Distortion Problem on Sansa

[Llorean]

Set the equalizer preamp to -1db, and does it reduce your problem? (Sorry, I haven't had time to make use of your test file yet). (And make sure the equalizer is also turned on, but flat beyond that).



Edit: Alright, I've tested the file. Is it at the "Su" sounds, that you hear twice during the file? Adjusting the EQ precut to -2.0 seems to resolve the sounds I think you might be hearing.

[Vortex]

Is it at the "Su" sounds, that you hear twice during the file? Adjusting the EQ precut to -2.0 seems to resolve the sounds I think you might be hearing.

Yes, that's exactly the issue I'm talking about.

While experimenting with some other files that distort on the Sansa, I noticed that some of them also distort when played on the PC, the distortion is just not as loud/noticeable as on the Sansa.

Judging from that I would say, that it is not entirely the Sansa's fault, since these files where incorrectly encoded/recorded. However, the Sansa seems to be a bit more "sensitive" than my Computer's sound hardware. That's why you can already hear some distortion on the Sansa while there still isn't any on the PC.

Maybe the Sansa only needs some "fine-tuning" of some decoder or sound-driver values?

Well, I guess it would be easier for me to fix my files, though.

Any lossy codec will add noise, which will push you into distortion.

You are right. I just tried it, and transcoded a FLAC file whose max. amplitude was 0dB (i.e. it didn't clip) to Vorbis. After the conversion I could detect clipping with Audacity (the peak-meter went red) but I couldn't notice any audible difference.
On the Sansa, however, the transcoded file distorts while on the PC it doesn't.

EDIT: Do you have any suggestions how I can avoid distortion when transcoding in the future?

[Llorean]

Did you try adjusting the EQ precut, and enabling it, as I suggested?

[Vortex]

Did you try adjusting the EQ precut, and enabling it, as I suggested?

Yes, this prevents the distortion but I already mentioned that in my first post.

For your testing pleasure I have uploaded a new sample clip (it's an instrumental track this time and doesn't require a warning ). The file archive contains two files. They are both the same snipplet from a source FLAC file, however one was left untouched while the other was transcoded to Vorbis.

On the PC both play without noticeable distortion. However, the Vorbis file clips while the FLAC does not.

On the Sansa, the sound from the cymbal (?) sounds (slightly) distorted on both files, though I'm not sure if the distortion is louder on the Vorbis file.

EDIT: Oops, forgot the link. Here it is:http://www.mediafire.com/?aclcdzddxbs

EDIT2: Another theory: Since the cymbal sounds and the vocal "s" sounds are somewhat similar, could it be that the Sansa distorts only at high frequencies?

[Llorean]

Somehow I completely blindly missed your mention of the equalizer precut fixing it.

I imagine it's all just a case of clipping, which can sound like distortion under certain circumstances. I mean that would explain perfectly why the precut is fixing it, and why on different hardware the same files react differently.

Try creating a WAV file and playing it in the original Sansa firmware and Rockbox?

[bodymind]

just want to congrat you all for the perfect sound of the lastest build - sansa :'D

keep it on  

[saratoga]

I don't see any evidence this is actually a problem with Rockbox.  Files with high gain are supposed to clip.  Thats why replaygain was invented.

[X86]

what is replay gain?,I use it but I dont know what a hell it is   ,and about high isn't a big trouble,just need to put volume down,and there is

[Vortex]

and about high isn't a big trouble,just need to put volume down,and there is

Nope, you can't fix this distortion problem by turning down the volume. Using the equalizer's precut works, though.

[Llorean]

That's because one is an analog solution, and one is a digital solution.

[audioffile]

I have, however, found a workaround for the problem: Enable the Equalizer and set the Precut to -5dB but leave all other settings untouched (i.e. leave the graphical EQ at the "flat" default setting). The distortion then disappears.

Does this "Precut" do the same thing as the "Pre-amp" setting that is available under the ReplayGain menu?

Edit: Answered my own question. Pre-amp is only applied to songs that are getting ReplayGain treatment and will do nothing on songs that are not being processed by ReplayGain. The "Precut" in the equalizer will be applied uniformly to all songs regardless of ReplayGain info.