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.
