Acoustics 201 : Loudspeaker measurements

Learn how to set up the miniDSP microphone for loudspeaker measurements, including USB connections, RCA and mini jack cables to the amplifier, a downloadable graphic guide, and real-time wiring demonstrations.

Connects the Dayton Audio microphone to an audio interface and amplifier, explaining USB type B to type A connections, XLR cabling, dual mono jacks, and RCA outputs.

Learn how microphone calibration files correct non-flat frequency responses and, for Room EQ Wizard setups, download unique calibration data from manufacturers.

Learn to set up the UMIK-1 with an audio interface using ASIO4ALL offline settings, load calibration files, select inputs and outputs, and compare Dayton with Focusrite setups.

Set up Room EQ Wizard with the Dayton Audio microphone and Focusrite interface, load calibration, perform relative measurements, apply smoothing and gate windows, and align readings for accurate results.

Explore the theory of loudspeaker measurements, using free-field and near-field techniques to adapt to different speaker configurations. Indoors, apply gating to isolate direct sound from reflections and approach anechoic data.

Learn how near-field measurements capture low-frequency response by placing the microphone close to the speaker. Combine and scale with far-field data to produce a full, anechoic frequency response.

Explore half space outdoors with a flush ground baffle and a 180-degree hemisphere, and analyze ground plane measurements on a hard surface with two-meter mic placement for the mirror image.

Position microphone one meter from bookshelf speaker on a stand with nothing in front to reflect sound, maintaining a 0.8 m distance to preserve 2.6 m reflection and anechoic response.

Measure floor-to-ceiling distance, set the speaker stand and microphone to 1.25 m, and position the speaker and mic 1 m apart using a reference point (tweeter or mid-bass).

Discover how Room EQ Wizard’s 2020 update changes the interface for loudspeaker measurements, with new placements for start and end frequency, level, sequence length, sweeps, and inputs and outputs.

Perform a far-field mid-bass measurement in Room EQ Wizard (20 Hz to 20 kHz), gate at 4.4 ms, and note low frequencies require near-field measurements.

Measure the far-field tweeter with mic and speaker positions. Connect to the amplifier and use Room EQ Wizard to apply a 0.6–4.4 s impulse window and a 350 Hz limit.

Place the microphone close to the center of the mid-bass for a near-field measurement during playback, ensuring it does not touch the speaker, and reveal the 51 Hz bass-reflex resonance.

Switch the speaker, place the microphone at the port center, perform near-field measurement with settings, apply smoothing, and note the port's max output aligns with a dip in speaker response.

Learn to perform consistent far-field and near-field loudspeaker measurements by standardizing levels across amplifier, audio interface, and Room EQ Wizard, with a practical correction for mismatched tweeter levels.

Combine the near-field port and speaker responses by scaling the port with the area ratio, then use a plus b to sum the curves into the port plus speaker response.

Explore how near-field measurements used in box diffraction simulate an infinite baffle and how finite enclosure dimensions require compensation using a baffle-based correction in Room EQ Wizard.

Merge near-field and far-field measurements to produce the full mid-bass frequency response, matching levels in the overlap region around 214–500 Hz and splicing the curves for a cohesive result.

Export the mid-bass and tweeter frequency response measurements as text, rename the files with a FRD extension, and load them into X-Sim to explore crossover design applications.

Measure a floor-standing three-way speaker with a dual woofer and bass reflex port at one meter, using the mid-range as the reference for crossover design.

learn how to measure a 3-way speaker with tweeter, mid-range, two subwoofers and a bass port, produce frd files for highs mids and lows, and align far-field and near-field levels.

Wire the woofer first to set levels, then perform far-field and near-field measurements for the tweeter and mid-range, noting phase plug and port details, and create three files for processing.

Process loudspeaker measurements by smoothing, applying far-field and near-field windows, and splicing bass, mid-range, and tweeter data with baffle diffraction to prepare frd files for crossover design.

Measure a loudspeaker's full frequency response by combining far-field, near-field (woofer and port) measurements for anechoic results, using Room EQ Wizard and a Focusrite interface.

Measure the speaker’s full frequency response at the listening position for left and right monitors, capturing the room response. Iterate with a graphic equalizer and room adjustments.

Measure harmonic distortion in loudspeakers using impulse response and distortion charts. Normalize to the fundamental, compare decibels and percent distortion, and relate results to crossover points and port behavior.

Learn to perform electrical measurements using the Dayton Audio Test System (DATS), calibrate impedance with a 1 kOhm resistor, and compensate for test-lead resistance for accurate results.

Measure Thiele/Small parameters for a tweeter and a midbass driver, including resonant frequency, impedance, Q factors, Vas, and Le, using free-air tests and added-mass methods.

Learn to create ZMA impedance files from impedance sweeps of a tweeter and mid-bass in a bass-reflex enclosure, and combine them with FRD data for crossover design in XSim.

Measure electrical components with the Dayton Audio test system, including capacitors, inductors, and resistors. Compare actual values to rated values to assess tolerance and ensure accurate component ratings.

Demonstrate how to use XSim to set up two drivers, upload FRD and ZMA files, apply the Hilbert Bode transformation, adjust tails, and determine acoustical offset.

Measure acoustical offset between tweeter and mid-bass using far-field measurements, create and compare FRD files in XSim, and refine offsets with Room EQ Wizard to align driver responses.

In XSim, connect two drivers, add FRD files, apply the Hilbert Bode transformation, and compare curves; tune mid-bass delay to overlap, 0.56 inch acoustical offset for crossover design.

Apply finishing touches in XSim by adjusting tweeter and mid-bass filters from FRD and ZMA data, adding capacitors and inductors, and observing real-time frequency response for a linear crossover.