. mulester7 Audioholic Samurai

    mulester7
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    .....but MDS, any substantial raising of the volume can multiply the wattage needed 6 or 8 times simply because of the woofer's requirements....the wattage used, being shown on a graph, goes virtually straight up right at the last of the continuous power limit of the amp, with the rule of 3db increasing the wattage twice not being applicable....I've never seen that to be a good rule anyway, mainly because of woofers....them boys can eat, Sir, and how......
  13. Buckeyefan 1 Audioholic Ninja

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    What I was getting at is that Klipsch, being one of the most efficient speakers, and very well made, don't have 200 watt rms ratings. I singled out the RF-7 because I feel they deserve something more powerful than a $350 AVR - but they will run on a $350 AVR.

    Even the huge JBL E100's with dual 10" woofers have a reasonable 125watt rms rating. An 80 watt AVR can drive these beasts, but I would definitely prefer the 125 wpc AVR over the 80 - especially for the treble peaks and bass notes. You're better off going with JBL's with an 80 watt rms rating. They'll play more efficiently and tax an entry level AVR less. They'll be less distortion when approaching reference levels.

    My advice - try to match the rms ratings of your front speakers, and ignore the peak power handling. A lack of power rears distortion sooner than having too much. Buy your speakers first, then match them to the receiver.

    People claim there's little difference between an 80 wpc 21lb AVR versus a 130 wpc 41lb AVR because the difference in watts is minimal. You start pushing that 21lb receiver a bit with a set of demanding speakers (200 watt rms ;) ), and that power supply will suffer, the capacitors won't deliver, and the output transistors will heat that sink up to a point where you'll be searching for a new AVR.
  14. mtrycrafts Audioholic Slumlord

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  15. Buckeyefan 1 Audioholic Ninja

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  16. mtrycrafts Audioholic Slumlord

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