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

With a Trends 15 watt t-amp and small tekton design speakers, with 6 inch fostex 167es, rated @ about 94db, i can get about 93-4 db sustained average (@ 1 meter per speaker) with peaks around 96-7. It sounds perfectly good, nice and clean, no treble break up, nothing different than @lower volumes, only louder.

BUT, at ANY higher volume the amp starts to clip. One hears of many such rigs with even lower wattage 300Bs and such, which is why i wanted the efficiency of the speaker (as well as its single driver design). I've never really used a solid state, much less digital amp before. I'm wondering, is this the nature of hard clipping in digital amps, to begin before there is any real noticeable distortion or is something wrong with the amp? Is this generally how solid state clips? How loud should speakers of this efficiency go with this many t-watts? Finally, how many watts do I need to have some more head room (let's face it, I'm only comfortable with my rig when I know I can accidentally destroy the speakers late one night) : )

Thanks in advance!
thomp9015
philjolet's avatar
philjolet
2,306 posts
 
I have found speaker and amplifier ratings to be misleading. You really just have to hear it for your self.

I easily drove 88db Trentes with a 18wpc Soro amplifier, they rocked! and when I switched to 94db AN speakers it did not seem much louder.

Of course a 3 db increase is not supposed to be audible to the human ear so maybe 6db is just a bit louder.
joelv's avatar
joelv
103 posts
 
For the sake of argument, let's assume that RMS measurements aren't meaningless. Taking audio science at face value, there is a reason for your clipping problem.

The math goes like this: If 1 Watt produces 94db at 1M, then...

97db requires 10 Watts
100db requires 100 Watts

so your amp is behaving quite normally if it clips when the speakers are at SPLs higher than 97db.

As I understand it, it is the behavior near clipping that give many amps their characteristic sound. Triodes are supposed to sound "glorious" when distorting.

Clipping, however, doesn't sound good coming from any amp, tube, digital, or solid state.

If you need over 97db peaks in your room, basic audio physics rules say you need a more powerful amp. I'd try something that has peaks at 100 watts or more to get the dynamics you want.
rockadanny
1,226 posts
 
Philjolet - huh? 3dB increase can be detected by most.

Joelv - huh? each 3dB increase requires around (not exact) double the power, not tenfold. so 97 requires 2 watts, 100 requires 4 watts.
johnk's avatar
johnk
1,975 posts
 
3DB twice as loud. 1 watt 97db if 8 ohms. 2 watts 100db, 4 watts 103db. A fe166e in a BLH is a much diferant beast can play louder more dynamic than a fe167e in BR. The BR versions of fostex horn drivers are poor performing unless used in nearfield or at low volumes more power will not help. A SET tube amp might give a wee bit more SPL before sounding hard. You just reached the max SPL that this fe167e driver in the BR cabinet can produce before sounding poor. 1 reason we offer no BR fostex fullrange except f200a. Our FE126e and fe166e are all BLH. As they should be.
gregm
3,405 posts
 
Johnk: 3dB = ~1,4x as loud. 6 dB = twice as loud. You know that, of course! It's sound *pressure* he's talking about.

Back on topic: in theory, your amp clips at ~103-104 dB. That's quite loud, btw!
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