Ever wondered just how good that cheap sound card in your laptop is? How about those tiny little speakers that sound more like a pair of headphones coming from someone’s nearby iPod? Well I’ve been hooked on this great tool called Room EQ Wizard (which is actually used to measure room modes and generate EQ profiles to combat them) but it’s got some other great uses as well, if used in the near-field, like measuring the frequency response of a new set of speakers or measuring the flatness and harmonic distortion of a sound card in a PC or laptop. So I put my new Inspiron E1505 to the test, and here are the results. Overall this is an excellent sound card and is very flat across most of the audible spectrum, see Figure 1. The 20Hz – 20kHz flatness is measured at -1.7dB, +0.8. Also, the 1st and 2nd harmonic distortion came in at 0.015% and <0.001% respectively. The -3dB points measured in at 14.3Hz and 20.497kHz. If you plugged this laptop into a stereo or receiver for playing MP3's, you'd probably never notice the +0.8dB peaks in the upper band or the 1.7dB drop at 20Hz. But it's definitely not quite as good as a real CD/DVD player's line out however.
So how do the integrated speakers fair? Well with the exception of providing any bass at all, see Figure 2, they are also extremely flat within their passband with no wild dips or peaks. Above 10kHz you start to see some peaks and valleys but overall they are pretty flat. The speakers in the E1505 are basically good down to about 300Hz where the response drops off like a rock. So even though the bass isn't all that impressive, quite pitiful actually, where it makes up for it is flatness across the usable range of the speakers, which is about 300-20kHz. And they do actually sound quite good, and play plenty loud for just about any occasion.
Figure 1. SigmaTel Audio Inspiron E1505 Frequency Response
Figure 2. Measured Frequency Response of Left and Right Speakers
