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.

Author: Kagis Taushura
Country: Netherlands
Language: English (Spanish)
Genre: Software
Published (Last): 3 April 2005
Pages: 171
PDF File Size: 5.10 Mb
ePub File Size: 16.2 Mb
ISBN: 866-3-27615-907-1
Downloads: 88520
Price: Free* [*Free Regsitration Required]
Uploader: Kegar

The measuring after this new doc. The gain of the first three amplifier stages was limited to approximately 31 db at each stage to preserve 28-1, leaving the shaping of the noise spectrum to the filter circuit. I think it is essential reading. This page does not concern high-level noise, such as the health-threatening environmental noise in workplaces, or in residential areas due to nearby road traffic or aircraft.

The dynamic response is described by requiring that a tone burst with a duration of between and ms must give the same indication as a continuous sinusoidal tone iex the same amplitude, as shown in curve 1 of Fig. I have not seen this paper. The measurement of noise voltage is “the most essential part” of C’s work. Each WG has a mailing list with a membership list and archives which are open to members of the WG.

Ernst Belger was born in in Jec, Germany.

Sound system equipment – Part 1: General

Unlike many of the papers cited here, which are only obtainable from the AES E-library, a version of this is available freely on the Neumann website. The A network is frequently used for measurements on speech interference and the annoyance level of low level sounds, such as fans and audiometric booth placement.

The weighting network tolerances are now much tighter. The noise should be weighted with high quality sound reproduction in conformity with ear response characteristic and noise impression; therefore, the curve according to fig.

Unfortunately, no tests of this type have been carried out since the early ‘s and such results as are available idc in some respects inconclusive or contradictory.

The implication is that equipment manufacturers given the choice of several noise measurement techniques will tend to choose the one which provides the lowest number. This reading with a faster rise time is called quasi-peak.

  KNAUF W623 PDF

Since the Mangold paper is the only reference datedI assume that the graph is from Mangold The IEEE link is here and the 268-11 is freely available here: This field is also important to the IEC standard on microphoneswhich as of the 4th edition adopts quasi-peak noise detection as the mandatory method of measuring the inherent self-noise of microphones: Conclusions Thus our review of the available methods showed that none of them fulfilled our requirements oec a practical system.

On the influence of group delay distortion and frequency range bandwidth limiting in the transmission of broadcast presentations. Concerning the weighting curve an immediate agreement was possible among the organisations participating in the CCIR.

SC microphones and SC digital audio measurement techniques.

AES E-Library ยป Programme Material Analysis

The method therefore had to give accurate results on impulsive noises, distorted crosstalk, dialing clicks, whistles, etc. If they were, then this would be a form of intermodulation “distortion”, including perhaps how the input signal alters the behaviour of iwc poorly designed sigma-delta analogue to digital converter to produce “birdie” tones.

In Marchmeasurement of low-level noise was being discussed on the SC mailing list. The first peak can be seen in Figure 3 below, in which RMS ied is plotted against voltage from the bias voltage source into the My viewpoint is on a separate page: Weeks states that these ieand have not “introduced any significant modification to the instrument’s performance” and that test equipment conforming to any of ief three specifications “therefore may be assumed to give identical readings”.

Later documents indicate that this weighting curve was adopted in CCIR and so is used to this day in the standards which are based on CCIR Comprehensive tests have shown – as is pointed out in CCIR Report – that curve A produces large errors, in case that certain types of noise prevail particularly with wide bandwidth circuits having frequency responses up to 15 kHz and with impulsive type noise.

Standard – Sound system equipment – Part 1: General SS-IEC –

The argumentation for the fundamental characteristics laid down in recommendation is contained i. On this subject, we can report only at a later date. This adjustment is for the difference between average and peak reading instruments; more about that later.

  FOUR QULS PDF

This seemingly “deterioration” of equipment has aroused a certain concern among the manufacturers of broadcasting receivers, but with pertinent explanation and correct complete indication of the values no problems should be left. IEC 60 is about to be revised to a 4th edition in late or in International Consultative Committee of the International Telecommunication Union, Geneva has been unknown to many audio engineers.

For a microphone, this leads to self-noise levels which are 11to 12 dB lower than when measured according to CCIR Ideally, we would be able to combine this measurement figure with the self-noise figure of the microphone and produce a third figure which accurately predicts the degree of annoyance or disturbance of the mic and recorder in combination, referenced again to the sound pressure of noise which would have to occur in air to create the same level of disruption if it was fed to a noise-free microphone, pre-amp and ADC.

This information led to a fairly clear-cut optimum system, that which the CCIR subsequently adopted unanimously Recommendation jec The weighting curve described by Wilms in as Q and as used???????

Methods of Measurements of Noise ,”p. This proposal presumably resulted in IEC A. According to this, the best agreement between measurements of the audio-frequency noise and the subjective assessment is obtained with the help of a modified version of the sound level meter by Niese [ Niese ] and a weighting curve according to fig. Peus mentions, without reference to any earlier version, that 2668-1.

Note that the commonly used integration time of approximately ms is similar to that of the VU meter, although the VU meter reading is sound pressure proportional rather than sound power proportional. Thus, we see that there is a discrepancy between these two international standards: A reference elsewhere gives the original title: Below are one or more PDFs of original papers, some from 60 years ago.

Dick Cappels’ project pages http: This 2nd edition of replaces IEC and its three supplements: