Why you need 500Wpc for good sound

[Randyman]

watts up Butch

[cjgeraci]

Seti, was your Tripath one of those $100 Teacs from a while back?

Just curious because if so, I agree with you. I was not that fond of the Teacs as well - the highs were too rolled off and the bass less than stellar.

In comparison, however, the upgraded model of the Sonic Impact amp (Super T) and the Trends 10.1 sound pretty different (much better IMHO) from the Teac even though based on a similar design.

Carl.

Yeah I got the trends 10.1. I tried the upgrade which resulted in me killing it. I had McIntosh mc30s just before and after I picked up the onix sp3. So that was my comparison not really fair but not my thang.

Completely understand. Bear in mind that while I love the great gang/buck, in a full-range application, I would not recommend them beyond what I use them for - my patio system driving my JBLs.

But..........for anyone who ever thought or is active bi-amping or tri-amping - certain digital amps are the bomb (with the upgraded power supply) for running the top end, whether a squawker, all the way up (500-20000) or a tweeter. I do think with the right power, they make the perfect upper horn amp.

Carl.

[jacksonbart]

Who is Butch?

[colterphoto1]

Jimmy Buffet stage right Bama Breeze tour 2007

[jacksonbart]

I saw Jummy Buffet in 2005 in Philly, sounded like crap, echo city and muddy. The best part of a Jimmy Buffet concert is the tailgate for 6 hours before and the other people, the music is "ehhh".

[ClaudeJ1]

OK...

What power would be required if you are say crusing along at 5 watts and you have a musical peak,,, say a loud bass drum hit or something... how much more power would you need to reproduce that. Would a low power amp be able to produce that in the time required ?

This one's easy when you use dbW(atts), which is why I'm making my point about this. 5W is 7 dbW, so you would add 7+20=27dbW, or 500 Watts of PEAK amplifier power. This is why many amplifiers could be designed with lots of short term voltage capability, but not continuous power capability, you need to address the dynamic nature of the music with a SYSTEMS approach, not just blindly make statements about power requirements. My speakers are 100X more efficient (20 db) than the "average" in the industry, so 500 Watts to you is like 5 to me. I know some watts are cheap, but when you consider the HUGE reduction in distortion that comes from an all-horn system, with incredibely DYYNAMIC IMPACT

[DrWho]

This one's easy when you use dbW(atts), which is why I'm making my point about this. 5W is 7 dbW, so you would add 7+20=27dbW, or 500 Watts of PEAK amplifier power.

500W for a single frequency. Make that 16 frequencies of equal amplitude and now you're looking at another 20dB for crest factor...

[JJkizak]

I keep seeing new terminology on this forum all the time like "crest factor', "head room", and about a zillion words to describe distortion. Let's see we have harmonic distortion, intermodulation distortion, transient distortion, time-delay distortion, DAC distortion, mechanical distortion, glide tone acoustical distortion, phasing distortion, coloration distortion, and "human ear response syndrome distortion". What about humidity, atmospheric pressure, and when the furnace blower turns on?

JJK

[WMcD]

Here's a link to a 70 watt Heathkit amp which gives the same reasons (basically) on why you need 70 watts. http://www.heathkit-museum.com/hifi/hvmw-6m.shtml

My guess is that the unit was in production in about 1965. (Correction: info from a website says 1958.)

Wm McD

[Coytee]

What about humidity, atmospheric pressure, and when the furnace blower turns on?

Don't forget spousel distortion...my wife distorts every time I talk about electronics...[:-*]

[pauln]

Mentioned above:

"20 db for headroom for musical peaks would mean that you would need double the wattage for each additional 3 db, or:

5 watts x2x2x2x2x2x2 = 320 watts available for peaks."

Where did the 5 watts come from? Is it not more correct to begin with a reference listening level rather than a power level, then do the math upward until you were at a 20dB higher listening level, then see what watts that requires?

For example, if I like an average loud listening level of 87dB, with speakers 105db/W@1m that level is acheived with just 15mW (or 0.015W, or 1/64th of a watt), and 20dB of headroom would call for less than 108dB, which would happen at 2W.

Now I don't sit 1m from the speakers, but there are two of them and they are in corners, so the level drop with seating distance must be about matched by the doubling with there being two speakers, and room effect.

So may I conclude that I have sufficient headroom for peaks with 2W? I still have another 1.5W of rated power beyond the 2W level...

If I started with the 5W level that would be starting with a rather loud 112dB wouldn't it?

[DrWho]

So may I conclude that I have sufficient headroom for peaks with 2W? I still have another 1.5W of rated power beyond the 2W level...

That works out only if you listen to single frequency test tones.

With music, you've got multiple frequencies happening all at once....which requires more power to drive. Even as few as two frequencies at once during a transient requires another 6dB, or 4x the power. You've got 3.5W on tap? I'd say that even with 105dB speakers that it would be quite easy to run out of steam before things even start sounding loud.

[SWL]

You guys know your stuff. My head is spinning.

I bought 500W Crown amps to drive my RF-7's with good results. Some are saying that is a waste......some are saying it is neccessary. I've come to the conclusion that while Klipsch speakers are easy to drive, take little power to make them go "loud" and that it is evident that even though those things are true........more power can make them sound better.....not neccessarily louder, but more dynamic etc......at least with RF-7's.

Distortion? Maybe so......but my ears seem to really like it. []

[pauln]

Hello Dr Who!

So why is it that multiple frequencies require more power?

Is it based on the area under the curve (for the positive side, and area over the curve for the negative side)? That would support the idea that square waves need lots of power.

Is it based on how much the wave changes direction from moving toward pos to neg and back? This would imply that a single high frequency might need more power than a slow square wave, so this is probably no true?

Is it based on the average time the wave is held further away from the zero level (square wave vs sine wave)? This supports the power hungry square wave even thought it is a "single frequency", but then there are the harmonics, right?

I'm guessing that the frequencies in question mean all the component sine waves that make up specific sounds, so a low frequency square wave approaching 0Hz would require the maximum power - actually be at the limits of the power available.

And white/pink broad spectrum noise would come in a close second place?

Just wondering, it all sounds loud enough to me.

[ClaudeJ1]

This one's easy when you use dbW(atts), which is why I'm making my point about this. 5W is 7 dbW, so you would add 7+20=27dbW, or 500 Watts of PEAK amplifier power.

500W for a single frequency. Make that 16 frequencies of equal amplitude and now you're looking at another 20dB for crest factor...

My experience dictates otherwise.

[ClaudeJ1]

Mentioned above:

"20 db for headroom for musical peaks would mean that you would need double the wattage for each additional 3 db, or:

5 watts x2x2x2x2x2x2 = 320 watts available for peaks."

Where did the 5 watts come from? Is it not more correct to begin with a reference listening level rather than a power level, then do the math upward until you were at a 20dB higher listening level, then see what watts that requires?

For example, if I like an average loud listening level of 87dB, with speakers 105db/W@1m that level is acheived with just 15mW (or 0.015W, or 1/64th of a watt), and 20dB of headroom would call for less than 108dB, which would happen at 2W.

Now I don't sit 1m from the speakers, but there are two of them and they are in corners, so the level drop with seating distance must be about matched by the doubling with there being two speakers, and room effect.

So may I conclude that I have sufficient headroom for peaks with 2W? I still have another 1.5W of rated power beyond the 2W level...

If I started with the 5W level that would be starting with a rather loud 112dB wouldn't it?

I have pretty much been saying the same thing. You need to start
with an average sound pressure level, and give enough headroom for the
peaks at the listening position. PWK's frame of reference was a full
symphony orchestra. He recorded their performance for his own listening
pleasure with only 2 microphones. I personally heard several of his
recordings on his 2PH3 all-horn speaker array in his home. They
sounded just terrific. I have been to many symphonies and I am amazed
at how soft the levels are and how "rolled off" the high end sound, but
crystalline clear in the natural acoustics of a good orchestra hall.
The most dynamic work I have ever experienced was Stravinsky's "Rite of
Spring" performed by the Detroit Symphony orchestra.......talk about
goose bumps over the dynamics!! Any how PWK told me that you only need
17 db. headroom in amplifier power and that Khorns with a Belle in the
middle (like he had) in a large living room only required that much
headroom vs. a nominal 1/4 Watts of average power. He was running Crown
D-60 and BGW-100 amplifiers.

Grasshopper, you were learning to
poop in your diaper when PWK told me this and I tend to believe him
more than your infinite db headroom comments, sorry.

[michael hurd]

Output @ speaker vs. SPL @ listening position. To reach a faily loud level ( at the listening position ) most people are clipping the heck out of their amplifiers without realizing it. Amp clipping behavior varies widely, with some getting downright nasty.

For a given output level you need less amplifier power, that is a given. It still doesn't change the fact that if you want to have 'more in the tank' for transients, you need MO' power. How much headroom do we need? 17db may be adequate, but that all depends on the recording.

[DrWho]

I'm still learning to poop in my diapers, but this really isn't up for debate. This is something easily measured, which Ive done plenty of times. Believe me, I would love to believe that 1W is sufficient, but real measurents indicate otherwise. If PWK wrote that the Earth is flat, you would believe it...I think many are totally taking his comments out of context.

But how bout someone show some measuremts that indicate otherwise? THAT would be true PWK spirit. However, what we will find there are songs without much dybamc range. Proper engineering takes in the worst case (most power needed) scenario.

[ClaudeJ1]

For a given output level you need less amplifier power, that is a given. It still doesn't change the fact that if you want to have 'more in the tank' for transients, you need MO' power. How much headroom do we need? 17db may be adequate, but that all depends on the recording.

I think 20 db headroom is plenty for the way recordings are made. Where you need those kilowatt amps is on direct radiator subwoofers to keep up with the 50 watt amplifier on horns, which are 20 db more efficient, at least.

[ClaudeJ1]

I'm still learning to poop in my diapers, but this really isn't up for debate. This is something easily measured, which Ive done plenty of times. Believe me, I would love to believe that 1W is sufficient, but real measurents indicate otherwise. If PWK wrote that the Earth is flat, you would believe it...I think many are totally taking his comments out of context.

But how bout someone show some measuremts that indicate otherwise? THAT would be true PWK spirit. However, what we will find there are songs without much dybamc range. Proper engineering takes in the worst case (most power needed) scenario.

What, you don't think that PWK took real measurements? He spent his lifetime doing it. No, I take everything ANYONE says in context, even PWK. I didn't agree with everything he said. He didn't like CD's or commercial recordings of any kind. He referred to it as "dilute stereo." This means that if it wasn't a symphony, it wasn't music, so I feel it was very narrow minded. I would have missed out on a lot of really good music recorded as "dilute stereo" if I had taken that all the way out. However, when it comes to non-synthesized music (only acoustic instruments), a full symphony represents the purest and most dynamic form of music. On the other hand, nothing beats the dynamics of close miked drums being pounded, obviously.

Check Richard Burwen's 20 Kilowatt setup with his concrete horns and subs. He claims that drums can reach peaks of 140 db when pounded hard, so he needs that much power. I agree with him and you in that sense, but to design and build a setup like that requires a substantial investment of time and money, not something that anyone here is likely to do. Even if we did, what's the point? I am satisfied with lower listening levels than I like when I was 19 years old, simply because I want to enjoy music without destroying my hearing in the process and enjoy it for my remaining years.To do what Burwen did and what you suggest is way overkill.

I'm just anxious to see what kind of system you finally put together for yourself now that you are out of school and earning a good living. That I will believe.