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LMS Analyzer

by November 09, 2006
LMS 1/24th octave grapgh

LMS 1/24th octave grapgh

The LMS hardware will run on virtually any legacy, decade-old, crusty computer which provides a full length ISA bus slot. For laptop use, the PAC4 can provide this external slot capability, and interface to the computer using a serial COM port for communication. You'll need to buy the laptop off eBay from a guy named "Gus" who tinkers with stuff in his garage for a living, but it's possible.

The LMS PC card contains a low distortion sine wave oscillator, dual state variable tracking filters, mic preamp, and gated peak/average level detection circuitry. A line level output is provided, along with a balanced line input, and a direct powered microphone input. Any of four locations can be selected for measurement, and external microphone preamps can be supported with level calibration. The basic frequency range of the system spans 10Hz to 100kHz and features a dynamic range of 90dB equivalent to 16bit digital audio.

The high resolution of the system allows up to 200 log-spaced frequency data points to be taken per decade of frequency. This is equivalent to one data point per pixel on the screen! One of the most powerful features of LMS is the dual tracking filters. These filters allow many different types of measurements to be made. The filters can be set for FLAT, LowPass, HighPass, BandPass, and BandReject responses. The accuracy and flexibility of the LMS analyzer rivals systems costing many times more, and is certainly far easier to setup and operate for both novice and experienced users alike.


About the author:
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Clint Deboer was terminated from Audioholics for misconduct on April 4th, 2014. He no longer represents Audioholics in any fashion.

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