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  • ICQ

    Hi fantum48, is the hissing/popping coming from the speaker or the amp? i've come across a situation where a high-frequency clicking/popping can result if CH1 and CH2 are paralleled together. in this specific case, the speaker neutrik connection had 1+paralleled with2+ and 1-paralleled with2-. Since the iTech has both channels available on CH1's neutrik connector, the amp was trying to drive itself, resulting in some strange noises in the meantime. just a thought...
  2. Hi All, When i set the front panel Bar Meter Display to indicate Input Levels the iQwic input level meters read 20dB lower! That is to say, sending a test signal into the analog XLR(s) that just causes the front panel Bar Meter Display to go Full-Scale shows up as -20dB on iQwic. Changing the input sensitivity just requires more/less signal to see the same effect. Having the DSP limiters On or Off doesn't seem to make a difference. Has anybody out there noticed this?
  3. Hi, In the iTech Operation Manual, the Output Signal Level Monitors "...are scaled so that 0dB is referenced to the full rated voltage output of the amplifier". Is the "full rated voltage output" 200V (rails)? 178.9V (calculated peak for 4kW/4-Ohm)? 126.5V (calculated RMS for 4kW/4-Ohm)? Thanks for your help, Jon
  4. iTech Efficiency

    Hi David, Thanks for responding. The efficiency i'm referencing is Power (Watts) Out / Power (Watts) in. I don't see the numbers working out. The Crown "Power Draw and Thermal Dissipation" paper has a column labeled "Watts Out per 1A Line current". This info is provided for 120VAC, 208VAC and 230VAC. Let's take what appears to be the best case scenario (according to the chart): 230VAC Mains with a 4-Ohm/Ch. Load (8-Ohm Bridged) with 1/3rd Power Pink Noise as an input. The chart indicates that the Itech 8000 will provide 144.2 Watts Out per 1A Line Current. 1A Line Current at 230VAC is equivalent to 218.5 Watts (assuming 0.95 PF, reasonable considering the fancy SMPS enclosed in the iTechs) The actual efficiency, or (Power Out / Power In) is thus 144.2 W / 218.5W = 0.66 (66%) I don't understand how "its efficiency can be up to 80-90%". Thanks, Jon
  5. Hi, The "AC Power Draw and Thermal Dissipation" White Paper has a table describing the Mains power draw and 'Watts Out'. Using this information it is possible to calculate the efficiency of the amp. I get what appears to be an efficiency of about 55% when powered off of 120VAC and 66% when powered off of 230VAC with the following equation: Eff. = (Watts Out / (Line Voltage * Line Current * 0.95)), where 0.95 is the assumed PF. (Power Factor). Can someone (in engineering?) please explain to me why this amp appears to have a Class-AB efficiency? Thanks, Jon