geoelectric
12-29-2005, 02:10 AM
I'm looking for ideas here. I have an iPod Photo 40GB hooked via direct connect to the AUX of a Kenwood head unit. The Kenwood unit has built in crossovers, and it's set with an 80Hz high-pass on the fronts and full range on the back. My car speakers are obnoxiously midrange heavy, and I listen to lots of metal, so I generally run the head unit at 6 bass, -3 midrange, 1 treble to compensate and get a good midrange drop and a little more bass fill. It sounds fine to my ears with CDs, and doesn't distort on its own.
Here's what's happening. If I play a song with heavy bass in it--particularly with the Rock, Latin, Bass Boost, any EQ with a heavy bass increase, but to an extent without it too--any trebly stuff going on over the bass distorts a little, like it's through a fan. It's basically that fluttery sound you get with crappy speakers.
The thing is, I hear it even if I:
A) fade all the way to the front (i.e. nothing under 80Hz is getting played at all due to the high-pass).
B) Turn bass all the way down on my head unit.
C) Turn the volume down on the head unit.
So it seems like the iPod is introducing the distortion. No surprise there, because the EQ supposedly sucks, right?
Problem is, my Sony MDR-EX81s (supposedly one of the most problem-prone headphones for iPod photo distortion) reproduce perfectly at 100% volume and Rock EQ on. No fluttering noises, clean bass, clean treble.
I should mention that I have all my files MP3Gained to 93dB. I tried knocking one of the problem files down to 90dB and it still distorted in the car setup. I didn't hear any difference over 93, but then, I didn't A/B it.
I should also mention that I tried this with the line-out from a Belkin charger, with no difference at any volume level. I'm going to drag the dock out there later tonight to try it with a line-out without an amplification stage to see if that makes a difference, too.
So possibilities:
1) Even though my average gain is now very conservative, the iPod EQ is still managing to overdrive somehow. I'd think I left enough headroom though, and if it were overdriving, wouldn't I hear it through the headphones?
2) Cable issue? Doesn't seem likely, and my Zen didn't have this problem that I ever noticed. It was using the same cable to AUX.
3) Crossover issue? Again, never noticed it in the Zen, which was running through the same setup.
4) The head unit has a pre-amp stage that can't handle the combined might (heh) of the bass and treble coming over line-in at the same time? The iPod does seem to have slightly hotter output than the Zen, but I didn't notice a difference turning the volume down--it just distorted more softly. I'd think that would fix that issue.
5) Impedance difference between the earbuds and the line-in of the head unit causing the different behavior? This seems the most likely. If so, how can I fix it?
I'm not an audiophile by any means. I generally -like- the way the iPod sounds stacking the EQ on top of the my head unit settings and will live with the occasional distortion if I have to. However, I'd like to not have to. Any suggestions?
Here's what's happening. If I play a song with heavy bass in it--particularly with the Rock, Latin, Bass Boost, any EQ with a heavy bass increase, but to an extent without it too--any trebly stuff going on over the bass distorts a little, like it's through a fan. It's basically that fluttery sound you get with crappy speakers.
The thing is, I hear it even if I:
A) fade all the way to the front (i.e. nothing under 80Hz is getting played at all due to the high-pass).
B) Turn bass all the way down on my head unit.
C) Turn the volume down on the head unit.
So it seems like the iPod is introducing the distortion. No surprise there, because the EQ supposedly sucks, right?
Problem is, my Sony MDR-EX81s (supposedly one of the most problem-prone headphones for iPod photo distortion) reproduce perfectly at 100% volume and Rock EQ on. No fluttering noises, clean bass, clean treble.
I should mention that I have all my files MP3Gained to 93dB. I tried knocking one of the problem files down to 90dB and it still distorted in the car setup. I didn't hear any difference over 93, but then, I didn't A/B it.
I should also mention that I tried this with the line-out from a Belkin charger, with no difference at any volume level. I'm going to drag the dock out there later tonight to try it with a line-out without an amplification stage to see if that makes a difference, too.
So possibilities:
1) Even though my average gain is now very conservative, the iPod EQ is still managing to overdrive somehow. I'd think I left enough headroom though, and if it were overdriving, wouldn't I hear it through the headphones?
2) Cable issue? Doesn't seem likely, and my Zen didn't have this problem that I ever noticed. It was using the same cable to AUX.
3) Crossover issue? Again, never noticed it in the Zen, which was running through the same setup.
4) The head unit has a pre-amp stage that can't handle the combined might (heh) of the bass and treble coming over line-in at the same time? The iPod does seem to have slightly hotter output than the Zen, but I didn't notice a difference turning the volume down--it just distorted more softly. I'd think that would fix that issue.
5) Impedance difference between the earbuds and the line-in of the head unit causing the different behavior? This seems the most likely. If so, how can I fix it?
I'm not an audiophile by any means. I generally -like- the way the iPod sounds stacking the EQ on top of the my head unit settings and will live with the occasional distortion if I have to. However, I'd like to not have to. Any suggestions?