Objective
Measurements
Data acquired
and reported of this type is done without any opinion or bias whatsoever.
For a quickie brush up course on audio terminology and measurements, point
your browser to the Audio
Reproduction Systems article.
Rated
R.M.S. Power Output
As I griped
earlier, a high distortion power rating is nearly useless when contemplating
higher end audio. Possibly a few teenagers, especially those with some hearing
to spare might enjoy massively distorted sound, but this reviewer cringes
at anything much over the 1% mark (which is plenty detectable). For
the purposes of all my audio reviews, I chose the generous 3% rating, which
was traditionally utilized for cassette deck/reel-to-reel testing until the
early 1990's. At 3%, the waveform when viewed on an oscilloscope starts to
visually "flat-top" or clip.
The main
voltage rails of the two 4700uF 35V capacitors measured 23.6 VDC at no load.
With nearly 48 Volts peak-to-peak, the following estimations were calculated
(not directly measured due to time constraints). The amplifier chips are higher
quality ICs, namely two TDA7296
chips and one TDA7294
chip. Based on the .pdf files and assuming peak power (for a fraction of a
second) ratings, this would give rise to 60 Watts (at 0.5% THD and a 4 Ohm
load) per satellite and 58 Watts (at 0.5% THD and a 4 Ohm load) for the subwoofer.
Thus, a total peak power rating at a low distortion would be 178 Watts. I'd
venture to extrapolate that at 10% THD, the entire package could pump out
well in excess of the 200 Watts claimed by Altec. Fancy that, a manufacturer
that under-rates their gear. Kudos Altec.
Miscellaneous
Measurements
Input impedance
is important because if your sound card can't drive the input of the speakers,
distorted or low levels of sound can be the result. Measuring slightly low
for my tastes, the 621s have an input impedance of 7.40 KOhms. I'd rather
see at least 10 KOhms, but better sound cards like the Sound Blaster Live!
series won't have many issues driving this model.
Cord length
has been an issue in past reviews. Why make a great set of speakers and then
prohibit/impede typical hookup scenarios by providing cables that are two
feet too short? The 621s had no such problems, giving the user generous lengths
in all key areas:
Satellite
Cable |
Controller
Cable |
Power
Cord |
Input
Cable |
>9.5
ft |
>
9.5 ft |
6.5
ft |
6.5
ft |
Pictures
|
|
|
|
|
|
ACS-48
& 621 Sat |
No
Covers |
Factory
Pic |
Sat
Stand |
Sub
Bottom |
Sub
Front |
|
|
|
|
|
|
Woofer |
Port |
Inputs |
Heatsink |
Amp
Module |
Amp
Chip |
| |
|
|
|
|
|
| |
|
Remote |
Factory
Pic |
|
|
