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In Reply to: Some more examples (non piano) from 2006-2007 posted by Christine Tham on March 10, 2009 at 23:43:59:
Perhaps the microphones on your field recorder have better frequency response in the ultrasonic range than were used on my recordings.
In addition to the recording of Beethoven Op 101 made in Jordan Hall (microphones in the usual position on an Ampex 350 series machine by the New England Conservatory audio department in 1975 and 1977) I have a recording I made in my home on my wife's Steinway B. A pair of AKG C-451E cardiods was placed just inside the open lid of the piano and recorded at 7.5 IPS on a 2 track Tandberg 6021. This recording was digitized at 96/24. For the entire sonata the peak to RMS ratio is 23 db. For the loudest 2 seconds that contains a highest peak, it is 14 db. This recording was made with very close miking to deliberately eliminate room reverberations. When played back on Snell A/IVs there was no significant difference between the piano and the reproduction, and with a 150 watt/channel amplifier there was a few db of headroom left prior to lighting the soft clipping lights on the amp. (It took much experimentation to achieve this result, and the recording doesn't sound particularly good in other rooms.) Perhaps I am getting a slight amount of compression from the tape, but the levels were kept down to eliminate distortion.
I also looked at another recording that I made at an excessively live room during a yoga retreat at which there were singers, acoustic guitars, harmonium, and various percussion instruments. For logistical reasons, the microphones were hung high from the ceiling and the resulting recording had excessive reverberation. The same AKG microphones were used and were recorded digitally at 44/16 using a Zoom H4. This resulted in a 23 db peak to average for 50 minutes of recording. It appears from looking at the recorded peaks that a small amount (less than 3 db) of compression was added by the H4 prior to digitization with this recording. By looking at some songs which were quiet and had no peaks above -6 dbfs the peak to average ratio was 23 db.
A similar result was made in a different recording using the H4 Zoom's own microphones. (This recording is for sale on Innersong.) My measurements are taken from the contents of the H4 memory stick. When mastering the album it was necessary to add a small amount of compression to the songs that had been recorded without invoking the compressor to make the recordings made on several successive days have a similar sound. Most of the songs were released at a peak to average ratio of 17 db. Personally, I would have preferred if there had been no compression in the original recording, but the recordings have to sound OK on boom boxes, etc.—these songs are marketed to yogis, not audiophiles.
I do have one recording where the peak to average ratio would have been more than 30 db, but the original was completely clipped. It was made in an open tent during a windstorm and at one point the tent collapsed, knocking down the mic stand. Fortunately, these were cheap dynamic microphones and were undamaged. :-)
Tony Lauck
"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar
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Follow Ups
- RE: Some more examples (non piano) from 2006-2007 - Tony Lauck 03/11/0908:04:42 03/11/09 (2)
- Just to clarify - Christine Tham 15:01:54 03/12/09 (1)
- RE: Just to clarify - Tony Lauck 17:43:19 03/12/09 (0)
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