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Crown XTI-4000 Amplifier Test Results
Budget amplifier from Crown
Good performance in general, although significant loss of power at 10kHz possibly due to internal high frequency protection. The amp includes lots of features including DSP based EQ, crossover, delay, etc. Construction quality is acceptable, although flimsy. Not bad for such a budget amplifier. Single PCB construction with virtually no wiring whatsoever makes for very inexpensive (and error-free) production.
Amplifier was tested in "DSP Bypass" mode, but the audio signal still goes through A/D and D/A conversion. There is no hard bypass of the digital circuitry (which operates at 48kHz sampling rate). As such, there was considerable phase shift at higher frequencies, and a 10kHz square wave was turned completely sinusoidal by the digital conversion stage filtering out all the harmonics. This may impact the transient response of the amplifier. This is not a form of distortion per se, but an act of signal filtration. Threshold of clipping showed no nasties whatsoever, and the amp clips gracefully at all frequencies and load impedances. See the waveforms for the Crown XTI1000 also tested here, the internal construction and topographical layout is almost identical. The customer did not want the amp tested at 2R.
Distortion was low even at full power, and hovered at about 0.08% at 3/4 power.
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All results taken with sine wave input into a resistive dummy load of 8, 4 and 2 ohms (where applicable), two channels simultaneously driven (unless otherwise stated), at the threshold of clipping. These results should be considered maximum 'continuous RMS' power ratings (>5 seconds). Distortion measurements, labelled THD%, are taken with an HP8903A audio analyser (80kHz Bandwidth). | |||||||||||||||||||||||||||||||||||
| Manufacturer | Crown |
|---|---|
| Model | XTI-4000 |
| Weight | 8 kg |
| Power to weight Ratio1 | 125.5 W/kg |
| Notes | Mains voltage hovered about 243V. 22-07-2010 |
| Manufacturer's Website | http://www.crownaudio.com |
1 Power to weight ratio is calculated by taking the average of the power measurements at 4 ohms, multiplying by the number of driven amp channels, and then dividing this value by the weight of the amplifier.
Click the images below for full-size versions
Description of Images:
- Amplifier front panel
- Amplifier internals. A big slab of foam covers the output devices
- Switched-mode power supply
- Additional switched-mode down converter for generating internal voltage rails. This is a class G amplifier.
- 10kHz sine wave, 8R, maximum power achievable. Significantly lower than other measurements, but visually distortion-free.
- 1kHz, 8R, at clipping. No nasties at clipping, good performance.
- 1kHz 8R full power square wave. The ripples on the tops and bottoms of the waveform are caused by the action of the ADC/DAC digital filter. Otherwise good.
