Thanks again for the discussion.

The iPod is wired to the ida via usb thru the ipod bottom end. Is that different from the fullspeed or are they the same thing?

The poor sound quality is substantially noticeable at higher volumes. The frequency that is painful is on the high side. If you have heard Korn's acoustic album there is a song with Amy Lee. During that song she hits notes that are downright harsh. Her voice isn't particularly bad, I'm just trying to isolate the range. I don't get this effect with the lower volumes although I am open to thinking the ipod eq may be a cause since I don't get the harshness at all with radio music.

 

AHHH, that is attributed to the Alpine head unit probably mixed with the IPOD eq. If you want to completely lose the harshness in that 3k-5k Hz range, you'll have to switch to a different head unit brand.

 

You are incorrect here. The iPod EQ has nothing to do with the sound that comes out of the HU. The signal the HU is seeing is pre-amplification, so there is NO adjustment done by the iPod EQ. The only thing that would affect it would be the EQ settings on the head unit (whether set to the standard "treble" "bass" and "sub" settings or to the more generic "pop" "rock" or other preset EQ's).

How is the EQ setup on your head unit? When you press the "audio" button, does it toggle between subwoofer, bass, treble, balance and fade? If any of the first 3 are left out, you have it configured for the preset iPod-esque EQ's, which SUCK! I will see if I can get you a map of the menu's to go through to verify this...

Yes, the USB connection is separate from the FullSpeed connection. If the EQ solution above does not fix the problem, I would drop $30 on the fullspeed cable, and try the iPod through that connection (will show up as iPod2 as the source on the HU). If the problem does not follow, you have a bad USB connection somewhere between the iPod and the HU, and the signal is getting screwed up. Chances are it is just the preset EQ, though.

Also, what is the "signal input" level set to on your amp? It should be at 2V to match the RCA output of the HU. If you went from a HU that had a lower than 2V output and did not correct the amp setting, the amp would clip as described above at higher volumes (but would work at lower volumes just fine). This would cause the radio, or any other input source, to distort with volume as well...

John

 

That harshness you describe is distortion, not lossy compression. What this means is, it's not the MP3s, it's distortion introduced by the HU. Since you said the FM radio sounds fine at high volumes, then it's not a problem with the pre-outs of the deck nor the amplification.

I think your problem lies with the poor quality DAC (Digital Analog Converter) used in the head unit. This chip converts your digital mp3 sound to an analog signal which can be played out by your speakers. Alpine these days is all flash, and they are amazingly stingy on the components they use. Shitty DACs don't surprise me.

 

^ Once again, incorrect. People need to stop spreading mis-information on this board. It is NOT the DAC in this head unit. This head unit utilizes a 24 bit Burr-Brown DAC (one of the best names in the industry). It is at least on par with any other DAC offering out there. I would be interested to see how XM would sound on his HU (sounds perfect with mine), but then again my iPod sounds great too...

It could very well be lousy compression (low compression = higher static noise content = higher audio distortion). It would only really be noticed at high volumes. It could also be the input associated with the USB source on the unit (might be a faulty connection), hence why I suggested moving it to the FullSpeed input to see if the problem persists. it could also very well be the tuning utilized (if he used the preset EQ's, then yes, it the HU that is introducing the distortion...). I think we need to the OP to post his tuning settings (whether using a preset EQ or a combination of treble, bass, etc.) and amp settings (input, crossover, filter settings, and gain settings). This would allow us to "rule out" certain situations.

John

 

Congratulations for buying into Alpine's marketing machine. Just because something has a name on it, it doesn't mean it's quality. FYI Sony HUs have been touting the Burr Brown name on their DACs for quite awhile, and we all know how great those are.

 

^ Personally I think the problem with sony is their crappy amplification... not the DAC. There is a LOT of components that all must function in harmony to get "proper" sounding audio.

Yes, the iDA does have some quirks, as does just about every unit that comes out for the first time, but it handles the iPod better than any head unit out there, short of an in-dash DVD player with touchscreen...

IMO, it is worth every penny of the $399 I paid for it... Plus if you are really that anal about sound tuning, you could just easily add one of these:

http://www.crutchfield.com/App/Product/Ite...=3&tp=428&avf=N

John

 

John, It's well known across the industry that Alpine has a nasty/harsh reproduction of the 3k-5kHz range that no EQ can get rid of. That's just fact. (I've had multiple Alpines, they all were the same).

Eclipse use the same DACs, but with no nasty harshness It also has easy to use IPOD controls and a USB jack. And from what I've heard, neither Pioneer nor Kenwood have the nasty harshness.

Alpine is not bargin bin by any means. It surely, however, is not top of the market either (by quite some stretch these days).

Part of the harshness the OP is experiencing is perhaps due to his Ipod EQ and how he has it hooked up (it does indeed affect the output). And quite a large part of it is due to his Alpine HU. If he's using the wrong amp, it can even amplify that harshness more than just the Alpine HU alone does (been there, done that, stick to nothing buy high-end ever since).

 

^ He is using the USB connection. The iPod EQ is moot the signal has not been processed yet. Hence his use of the Burr-Brown DAC. I believe the FullSpeed does not use the DAC, but I cannot verify this...

The harshness he is complaining of is not the "quality" associated with all Alpine head units. He obviously is not using the internal amp, thus avoiding the "nasty 3k-5kHZ range." My tweets are nice any high, set nice and bright, and no harshness at all (I too am using external amps to avoid the inherently crappy amplifier of any head unit, not just the Alpine ones...). I think Alpine has cheaped out on their sound processing capabilities, but there has been a boost in amplifier tuning / development. I think they are mainly gearing their units to manage the amps and the user interface as fluently as possible.

John

 

I have the same head unit connected to a pair of Boston Acoustics SL60s. I basically had the same problem of distortion with MP3s at high volume settings. The fix was actually quite simple.

Turn off the Media eXpander (MX) under the audio settings.

The Alpine documentation says this,

[QUOTE]"This corrects information that was lost at the time of compression.