Woofer Impedance (Cont.')
Even though
significant factors (especially near the free air resonance frequency) of
inductive and capacitive reactance are left out for simplicity, the 4"
subwoofer has quite a high impedance. The best estimate I could muster would
be approximately 9 Ohms. Based on that figure, the power output of the amp
to the sub will be rather low, but I get ahead of myself.
The Satellites
Like the subwoofer, the
satellite specs are not specified by the manufacturer. My best guess would
be approximately 6 Ohms which will, of course, affect power calculations.
Satellite
Impedance
|
Frequency
(Hz)
|
Voltage
(mV)
|
Current
(mA)
|
Impedance
(Z)
|
|
315
|
220
|
18.9
|
11.6
|
|
1000
|
198
|
34.2
|
5.79
|
|
3150
|
191
|
31.6
|
6.04
|
Frequency Response
With such a tiny subwoofer,
in fact since it's so small, the low end was more or less nonexistent. Considering
the nearly $200 USD price tag, this is unacceptable.
Otherwise, the woofer itself had a very flat curve. The effective low end
cutoff was the highest (meaning worst) ever measured at TargetPC for a subwoofer
based system. A very popular low frequency octave these days, from 40-80Hz,
is completely missing. And those measurements were taken at the junction of
two walls, which gives a theoretical bass boost that centers its maximum output
at 100Hz.
Overall
Frequency Response
|
Bass
(rel. 100Hz)
|
Midrange
(rel. 1kHz)
|
Highs
|
|
95-150Hz
= -3 to +4dB
|
150Hz-11.7KHz
= -3 to +4dB
|
11KHz
= -3dB
|
|
95Hz
= -3dB
|
|
16KHz
= -6dB
|
|
85Hz
= -6dB
|
|
|
Don't be fooled by the
moderately flat midrange. Peaks and valleys were so numerous that voices took
on an edgy, distorted quality at all times-a "fuzzy", unclear sound
that took some getting used to.
The high end extension
was the best ever measured from a full range driver (no tweeter). Having good
extension well beyond 10KHz is difficult to muster. The Diamond
Audio 3025's had far too much HF boost, while the 5.1's curve gently rolled
off in the last hearable octave.
Rated
R.M.S. Power Output
Frankly,
JazzSpeakers' ridiculous claim of 2500 Watts makes me very angry. Possibly
that's why they have no U.S. dealers due to totally false power specs that
would never pass under the noses of the F.T.C. This number was pulled out
of thin air for many reasons, the first being that the transformer can't supply
that much juice.
Rated at
65VA (volt-amps), I would love to hear how this sizable unit could be forced
to crank out over 30 times it rated wattage. And as mentioned
earlier, since most people's 120V sockets are fused at 15 Amps (some have
more of course), is JazzSpeakers implying that the ROCCO's must be plugged
into a dedicated 20 Amp 120V line?
As measured,
the 3" satellites sucked down 5.30 Watts each at 1KHz. Adding that to
an sub estimate of 13 Watts (11 Volts @ 9 Ohms) and not forgetting the 2.5"
center channel drivers at approximately 5 Watts each, we can arrive at a reasonable
estimate. Adding up to just over 44 Watts RMS before the onset of clipping
(3% THD), the ROCCO 5.1's do play very loud. Just not at the 2500 Watt level.
