The crossover frequency between these two drivers appears to be close to the specified 250Hz. The woofer's output rolls off above 150Hz with what appears to be an 18dB/octave slope, and the midrange unit's output, measured in the nearfield (green trace), rolls off below 300Hz with the same third-order slope. The port's upper-frequency rolloff is clean overall, though some low-level peaks are present at 150Hz and between 200Hz and 500Hz. The woofer's nearfield response (fig.3, blue trace) has the expected notch at this frequency, and the port's output (red trace) peaks sharply between 30Hz and 60Hz. The Tad speaker's impedance-magnitude plot has a low-frequency saddle centered just below 40Hz, suggesting that this is the tuning frequency of the reflex-loading slots between the wooden side panels and the metal plates. Its low effective resistance and lowish sensitivity mean that the CE1TX needs to be paired with amplifiers that can deliver both voltage and current.įig.3 Tad CE1TX, anechoic response on tweeter axis at 50", averaged across 30° horizontal window and corrected for microphone response, with the nearfield midrange (green), woofer (blue), and port (red) responses respectively plotted below 400Hz, 800Hz and 500Hz. The minimum EPDR values are 1.45 ohms at 35Hz, 2 ohms at 60Hz, and 2.03 ohms at 861Hz. The electrical phase angle (dotted trace) is occasionally high, which means that the equivalent peak dissipation resistance, or EPDR (footnote 1), lies below 3 ohms from the midbass region through the upper midrange and in the top audio octave. The magnitude is higher than 8 ohms in the very low bass and for almost the entire treble, however. My measurement, taken with Dayton Audio's DATS V2 system, indicates that the impedance magnitude (fig.1, solid trace) drops slightly below 4 ohms in the lower midrange, with a minimum value of 3.61 ohms at 124Hz. The speaker's nominal impedance is specified as 4 ohms. Tad specifies the CE1TX's voltage sensitivity as 85dB/2.83V/m, which is 2dB lower than average my B-weighted estimate was within experimental error of that figure, at 84.7dB(B)/2.83V/m. Fig.1 Tad CE1TX, electrical impedance (solid) and phase (dashed) (2 ohms/vertical div.).
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