Real-Time Acoustic Analysis (RTA)
The Speaker Tester measures in-air acoustic response with MLS, Noise, Impulse or Chirp in real-time allowing you to easily position speakers perfectly in the room. Simply move the test microphone around the room and watch the response on the screen. For Best noise rejection (Sweep and collect), use Sine and Pulsed Sine modes. Reject room reflections using a Time Window
(MLS and Step) and create Cumulative Spectral Decay and Waterfall Plots.
Click on Images to Enlarge
Time Gated Impulse Response
The Speaker Tester measures the impulse response of the entire system, including room reflections. By cutting out the room reflections, a nearly anechoic response is revealed. The ability to see the room reflections allows you to pinpoint their source and apply room treatment where necessary.
Room Decay Measurement
Getting the right balance between an acoustically live or dead room is now recognized as an important consideration when installing a sound system. Room decay measurements show how quickly echoes and reflections dampen. The tester shows room decay in two ways: impulse magnitude and waterfall plot. Impulse magnitude can also be shown on a logarithmic scale magnifying energy decay further out in time.
3-D Waterfall plots show energy decay (or growth) versus time and frequency. This can be useful for showing loudspeaker energy as it is absorbed or reflected from surfaces in a room. Not only does this show how your speaker response changes with time, but it also shows the attack and decay characteristics of the room. This is ambience, where most people recognize that totally dead or acoustically live rooms do not sound good. A room that decays 40db in a quarter second is generally acceptable.
If the room shows strong resonances that do not decay, moving the speakers or some kind of treatment might help.
Interactive Crossover Design™ (ICD)
The new, innovative approach to crossover design introduced by Smith & Larson Audio greatly speeds up crossover design time by allowing you to simulate various crossover designs without actually having to build them!
Designs are entered via an ICD circuit file, which is converted into filtered left and right test signals. The test
signals are then used to excite two drivers connected directly to an amplifier. The results of the simulated crossover match the physical crossover to fractions of a db, as shown in the overlay of response magnitude and phase plots below. The Speaker Tester also measures driver time alignment to mm accuracy.
XVR Response Tool
The XVR Response Tool is used to enter response using magnitude and phase. The data is entered via a text file that specifies the parameters for right and left channels, as shown below.
XVR Data File
The tool also allows you to define and simulate a perfect crossover with an ultra-sharp cutoff in order to test the behavior of a particular design. Electronic or DSP filters can be added to advanced crossover designs by defining the filter characteristics in a text file similar to the file for entering response.
Amplitude of Both Channels
Analyzing the Crossover Point
To help you find the optimal crossover point, the Speaker Tester measures acoustic distance to <.1mm and finds delta
phase at the crossover frequency. Crossovers are also affected by voice coil alignment. The ICD control window includes a time delay option to test these effects without having to physically move the drivers.
Delta Phase at XO frequency
Support for Driver Protection Circuitry
To avoid costly mistakes and protect your drivers during the design phase, the software supports tweeter protection circuitry by reversing the response effects. The User Guide contains instructions on how to build a physical tweeter protection circuit.
Working with 3rd Party Schematic Entry Tools
Electronic circuits designed in 3rd party schematic entry tools such as Linear Technologies' LT-Spice/Switcher-Cad can be imported into the Speaker Tester via the common SPICE net-list file format.
Harmonic, Inter-Modulation & SINAD Distortion Measurement
The Speaker Tester includes 1st through 6th Harmonic, Inter-modulation and SINAD distortion measurement. In addition to raw data values, THD and IMD data can be plotted by frequency, and SINAD can be viewed using an Oscilloscope or Lissajoux format.
Tweeter Response & Harmonics 1-6 on Absolute Scale SINAD at 1 kHz Shown as Lissajoux Pattern
The Speaker Tester supports MLS, Step, Noise, Chirp, Continuous Sine and Pulsed Sine modes
for accurate as well as fast testing. High precision measurements are crucial for modeling and the
Continuous Sine mode provides the best signal to noise ratio. With the Speaker Tester, results are as
accurate as .02%. Continuous Sine mode is best used for close microphone response or within an
SnapTS™, our fast test mode, is a great way to analyze speakers as they come off the production line. Just enable any real-time impedance testing mode. The DC analysis module also uses SnapTS™ technology to find mechanical offset information.
By default, the tester constantly processes data. In most situations continuous operation is advantageous, but in some cases, being able to stop and restart processing is helpful. An example would be the reprocessing of a series of in-air response measurements from a common unchanging data set for comparison. The RUN-STOP-RUNn control button allows you to capture and hold a frame of data, that can then be reprocessed using different parameters. Additionally, the RUNn operation tells the system to wake up, collect data (for a specified number of frames) and then go back to STOP mode.
The RUN-STOP operation also works with sweep modes. When conducting a sweep, as for example when performing an ARB sweep, the sweep can be halted.
Clicking on RUN again allows the sweep to continue where it left off.
Since microphones are rarely 'perfectly flat', using a compensated microphone will improve the quality of your measurements. Compensation is the deviation from 'flat' and is usually supplied as an FRD file, or as a strip chart response. Compensation is applied to microphones connected to the XLR inputs, or to line level devices plugged into the RCA jacks.
Dual microphones are often used for on and off axis measurements, or when measuring room modes. The room mode measurement is simple. Place one microphone at the speaker (the reference) and the other in the room location you want to measure (measurement). The difference in the response shows the room modes.
Advanced Thiele-Small Simulator & Box Analyzer
The advanced Thiele-Small simulator in the Speaker Tester supports all box types - Vented,
Sealed, Band Pass and Passive Radiator. Using Frequency Dependent Inductance modeling, results
are improved over the traditional, flat or simple Le models. The simulator calculates Response, Impedance,
Phase, Velocity & Xmm of all Radiators.
The Box Analyzer automatically finds box alignment and losses with the built-in Auto-Align feature. It calculates box, port and stuffing losses and models the effects of room/car pressurization as well as vent resonance (pipe organ effects). In addition, our sophisticated box alignment methodology refines your driver parameters even if they have shifted due to drive level, temperature, break-in or box and driver interaction. Data can be imported from the Speaker Tester Test Environment or a manufacturer's data sheet. T/S versus Drive Level test data can be imported as well.
Compare simulated to real-time response with extreme precision (< 0.5dB error) as shown in the graph below: