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Frequency Sweeps CD

L

Linn Naim

pfm Member
Is it possible to get a cd of frequency sweeps to asses speaker frequency range in one's listenig room?

Regards

Chris N
 
I seem to remember isotek did / do one. Not sure how you would actually use it without a meter and knowledge of what you are doing?????
 
You could also pick up a copy of the Stereophile Test Cd Vol-2 which provides on tracks 16, 17 and 18, frequency sweeps from 20 Hz to 20 kHz. The Stereophile tracks used warble tones, which, in contrast to pure tones, will minimize the development of room resonances.

http://www.stereophile.com/content/istereophileis-test-cd-2-tracks-15-19


The warble-tone tracks (which roughly illustrate the extent of the terms "bass," "midrange," and "treble") were recorded on a JVC XD-Z1010TN DAT recorder from the output of an Old Colony Sound Lab warble-tone generator, the frequency quoted being the approximate center frequency of each. The generator contains a sinewave oscillator that is frequency-modulated at a rate of 5Hz or so; this is fast enough that the effect of low-frequency room resonances on the perceived level will be minimized, the test tone changing sufficiently quickly that the resonance doesn't have time to fully develop.

The bass warble tones can therefore be used to give a good idea of a loudspeaker's subjective bass extension in the listening room, either by listening or by using a sound-level meter—Radio Shack sells quite a good one for around $30. Set a reference level with Track 17, Index 7, the 1kHz band, then note by how much the sound level drops with each successive warble tone (footnote 7). (If your cassette deck came with a microphone, put the mike at your listening chair, set the recorder to "Record," and monitor the sound level with its meters.) The 200Hz-100Hz bands can be considered the upper bass, 80Hz-40Hz the midbass, and the remaining bands the low bass. If these bass warbles sound or measure uneven, with some either sticking out more than others or missing in action, then try moving the speakers or your listening chair around the room. The object is to get the tones as even-sounding/measuring as possible.

Tracks 17 and 18 offer sets of warble tones covering the Midrange and Treble decades (footnote 8), so that you can measure the in-room response of your loudspeakers without having to pop for an expensive spectrum analyzer. The 1kHz warble tone can also be used to get a relative idea of a loudspeaker's sensitivity: measure the sound-pressure level with a loudspeaker whose sensitivity you know, then, without changing the playback level, measure the spl of an unknown loudspeaker substituted into the system.

The disc is available from Amazon, amongst others,

Jan
 
Linn Naim said:
Is it possible to get a cd of frequency sweeps to asses speaker frequency range in one's listenig room?
Click to expand...

If you have an iPhone the rather wonderful Sound Meter app by Faber Acoustical has a signal generator so you can do a whole range of manual or set sweeps plus white / pink noise etc. I find this far more useful than a fixed sweep on a CD or whatever as you can really dial in on where the problem is, e.g. I know I have a room issue at 49Hz. Just be careful with it as speakers don't like sustained waveforms very much and can overheat / blow, especially tweeters. I find running this kind of thing very quietly is significant to highlight any room or cabinet issues.
 
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