TLDR;
This episode of Tuesday's Tech Talk discusses loudspeaker measurements that are indicative of sound quality. It emphasizes that while no single measurement can fully describe a speaker's sound, certain measurements provide valuable insights. The key measurements discussed include frequency response, off-axis responses (horizontal and vertical), impedance curves, and spectral decay. The spectral decay is highlighted as the most telling measurement for identifying potential issues like ringing or cone breakup, and for assessing the speaker's speed and clarity.
- Frequency response and off-axis responses reveal a speaker's accuracy and how it loads a room.
- Impedance curves indicate how well-balanced a speaker is and whether it presents an easy or hard load for an amplifier.
- Spectral decay shows how quickly a speaker dissipates stored energy, indicating its clarity and speed.
Introduction [0:16]
The host introduces the episode as a follow-up to the previous week's discussion on loudspeaker measurements. This week's focus is on measurements that provide insights into a speaker's sound quality. While acknowledging that measurements cannot fully capture the subjective experience of listening to a speaker, the host emphasizes their value in understanding specific aspects of performance. He uses the analogy of checking a car's flat tire to illustrate how a single measurement can reveal important information about overall performance.
Key Measurements for Sound Quality [3:11]
The host identifies four key measurements that he regularly uses to evaluate speakers: frequency response, vertical and horizontal off-axis responses, impedance curves, and spectral decay. Frequency response indicates a speaker's accuracy across the frequency range, with deviations like dips and peaks signaling inaccuracies. Off-axis responses, particularly vertical, reveal how consistently a speaker performs across different listening positions, affecting room loading and overall sound balance.
Impedance Curves and Spectral Decay [5:47]
Impedance curves provide information about a speaker's balance and how it loads an amplifier, indicating whether it's an easy or hard load. The curves can also reveal cabinet resonances and internal standing wave resonances, which are audible problems. Spectral decay is presented as the most informative measurement, showing how quickly a speaker dissipates stored energy. A clean spectral decay with a fast drop-off indicates speed and clarity, while long decay times suggest ringing or cone breakup, resulting in a blurred sound.
Found Tech FR ATX Full Range Driver [9:39]
The host begins by examining the frequency response of a Found Tech FR ATX full-range driver, both before and after applying a correction filter. The correction filter includes a baffle step compensation to level the output. The spectral decay of the driver without the filter shows significant ringing across the board from about 700-800 Hz and up, indicating cone breakup. Even after applying the filter, some ringing remains, demonstrating that filters cannot eliminate all such issues.
Jordan Econia Model [11:21]
The spectral decay of a Jordan Econia model is examined, revealing a significant amount of stored energy around the 1kHz region, splitting into multiple ringing points. This indicates that the speaker may sound aggressive, harsh, and fatiguing in that frequency range.
Production Speaker "L" [11:57]
The host analyzes a production speaker (referred to as "L" to avoid naming the brand), noting a long ridge line around 2200 Hz in the spectral decay, indicating stored energy and ringing. Additional ringing is observed around 5kHz, attributed to the woofer playing too high. By lowering the crossover point and allowing the tweeter to cover these ranges, the spectral decay is significantly improved, resulting in a cleaner sound.
LGK Driver and Mark Audio Driver [13:03]
A spectral decay of a small LGK three-inch driver is presented, highlighting its low mass and quick energy dissipation, resulting in a clean response. This is contrasted with another three-inch driver from Mark Audio, which exhibits significant cone breakup and ringing around 1200 Hz, as well as substantial ringing in the upper ranges, making it harsh and difficult to listen to.
Merlin VSM Speaker [14:19]
The host analyzes the spectral decay of a Merlin VSM speaker, a popular model in its time. The woofer shows a considerable amount of stored energy around 1kHz, continuing to play for several milliseconds longer than it should, which makes it sound harsher.
GR-Research In-One Kit [14:53]
The on-axis and off-axis responses of the GR-Research In-One kit are examined, revealing a flat response and high level of accuracy. The horizontal off-axis response shows smooth performance, while the vertical off-axis response demonstrates that the frequency response remains almost unchanged as the microphone is moved up, indicating consistent room loading. The impedance curve is smooth with no resonant peaks, and the spectral decay shows that the small drivers dissipate stored energy quickly, resulting in a clean sound.
Recital Speaker Analysis [17:46]
The host analyzes a speaker called "Recital," noting that the woofer and tweeter are out of phase, resulting in an incoherent sound. The impedance curve shows issues, with the impedance rising significantly at the crossover point. Resonances are also observed, indicating internal standing wave or cabinet wall resonances. The spectral decay reveals stored energy and ringing in the upper range of the woofer, making it harsh and fatiguing to listen to.
GR-Research Studio Monitor and Super Seven [20:19]
The spectral decay of a GR-Research studio monitor is presented, showing a clean response, especially for a six-and-a-half-inch woofer. The impedance curve of the Super Seven, a planar magnetic speaker, is almost completely balanced, indicating a pure resistive load.
Super 12 Full Range Driver [21:00]
The host examines a twelve-inch full-range driver called the Super 12, noting that it has a lot of stored energy in many areas. The frequency response is shown before and after compensation with an eight or nine-component filter to reduce the rising response. The spectral decay, even after compensation, indicates that it would be difficult to listen to without the filter.
SuperMini Open Baffle Speaker [22:02]
The SuperMini, a new speaker design with a single Neo 10 and Neo 3 in an open baffle, is analyzed. The planar magnetic drivers exhibit super-fast decay rates, resulting in a clean sound, especially for the larger diameter driver.
TB W8-1808 Full Range Driver [22:27]
The measured frequency response of a TB W8-1808 eight-inch full-range driver is shown before and after compensation with a baffle step loss and notch filter. The spectral decay reveals some ringing in several areas, which is typical of many wideband drivers.
Unity Audio Full Range Driver [23:29]
A full-range driver from Unity Audio is analyzed, showing peaks in the upper frequency range. The off-axis response drops off significantly, which is typical of full-range drivers. The impedance curve shows blips that may indicate breakup or ringing, and the spectral decay reveals stored energy and ringing in the upper frequency range, making it rough to listen to.
VMPS 626R Speaker Analysis [24:52]
The host examines a VMPS 626R speaker, which features a waveguide over the midrange driver. The frequency response is rough, with significant variations in output. Removing the cover improves the response. The spectral decay with the cover on shows lots of stored energy and an internal resonance caused by the waveguide. A crossover designed for the speaker results in a much cleaner response, with each driver within its own range and in phase.
XLS Encore Kit [28:24]
The spectral decay of the XLS Encore kit, featuring a six-and-a-half-inch woofer and a dome tweeter, is presented. It exhibits exceptional speed and no stored energy.
Conclusion [28:42]
The host concludes by summarizing the measurements discussed and their significance in understanding speaker performance. He encourages viewers to use this information to better interpret measurements and gain more useful insights into speaker sound quality.
