READ THIS: Serious flaws in ipod classic

[Skylab]

Quote:

Originally Posted by Todd R /img/forum/go_quote.gif Thought Vinny told us there wasn't much difference? Kind of a strange thing for a manufacturer to say, but I appreciated his honesty. When I heard the iMod, I thought it was killer good, so when he said the Classic was real close to it I decided to get one.

I was surprised to read that too, but if you read carefully, he does say that the iMod + VCap does sound better than the Classic. And this is my finding as well. Just my opinion!

 

[akira281]

Quote:

Originally Posted by Skylab /img/forum/go_quote.gif And the ability to hold 160GB of lossless files outweighs for me any difference. I am going to try to put the 160GB drive in my 5.5G iMod iPod, because the iMod iPod clearly sounds better than either th5 5.5G stock or the Classic. That is a difference that is very easy to hear and that I think almost everyone would prefer the iMod versus the Classic.

Interesting. Are you going to keep the same firmware as what's on the 6G? Would it be compatible with the 5.5 logic logic board and DAC?

 

[Skylab]

Quote:

Originally Posted by akira281 /img/forum/go_quote.gif Interesting. Are you going to keep the same firmware as what's on the 6G? Would it be compatible with the 5.5 logic logic board and DAC?

I don't know - I'm not actually doing the work myself

 

[Hifivoice]

Quote:

Originally Posted by jook /img/forum/go_quote.gif Also to add, he is testing this on an European iPod which has the infamous EU Volume Limitation. In previous generations of iPods, the headphone output was significantly impaired when the volume was low. As he is restricted to lower volumes, this could make a difference to his measurements. He also pointed out that his measurements are unloaded, which means it's really not giving a realistic picture of what is happening. I do hope someone can do some proper measurements. This is already getting around quite a bit, and misinformation spreads like hell fire.

Misinformation spreads fast indeed!

If you would read carefully, you can see exactly the same characteristics are measured on the line output. No need to load the headphone output, it could make things worse at best.

 

[Hifivoice]

Quote:

Originally Posted by jook /img/forum/go_quote.gif I question the accuracy of the the measurements made by the page in the original post. He says that the bass attenuation is due to his measurement setup but with no explanation as to why he thinks this. And the attenuation looks remarkably similar to what was present in previous generations of the iPod but he does not seem to be aware of this.

You thought I wasn't aware?

 

[Hifivoice]

Quote:

Originally Posted by mirumu /img/forum/go_quote.gif For the impulse response graph, I get the following which looks very similar to the graph he posted except it's spiking in the other direction.

That's because the phase of the output signal of the iPod 6G is inverted compared to the 5G. To be able to compare the phase response, I had to invert the recorded audio. I've posted new curves for easier comparison on my webpage.

Quote:

Originally Posted by mirumu /img/forum/go_quote.gif I do see that the amplitude of the spikes on my graph are bigger too although I don't know if that means anything important or not.

Differences in volume, and the exact moments of sampling are the reason.

Marc

 

[Hifivoice]

Quote:

Originally Posted by Arainach /img/forum/go_quote.gif 0.1Khz at 10Khz is inaudible.

It depends on the reason. 0.2dB raise, 3 octaves wide, 1/3rd of the audible frequency range, caused by intermodulation products. It's something else than "just a raise".

I don't care about curves in the first place, but they help to explain what I hear.

Marc

 

[Hifivoice]

Quote:

Originally Posted by mirumu /img/forum/go_quote.gif Here you go. This is from the "Treble Booster" EQ setting. It's not really as flat as I would have expected and it seems to have quite a dip at 7KHz.

How large did you set the FFT window?

 

[Hifivoice]

Quote:

Originally Posted by bigshot /img/forum/go_quote.gif Frequencies above 10kHz are the least important frequencies. The amount of information up there in recorded music is very small. You could roll it all off and the music would still sound good. Imbalances above 10kHz are only going to cause masking in frequencies beyond the range of human hearing.

Take a good headphone, connect it to a decent headhone output to a PC/Mac, take the iTunes equalizer, and add 1dB to the 16kHz tab. This shows how much info there is in that area.

Now, don't make the mistake to make a link to the 0.1dB uplift in the curve of the iPod. What is really important is the REASON for the uplift. The 0.1dB uplift is a consequence of something. That's where the curlpit is hidden.

Quote:

Originally Posted by bigshot /img/forum/go_quote.gif They want someone else to tell them what good sound is. They don't want to take the time to figure things out for themselves. They'd rather be sheep and follow "conventional wisdom" even if that conventional wisdom is totally bogus. Being an audiophile involves more thinking than that.

Whether the reasoning is bogus needs a bit more arguments than hand-waving. Nevertheless, I fully support your reasoning that everybody should decide for its own whether the iPod 6G is OK for themselves.

The curves on the web only show an engineering flaw in the design, and a link to the things I hear.

 

[som4ew]

Quote:

Misinformation spreads fast indeed!

Bad news always spreads fast like wild fire.

 

[mirumu]

Quote:

Originally Posted by Hifivoice /img/forum/go_quote.gif How large did you set the FFT window?

For some reason I hadn't seen any new posts in this thread today and appear to have missed a lot. Anyhow, I'm not familiar enough with FuzzMeasure to know exactly what you are referring to there. Essentially I just activated the treble booster EQ, made the recording, aligned the waveforms and then compared with the stimuli file using FuzzMeasure. I didn't change any of the defaults or resize anything. I just changed the bar color and exported the resulting image.

 

[me7]

A store near me finally got some iPod classics and I feel very tempted to buy one.

mirumu, did you notice any audible timing issues with different frequencies yet? Your older posts say that you didn't hear anything wrong, do you stick to that opinion?

 

[bigshot]

Quote:

Originally Posted by Hifivoice /img/forum/go_quote.gif Take a good headphone, connect it to a decent headhone output to a PC/Mac, take the iTunes equalizer, and add 1dB to the 16kHz tab. This shows how much info there is in that area.

The iTunes equalizer isn't an accurate. It has spill between frequencies all over the place. In Peak, I use Bias Freq4 to make precise EQ adjustments. 16kHz is the absolute top of the top. Almost nothing up there. Listening to music, a 1dB boost at 16kHz is for all intents and purposes inaudible. A one dB boost somewhere around 1kHz - 3kHz would be just audible with tones, but it still wouldn't amount to much.

See ya
Steve

 

[mirumu]

Quote:

Originally Posted by me7 /img/forum/go_quote.gif A store near me finally got some iPod classics and I feel very tempted to buy one. mirumu, did you notice any audible timing issues with different frequencies yet? Your older posts say that you didn't hear anything wrong, do you stick to that opinion?

I still have some more music and gear combinations I want to try, but yes, as of yet I cannot hear any phase issues with my 6G. If anything I think it sounds very good overall. Marc did indicate to me that the phase response shown in the graph I generated appeared better than those in his measurements. I don't really want to speculate as to what the cause or effect may be at this point but that is where things currently stand from my perspective.

 

[bigshot]

I found a couple of great examples to put these specs in better perspective. We're talking about a .1 to .2 dB rise between 15 and 20 kHz.

On this page is a Flash example of volume of broadband noise descending in .3 dB steps. This is double the amount of difference measured in the 6g iPod.

http://www.phys.unsw.edu.au/jw/dB.html
(scroll down to What if the difference is less than a decibel?)

And here is a test tone showing what 15kHz sounds like...
http://ia301124.us.archive.org/0/ite...z_audacity.wav
(Adjust your volume carefully before clicking. This can hurt if it's too loud.)

Less than half that degree of difference at that frequency. Every other frequency is stone flat.

It's amazing at how remarkably good measurements like this can be reported as being bad. It just shows how little people know about the numbers they are slinging around.

See ya
Steve