iPod under load
February 16th, 2006 by George Tyshchenkousing Apple standard headphones
This test demonstrates what happens when iPod is driving headphones connected in parallel. As you can see the frequency response is much narrower. I have used standard iPod headphones, which seems to be a good match for the iPod. They measure around 33.2 Ohms (each driver). Use of headphones with different impedance may significantly alter the audio quality.
| Test | iPod 4G no load | iPod 4G under load |
| Frequency response (from 40 Hz to 15 kHz), dB: | +0.02, -0.10 | +0.12, -2.31 |
| Noise level, dB (A): | -105.8 | -109.3 |
| Dynamic range, dB (A): | 86.5 | 85.5 |
| THD, %: | 0.0095 | 0.025 |
| IMD + Noise, %: | 0.015 | 0.358 |
| Stereo crosstalk, dB: | -104.9 | -49.2 |
You can view the full RightMark report here
March 13th, 2006 at 5:56 pm
Great site! I hope you continue to benchmark the varius iPods and other players under load (which is the only way we’ll ever use the device). May I suggest benchmarking using the provided headphones and again using a “reference” set? Perhaps the Bose, or other highly regarded set?
July 2nd, 2006 at 7:06 pm
Well done for a much needed and fantastic website detailing the analogue output sound quality of the iPod range.
I am hoping that along with the ‘unloaded’ tests you will also run ‘loaded’ tests for ALL of the iPods. From your comparison here http://hifiipod.co.uk/?page_id=52 you have drawn attention to the difference between the loaded and unloaded results, but of course, what we all hear through our headphones is the loaded case.
It would be great if you therefore could test the iPod range (and maybe some of the obvious competitors) under loaded conditions so we can predict the sound quality through headphones where most of us listen to them.
Please keep up the good work – I know there must be a lot of people interested in your findings…
July 6th, 2006 at 8:01 pm
The following include tests under load.
http://www.pcmag.com/article2/0,1759,1777890,00.asp
http://home.comcast.net./~machrone/playertest/playertest.htm
See how good the Shuffle is when under load!!!
July 6th, 2006 at 9:38 pm
No bad. He says interesting things about possible Push-pull design of the convertors. Surely apple didnt designed them in-house?? I think they are one of the stock chips, nothing really stops other company to use the same.
July 30th, 2006 at 6:48 pm
I think there are two interesting features of the D to A of the Shuffle:
One is the Push-Pull output stage, but also Sigmatel, who provide the chipset, have something called DDX, that I think may be a PWM-type DAC converter.
Whatever, they’re crowing about it and have seen fit to patent it…