The Decibel (dB) and the Violin/Piano Recital

[admin]

One of the most difficult-to-understand terms for newcomers (and even experienced enthusiasts) in audio and sound reproduction is the decibel, partly because it’s a measure of relative intensity or power in both acoustics and electrical circuits. It may help to understand it better if you know how the engineers at Bell Laboratories, back in 1924, came up with the term from which the decibel was derived.

Discuss "The Decibel (dB) and the Violin/Piano Recital" here. Read the article.

 

[cbraver]

Based on past discussions, some on this forum most would disagree with the usefulness of big power amplifiers for anything other than impedence matching since most receivers seem to only be stable to 6-ohm. This article seems to support using large amplifiers. I remember talking to a Crown rep who agreed, and also added that good power supplies are largely important too. I'm getting a tad confused. It seems the guys that don't make or use big amps say they aren't really useful in our application, and the guys that do use or make big amps say they are.

That said, I'm always going to use big amps, if for nothing other than they are cool.

Oh, and I can't get that log chart to load? Is it me or the website?

 

[gene]

Based on past discussions, some on this forum most would disagree with the usefulness of big power amplifiers for anything other than impedence matching since most receivers seem to only be stable to 6-ohm. This article seems to support using large amplifiers. I remember talking to a Crown rep who agreed, and also added that good power supplies are largely important too. I'm getting a tad confused. It seems the guys that don't make or use big amps say they aren't really useful in our application, and the guys that do use or make big amps say they are.

That said, I'm always going to use big amps, if for nothing other than they are cool.

Oh, and I can't get that log chart to load? Is it me or the website?

All things being equal more power is always better to minimize clipping during large transients and to also handle lower impedance speakers. That being said a 100wpc amp with 3dB of headroom is just as good as a 150wpc amp with 1dB of headroom, all other things being equal.

 

[cbraver]

All things being equal more power is always better to minimize clipping during large transients and to also handle lower impedance speakers. That being said a 100wpc amp with 3dB of headroom is just as good as a 150wpc amp with 1dB of headroom, all other things being equal.

Doesn't 150wpc just mean you have 50 watts more headroom than the 100wpc amp?

 

[mtrycrafts]

Doesn't 150wpc just mean you have 50 watts more headroom than the 100wpc amp?

The 100 watt amp with a 3 dB headroom is capable of 200 watt dynamic output. That 150 watt amp is capable of about 187 watts dynamic out with that 1 dB headroom.

 

[mtrycrafts]

One of the most difficult-to-understand terms for newcomers (and even experienced enthusiasts) in audio and sound reproduction is the decibel, partly because it’s a measure of relative intensity or power in both acoustics and electrical circuits. It may help to understand it better if you know how the engineers at Bell Laboratories, back in 1924, came up with the term from which the decibel was derived.
].

Yes, interesting but

In fact, I have a classical CD recording where the loudest portions of the music are almost 30 dB louder than the quietest passages. Think about how much amplifier power that requires cleanly reproducing the 98-dB peaks in my 2,200 cu. ft. living room.[/]

With his example of that small 300 seat concert hall, not reducing the intensity by 6 dB when he moved, although two different pieces were played and may not have had the same peaks to begin with, it was about a 3dB reduction or so.

Now, a 90dB spl 1w/1m speaker would need say 10 watts to make it simple, for that 98 dB peak at 1m or 100 watts for 108 dB spl. Now if he moves back to 12 ft, say a 6dB to 8 dB reduction at the most, that would be 100 dB spl peak, like the one in that hall And the quiet passage on that Cd would be 70dB, still rather loud So, no I don't think he needs his super duper amp

 

[cbraver]

I must say some of the Internet brands don't seem to be passing the savings on very much anymore. Almost four grand for this thing, and when you see MSRP on a typically amp you can expect to get a significant chunk of that off when you actually buy it. Not saying this isn't a good product, but, just talking out loud. You could get a stack of Crown XTi amps with variable speed fans (important for noise) and much more power per channel (overkill) for less money. I guess the packaging and having it in one box is certainly important for a lot of people though.

Yes, interesting but

In fact, I have a classical CD recording where the loudest portions of the music are almost 30 dB louder than the quietest passages. Think about how much amplifier power that requires cleanly reproducing the 98-dB peaks in my 2,200 cu. ft. living room.[/]

With his example of that small 300 seat concert hall, not reducing the intensity by 6 dB when he moved, although two different pieces were played and may not have had the same peaks to begin with, it was about a 3dB reduction or so.

Now, a 90dB spl 1w/1m speaker would need say 10 watts to make it simple, for that 98 dB peak at 1m or 100 watts for 108 dB spl. Now if he moves back to 12 ft, say a 6dB to 8 dB reduction at the most, that would be 100 dB spl peak, like the one in that hall And the quiet passage on that Cd would be 70dB, still rather loud So, no I don't think he needs his super duper amp

Have you seen this article from Crown?

http://www.crownaudio.com/amp_htm/amp_info/how_much_power.htm

Also this calculator:

http://www.crownaudio.com/apps_htm/designtools/elect-pwr-req.htm

It's interesting to me the difference required for something like a 87dB/w speaker versus a 90dB/w speaker. It's pretty significant.

 

[gene]

What this article doesn't take into account is the additive SPL effect of multiple speakers playing in the room.

What separates the A-1400 from most high power amps is you've got that high power in a high efficiency design in a compact box that also appears to offer very high quality audio, comparible or exceeding some of the better class A/B amps. When I get one in for review, I will find out

 

[mtrycrafts]

...It's interesting to me the difference required for something like a 87dB/w speaker versus a 90dB/w speaker. It's pretty significant.

Yep, 2X the power