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Measurements are done with a variety of instruments namely :-

• Prism dScope III Audio Analyzer,
• Custom designed LPF for measurement of class-D amplifiers similar to Prism ds-LPF
• Agilent 34401A 6.5 digit Digital Multi-meter
• Tektronix Digital Oscilloscope models, TDS784A, TDS3012, TDS7054
• Tektronix CRO model 2246A
• Leader LDC-824 6.5 digit 500MHz Frequency Counter with Oven Controlled crystal oscillator
• E-MU 0404 external 24 bit 192KHz sound card

[Continuous 1KHz Sinewave into 4 ohms before clipping with one channel driven corresponding to 595 watts into 4 ohms.]

Some simple power measurements on the Ultimate Amplifier using a scope. The first two channels are powered by a Hypex NCore NC502MP amplifier module which would typically be assigned to the low frequency channels in an active speaker system. This is the most powerful of all amplifiers in the Ultimate Amplifier with a name plate rating of 500 watts per channel into 4 ohms. We used the channel clipping indicators to determine the maximum power threshold before clipping but later on we will use the dScope III audio analyzer to accurately measure the power output at a given THD level and show how conservatively rated these amps really are The results will shock you at how powerful these amps really are and how well designed the switch mode power supplies are to maintain tight regulation and almost doubling power into 4 ohms

Continuous 1KHz Sinewave into 4 ohms before clipping with one channel driven corresponding to 595 watts into 4 ohms.





Continuous 1KHz Sinewave into 8 ohms before clipping with both channels driven corresponding to 321 and 317 watts respectively.





Full Power 20Hz Tone-burst with 1 to 5 duty-cycle (5 cycle on 20 cycle off) single channel into 4 ohms





Full Power 100Hz Tone-burst with 1 to 5 duty-cycle (5 cycle on 20 cycle off) single channel into 4 ohms





Full Power 1000Hz Tone-burst with 1 to 5 duty-cycle (5 cycle on 20 cycle off) single channel into 4 ohms





Top Trace = Full Power 100Hz Tone-burst with 1 to 5 duty cycle with 5 cycle on 20 cycle off single channel into 4 ohms
Bottom Trace = Current measurement of voltage across a 0.1 ohm sense resistor (20 amps per division)





Full Power 1000Hz Tone-burst with 1 to 5 duty-cycle (5 cycle on 20 cycle off) single channel into 8 ohms





Continuous Sinewave at 1000Hz After Clipping with both channels driven into 8 ohms

We are always on the lookout for new and useful test equipment to add to our lab, and one of the things we have always wanted was a decent audio analyser. Although we have a couple of external sound cards which have been quite useful, nothing beats a dedicated audio analyzer, so when a Prism dScope III came along at the right price we jumped at the chance and purchased it. The Audio-Precision APx555 at $28,000 USD was way out of our budget and save for a few dB less dynamic range, in terms of over all features and customization, the dScope III offers everything we need a plus a whole lot more. We have already used it to chase down a few illusive issues in our existing preamp design and incorporated the changes in our new Preamp designs. Such is the benefit of having access to the right test gear