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Frequency Response

The intentional bass hump is moderately narrow in frequency range, but very pronounced. Remember, a 10dB boost essentially means a relative doubling of loudness for sounds produced in that affected frequency area. The low frequency cutoff in room measured an average-for-size 108Hz, with only a small rolloff beginning at 111Hz.

The midrange response was so flat that for all practical intents and purposes I've labeled it as such. Remember, a ruler flat response doesn't equate to "perfect" sound, it's just an objective measurement, a starting point if you will. In the listening environment, the high frequency extension was excellent for a single 3" driver. Basically flat to 10KHz, only a welcome gentle rolloff beyond that was apparent. This highs were not overboosted in any way. While there is no substitute for a tweeter, DA's use of a single full range driver is pretty good excepting the low end problems.

Overall Frequency Response
Bass (rel. 1KHz)
Midrange (rel. 1KHz)
Highs
146-122Hz = +3 to +11dB
Essentially Flat
Flat to 10KHz
134-136Hz = +11dB
 
Gentle rolloff above 10KHz
111Hz = -3dB
   
108Hz = -6dB
   

Rated R.M.S. Power Output

Since DA was so adamant about power ratings, I was very eager to put the TDA2007A and power supply to the test. What I measured was shocking. After checking with SGS-Thompson, I viewed the .pdf spec sheet for the capable amp chip and it can do 6 watts per channel easily into a 4 or 8 Ohm load with voltage rails of 18 and 22 volts DC respectively. By this time I'll bet that you can guess that I measured something dramatically less than 6 watts per channel.

If DA merely beefs up the included wall wart, I'd lay money that their power claims could be easily met, but until that happens, all I could muster at the point of clipping (about 3%) was a lousy 2.97 watts RMS per channel with both channels operating. At no load conditions, the wart supplies the 4700uF filter cap (nice size actually) with 19.9Vdc. At full load, this figure drops an astonishing 5.1 volts to 14.8, which indicates a distorted AC sine wave from the wart. Why does it drop so much? Because at 2.97 w/ch or just under 6 watts total power, the total current draw greatly exceeds the rated 1.1A wart spec. If DA chooses to do so, simply including a wart that is rated at about double the current, say 2.2A or more, the 2012's will meet their power claims. It would also improve the sound quality and the filter cap wouldn't have to work so hard to squelch massively clipped AC waves.

Loudness & Miscellaneous Measurements

Using a 1KHz tone and various music selections, a total maximum output with the speakers placed at either side of my 19" monitor measured 103dB SPL at 0.5m. This is significantly louder than the 96dB SPL that Diamond Audio claims. Of course, as distance increases, total volume decreases, so DA may have chosen to rate the 2012's at 1m rather than 0.5m.

Input sensitivity, the amount of output from your soundcard needed to drive the 3025's to full boom levels was rated at a high-ish 300mV, which many sound cards cannot muster. However, it measured 200mV, which most if not all soundcards can easily output.

Signal to noise, or the amount of hiss heard was the among the highest (meaning best) ever measured at TargetPC. Weighing in at 86dBC relative to full output, these units were very quiet, even with no input.

Input impedance measured a high (meaning good) at 19.7KOhms and 20.2KOhms for the left and right channels respectively. No sound card will "load down" or be stressed simply by being plugged into the input of the 3025's.

The rear port center frequency measured 130Hz, which was a reasonable choice for the 3" driver. However, as the FR curves show, the bass response was overboosted, peaky and uneven in the area of 122-146Hz.

Lastly, the bass and treble controls both had a ±7dB range centering at 100Hz and 10KHz respectively.

 





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