Sidebar 3: Measurements
I used DRA Labs' MLSSA system and a calibrated DPA 4006 microphone to measure the GoldenEar Triton One.R's frequency response in the farfield, and an Earthworks QTC-40 mike for the nearfield responses. I removed the loudspeaker's front and side grilles for the nearfield measurements but left them in place for the farfield measurements (footnote 1).
The Triton One.R measured very similarly to the original Triton One. As with the original, GoldenEar specifies the One.R's sensitivity as 92dB/W/m. My estimate was 91.2dB(B)/2.83V/m, which is both within experimental error of the specification and identical to the earlier speaker's sensitivity. The One.R's impedance is specified as being "compatible with 8 ohms." The solid trace in fig.1 reveals that the impedance magnitude ranges between 3 and 6 ohms for much of the audioband, with a minimum value of 3.1 ohms between 290Hz and 390Hz. Like the original One, the One.R's use of a passive high-pass filter with a low corner frequency means that the electrical phase angle becomes increasingly capacitive below that frequency. Although the impedance magnitude rapidly increases below 100Hz, mitigating the effect of that phase angle, there is still a combination of 4 ohms and –48° at 100Hz, which will require a good 4 ohm–rated amplifier to drive the speaker to acceptably high levels.
Higher in frequency in fig.3, the response of the midrange units and tweeter on the tweeter axis is impressively flat, though like the original Triton One, the top octave is elevated. Looking at the One.R's lateral-dispersion plot (fig.4), which is normalized to the tweeter-axis response, it appears that the speaker's output declines rapidly to its sides above 10kHz. This will tend to produce a flat top-octave balance in small to medium-size rooms. The contour lines in this graph are evenly spaced in the midrange and low treble, which implies stable stereo imaging. In the vertical plane (fig.5), the GoldenEar's on-axis balance is maintained over a relatively wide listening window, which is a good thing when you consider that the tweeter is a high 40.5" from the floor. A suckout does starts to develop in the upper crossover region 15° above and below the tweeter axis, but these are unrealistic listening axes.
Looking at the Triton One.R's behavior in the time domain, the loudspeaker's step response on the tweeter axis (fig.6) indicates that the tweeter and midrange units are connected in positive acoustic polarity, the woofers in negative polarity. (I confirmed that this was the case by looking at the individual outputs.) More importantly, the decay of the tweeter's step blends smoothly with the start of the midrange unit's step and the decay of that driver's step blends smoothly with the start of the woofers' step. The bulky grille and grille frame are responsible for a strong reflection of the tweeter's output 500µs after the initial arrival. This reflection results in ripples above 2kHz in the on-axis response and some low-level, top-octave hash in the GoldenEar's cumulative spectral-decay plot (fig.7). This plot is very clean at lower frequencies, however.
Footnote 1: Despite what Kal wrote, the grilles can be removed—with difficulty—although removing them may invalidate the warranty.—Ed.
Fig.1 GoldenEar Triton One.R, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).
The impedance traces are free from small discontinuities that would imply the presence of panel resonances. When I investigated the cabinet's vibrational behavior with a plastic-tape accelerometer, the only resonant modes I could find were at 452Hz on the sidewalls (fig.2) and another at 609Hz on the back panel. These modes are probably too low in level and too high in frequency to affect sound quality.
Fig.2 GoldenEar Triton One.R, cumulative spectral-decay plot calculated from output of accelerometer fastened to center of sidewall level with lower midrange unit (MLS driving voltage to speaker, 7.55V; measurement bandwidth, 2kHz).
Like the earlier GoldenEar speaker, the response of the One.R's midrange units extends almost to 100Hz, with a steep rolloff below that frequency (fig.3, blue trace). The powered woofers' nearfield response (fig.3, green trace) rolls off sharply above 80Hz, without any peaks evident in their upper-frequency output. The woofers have their minimum-motion notch at 27Hz, with then a steep low-frequency rollout. Because of their large surface area and correspondingly small motion, I measured the passive radiators' nearfield response with an accelerometer rather than a microphone in order to minimize acoustic crosstalk from the woofers. Their output (red trace) peaks between 20Hz and 30Hz, implying excellent low-frequency extension, and like that of the woofers, their low-frequency rollout is also very steep, close to 6th-order, 36dB/octave.
Fig.3 GoldenEar Triton One.R, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield responses of the midrange units (blue), woofers (green), and passive radiators (red) respectively plotted below 300Hz, 450Hz, and 125Hz.
Fig.4 GoldenEar Triton One.R, lateral response family at 50", normalized to response on tweeter axis, from back to front: differences in response 90–5° off axis, reference response, differences in response 5–90° off axis.
Fig.5 GoldenEar Triton One.R, vertical response family at 50", normalized to response on tweeter axis, from back to front: differences in response 15–5° above axis, reference response, differences in response 5–15° below axis.
Fig.6 GoldenEar Triton One.R, step response on tweeter axis at 50" (5ms time window, 30kHz bandwidth).
Fig.7 GoldenEar Triton One.R, cumulative spectral-decay plot on tweeter axis at 50" (0.15ms risetime).
Like its predecessor, GoldenEar's Triton One.R offers excellent measured performance.—John Atkinson
Footnote 1: Despite what Kal wrote, the grilles can be removed—with difficulty—although removing them may invalidate the warranty.—Ed.
