Ripping CD's - Bypassing Computer CD Player

The timing in most USB connections today is controlled by the converter or the DAC, not by the PC. So, there should be no timing issues specific to the PC. All it has to do it keep the buffer full and deliver the data when asked. I guess it is possible that the USB on the PC does not handle the interrupt request from the converter/DAC correctly, but I think that is a remote possibility. In any case, that should be independent of the CPU and disk usage, unless the USB implementation is really bad.

People are concerned about electric noise on the USB ground and on the signal lines, as well as RF noise from the PC that can effect the converter or DAC. That is why the devices I mentioned earlier are available. More and more equipment has galvanic isolation on the data lines, usually in the form of small transformers. Expensive cables can be used to try to eliminate RF problems on the cable and connectors.

Using a separate +5V power supply certainly makes sense if the USB device is powered by the +5V on the USB cable. Certainly, a $500 linear power supply will be much cleaner and more stable that the signal on a USB. However, that has nothing to do with file formats, HD usage, CPU usage etc.

As to bit identify files in the same format sounding different, that makes absolutely no sense to me. In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them.

If people think they hear differences from all these things, who as I to say? For me, these effects are interesting to think about, but I don't hear most of the differences that these people report.

I did not mean to get this thread off topic, just wanted to summarize some of the issues that people discuss.

" When rip wav->flac->wav, depending on the software, possible loss of precision?"

That is not likely. The data is integer not floating point format. And, you can compare the first and last wav files and they will be bit for bit the same. People do binary compares, find the files identical, and report they sound different. At one point I spent a lot of time doing binary compares and looking a file formats. I taught computer science for years, so I am pretty familiar with the issues here. I never found any differences in the files people claimed sounded different. It makes no sense to me that those 2 wav files would sound different, but some people have reported it.

"If file is already wav, why rip again to wav?"

Some people have ripped to flac and then decided to convert to wav because they think it sounds better. Somebody then pipes in and says they should re-rip everything, since the converted wav file will not sound the same as the ripped wav file, even though they are bit for bit identical.

Let's not get too deep into this. There are lots of discussions on AA and other places about this and nothing ever gets resolved.

If people think they hear differences from all these things, who as I to say?

Nothing. There will never be a consensus in anything.

" When rip wav->flac->wav, depending on the software, possible loss of precision?"

That is not likely. The data is integer not floating point format.

What does not floating point have to do with potential errors? It's a software program. Data is probably processed in bytes.

People do binary compares, find the files identical, and report they sound different. At one point I spent a lot of time doing binary compares and looking a file formats.

If binary compare returns TRUE, STOP!!! Like I said, people likes to exaggerate and sometimes have no clue in not comparing apples to apples but apples to oranges as we've seen in this forum.

Some people have ripped to flac and then decided to convert to wav because they think it sounds better. Somebody then pipes in and says they should re-rip everything, since the converted wav file will not sound the same as the ripped wav file, even though they are bit for bit identical.

Where's the original wav? When you rip into another format, it doesn't overwrite the orig but just create a new copy in new format. No?

Let's not get too deep into this. There are lots of discussions on AA and other places about this and nothing ever gets resolved.

Don't worry I won't. Have NO plans jumping in AA.

In the Absolute Sound article I mentioned, the authors said the sound go worse the more times files were converted, even if they ended up bit identical. I will say, they did get a lot of push back on that topic. However, others do report similar experiences. But, hey, if people believe they hear differences, that is up to them.

Perhaps authors are members of mentioned AA?

Loss of precision is often a a result of floating point calculations. That is why I mentioned it. The calculations used to compress and decompress files is entirely an integer process. The program may make mistakes, but given you can convert to wav to flac and back to wav and have a bit identical file says that the conversions are being done properly. There is no evidence of any program error or loss of precision. The files before and after conversions are the same based on binary compares, not just checksums.

As to bytes versus integer, in a typical 16/44 file each datapoint is an 16 bit number, which cannot be represented by a byte. Hence, my reference to integers rather than bytes. But the real point is that the calculations do not result in any loss of precision.

The wav to flac to wav tests are just that - tests. They try to see if the conversions influence the sound. People have done this because of the reasons I stated. Some people believe the original and final wav files do sound different, even though the original and final wav file are bit for bit identical. You can say STOP, but people report that they can sound different. I am just summarizing what some people report.