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High Efficiency Speaker Asylum Need speakers that can rock with just one watt? You found da place. |
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In Reply to: RE: Dynamic range power posted by Paul Joppa on January 7, 2009 at 20:58:18:
Hi Paul
Regarding tape recorders of the day , keep in mind that back then the S/N ratio was the main “selling number†like peak music power was etc, hence tape decks normally had very optimistic numbers compared to what one got in practice.
I still have a couple a pair of 3340’s, an A-77 plus a military surplus mastering transport and had recorded portions of an album in the 80’s on the 3340’s so I am fairly familiar with what they could do first hand.
Also, when compared side by side to the decks below, my daughters Korg D1200 beats the pants off them subjectively and approaches being “blameless†at 24/96.
http://cgi.ebay.com/Korg-D1200-Digital-Recording-Studio_W0QQitemZ220339008547QQcmdZViewItem
Teac 3340
http://www.angelfire.com/electronic2/vintagetx/TeacA-3340S.html
Revox A-77
http://www.reeltoreel.de/worldwide/A77.htm
So far as what is in music, a few samples run through Cool edit to get the numbers.
Avenged seven fold “Bat country†Avg rms –11.3, peak .09, minimum –36.7
Beatles “eight days a week†Avg –16.5, peak –1.5, minimum –45
Doug Mcloud “you can’t take my blues†Avg-21.2, peak -.68, minimum –47
James Newton Howard “buttlefishing†Avg –26, peak 0, minimum –60dB
Home recording of “John’s kids†Avg-26.3, peak –2, minimum –46
Home recording of Fireworks in backyard Avg-37, peak ,-09 minimum –62dB
Now, from this one can say that in commercial recordings on CD’s sampled here, the most compressed was the first one, my daughters CD, exhibiting about a 11dB peak to average ratio and 37dB dynamic range.
A more hifi recording although old was JNH which exhibited about a 26dB peak to average ratio and 60dB dynamic range.
At the top was the fireworks recording which had about a 37dB peak to average and 62dB dynamic range.
Now granted these weren’t from an LP, those have a much more limited range in comparison.
Looking at the JNH track, one finds the peak level requires 400 times more power than the average level does while the fireworks requires about 5000 times more.
For JNH, if one wanted to have an average SPL of 85dB you mentioned, the peak levels would be +26db over that or 111dB.
If one had a speaker that was 90dB 1W1M and one was 4 meters away from the speaker (-12dB RE: 1M) , it would still require a peak power of 33dB over 1W (about 2400 Watts) and that is if there is no power compression or non linearity.
Similarly, with the fireworks, if one listened where the average level was reduced to 70dB, the peak level would still be 117dB and require more than 4000Watts with NO power compression.
Working backwards, if one had 90dB sensitive speakers and 100Watts, the peak level before clipping, if there was no power compression or non linearity and you were at 4 meters would be 90-12 +20 = 98dB.
This puts the average level for JNH, at onset of amp clipping at about 72dB, for the fireworks at about 61 dB. With the recordings total dynamic range of 62 dB, this would drop the lowest 20 or 30 dB or so of the recording below the noise floor in most homes.
Granted one has two loudspeakers generally but these are too far apart to couple above the low end and are supposed to be independent sources so for simplicity we are talking about one channel’s capacity.
Again, keep in mind we are not talking about subjective loudness or VU reading but rather what is needed to preserve what is on the recording.
People wonder why recordings don’t sound like live, these lost dynamics are certainly part of the answer. Gradual clipping or limiting may be much less audible as a flaw than hard clipping but the effect is still present in the dynamic presentation when you compare to the “without†version.
Best,
Tom
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Follow Ups
- RE: Dynamic range power - tomservo 01/8/0907:56:05 01/8/09 (0)
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