Saturday, September 17, 2005

Amping the iAudio X5

Amping is something that I don't do very often, but the performance of the iAudio X5 in relation to the monochrome iPods has me wishing to reach for the Porta Corda II rather more often than I would like.

The Meier-Audio Porta Corda II (now replaced by the Porta Corda III) is a generally high-performance portable amplifier. Because some elements of the signal passing through can be noticeably changed and sort of cleaned up by an amp, applying good amping to an underperforming player can sometimes have a bigger felt impact than amplifying a good one... although of course, amping a good player is the best solution!

When I had the iAudio M3, the X5's predecessor, I didn't really bother amping it as I felt the subpack assembly (a 'dongle' that fits without any means of retention on the underside of the M3) was too delicate to use for portable amping purposes. The X5 sticks to exactly the same arrangement and I still feel it's too delicate. However, I tried amping it this time around.

The X5 and subpack. Darn, that carry bag was dusty... :D

The X5 subpack connector and the iPod dock connector.

The problem I encountered is something that's already discussed a lot on the iAudio related forums. There is a bass fall-off, like the iPod's headphone out... only on the X5, you get a fall-off from both the headphone out and the Line Out.

The X5 headphone out's bass fall-off and other factors contribute to a sonic performance on aggregate on a par with, or maybe just slightly better than, the iPod Photo... which correspondingly has a lower audio performance than the monochrome iPods. So it's not bad at all, although it could be better.

However the Line Out fall-off is something that I've rarely seen on modern players. According to my measurements at the headphone side of the Porta Corda II amplifier (input impedance: 3.6kohms), it is registering a 4.5db falloff at 47hz, with a 1db falloff starting at 130hz. Plugging in the Porta Corda II amp into the headphone socket of the X5 however, turning the volume up to max and turning off all effects, I'm rewarded by a ruler-flat frequency response and significantly decreased distortion compared to the subpack line out... a very audible difference, I ought to say.

Both measurements were made at the headphone socket of the Porta Corda
at nominal listening levels, with a 32 ohm headphone in the chain.

Now, there are plusses and minuses to this. Firstly, as I said the subpack design hasn't changed, and in my opinion it is too fragile to use portably with a Line Out cable plugged in on a regular basis. So you could argue that there's no point in portable amping using the subpack... and this is true to an extent. However, using the subpack allows the use of a remote, which is very handy while using a portable amp.

The same falloff by the way happens with the optional dock.

Having said all that, even though the measurement looks pretty dire the Line Out is not a dead loss... it's still perfectly listenable as it were. Apart from the bass loss, there's nothing particularly crappy about the sound. It's just not as good as it should be given the performance of the headphone out when used in the same way. It just looks like lazy design or a component mis-spec that wasn't corrected for a long time (the X5 sub-pack uses the same PCB as the M3 sub-pack... so I'm assuming the components are the same, and the M3 had the same problem).

I must admit on the basis of problems like this, I'm having second thoughts about getting rid of the iRiver H320. The H320 definitely doesn't work as well in daily use and is a a bit of a huge tank in comparison, but it seems to be sonically and physically better sorted out. Sigh...

Click here to go to a later post about what the falloff sounds like

1 comment:

bangraman said...

The original 'classy' comments from iPodstudio and the ensuing discussions have been moved here as it was way too off topic.