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The Celestion CDX1-1747 is the bigger brother of the CDX1-1446 that I reviewed back in October last year. She weighs 5.1 lbs, almost twice that of the CDX1-1445. But it’s more than her weight. Her power rating is now 60W (120W continuous) as opposed to 20W. That’s a significant jump. Equally important is her minimum recommended crossover frequency is at 1,600Hz (12dB/oct). This will allow me to cross at my favorite region (1,600Hz ~ 2,000Hz). With regards to the LaVoce HD1004, this is the first time I’m testing her out. She’s made of aluminum, strong enough to support the weight of the CDX1-1747. Her nominal coverage is 90°x60° with a cutoff frequency of 1,200Hz. Dimensions are 7.1″ wide, 6.1″ high and 3.9″ deep. She will fit nicely with 8″ ~ 10″ woofers. That will work out well for a mid/high satellite supported with a subwoofer.
Fig 1 is the RAW response of the CDX1-1747 with the LaVoce HD1004. No passive or active crossovers are used for this plot. However, the bass is removed from the sweep to protect the compression driver. From the plot, we can see the HD1004 indeed cuts off at 1,200Hz. The response is not exactly Constant Directivity (CD). She tapers down at 2.5kHz but levels off at 5.5kHz. From that point onwards, she is flat all the way to about 13kHz before gradually tapering off.
The Impedance of the CDX1-1747 with the LaVoce HD1004 horn is in Fig 2. I’m quite concerned with the two peaks, especially the one at 1.5kHz. It’s very close to my crossover region. I won’t know whether this will be a problem until I work on the crossover. If it is, then I’ll have to resort to a LCR filter to tame it. That’s not really an issue. It just adds to the crossover cost.
The Waterfall plot in Fig 3 shows a relatively clean response. Note my time (z-axis) is at 2ms. In other words, this is a highly magnified view of the artifacts.
Fig 4 is the ToneBurst plot of the CDX1-1747 with the HD1004 horn. I find this plot easier to see the artifacts (light blue slices). The ones at 5kHz and 15kHz may look bad but don’t forget, the z-axis is in “cycles”, not time as in the Waterfall.
Fig 5 is the Spectrogram. When referenced to time, we can see the “artifacts” at 5kHz and 15kHz do not even extend beyond 1ms. In all practical use, they are insignificant.
Fig 6 is the Distortion plot. It’s encouraging to see the 2nd harmonics dominate. The 3rd harmonic distortion is on average about 10dB less than the 2nd which is a good sign. Summary I am very pleased with the performance of the Celestion CDX1-1747 with the LaVoce HD1004 horn attached. When in use, I expect very “clean” and “smooth” treble. By this, I mean no harshness and peaks. Now that I know what this combo is capable of, the next step is to see how she performs with a woofer. For a start, I will mate her with the Eminence Beta 8A since she’s already mounted. Unless otherwise stated, all measurements were made in Full Space (4 pi) with the mic at 36 ins, tweeter axis. Impulse Window=5ms. No smoothing applied. |
November 2, 2025Drivers Evaluation, PRO DRIVERS
