I don't think "bad" speakers are intentionally made that way. anyway, the malignant frequencies are around woofer resonance and unfortunately there's where most of the energy in music lies.
here's the impedance of my (now almost vintage) Dynaudios. they're obviously equalized but they don't do them like that anymore. now they're renowned for being hard to drive.
but to get back to the subject, what we're actually measuring in this thread is more like SPL level derived from power dissipated on the speaker.
since I have a class D amplifier and an impedance-equalized speaker I'm pretty close to ideal (that is: power requirement is closer to the one calculated based on measured voltage and nominal speaker impedance) but that's not true for everyone obviously. for instance, it'd be interesting if back told us what speakers and amplifier he's using.
all in all it's an interesting subject and I'm glad it's been brought to discussion.
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Hmmm... I'll have to think about that. What I hope we're measuring is amplifier output voltage at 25% of absolute peak voltage. From there, all else is calculation based on Ohm's law.
It's meant as a simple but accurate way to find out if your amp will be clipping when you play music at your loudest levels.
i can't find my amps clipping when i play music at my loudest levels....but how do you know where the amp is clipping? for instance mine clips at ~22V, how to I get that voltage from your test?
I don't have a huge amount of data to back this up of course, but here's a Dynaudio speaker from 2009 and that still shows impedance equalisation. I suppose if they've changed designer in the last couple of years then they could have done away with that, a shame imo. Almost all the reviews that I've seen of Dyn loudspeakers over the years, that come with measurements, show at least some attention to keeping things easy to drive.
Dynaudio Sapphire loudspeaker Measurements | Stereophile.com
I am not saying that loudspeakers are intentionally designed to be hard to drive, just that designers tend to gloss over the difficulty of drive issue assuming people will be happy buying a bigger amplifier.
Exactly and it doesn't at all take into account the current demands placed upon the amplifier by a reactive load. The test is assuming that the amplifier is capable of driving the loudspeakers up until the point it clips from voltage rail limitations. Of course something like that is really beyond the scope of this thread and measuring this accurately does require an oscilloscope. The mentioning of reactive loads is important however, which is why I tried to describe them to a certain degree above, just so people are aware that there's more to this then first meets the eye.
It is all within the calculations. Quoting Pano from earlier on...
Ergo if you're amplifier can provide 22volts then divide by 4 = 5.5V required on the test signal. So run the test signal and set your volume control so that your meter reads 5.5V.
well it's weird with Dynaudio, they don't seem to follow a specific approach.
with the Confidence C1's (not mine, the new series) it's much worse, the impedance wanders from 4 to 10 ohms from 100 to 20kHz: Dynaudio Confidence C1 loudspeaker Measurements | Stereophile.com
yes, regardless what the point of all this is, everyone should be aware that it's not as simple as it may seem.
I don't understand. I mean, an amp can clip at any voltage. mine is powered at 37V and starts clipping at 22. without analyzing the output signal from the amp I wouldn't know that. say that Pano's test is giving me 8 volts. multiplied by four that gives a peak of 32V. how can I know that my amp doesn't clip at 32V? I can't.
Yes but you cannot just look at the impedance on its own, the impedance wandering from 4 to 10 ohms is nothing of real consequence and is 'easy' to drive by itself. The phase angle is also benign, so once again keeps the loudspeaker easy to drive. The small increase in the top octave isn't important to anything other then amplifiers with a higher output impedance and class D amplifiers with their output filters. I'd say that it's highly likely that Dynaudio could have used an impedance flattening network somewhere throughout the midrange too.
This is irrelevant as it is included in the amplifiers specifications. If you buy a decent quality hifi amplifier that is specified as to being able to provide 100 watts into an 8 ohm load at less then 1% THD, then you know, from back calculating, that it can provide 28Vrms or 80 volts peak to peak. It doesn't matter what its rail voltages are.
If you purchased an amplifier like yours, that had a 37V power supply, but clipped at 22V into an 8 ohm load then it would be specified as being able to provide 30 watts per channel.
Most of the amps I use have clipping indicators.
The high power low frequency distortion tests I have done have been below amp clipping levels, some amps I use are capable of output in the 90 volt range.
Speaker distortion at high levels can be quite high (above 100%), just because an amp has (virtually) no distortion at a given voltage does not insure the speaker will be linear in either terms of distortion or dynamic output when measured at only 25% of peak voltage.
Many of the responder’s speakers may already be distorting badly at a few watts.
Distorted speakers tend to tell one it is time to “turn down”, it is much more pleasant to listen to wide dynamic range when it does not sound like hammered dog poo.
For the last week I have been mixing sound for a variety of sources from DJs, movies, comedy, and live bands of many genres.
Low frequency levels below 100 Hz have been peaking at maximum around 110 dB midpoint in the 55 x 150 foot room, up to a bit over 125 dB within a meter of either of the two LF cabinets.
Although I would not prefer to stand that close, a woman dancing by the sub asked me to turn it up while I stood there with a dB meter...
Surprisingly high levels of undistorted LF (below around 100 Hz) cause little discomfort.
I think that speaker distortion may be more of a limitation to how much amp power is needed, the (around) 100 watt sub amp in my home stereo clips about at the same point the sub reaches over 10% distortion, I can’t stand listening to it above that level, but I find listening to occasional 130 dB peaks from my low distortion PA system subs fun.
Art Welter
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And you are free not to trust them, but the specs of most decent hifi amplifiers from reputable manufacturers can be trusted.
I lol'd irl.
When I metered mine at around 5.4 volts, the music that I was playing before hand wasn't really high enough to start stressing the speakers into heavy distortion, above what you'd normally expect anyway.
I try very hard not to listen above the point where it sounds like my speakers are "running out of gas" for lack of a better term.
I tend to get listener fatigue a good deal before I get into the hammered dog poo range.
or maybe she liked the high distortion? I have friends who seem to enjoy what I think is unlistenable. I'm at this gig and the sound is terrible and some friend comes to me saying "great sound, man!". with each day that passes I'm more and more convinced that I should only trust my ears
years and years of listening to music on earbuds and PC speakers must have an effect.
or maybe she liked the high distortion? I have friends who seem to enjoy what I think is unlistenable. I'm at this gig and the sound is terrible and some friend comes to me saying "great sound, man!". with each day that passes I'm more and more convinced that I should only trust my ears
Oh, the mp3 generation.
We're doomed, DOOMED.
PS it clips at 22V into 4 ohm. and that is 22V RMS. so it's more that 100 W per channel actually.
this is way off-topic, but my experience showed me that some people simply can't tell good sound even if beaten with a stick.
I wouldn't be surprised if some even liked the sound of heavy clipping.
As a member of the MP3 generation, I can (fairly) safely say that I can recognise good sound. The system I have at the moment I consider decent: I rarely drive it hard, and it lets me know when I do.
As a guitarist, heavy clipping sounds great. I prefer a clean bass guitar sound, but some light overdrive can add some character.
Chris
Originally Posted by weltersys
Although I would not prefer to stand that close, a woman dancing by the sub asked me to turn it up while I stood there with a dB meter...
Surprisingly high levels of undistorted LF (below around 100 Hz) cause little discomfort.
That is actually quite low distortion for that SPL from a single speaker, most would find low frequency THD in that range undetectable by ear with most types of music. The rattling of garage doors in the venue was easily detectable during some of LF movie sound effects though ;^).
Over 100% distortion in commercial subwoofers when run at rated power within the rated passband is common.
Like your friend, I doubt the dancer cared much about distortion, though she may have not asked me to turn it up had the sub been distorting badly.
Art
Although I would not prefer to stand that close, a woman dancing by the sub asked me to turn it up while I stood there with a dB meter...
Surprisingly high levels of undistorted LF (below around 100 Hz) cause little discomfort.
The subs used averaged 126.52 dB SPL over the passband at one meter with 5.438% distortion with 77.5 volt sine wave input, about 1500 watts in to the nominal 4 ohm load.
That is actually quite low distortion for that SPL from a single speaker, most would find low frequency THD in that range undetectable by ear with most types of music. The rattling of garage doors in the venue was easily detectable during some of LF movie sound effects though ;^).
Over 100% distortion in commercial subwoofers when run at rated power within the rated passband is common.
Like your friend, I doubt the dancer cared much about distortion, though she may have not asked me to turn it up had the sub been distorting badly.
Art
I happen to have the ASHRAE handbook of fundamentals on hand. It describes 70 db as "loud," 90 db as "Very loud," 110 db as "Threshold of discomfort" and 120 db as "Threshold of pain."
Most of my club PA sound experience has been in the threshold of discomfort to pain category. Although, after a while, you tend to accept it as normal (especially when weighed against other positive environmental variables).
Distortion or not, these levels are extremely loud, and I cannot see the point of striving to hit these levels in the home environment. In other words, it doesn't matter if your amp can swing that much voltage or not, it's almost never going to happen at home. Which brings us nicely to the point this thread is trying to make. You don't need megawatt amps for home use.
Most of my club PA sound experience has been in the threshold of discomfort to pain category. Although, after a while, you tend to accept it as normal (especially when weighed against other positive environmental variables
).Distortion or not, these levels are extremely loud, and I cannot see the point of striving to hit these levels in the home environment. In other words, it doesn't matter if your amp can swing that much voltage or not, it's almost never going to happen at home. Which brings us nicely to the point this thread is trying to make. You don't need megawatt amps for home use.
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