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How much power is enough... really?

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  • How much power is enough... really?

    I'm sitting here tonight cross-legged on the couch in front of my Ushers, running my soon to be finished gainclone. Diana Krall... good lord. Besame Mucho. I don't even know what she's saying and it's a great listen. Detailed, quiet.. stand up bass.. anyways.. back on topic. Now, this GC is running the national LM3886 with the chipamp kit. I can literally run my dog out of the room and almost run myself out of the room with zero distortion. Pop over to some Rap or R&B and this setup can dig down into the low 30s with little effort. An honest power number I'd guess at 40-50W.. maybe.

    Guys running more power.. 150-300 x 2.. whatever. Really? I can't imagine ever owning an amplifier that powerful and tapping into its potential on any kind of normal listening situation. Juicing a block party on some PA gear maybe.

    I am quite the DIY HT virgin; non-experienced ears I guess you could say. Not having owned a 150-300W x 2 amplifier I reckon I could be mistaken. What say you guys that do have this kind of juice on tap? Is there REALLY a difference? Or is it just placebo?
    ~Mark

    Stuff I've builded http://techtalk.parts-express.com/co...lies/smile.png

  • #2
    Re: How much power is enough... really?

    Ive always wondered the same thing especially when it comes to subs.

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    • #3
      Re: How much power is enough... really?

      I too enjoy the sound of chip amps. IMO, my ice amps have better low end control and better dynamics.
      "He who fights with monsters should look to it that he himself does not become a monster. And when you gaze long into an abyss the abyss also gazes into you." Friedrich Nietzsche

      http://www.diy-ny.com/

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      • #4
        Re: How much power is enough... really?

        Originally posted by WWWJD View Post
        I'm sitting here tonight cross-legged on the couch in front of my Ushers, running my soon to be finished gainclone. Diana Krall... good lord. Besame Mucho. I don't even know what she's saying and it's a great listen. Detailed, quiet.. stand up bass.. anyways.. back on topic. Now, this GC is running the national LM3886 with the chipamp kit. I can literally run my dog out of the room and almost run myself out of the room with zero distortion. Pop over to some Rap or R&B and this setup can dig down into the low 30s with little effort. An honest power number I'd guess at 40-50W.. maybe.

        Guys running more power.. 150-300 x 2.. whatever. Really? I can't imagine ever owning an amplifier that powerful and tapping into its potential on any kind of normal listening situation. Juicing a block party on some PA gear maybe.

        I am quite the DIY HT virgin; non-experienced ears I guess you could say. Not having owned a 150-300W x 2 amplifier I reckon I could be mistaken. What say you guys that do have this kind of juice on tap? Is there REALLY a difference? Or is it just placebo?
        The only way to tell for yourself would be to put the big boy amp on it and listen for differences at those higher volumes. There may be a bit more clipping going on than you realize, just not enough to really draw attention to your ears.

        Maybe that's the reason it drives your dog out of the room?
        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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        • #5
          Re: How much power is enough... really?

          Originally posted by WWWJD View Post
          Is there REALLY a difference? Or is it just placebo?
          The only place higher power buys you anything is in the low bass, and even there most systems are way overpowered. You do a few minutes of unreasonably loud "show and tell", and, if you've got any sense, don't do that again.

          The 3886 actually delivers, as you have observed, 40-50 undistorted watts, and that's enough to get uncomfortably loud with any reasonable efficiency speaker. Linkwitz ORION are speced for 60 Watt amps (admittedly one per driver, many people use 3886 amps on them) . . . and it's PLENTY. And you won't find a cleaner sounding amplifier . . . there are a number that can match it (some of the new Class D stuff included), but the 3886 does not produce any distortion that humans can hear, so there's no way to do "better". If another amplifier sounds "different" from a 3886 it's the other amplifier that's "bad".

          People talk about "headroom" . . . that's just justification for money spent on power never used. With digital sources there is no such thing . . . when you hit 0dBfs that's it. There are no "dynamic peaks" above that, it's a hard limit. Playing a CD the noise will be at best 90dB below that, more commonly you'll hear the mic pre-amps and other noise sources at 80dB down, or less. In other words, if you have the volume set to max out the 3886 there will be noticable "hiss" in the background *from the recording*, and you'll probably be driving the speakers to their limit. You won't listen long at that level anyway.

          For speakers with 87dB/Watt sensitivity ~60 Watts gives you 105dB at one meter . . . quite loud enough if you still want to be able to hear anything next year, or the year after . . .
          "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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          • #6
            Re: How much power is enough... really?

            Originally posted by WWWJD View Post

            I am quite the DIY HT virgin; non-experienced ears I guess you could say. Not having owned a 150-300W x 2 amplifier I reckon I could be mistaken. What say you guys that do have this kind of juice on tap? Is there REALLY a difference? Or is it just placebo?
            200 watts will get you a little more than 5db louder than 60 watts which isn't all that much. I have knocked the clock off the wall with my system. I'm not into listening to my system that loud all the time but it's kind of fun on occasion.

            I have a friend who enjoys 8 hz organ notes. He has enough amplifiers in his basement that he uses industrial motor start relays to turn them on remotely. It's the only system I've ever heard that could recreate the sensation of standing on a railroad crossing when the train went by at 60 mph.

            Ron E.
            C-Note Iron Driver Build
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            The good thing about science is that it's true whether or not you believe in it. - Neil deGrasse Tyson
            http://www.youtube.com/watch?v=cjuGCJJUGsg

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            • #7
              Re: How much power is enough... really?

              I've only every seen one possibly valid argument for more watts at reasonable listening levels. A few years ago a person (don't remember who) did a test to see what the peek levels of power draw were while listening to a rather dynamic orchestral number at only a few watts rms. The peak output demanded of the amplifier to reproduce full unclipped dynamics was close to 100X the rms value!!! So if you have somewhat inefficient speakers (82-85db) you may actually see an improvement by having "dynamic" power capabilities in the hundreds of watts. I personally have found that it is more important to have a well designed amp than an amp with a lot of watts. I will say that I hold myself to a minimum of 60 watts, but that's because I'm driving inefficient speakers. And in the end what's 300 watts worth if it isn't done well?
              It's not how far you go, it's how go you far http://techtalk.parts-express.com/co...es/biggrin.gif

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              • #8
                Re: How much power is enough... really?

                There may be a bit more clipping going on than you realize, just not enough to really draw attention to your ears.
                Not with a 3886 . . . it goes into protection mode, and you can *definitely* hear it. The overload threshold is *abrupt*. With most speakers you're already hearing distortion from the drivers before that happens . . . there's not much point in having enough excess power to throw a voice coil across the room, especially since that power usually comes at the cost of higher distortion at the lower levels where you normally listen.
                "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                • #9
                  Re: How much power is enough... really?

                  Originally posted by Deward Hastings View Post

                  For speakers with 87dB/Watt sensitivity ~60 Watts gives you 105dB at one meter . . . quite loud enough if you still want to be able to hear anything next year, or the year after . . .
                  Yes, that is pretty loud, dolby reference for peaks actually. But dynamic range aside, at a more normal listening distance, say 12 feet, that 105db at one meter is down to 95 db, and will be perceived as half as loud. Still pretty loud, but not 105. To get that same 105db peak at 12 feet requires 400 watts.

                  My Krell 5 channel amp puts out 300 watts per channel into 8 ohms and double that into 4. I do listen to movies at reference levels now and again and have yet to run out of power. With my old 100 wpc amp, that was not the case when I could drive the amp to clipping with a bit of effort. As to your point about woofers, or subwoofers, I agree. I have 3kw of sub power (4 subs) and still manage to clip the amps on movies like War of the Worlds.

                  Regards,

                  Dennis

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                  • #10
                    Re: How much power is enough... really?

                    Only one time have I ever really needed an excessive amount of amplifier power. I still have a pair of Carver Amazing Loudspeakers (that are currently sitting in a storage closet waiting their turn to get played again) that require two Carver M-500t amps each in bridged mode to really get any appreciable sound pressure level or bass from them. A M-500t in mono bridged mode will output about 700W, so I had a total of about 1400W of amplifier power hooked to those two speakers. One of my M-500t's needs a new relay, so the whole setup has been out of the listening rotation for quite some time.

                    The ALS's were rated at 85dB @ 1M/2.82V with a recommended power of 300 watts minimum to 1000 watts maximum (http://arafel.org/audio/als/amazing_service.pdf).

                    Other than those monstrosities, I've used lots of amps in the 40W to 100W range and have never felt like I needed more power (for 2 channel stereo listening, HT is a whole other story). Then again, I don't listen to music at rock concert levels either, I guess I'm just getting old...

                    Edit: Just to clarify, for my HT subwoofer setup, I don't think I can get enough power!

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                    • #11
                      Re: How much power is enough... really?

                      Originally posted by djarchow View Post
                      at a more normal listening distance, say 12 feet, that 105db at one meter is down to 95 db, and will be perceived as half as loud. Still pretty loud, but not 105. To get that same 105db peak at 12 feet requires 400 watts.
                      That's true, in "free air" or in a ballroom, perhaps. Not so much in a "normal" size living room (mine's 16x24), where there are two (or more) speakers and several hundred milliseconds of reverb to maintain the level.

                      It's really hard to produce a "measurement", but I'd estimate that two speakers at 3 meters in my listening room play as "loud" as one of those speakers at one meter outdoors . . .
                      "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                      • #12
                        Re: How much power is enough... really?

                        Originally posted by Deward Hastings View Post
                        Not with a 3886 . . . it goes into protection mode, and you can *definitely* hear it. The overload threshold is *abrupt*. With most speakers you're already hearing distortion from the drivers before that happens . . . there's not much point in having enough excess power to throw a voice coil across the room, especially since that power usually comes at the cost of higher distortion at the lower levels where you normally listen.
                        The 3886 only goes into Spike protection mode if the speaker impedance is below a certain value, for the psu design.

                        Search on "Overture_Design_Guide15", a tool by National for calculating wattage, power supply rqts, and whether the spike kicks in. Keep the speaker impedance above about 5 ohms, and its trivial to design a chip amp that never kicks in Spike. It'll clip first.

                        I'm building a chip amp now, and I would never pair it with a speaker that dips below 5 ohms.

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                        • #13
                          Re: How much power is enough... really?

                          Originally posted by Fairlane64 View Post
                          The ALS's were rated at 85dB @ 1M/2.82V with a recommended power of 300 watts minimum to 1000 watts maximum (http://arafel.org/audio/als/amazing_service.pdf).
                          Yes, there are exceptions. Older magneplanars were perhaps 84dB @ 1 Watt, and low impedance to boot . . . they just suck current, which a 3886 would not be able to deliver enough of. Highly reactive loads, like some of the large electrostatics, would not be a good match for gainclones, either . . . and the kinds of output stages that can handle reactive loads will generally allow a very high power rating with more "normal" loads. OTOH the 3886 and the Seas Millennium (T25CF-002) tweeter make a perfect match . . .
                          "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                          • #14
                            Re: How much power is enough... really?

                            Originally posted by DDF View Post
                            I'm building a chip amp now, and I would never pair it with a speaker that dips below 5 ohms.
                            That's an unnecessary restriction, since they sound fine (and have no problem) driving 4 ohm loads as long as you don't overdrive them. And although tripping the protection produces unpleasant sounds :D it does so without damage to either the amp or the speaker. It's just a very unsubtle warning to "turn it down" . . .
                            "It suggests that there is something that is happening in the real system that is not quite captured in the models."

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                            • #15
                              Re: How much power is enough... really?

                              Originally posted by Deward Hastings View Post
                              For speakers with 87dB/Watt sensitivity ~60 Watts gives you 105dB at one meter . . . quite loud enough if you still want to be able to hear anything next year, or the year after . . .
                              That's a big stretch. There's not a 60W amp anywhere that will put out 60W RMS while playing actual music.

                              Music is not a sine wave. Typical peak to average ratio is 5:1 or more. 60W will produce, at best, 12W RMS with actual music playing before the onset of clipping. If you're listening to symphonic stuff, maybe 6W before clipping at the peaks.
                              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                              95% of Climate Models Agree: The Observations Must be Wrong
                              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

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