DRA Laboratories

Welcome to the home page of DRA Laboratories and the
MLSSA Acoustical Measurement System.

MLSSA 10WI Rev 9 and MLSSA SPO 4WI Rev 9 Released

MLSSA version 10WI Rev 9 will run under Windows XP for analysis-only of measurements stored on disk. MLSSA was also updated to conform to the latest specification for Male and Female STI measurements according to IEC 60268-18 Third Edition (2003-03).

MLSSA SPO version 4WI Rev 9 was updated to automatically switch the MLSSA RCAI into impedance mode. This feature allows you to automatically switch between T/S measurements of driver parameters and normal acoustic frequency response measurements using a microphone.

Many other new software features were added to MLSSA and MLSSA SPO. A list of all new features with full descriptions can be found in the Cumulative Release Notes: MLSSA 10WI thru 10WI Rev 9.

This upgrade can be downloaded and installed at no charge by owners of MLSSA versions 10WI or higher.

The MLSSA, MLSSA SPO and MLSSA RCAI reference manuals were also been updated and are now available online in PDF file format. See below under Online Documentation. Note that Acrobat Reader's search function can be used to quickly search the PDF manuals.

MLSSA 2000 Mothercard Upgrade

The MLSSA 2000 mothercard features a pink-filtered MLS output for improved SNR in the bass region.

MLSSA 2000 mothercards are full-length ISA cards compatible with ISA bus speeds up to 16 MHz.

A MLSSA 2000 Mothercard Upgrade Kit is available to upgrade your existing hardware and software to the latest version.

For details and other features of the MLSSA 2000 mothercard upgrade, please see the MLSSA 2000 Mothercard Upgrade Kit brochure.

Theory of Upsampled Digital Audio

Upsampling has become a boon to audiophiles who hear significant and sometimes dramatic improvements in the sound quality of CDs played back through commercially available upsampling digital-to-analog conversion products. A great deal of confusion surrounds this advance in digital audio reproduction. The paper published here defines the process of upsampling and presents a scientific explanation of its effects upon digital audio sound quality.

For the complete paper, see the Theory of Upsampled Digital Audio

Product Literature

MLSSA is the industry standard loudspeaker measurement system and the MLSSA Speaker Parameter Option (SPO) is the industry standard for measuring the Thiele-Small parameters of loudspeaker drivers. MLSSA and SPO both include QC (Quality Control) PASS/FAIL functions for high-speed automated production line testing of loudspeakers and drivers. Other important applications of MLSSA include speech intelligibility measurements according to IEC 60268-16 Third Edition via the Speech Transmission Index (STI) and Rapid Speech Transmission Index (RASTI) as well as room acoustics measurements according to ISO 3382. For details, see the MLSSA Acoustical Measurement System and MLSSA Speaker Parameter Option brochures below.

MLSSA Acoustical Measurement System

MLSSA Speaker Parameter Option (SPO)

MLSSA 2000 Mothercard and Upgrade Kit

Earthworks Model M30BX Battery-Powered Microphone/Preamp

Compatible Third-party Accessories

Note also that the microphones listed here are sold only in combination with MLSSA or to those who have previously purchased MLSSA from DRA Laboratories.

Ordering Information

For current prices and ordering information please contact DRA Laboratories at dra@mlssa.com

Online Documentation

The following PDF files include a navigation bar and a linked table of contents. They can be searched using Adobe Acrobat Reader version 5.0 and above.

MLSSA 10WI Rev 8 Reference Manual

MLSSA SPO 4WI Rev 8 Reference Manual

MLSSA RCAI 2.0 Reference Manual

Cumulative Release Notes: MLSSA 10WI thru 10WI Rev 9

About DRA Laboratories

Famous MLSSA Users

DRA Laboratories
4587 Cherrybark Court
Sarasota, FL 34241-9213 USA
Tel +1 941-927-2617
Fax +1 941-925-0964


Revised December 12, 2007