Ben Hughes

11 Apr 2009

Driving DT880s

Over on the Headphonic forums someone asked me to give them a bit of a run-down on how capable a PA2V2 is for driving Beyerdynamic DT880s. Although the PA2 performed quite well with the Ultimate Ears SuperFi3 canalphones, the DT880s are notoriously hard to drive (at least according to most of the headphone-centric websites around the place) so I was expecting the little amp to struggle a bit. I initially planned a 3-way test, driving the DT880s from

the headphone socket of a 5th Gen iPod video
a PA2V2 using line out from the iPod, and
an O1 amp using line out from the iPod

The iPod headphone socket was intented as a baseline - most people have access to an iPod of some description so it could be used to put the other results in context. I started with iPod vs PA2, using my usual testing procedures.

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13 Mar 2009

iPod headphone socket vs line out + PA2V2 amp

A little while ago my main amp - a NAD 3150 integrated - developed a problem in the pre-amp stage which has meant that I've been using a PA2V2 portable amp in my main setup. As timing would have it, the PA2V2 never actually made it to work, which is what I bought it for. With the immenent arrival of my new headphone amp and DAC, the PA2 will be free to head to work. Before it does I wanted to do some quick tests to see if it actually improves sound quality at all. The testing setup was pretty simple:

60Gb iPod video in a standard Apple dock, playing 320kbs CBR mp3s (lame --preset-insane)
A/B switch box connected to the iPod's headphone jack
PA2V2 connected to the line out of the dock
A/B switch connected to the PA2V2
Ultimate Ears SuperFi3 canalphones

After level matching the volume by ear using a 400hz sine wave I started as I usually do: fully sighted subjective listening. It was immediately obvious that a simulated blind test wasn't going to be needed - there was a very significant, easily detectable difference in the sound. The first stand-out difference was in the quality and amount of bass. Initially I thought it may have been the amp adding some mid-bass EQ (which it may do) but the sound didn't become muddy as is usual with in that case. In fact throughout the specturm instrument separation seemed to improve, and the soundstage widened appreciably. Best of all, the sound was much more dynamic and lively with the PA2V2. By comparison, the headphone socket sounded flat and dull. Given how little power the SuperFi3s require (I often listen to them on the ipod's lowest volume setting at work) I was really surprised at the difference even a cheap amp like the PA2V2 made. Is it enough of a difference for me to carry a LOD and amp for portable use? Nope - it's just not worth the fuss to me. However it's definitely worth the price of an iPod dock for work.

7 Mar 2009

Audio shootout: EeePC 900HA vs 6th gen iPod Classic

It's true - I can't help myself. Once I noticed that the headphone-out on my 900HA was much cleaner than I had expected, I decided I needed to do some testing. Nothing too serious, as I have no plans to actually use an eeepc as a music source, but enough to satisfy my curiosity. The setup was as usual: both sources connected to my DIY switch box, then into the PA2V2 amp and the MS Pros. I level matched the sources by ear using a sine wave, ending up with the ipod on full volume and the 900HA 4 steps below full volume (jack set to line out mode). The 900HA was booted into Windows, as the audio seems to be better quality. Both sources were playing WAV files. The A/B testing was done fairly subjectively, without the usual rigour. Rather than having a certain number of guesses and recording the results, I just listened to a dozen tracks or so, switching back and forth, checking my guess, then re-randomising the input selection. Suprisingly both were quite similar in sound, and it wasn't until near the end of the listening session that I identified the different sound signatures. The ipod was noticably smoother, especially in the mids, whereas the 900HA had a more live/harsh sound. By the end of the session I could pick the source around 8/10 times. Despite being still very impressed with 900HA, the ipod subjectively has a much nicer sound. But it's impressive that a netbook that cost only slightly more than the ipod is so close sonically. Especially when every full-size laptop I've heard has utterly terrible audio. As an aside, synching the tracks between sources was a bit of a challenge, as both had a slightly different delay from button-press to track start. I eventually got the swing of it, although never got it perfect. It's much easier to test amps than sources.