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#11
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Re: speaker measurement
thanks all for the input and info
i'am very limited with what i can load on my works laptop, i have a pc but cannot down load anything to it.. so stuck really in that direction the info richard has posted is very useful i have printed that for further reference.. thanks that should do me for present needs thanks again to you all cheers steve |
#12
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Re: speaker measurement
Hi Richard
that diagram is priceless. I've just worked out that its not a hedgehog doing the measurements. lol Ed |
#13
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Re: speaker measurement
This little essay was made in the days when not many speakers had a smooth response or good dispersion. The recommendation for a graphic equaliser shows how pathetic much mediocre equipment was then.
Nowadays we regard the graphic equaliser as an anathema largely because our equipment is so good it shows up the distortions introduced by such equalisers or tone controls. In fact just one measuring point in a room is unlikely to tell you much, other than the room modes for that position. To measure speakers accurately in-room you need to take a series of measurements in an arc in front of the speaker - a minimum of six is recommended. You can then plot these on a graph and draw an averaging line through the points. The standard anechoic measurement is at 1 metre with 2.83v output from the amplifier. This is equivalent to 1 watt into 8 Ohms. This favours low impedance speakers which take more current from the amplifier for the fixed voltage and therefore seem more efficient - on a transistor amp that is! Also 1 metre doesn't give you much idea of what the speaker sounds like. Most listeners sit at 2m from their speakers or more where the drive units integrate better. To do comparative measurements you must put the microphone, or sound level metre, in the same place every time, and don't move the furniture in between measurements. A tripod is necessary - you can mount the Tandy (Radio Shack) unit on a photographic tripod and it will do a pretty good job between 200Hz to 7kHz. |
#14
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Re: speaker measurement
Speaker workshop at
http://www.speakerworkshop.com/ is a free program that uses a pc sound card and sound card and mic to perform a wide range of measurments, may be more than you need but the forum is a big help on using the software and it is possible to get the panasonic electret mics quite cheaply. |
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