How Loud?

A couple of weeks ago I wrote about Dynamic range. You’ll find that in my Blog HERE.

In that writing I talked about loudness

“If you wish to reproduce a sound at its original level you only need a sound system capable of reaching that level at the distance you might be from the sound. For instance, a concert grand piano at around 20 feet listening distance can exceed 90dB in peak level. The piano is a percussion instrument. The hammer hits the string unlike a harpsichord where the string is plucked. Played softly it might be only 20dB SPL at 20 feet. These numbers are intended to be illustrative not absolute. You may find writings that indicate more precise values than I am using here.”

And

“One must always factor in the distance from the source. In an open environment the SPL decreases at the rate of 6 dB for every doubling of the distance from the source.”

Recently I read a piece about loudness that caught my attention. It said, more or less, that a sound system cannot reproduce the maximum level of live music from acoustic instruments and gave some examples of how loud some instrument might be.

I found this to be contrary to my experience so read further. Indeed, the numbers mentioned where very high. Missing was any mention of the distance the listener might be from the instrument.

All we need to do is reproduce at our listening position the level at the distance we would ideally or probably sit from the instrument being played.

You might like it louder or softer. That would be a personal choice. Typically, at my preferred listening position in a concert hall I have measured peak levels between 90dB SPL and 106dB SPL. If you like to sit closer than I do you might experience higher peak levels depending on the venue.

What does this mean in a practical sense? In your listening room you might sit 12′ from the speakers. If you do and the speaker has an output of 90dB SPL at 3 feet for 1 watt input (typical of a larger Wilson speaker), it will not be less than 78dB at 12′. That would be the level in a free field such as outdoors. Probably, the loudness in most rooms would be in the mid-80sdB SPL at 12′, depending on the room. However, the direct sound from the speaker will be an increasingly smaller component of the overall sound. If the loudness at the listening position was 10dB SPL lower than at 3’, you would need 10 watts for a level of 90 dB SPL, 100 watts for 100dB.

Clearly, you can reproduce live acoustic instrument music at realistic levels. Larger Wilson Audio, Rockport Technologies, and Sonus Faber speakers have an efficiency in this range. A Gryphon Diablo 300 amplifier has a peak power output into 4 ohms of 600 watts per channel. This would clearly be more than adequate.

These numbers are all illustrative not absolute but can give you an idea of what is possible. The usual distance given by manufacturers is 1 meter not 3 feet. The efficiency is often referred at 2.83 volts which is 1 watt into 8 ohms even though the nominal impedance of the speaker may be 4 ohms. Furthermore, the momentary impedance of a woofer that is not moving and needs to get it in gear can be much lower than the nominal impedance. If your speakers are only 80db efficient, you cannot reach levels of 100dB at your listening position. That would require 1000 watts and might toast your speakers if your amplifier could even deliver that power. A Gryphon Colosseum amplifier can. At the other end of the spectrum, if you are using a 10 watt tube amp you are not going to get there either, even with an efficient speaker.

These are complex issues. I would be happy to discuss, just E-mail me.

Come into The Sound Environment and hear what can be done and what you want.

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