Receivers and speakers watts newbie question

Discussion in 'Archived Threads 2001-2004' started by Guillaume H, Jan 28, 2003.

  1. Guillaume H

    Guillaume H Auditioning

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    Hi

    This is my first post on this forum, and maybe it has been answered somewhere else, but I didn't really knew what terms to search for.

    Anyway I'm very interested in home audio, although I don't have the money to upgrade my old Technics amplifier and speakers.

    This is purely hypothetical, maybe I choose poorly rated items, but that is just to base myself on something.

    Let's say I have a Sony STRDE685 receiver. In the description, it says:
    - 5 Channel Power: 100 Watts X 5
    - Stereo Power Per Channel: 100 Watts X 2

    Does it means that having a set of speakers rated more than 100 watts, like the JBL ND310II rated 250 watts, is useless?

    But at the same time, does it means that speakers rated, for example, at 60 watts would break if the volume would be set too high?

    Another thing I don't understand. The receiver is 100 Watts X 5, so does it means that all the 5 speakers will receive 100 Watts of signal? If this is true, well there's no way rear speakers can handle the power of front speakers... and does this goes for the subwoofer too?

    Okay maybe I'm completely out of the track. All that watts thing is unclear to me.

    Thanks for helping me out.

    EDIT: I think I can kind of summarize this in one question: What specs should match between the receiver and the speakers?
     
  2. Ali_Techra

    Ali_Techra Auditioning

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    Well, I'm a newbie to this forum as well but let me see if I can help you.

    First thing you have to realize is that the watt ratings of receivers varies GREATLY depending on the manufacturer. For example, Sony's 100 watts isn't as "clean" as Onkyo's 100 watts (from my personal experience). In other words, the receiver may be able to achieve that but it would be nothing but distortion at those levels.

    Now on to matching the speakers. The most important thing is not to under power speakers...that will lead to distortion and can ruin your speakers. I have over powered many a set of speakers and as long as you listen to them before the point of distortion you will have no problems. Now under powering a speaker might cause you to turn up the volume too much therefore having the amplifier (or amp/receiver) "clip". That will cause more harm than good for both the amp and the speakers.

    Speakers also have a range usually (ie: 50 - 250 watts) that you should really be in the ball park with. Don't get a 500 watt per channel amp for a 30 watt speaker. However, if you end up getting a smaller speaker for the rears, you can always adjust the level of the channel to compensate for it's lack of power handling.

    One thing I would like to say, I don't understand why most people feel the need to use "small" speakers for the surround channels. After all, Dolby Digital is 5.1 (5 FULL RANGE channels) so why not put a full range speaker? Granted, it will take up a bunch of room and more money but the sound gain is well worth it IMO. Oh, also in the opinion of everyone who has listened to my home theater [​IMG]
     
  3. JeremyFr

    JeremyFr Supporting Actor

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    100x5 means that your reciever will produce 100 watts per channel to all 5 speakers. Rear speakers will handle this power if they are good speakers. With older "matrix" surround systems where there were not 6+ discret (seperate) channels of full bandwidth audio and so did not need as much power because generally your rear channels were only recieving between 100hz and 15khz or so, depending on the content and how good your processor/amp were. With descrete audio you have a full 20hz to 20khz capability to all 5 channels which means you need to have equal power bandwidth to power each channel since they all will and can recieve the same quality signal from there respective channel of content.

    Now most recievers do not power a subwoofer I say most because some very high end recievers do have a powered subwoofer out but its very hard to find a passive (non powered) subwoofer these days.

    Now onto speakers, you can run 60 watt speakers off a 100 watt amplifier and yes you do run the chance of damaging them if you were to push them too hard, but a key to remember about amplifier speaker relationship it is always better to have speakers that handle less than your amp for one simple reason, it is easier to blow a speaker by underpowering it than overpowering it.

    In a nutshell the reason for this is if you are to run an amplifier into a clipping state (meaning it cuts the top and bottom of the signwave of the audio off) this causes your speaker to stop while it is moving which then causes the voice coil to heat up and eventually can lead to failure.

    Where as overpowering a speaker is less stressful because there are few times you'll be running the full amplifier power to the speaker you have peaks which are sudden bursts to a speaker say for instance a gun shot this may only be a burst of less than a second of 100 watts to that speaker now mind you if you are grossly overpowering that speaker then yes you could blow the cone right out of the basket but say you're powering a speaker rated at 75watts RMS chances are it will probably have a peak power handling of twice that so you are still safe in most instances. This is why you will see alot of high end subs that are rated for say 600 watts output and 1400 watts peak, this translates to the amp being able to supply a steady power of 600 watts continuously without any problems but can produce transient peaks upwards of 1400 watts or short bursts like a gunshot or someone getting punched etc.

    Having a speaker that handles twice as much as your reciever is not an issue because to say 200 watts is twice as much as 100 watts is not the case as wattage goes up the actual increase in volume is negligable.

    For instance I had a very nice stereo in my car with a single 12" subwoofer, the sub I had was rated to handle up to 1000watts RMS and well over that peak, I was powering it with a 500watt RMS amplifier and was able to achieve very high volumes with it even though the amp in theory was only "half" the power the speaker was rated at. Well I'm rambling I hope this can be of help to you.
     
  4. Guillaume H

    Guillaume H Auditioning

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    It makes sense, although it doesn't sound right to pay for something unused (having a bigger amp or bigger speakers).

    I understand your definition when you say it's easier to ruin a speaker by underpowering it than overpowering it. I understand it but at the same time it doesn't sound right that a speaker meant to handle 200 watts RMS could be broken by using a 150 watts amplifier turned all the way up.

    Would it be ideal to have, matching receiver and speakers, like a 100 watts X 5 receiver and five 100 watts RMS speakers?
     
  5. JeremyFr

    JeremyFr Supporting Actor

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    My personal system is as follows I run a Yamaha RX-V730 which has 75 watts X 6 channels (being a 6.1 reciever it has the rear center channel as well being the 6th 75watt channel.) and am running Energy Take 5+1's off of it which are rated at 100 watts a piece in handling.

    Even though my reciever runs 25 watts per channel less on paper than what my speakers are rated it at I can get it more than loud enough to want to turn it down without clipping the amp or overdriving the speakers.

    Wattage in the long run doesnt mean a whole lot as long as you know you've got a good reciever and a good set of speakers that will more than handle that recievers output your good. Alot of people are going to say I'm wrong in saying this and I understand why but what it comes down to in the end is
    1.) do you enjoy how it sounds
    2.) does it get loud enough for you and
    3.) does its play cleanly at the volume you want it to without sounding like you are pushing one piece or another too hard.
     
  6. Guillaume H

    Guillaume H Auditioning

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    I have another question now.

    If it's better to have an overpowered amp (instead of overpowered speakers), then why 150-200+ watts speakers? Even the most expensive receiver found on the site I am referring to in my first post, the HK AVR525, "only" outputs 70 watts in Surround Mode and 85 in Stereo Mode.

    So having 150 watts speakers would be useless?
    Or am I getting something wrong?

    One last thing (for now [​IMG])... if a receiver outputs 100 watts to each channel and I would want to have speakers rated at 100 watts too, I would have to look for 100watts RMS, right?

    100 watts RMS means the power the speaker can handle continuously, and peak watt means the power it can handle on short periods (like gun fire)... right?
     
  7. JeremyFr

    JeremyFr Supporting Actor

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    Ok now we get into the subject of low/mid vs mid/high range recievers.

    With lower line recievers alot will rate full bandwidth power which is decieving because they are measuring the full power spread from say -100 watts to +100 watts and saying that its a 200 watt amp (car audio companys are notorious for this).

    Negative wattage is useless and does nothing for you another way to look at it is you have a signwave put a line through the middle everything above the line is positive everything below the line is negative.

    You should only be measuring from the line up and discarding the line down since its useless, but alot of companys measure this way to boast they have larger output than they do. So say you buy a Sony STR-DE475 that claims 80 watts per channel that reciever in all reality is probably giving you closer to 40-50 watts per channel and even that is probably gonna have a high amount of distorion where as you can take a Yamaha say like mine an RX-V730 and it will level a "130 watt per channel" Sony reciever.
    This is because Yamaha rates positive wattage only which is the most accurate measurement of the amplifiers output.

    Now mind you that companys like Yamaha, Denon, Onkyo, etc rate there amps very conservatively typically, and that a good amp will typically give you a very good reserve amount of power above what it is rated at for RMS power.

    Now onto a speaker rated at 250 watts RMS mated to say a 75 Watt per channel reciever its gonna sound great especially if the speaker has a high sensitively rating say 90db and above 1w/1m.

    Power Handling of a speaker really is gonna be irrelevant in the long run, what you want is a Receiver with good clean power, and a good set of speakers with a high sensitivity, the higher the sensitivity the louder they'll play with less power from the reciever.

    Wattage is more or less a thermal rating for a speaker, for instance many speakers used in Pro Audio applications ie night club/local cineplex/concerts will have ratings that are broken down into time, how long the speaker will handle a certain wattage before it overheats and blows. so lets say you have say an RCF brand 18" pro audio transducer thats rated at 600 watts rms that means you could basically play it all day and night at 600 watts without damaging the speaker, and then it will go up say 1200 watts for 4 hours, and then 18 watts for 2 hours and 2400 watts for 1 hour etc.

    Its basically how much heat the speaker can take before you put it sometimes quite literally into meltdown. Many times you'll see speakers that say they'll handle 250 watts and most time peak rating and they know you'd never push it that high in most applications I'm rambling again but if you have more questions feel free to ask.
     
  8. Lee Carbray

    Lee Carbray Second Unit

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    Guillaume, The best thing to remember is either way, receiver watts > speaker's or speaker watts > receiver's, if you play to loud you can do damage. It is just a matter of what you want the limiting factor to be. The best thing to do is find a receiver and speaker that sound good to you at the volumes you like to listen at. Don't put too much faith in the specs.
     
  9. Guillaume H

    Guillaume H Auditioning

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    Yeah Lee, I understand this is totally true. But when buying expensive things like these, I really really like to know I bought the best for my money.

    I'd like to have a system powerful enough so I can be in the kitchen and have the music still LOUD. Not loud to rock a stadium, but you know what I mean. I just love listening to my AC/DC with the volume pumped up.

    I currently have a 20 years old Technics system (amp and speakers) plus a Realistic 14-frequency equalizer/amplificator (I don't know the exact name) and the speakers at rated at 60 watts for the music, but it is not quite loud enough when I get outside of my room.

    My mom bought a Sony RHX-77 (I'm not sure about the 3 letters). It is rated at 100 watts per channel, but it is not quite as loud as my Technics floor speakers... but I think it sounds better than mine though (maybe I just can't find the proper ajustment on the equalizer).
     
  10. Mat_M

    Mat_M Stunt Coordinator

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  11. Guillaume H

    Guillaume H Auditioning

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    I think I just can't estimate how loud is x or y watts.

    Like I said above, my mom's Sony stereo is rated at 100 watts per channel... but I'm 200% sure that "real" receivers and speakers rated below 100 watts are MUCH louder than hers.
     
  12. Ted Lee

    Ted Lee Lead Actor

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    don't put too much emphasis in wattage. during normal usage a receiver uses very little power - it's something like 10-15 watts.

    all that extra wattage only comes into play during peak dynamic changes (a.k.a explosions).

    to double the loudness of a receiver would require a ten-fold increase in power. so there's really not a whole lot of difference between a 100w/ch receiver and a 130w/ch receiver.

    also, don't put a lot of trust in specs. a better specification will tell you how many watts into how many speakers at what frequency response with what variance into what ohm load. something like:

    100w/ch (5-ch) from 20hz-20khz (+/- 2db) into 8-ohms

    i think i'm missing some other factors, but my brain is kinda fried right now. anyway, the point is that that spec tells you more than just the receivers wattage. it tells you how accurately it can reproduce the range of sound and how much distortion it puts out.

    or think of it another way.

    yeah, i've got a receiver that can do 100w/ch. but when i put it up to just 80 watts it starts distorting. by the time i'm at 100 watts it sounds like crap. my friend's receiver only does 70w/ch but it sounds darn good at only 50 watts. why?

    because he has a cleaner amp that can produce more sound at lower volumes.

    my advice is to take a look at the features of the receiver. do you like the ergonomics, the remote, the layout of the buttons, the aesthetics, etc. ultimately those will have *much* more to do with your day-to-day enjoyment of the unit.

    man...i gotta stop typing now.
     
  13. Lee Carbray

    Lee Carbray Second Unit

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    Well said Ted. Btw you missed %THD.

    Guillaume, the specs stated by a lot manufactures are notoriously generous. When buying audio equipment it is better to go with your ears not your eyes.
     
  14. Vince Maskeeper

    Vince Maskeeper Producer

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    I'll see if I can muddy the waters a little further:

    1) Specifications mean exactly shit. There is unfortunately no real standard for measuring equipment, so when comparing numbers, you might very well be looking at apples and oranges.

    The truth is, an amplifier that is said to do "100 watts" might actually be capable of 200 watts. Amplifiers have electrical characteristics that they basically make "bigger" as output whatever they get coming in. The problem is they have a maximum level of input before the signal starts exceeding the input of the amp and becoming distorted.

    So the question in rating amplifiers becomes, how much distortion is too much distortion? Do we stop when the signal become .01% distorted, and measure the wattage output at that point? Or do we push it to .1% distortion, and publish that wattage as our output?

    You see, we can keep pushing the input of the amp, and get more wattage output- but the question is - HOW CLEAN IS THIS SIGNAL? Amplifier power ratings will often have a "THD" figure next to the wattage- tell you what level of distortion (THD = total harmonic distortion) at which they decided to stop. Some shady manufacturers will run their distortion up to 1% or higher, and publish that figure as their output wattage. Other companies put the brakes on when it reached .01% distorted

    So the truth is that the specs are misleading- and your ears will often tell you more than the paper will.

    And like Ted pointed out above, the issue of full wattage output is often moot- as the average level is going to be minimal. The extra wattage available for headroom extension during loud passages is key-- if your system doesn't have enough oomph for loud passages, you risk damaging your speakers...

    2) Trying to match speaker wattage to receiver wattage is a waste of time. Partially because the specs are lies to begin with, and partially for other reasons.

    Rating speakers in wattage is like rating tires in max MPH. There are so many variables to consider in a case like this that it's tough to put a firm number on what they'll take.

    But I've worked with speakers in some form nearly every day of my life for over 10 years. I have ROUTINELY put 1000-2000 watt amplifiers to speaker drivers rated for levels as low as 250 watts. I can honestly say I have never blown a speaker due to excess wattage (unless I did it on purpose [​IMG] ). Excessive wattage rarely damages speakers.

    In fact, inadequate wattage is 100 fold more dangerous!

    Why you ask? Well, I went into this idea a bit in this post-- but I'll try to explain it again here...

    As I said, wattage doesn't damage speaker- more often than not it is distortion that kills our little friends. Distortion happens, primarily, when you are forced to overdrive your preamp stage in your receiver (run the volume too high). By pushing the receiver real hard, the signal getting to the amp is usually in excess of what the amp wants to get- and the result is that the signal is distorted.

    Now, if you think about that for a second, what would be the best way to be able to keep the volume knob real low? Well, having way more powerful amplifier section! By having more power available to you in the amp stage - you will run everything lower, and instead of driving the preamp electronics beyond their limits- they can pass nice clean signal.

    I would say you could hook a 200 watt amp to speaker rated for 100 watts with ZERO problem, as long as your system was running clean signal (not being push to the limit)-- you'll find the speakers will be fine well into old age.

    It's when you get obsessed with getting the exact minimum amplifier level to match with the rated specifications on speakers that you get into trouble. You create a situation where you might very well need to push your system at 80-90% of it's ability to get what you're looking for, resulting in damage. Instead, By finding an amplifier product which can put out a good amount of power at very low distortion levels- you can likely drive nearly any speaker without issue! This creates a situation where you'll be using 20 watts on average, but when things get big- you have plenty of room to reproduce the loud stuff without running out of headroom!


    Don't think in terms of things going "unused"-- think in terms that the more power you have, the more "headroom" you have to keep everything clean. If you're always using your system at 65% or less of it's potential- you will have gear that will last a long time. If you're trying to target yourself into getting something you will have to run into 90%, you'll have a pile of damaged and melted electronics in no time...

    Hope that helps some.

    -Vince

    PS: JeremyFr, could you consider a few paragraph breaks in your posts? I basically tried a few times to read what you wrote, but gave up as it's difficult to read. I would strongly suggest breaking up long text blocks like that if at all possible.
     
  15. JeremyFr

    JeremyFr Supporting Actor

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    yeah sorry bout that I just get to typing and dont really pay attention to format but we basically said the same things I'll go edit my posts though so they're easier to read.
     
  16. Guillaume H

    Guillaume H Auditioning

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    Thanks Ted and Vince for giving two other point of views, and completing the blank spots Jeremy didn't had time to fill.


     
  17. Ted Lee

    Ted Lee Lead Actor

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  18. Guillaume H

    Guillaume H Auditioning

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  19. JeremyFr

    JeremyFr Supporting Actor

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  20. JeremyFr

    JeremyFr Supporting Actor

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