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About craigyoung

  1. XTI 4000 Voltage

    I live in New Zealand and am using XTi 2000 amps in my home theater. The amps are rated 110-240V and work perfectly here. There is no switch required, just replace the U.S. mains cable with a Australia cable and it will work fine.
  2. XTI-2000 Level Control

    Thanks Kevin, you've been a great help. You are right that the quantitative settings performed so far are only a baseline to start from. I have a Behringer ECM8000 mic and using the REW software to begin calibrating the system. The good thing is I know exactly what affect the various settings have on the signal so given a sound measurement I then have a good idea what to change on the various stages. Next will be to use the parametric equalizer on the amps to adjust for room acoustics. I could do it on the PC but I'd rather keep those cpu cycles for other things and shift that workload to the DSP on the amps.
  3. XTI-2000 Level Control

    Thanks Kevin for taking the time to provide these parameters, they are really valuable in setting up my Home Theater system. For my system, here is the signal chain: DVD audio track (16 bits) --> Windows Media Player --> Xonar Deluxe 3.1 Audio Card --> Crown xti-2000 --> Klipsch K-Horns First, the max output level of the audio card is 2.2 vrms, which would overdrive the input of the amp with no attenuation. Using your figures above for the attenuator I would want to bring it down 4 notches, -4.5 dB to keep the max output from the sound card over driving the input to the amp. Next, at this max level, the output from the amp is approx 62 vrms which is too much for the K-Horns. The sustained level for the K-Horns is 100w (28 volts), peak is 400w (56 volts). So as a minimum, the max output of the amp cannot exceed 56 volts .. so I would limit the input to the amp by another notch which would bring the max output voltage down from 62 volts to 52 volts. Given that the music level cannot be any greater than +/- 32765 (15 bits) in the source file, the maximum output signal from the sound card will be 2.2 vrms which is the input to the attenuator. With the attenuator down 5 notches, or -6dB, the output voltage will be 52 volts .. or about 338 watts (assuming 8 ohm speaker). This will result in an SPL of 124dB which is a bit excessive for a home theater. THX recommends an ave listening level of 85dB with a 20dB headroom, so max would be 105dB, which is 1 watt for the K-Horn or 2.83 volts. So to make sure that max output from the source material did not exceed 105dB out of the speaker, I would need to attenuate -25dB .. or, rotate the attenuator clockwise from full attenuation to about notch 6. I tried this and that seems to work quite well. At max output from the sound card, the speakers are loud but not damaging. I have a calibrated mic and will attempt at measuring SPL to confirm all this. Comments?
  4. XTI-2000 Level Control

    Also, if the xti-2000 is a 32.9 dB amplifier and the input sensitivity is 1.4 vrms then is the max output = 61.82 vrms?
  5. XTI-2000 Level Control

    Excellent, exactly what I needed. This would mean at full attenuation the input signal is reduced by 30.5 dB. Next, if the input sensitivity of the amplifier is 1.4 vrms, with no attenuation, giving full amplifier output, then if I enable full attenuation then I can increase the input voltage by 30.5 dB such that the output from the attenuator would be 1.4 vrms. 1.4 vrms is approx 5 dBu, so why is the maximum input signal spec'd at +22 dBu (9.75 vrms)? 1.4 v raised by 30.5 dB is approximately 43 vrms.
  6. What is the dB attenuation for each detent setting on the XTI-2000 amplifier? Is there an attenuation chart or curve for the rotary switch? Craig