LoudSpeaker LAB 3 Description

This is the 3:rd big revision of LoudSpeaker LAB and it is now totally re-written in C++ which is an object oriented language. The program can be used for box design, x-over design and measurement.

Box Design

At the moment is it possible to design and simulate closed, vented and band-pass enclosures. Passive radiator and dual vented band-pass enclosures will be added soon as a free upgrade. The drivers is stored in a big database this has the advantage of easier selection of a driver, if you measure the Thiele-Small parameters can they easily be inserted in to the driver database. In previous versions where the parameters entered in another window which was hiding the curve windows, in version 3 is the curves shown in the resizable design window.


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X-Over Design

The x-over part have been totally re-written, the simulator is now a nodal analyzer like SPICE. You can either start a new design with the guide or you can place components by yourself in any combination by dragging them from the toolbar. The simulation result is collected in one window where you can zoom in on a specific curve by just double clicking on one of the curves (zoom out by double clicking again).

Issues

At the moment are there a bug in the simulator that makes the result only valid for 1:st and 2:nd order filters, this will be fixed ASAP.


Click on image to zoom


Click on image to zoom


Click on image to zoom

Measurement

This is the heart of the program and the wave engine have full support for 192 kHz/24 bit audio with VXD or WDM (WinMe/2K/XP) mode, so most of the good soundcards out there should work. The measurement support absolute measurements and it will only require a good multi-meter with a low voltage (<= 30 Volts) ave or rms AC mode for calibration (the procedure use a 110 Hz sine wave).

Time-Domain Stimulus Types

White MLS
Pink MLS
Spike
External Wave File

The MLS is the preferred choice for acoustic impulse measurements but for electrical measurements is a spike just as good. The external wave file is for those who want to test strange stimulus waveforms.

Frequency-Domain Stimulus Types

Gated Sine Wave
Log Sine Sweep

The Gated Sine Wave is used for distortion testing and the Log Sine Sweep is used for near field high resolution measurements and impedance measurements.

Analysis Result Windows

Frequency Response
Polar-Plot - This window is combined with a frequency graph where you can select which frequencys that is visible in the polar-plot.
Impedance - This can show both single impedance curves and complete Thiele-Small impedance curve pairs.
Impulse (PIR) - This window also have these result curves: Step Response, Shroeder Plot, ETC and Log Square.
CSD (Waterfall) - This can be shown in standard 3D form or as a sonogram where the color show the magnitude.

Multi-Graph - Can show several frequency and impedance curves at the same time (good for comparison and documentation).

See my speakers for some result curves...

Quality Control

The program have full support for QC testing, the lower and upper limits can be manipulated separately and they can be set to check different columns. Sweep tables are also supported for fast testing e.g. with 3 frequency's like 20, 1000 and 20000 Hz. The editing of the limit values takes place in an Excel like window.

Post Processing

An impulse response can be processed with an Adaptive PIR Filter which remove most of the reflections on the curve, this makes it possible to make far-field measurements down to around 100 Hz in a normal living room. And there is of course smoothing, normalization etc for frequency and impedance curves.

Instruments

L-C-R meter
Function Generator
Oscilloscope
Spectrum Analyzer
RTA

These instruments is very valuable for real-time measurements like when optimizing the placement of your speakers or just for electrical measurements.

Calculators

There is a menu with curve calculators, you can Add, Subtract, Multiply, Divide and Average curves, you can also merge far and near field measurements to form an anechoic equivalent frequency response.

Import/Export

The program can import a whole bunch of formats including the MLSSA formats, the file is analyzed when it is imported so it can also import many unknown file types. Export of frequency curves, impedance curves and polar plot's is possible in text format, impulse curves can be exported in both text and PCM Wave format.

Hardware

There is no measurement box bundled with LoudSpeaker LAB anymore. I recommend Behringer UB802 mixer and a Behringer ECM8000 microphone as a good starting point, for those who want better quality do I recommend you to take a look at Earthworks Audio Products measurement microphones. There are many soundcards out there and I have used Terratec (EWX 2496 and DMX 6 Fire LT) and Creative (Extigy and Audigy 2 NX USB) cards while developing, with these should everything work flawlessly.

Well there's much more, please download the demo on the download page.