Read the first part of thishttp://sound.westhost.com/dynamic-range.htm
to understand why you need POWER!
Jez
On Mon, May 18, 2009 at 5:40 PM, Ken Norton <ken@xxxxxxxxxxx> wrote:
>
> > Why 250 - 300 W/Ch? Amps able to deliver such an amount of power are
> better
> > constructed, therefore they distort less and have an amazing dynamic
> > range. Of course, I take my exceptions - sometimes I feel in the mood
> > for turning that volume knob clockwise ... :-)
>
>
> It does depend on the amplifier design. Few amplifier designs are linear in
> response in dynamic response. Your better amplifier designs will expand at
> the lower levels and compress at the high levels. This is especially true
> with tube amplifiers. Lower-quality solid-state amplifiers compress at the
> lower levels and will expand at the higher levels and then when it clips,
> it
> distorts noticably. Amplifiers designed for sound-reinforcement are
> generally linear until they hit about 25% of maximum and then will slightly
> compress mimicking tube amplifiers. Unlike a tube amplifier which will have
> a continously smooth level of compression, solid-state amps tend to be a
> little more harsh about it.
>
> 300 watts per channel is not really all that much for a home system. 25%
> volume level (assuming linear amplifier response) is 75 watts. Your better
> quality speakers have HUGE loss levels--this is part of the design which
> uses passive means to control dynamic and frequency response. A lesser
> speaker will be louder watt-for-watt than a high-quality speaker. For
> example, Bose speakers (there I go again...) are power hogs. depending on
> the speaker, they may require two to three times the wattage for the same
> SPL than a traditional speaker design. As a result, these particular
> speakers will get quite warm (hot!!!!) when played loudly. After all, a
> speaker is nothing more than a linear electric motor.
>
> Also, consider the subs. If you want to maintain a 25% level as an
> operational max for the amplifier, you have to consider what 75 watts is
> giving you. Most woofer designs, any more are tuned-tube designs (cannons)
> which conserve space and require a much smaller cone. Instead of moving a
> big cone a little, we're moving a small cone a lot. But these speaker
> designs are horribly inefficient and need substantially more amplifier to
> drive. I deal with this in sound-reinforcement systems for Houses of
> Worship. (we pentecostals like it loud--come on out for your weekly
> rock-n-roll concert). One church I work with has six dual-18" subs as well
> as the flying speakers have their own 18" woofer, which is essentially
> worthless since the cross-over is at about 80 Hz. We can do full-spectrum
> to about 128dB anywhere in the room (1500 seat auditorium). But in another
> venue, we installed the Bose system for the subs. The Bose system utilized
> four small tubes which were computer aligned to the room. These four tubes
> directed the bass sound to the listening position and not into the rafters.
> The sound was extremely tight and bonded well to the rest of the main
> speakers. It was an expensive way to go, and according to the
> specifications
> wasn't all that good, but the proof is in the listening. Nobody has said a
> bad word about it and the musicians like it because there is nearly no
> heavy
> sub sound on the stage so we could use a lower SPL in the monitors. As the
> tubes were flown, you don't blow dry the hair of the first three rows of
> people.
>
--
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