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NuForce P-9 Stereo Preamplifier

Part II

August, 2007

John E. Johnson, Jr.

 

On the Bench

I measured the P-9 using one RCA input and the corresponding XLR output into a 100 kOhm load (Audio Precision SYS 2722). The bandwidth for THD+N tests was 80 kHz.

At 1 kHz and 2 volts output, THD+N was extremely low, at 0.003%.

At 10 kHz, THD+N was the same as at 1 kHz.

IMD was also very low, at 0.002%. This is important because it results in a detailed sound that would otherwise be "mushy" due to too much interaction between the different frequencies in the music.

With 10 kHz and 11 kHz sine waves, we can see a few peaks, but they appear to be mostly harmonics of the fundamentals rather than IM. The low frequency peaks are multiples of the 60 Hz AC in the power supply.

Here, you can see why the P-9 is so neutral. Look how flat the THD+N is all across the audible band, and in fact, all the way up to 50 kHz. It's something you usually do not see in a preamplifier at this price. It implies neutrality in the sound, and also that it will output the same high voltage at clipping in the upper frequencies as it does at 1 kHz, which is the standard frequency for testing THD+N vs. Output.

The P-9 output a maximum of 16 volts (at 1 kHz) before clipping (voltage at 1% THD+N). This is a pretty healthy output capability.

The measured frequency response was ruler flat across the audible band and only down 2 dB at 200 kHz. That is quite a bandwidth.

Conclusions

At $3,150 the NuForce P-9 is a stunner in the performance department, if not in its looks. It is manufactured in Asia, and if anyone still thinks that means "not so good", it is time for them to wake up and listen to the music. Those days are gone. Now you can have truly high end quality that doesn't break the bank.

 

- John E. Johnson, Jr. -

Copyright 2007 Secrets of Home Theater & High Fidelity

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