15 watts & 94 db eff. speakers: how loud?

rockadanny - I read (in TAS I think) that 3db is not detectable to the human ear and that 10db sounds like double the volume even though 3db is actually double when instruments are used.

thanks everyone, i'm in touch with the speaker manufacturer and working on an amp solution. johnk, fyi, to repeat the speakers never sound hard or poor or even distorted before clipping, they sound very good and then they begin cutting off and back on which i can only assume is clipping as it only happens at these higher volumes....from the sound, i am fairly certain they can play somewhat (not a lot)louder. obviously the question doesn't have the clearest of answers. i think it depends on the particulars of the amp, but i guess few have experience with the Trends 10.1 amp.

DESIRED LOUDNESS
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from http://www.enjoythemusic.com/magazine/manufacture/0907/

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Secrets of Amplifier And Speaker Power
Requirements Revealed!
Alan Lofft as supplied by Axiom Audio

As audio/video hobbyists, most of us grew up thinking that if we have an amplifier with 50 watts of rated output power into 8-ohm speakers, and that combination produces reasonably clean and loud music, then by doubling the amplifier power to 100 watts per channel, the system would then play twice as loud. Many readers likely still believe that. Not so.
Although it's not the easiest thing to comprehend, doubling the amplifier power does not double the loudness. In the above example, the sound from the speakers would not be "twice as loud"; it would only be "a little louder," an increase of 3 decibels. How loud is that? Hearing tests with large groups of people have revealed that a one-decibel (1 dB) change in loudness is approximately the smallest audible step that the average listener can detect, so an increase of 3 dB most listeners term "slightly louder."
So why doesn't that 100-watt amplifier always sound twice as loud? Because the acoustic decibel--the decibel (dB) being the unit of measurement used worldwide to quantify the acoustic loudness of sound--has a peculiar relationship to amplifier power output measured in electrical watts. That relationship is called "logarithmic." If that word gives you an instant headache (nightmares of high-school math), then here's a simpler explanation:
If a sound gets louder by 3 decibels or "slightly louder," it takes twice as much electrical power from your receiver or amp to produce that modest increase. Therefore, a 100-watt amplifier will produce sound only slightly louder than a 50-watt amplifier.
So far, so good. But what if it's party time, and you're listening to music "very loud," a level defined as about 90 dB Sound Pressure Level (SPL), and your speakers are gobbling up swings of 15 to 20 watts per channel on those musical peaks.
Drink in hand, you advance to the volume control on your receiver thinking, "I'll just crank this up to make the music twice as loud," and you turn up the volume control until there's a 10 dB increase in the sound level. Now your party-time goal of "twice as loud" will make huge electrical demands on your nice little multi-channel receiver or power amp. The receiver must deliver ten times as much power to double the subjective loudness. Between 6 dB and 10 dB is double the volume level, where 6 dB is four times the power and 10 dB is 10 times the power. In the aforementioned example, the amp must produce 150 to 200 watts per channel for those peaks in loudness. Therefore, every 10-dB increase in acoustic loudness--from 80 dB to 90 dB, or 90 dB to 100 dB--requires ten times as much electrical power in watts.
That's all very well if you have a monster amplifier or multi-channel A/V receiver with huge reserves of power output (most of us don't). If not, watch out. Your receiver or amp may "clip" or distort (or both), which will put a clamp on the output of the amp. When you push your amplifier into overload or "clipping," several things may happen. First, the top and bottom of the waveforms (representing the audio signals) are clipped off, generating distortion. Next, the amplifier's protection circuits are activated, removing those portions of the signal that are causing the overload, generating distortion. And finally, the amplifier's power supply may fluctuate according to the demands of the music signals....
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Simon Thacher's article in http://www.enjoythemusic.com/magazine/manufacture/0708/index.html

describes the distortions associated with reporduction of musical peaks - clipped or not clipped.

Print these two articles and keep for your references

All The Best
Rafael

Apologies for my lecture on incorrect math- no more drinking and posting, I promise!

My numbers were supposed to be based on the general rule of 6db increments, not 3db, and for that, it obviously doesn't make sense that the amp is clipping. I even sounded so smug, how embarrassing. I'm terribly sorry to have added to the confusion.

I read (in TAS I think) that 3db is not detectable to the human ear and that 10db sounds like double the volume even though 3db is actually double when instruments are used.

I believe we can all agree that 3db is extremely "detectable" though. I believe 1db is the smallest increment the average human ear is supposed to be able to detect.

Just for reference, I'm a recording engineer by education. I promise you can hear a 3db increase. even from just one instrument.

You just won't need 10x as much power :)

rockadanny - I read (in TAS I think) that 3db is not detectable to the human ear and that 10db sounds like double the volume even though 3db is actually double when instruments are used.

Good critical ears can detect about 0.2 db SPL differences provided it is over a broad range of frequencies in the midrange (as would be the case with volume). Adjustment of treble, for example, by 0.2 db SPL is probably not audible for most people - around 1 db SPL change in treble would become audible to many.