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iPod Classic Firmware 1.1 WARNING - Page 4

post #46 of 147
1/21/08 at 10:10am
Nice one Ipodhappy for posting over at the Apple forums. On an unrelated topic, my cover flow seems to be slower than before

EDIT:
Quote:
Originally Posted by smallmouth
I was wondering why I haven't noticed this problem.
The hiss for me occurs regardless of what I do
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post #47 of 147
1/21/08 at 5:19pm
Quote:
Originally Posted by Clutz View Post
I've also noticed that there is significant DC offset even while music is playing. I don't think I will be using any of my good headphones with this iPod until they fix this issue with the DC offset!
This is the post that had me set my Classic 160 back to 1.0.3 (thank again, jantze). It's one thing to me if DC offset is found after off-by-pause, but another to read that someone is measuring it during music playback.

So I'm back to 1.0.3, got re-synced overnight, and the hiss problem is now gone.

I'll wait until I read of a certain fix for the hiss/offset problem introduced with 1.1 before I upgrade again.

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post #48 of 147
1/21/08 at 5:49pm
Quote:
Originally Posted by IPodPJ View Post
"Can someone explain what DC offset means and why it can cause damage to your headphones? I'm curious.
Sure. Audio/Music/Sound/etc is AC - or alternating current. It means if you connected it up to an oscilloscope you would see waves on the screen that look somewhat like a sine wave. DC stands for direct current. If you saw DC on an oscilloscope you would see a straight line going left to right somewhat above or below the mid-line of the scope which represents 0V.

When you hear music coming through your headphones it is because the sinusodal AC is pushing and pulling the diaphragm away from it's neutral (electricity free state) of the headphone causing the air to vibrate. If DC current is present it will either constantly pull (or push, depending on the polarity of the DC) away from it's neutral position. That constant force on the earphones from the DC can damage the headphones voice coils.

Hope this answers your question!

Brad
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post #49 of 147
1/21/08 at 6:23pm
Quote:
Originally Posted by jude View Post
This is the post that had me set my Classic 160 back to 1.0.3 (thank again, jantze). It's one thing to me if DC offset is found after off-by-pause, but another to read that someone is measuring it during music playback.

So I'm back to 1.0.3, got re-synced overnight, and the hiss problem is now gone.

I'll wait until I read of a certain fix for the hiss/offset problem introduced with 1.1 before I upgrade again.

Jude,

Have you seen any other sites discussing this issue? Im struggling to find anything, even on Mac Rumors. It surprises me that this issue has gone so un-noticed.
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post #50 of 147
1/21/08 at 8:18pm
Quote:
Originally Posted by J.D.N View Post
Jude,

Have you seen any other sites discussing this issue? Im struggling to find anything, even on Mac Rumors. It surprises me that this issue has gone so un-noticed.
No, I haven't seen much about it elsewhere--most of what I've read links back to this thread (look at the linkbacks at the bottom of the page). Seriously, though, there aren't too many forums in which any of its members would be inclined to measure DC offset from an iPod.



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post #51 of 147
1/21/08 at 8:24pm
Quote:
Originally Posted by Clutz View Post
Sure. Audio/Music/Sound/etc is AC - or alternating current. It means if you connected it up to an oscilloscope you would see waves on the screen that look somewhat like a sine wave. DC stands for direct current. If you saw DC on an oscilloscope you would see a straight line going left to right somewhat above or below the mid-line of the scope which represents 0V.

When you hear music coming through your headphones it is because the sinusodal AC is pushing and pulling the diaphragm away from it's neutral (electricity free state) of the headphone causing the air to vibrate. If DC current is present it will either constantly pull (or push, depending on the polarity of the DC) away from it's neutral position. That constant force on the earphones from the DC can damage the headphones voice coils.

Hope this answers your question!

Brad
Thank you Clutz. Sure did.
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post #52 of 147
1/21/08 at 11:21pm
Quote:
Originally Posted by Clutz View Post
That constant force on the earphones from the DC can damage the headphones voice coils.
Clutz, do you know how this damage would manifest itself? Would the driver go silent or sound very distorted, or would the deterioration be more subtle?

I just want to make sure I didn't damage my phones for the short time I used them with the iPod on 1.1.

Rick
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post #53 of 147
1/22/08 at 12:42pm
I to would like to know how I can tell if damage has been caused as just days before the update and the hiss/crackle problem started, I ventured into the world of good portable sound with a pair of Super.fi 5 pro's.
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post #54 of 147
1/22/08 at 2:49pm
I'm unaware of any way of directly testing for damage caused by DC offset in the headphones. The most important test would be that there is an audible difference in the sound quality.
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post #55 of 147
1/22/08 at 5:31pm
Should this damage occour immediately or only when the DC is applied over longer time?
Do headphones differ in sensitivity to DC (maybe by impedance)?
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post #56 of 147
1/22/08 at 7:02pm
Yes, i recently upgraded to the 1.1 Firmware in my 80GB classic, and was at a friends house when my headphones went shot. At first i thought it was the ipod itself that was messed up... then i tried my friends headphones and they sounded great, for a matter of a few minutes, until they also shot. Both headphones now are way over modulated now and sound horrible, so bad i need to replace my $60 set, and his $20 set. It really makes me upset that they would supply such a harmful realease.
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post #57 of 147
1/22/08 at 7:34pm
I guess I am the luck few whose iPod Classic model does not have any hissing issue after the firmware 1.1 update...not yet anyway. I am using LOD to my portable amps. This definitely will suck if this firmware update causing any damage to my amps or headphones. Hopefully Apple will rectify this situation real soon. I am sorry to hear, mrfenderbender, that your headphone is damaged by this.
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post #58 of 147
1/22/08 at 7:45pm
I have 1.1 and I am not hearing anything while my player is off. Maybe I am lucky not to have this problem.
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post #59 of 147
1/22/08 at 8:02pm
Just because you're not hearing anything doesn't mean your iPod doesn't have the DC offset problem. The only way to be sure would be with an unused male 1/8th TRS jack and a DMM.
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post #60 of 147
1/22/08 at 8:28pm
I updated my ipod before I found out about all this. I have the static issue. Now I just make sure to unplug the LOD before shutting down the ipod.

I have noticed that if the ipod is off for a while, then I plug the LOD back in, there is no static. So maybe after like 5 mins it truly shuts off and doesn't just sit in stand by off.

Downgrading isn't an option for me. I don't use itunes like normal people do. I don't have a library, I don't sync. I like to manage it all manually. Mainly because itunes is a big POS. So downgrading = copying all the music over and redoing all the playlists. Major pain in the ass.
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