IEC 268-1 PDF

IEC 268-1 PDF

Sound system equipment – Part 1: General – SS-IEC Buy SS IEC Ed. 1 () Sound System Equipment – Part 1: General from SAI Global. Hi, I am reading a tech note named “The Loudspeaker Toster” by Pat Brown of Synergetic Audio Concepts and I would like to know what the.

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While this standard was modified in some respects in later versions, andits weighting curve “Q” in the diagram below from Wilms has remained the same to the present day.

This contains details of the weighting curve, meters and a photo of the experimental apparatus and listening room.

The temporal weighting is also a decisive magnitude.

This German technique of quasi-peak measurement has been applied in Germany and some other European countries since aboutalthough the first standard was not published until Equivalent sound pressure level due to inherent noise uses CCIR iev the “Q” curve 268- Wilms and quasi-peak metering. The work of the C.

For instance, when specifying the self-noise of a microphone, the self-noise figure relates to the equivalent sound pressure level in air which would be required to produce such a noise signal in a noise-free microphone. My thanks to an astute engineer named Steve who pointed this out.

The History of Low-Level Audio Background Noise Measurement

The higher reading then reflects the severity of the audible effect and the consequent increase in annoyance factor. Unweighed noise measurement of any kind. According to Smitha there is a standard: His “recipe” for constructing a quasi-peak metering system to comply with CCIRor is page The steep rolloff of response above 10 kHz in the CCIR weighting function was probably incorporated because the function was intended for broadcast applications with a high-frequency bandwidth limit of 15 kHz: This is a stable URL and I intend to maintain and ultimately improve this page in the future.


This would also be advantageous for the world-wide use of the CCIR Recommendationand not only in broadcasting and television studio technique. In Marchmeasurement of low-level noise was being discussed on the SC mailing list. Wilms gives the title for ASA S1.

The proposal by R. He also notes that this method “has been used in the UK since for most noise measurements on audio transmission systems by formal agreement between broadcasting and transmission authorities”.

This is cited in Wilms 268-11 This combination had never been used or suggested by anyone. Added an English translation of Ernst Belger’s 2668-1. One must instead use a special “subjective audio noise meter,” usually known especially in Europe by the Greek word for noise meter, psophometer so’fameter.

There are two widely-used weighting responses for psychometric assessment of noise. According to Wilmsthis paper, or at least work around this time by Ernst Belger see mention below of his paperappears to have had a lasting influence on the field regarding both weighting curves and quasi-peak detection.

Wilms ifc mentions DIN 45 Part 2: Noise voltages should thus be measured with a true RMS reading voltmeter. The average-responding, rms calibrated detector which is the common type employed in ac millivoltmeters will read approximately 1 dB less than a true-RMS-detector-equipped meter. No such meter was available, and a modified version of an OITR-specified meter was used instead. Some quotes from Section 3 on self-noise: Hertz also cites it, and it is 2681- that a chart in this paper comes from Mangold, lec it is the only reference.

A Google Books page has a somewhat different citation: The C weighting network frequency response in the ASA revision is no longer flat but now has specific upper and lower -3 db points.


In one case so far I have also provided an English translation of such a paper, thinks to the kind efforts of someone else.


Consideration of the time-constant section shows that an isolated short-duration transient may charge the first section to nearly full amplitude. There is very little trace of this standard inbut it seems to have played an important role in this field. I have not found any BS British Standards which play a primary role in this field.

The gain of the first three amplifier stages was limited to approximately 31 db at each stage to preserve bandwidth, leaving the shaping of the noise spectrum to the filter circuit. The DIN 45 approach was rejected on two grounds. This standard last edition: For a microphone, this leads to self-noise levels which are 11to 12 dB lower than when measured according to CCIR The use of weighting or psophometric networks for the measurement of audio noise levels originated with telephone and telegraph companies who wanted to verify the quality of their lines for speech circuits.

Sound system equipment – Part 1: General

This web page will remain on the internet with this warning since other aspects of the design might be helpful to others. Geneva 3 – 18 May part 1″. But the results of the CCIR are relevant to the field of studio techniques in general, the parameters of which formerly were higher by some orders than those applied for entertainment electronics. Please see for DIN 45which I think is related to this.

The Zener voltage is approximately 6. This proposal presumably resulted in IEC A.