posted
Wayne's post in the General forum go me thinking too. Does anyone know if the burning process that is available today to the consumer, is capable of high quality sound? If you put in an HDCD, or higher quality recording, will there be any "compression" involved in the reproduction? Can you notice any difference on a higher quality CD player (home or car)? What type of DAC process is used?
------------------ E.C. Wuz here
[This message has been edited by Eli47 (edited 12-28-1999).]
Posts: 1057 | From: Vancouver, British Columbia, Canada 'eh | Registered: May 1999
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posted
I havn't heard any differences between a burnt CD and a premade one. Since your doing it from your computer, you've pretty much got about the best DAC available for data transfer, which is all your doing. Use a good CD rom drive to read the disc to .wav format, then use a program like Gear to create the CD-R. I've not run into any compression problems. When you record into .wav format, make sure your settings are the highest they can be. I use Music Match Jukebox to make the .wav files. It seems to have the best interface, or at least it's easy for me to use...
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
Uh, yes it does if the signal is compressed or altered in any way in the transfer.
Posts: 490 | From: Fort Frances, Ontario, Canada | Registered: May 1999
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There are so many things things in going from analog to digital (ADC) and digital to analog (DAC). For an ADC, first the signal goes through a low pass analog filter to prevent the sampler from trying to sample frequencys greater than it is capable of. To create a digital signal out of an analog signal you must sample the analog signals values at even intervals in time. The minimum sampling rate is double the maximum analog frequency in the signal being sampled. The sampling frequency fs = 2fmax is called the Nyquest rate. If the analog signal is not band limited, then frequencies greater then fs will be aliased to another lower frequency in the sampled signal. This new lower frequency fa can be calculated using a formula.
In a 16 bit audio format a sinusoid can be represented by 2^16 or 65,536 discrete levels. Since the sinusoid has an infinitely varying voltage amplitude each sample must be rounded of to the nearest discrete value. This is called Quantization. Quantization therefor introduces error into a sampled signal. This error can be expressed as a signal to error (S/E) ratio. S/E (dB) = 6.02n+176 n = number of bits. A 16-bit word would have a S/E of 98 dB. When the signal being sampled becomes a low value the quantization error becomes the signal. This unacceptable effect can be removed by the use of dither. Dither Dither is the process of adding low level analog noise to a signal. The effect of dithering is to make the overall quantization error behave as a white noise signal.
After the signal processing has been performed the digital signal is sent to a digital to analog converter. A DAC converts a digital word into a voltage. It does this many times per second. Two different types of converters are multi-bit and low bit converters. Multi-bit converters convert whole data words in parallel at the sampling frequency. Low bit converters use different types of modulation. Phillips uses a technology known as pulse-density modulation (PDM) or Bitstream conversion. In this technique, the density ratio of the sign of the pulses is related to the original 16-bit data word. Once the data words have been converted into a voltage it is not smooth but a whole bunch of little steps. These little steps can be thought of as high frequency components that need to be filtered out. After the DAC stage is a low pass filter designed to smooth this response. There are many advantages of digital audio over analog audio. One major advantage is that with digital implementation you don’t have the problem of the specifications changing with time. In an analog filter, resistors, capacitors, and inductors change value in time. To design a high order analog filter for example, a 5’th order butterworth bandpass, you are required to have very precise component values in order to achieve the high Q’s (not speaker Q's) required to complete the design. Filters like this are almost impossible to mass produce. Dont ever buy a high order analog signal processor and think is going to work accuratly. Components just dont have the toerances needed to do it. Another advantage of digital audio is you can make copy’s of copy’s without summing the noise and distortion from each new copy like that introduced by say the analog tape player. Digital audio also has a flat frequency spectrum across the entire audio bandand can be signal processed without phase distortion, not to mention you dont add the S/N ratio of the EQ and or crossover. compression is not done on general things like a cd player. but you do get in to rounding off numbers that get big when doing the multiply accumlates of the 16 bit words when signal processing. Some DSP's use higher bit multiply accumulates to help solve this problem thats not really even a problem. The most important part is probably the DAC. I believe the bit stream conversion (Pulse density modulation)by phillips is the most accurate. In the future digital signal processing will probably replace the analog stuff as it wont be able to compete in terms of accuracy and S/N ratio.
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Posts: 1259 | From: Fullerton. CA ,USA | Registered: Oct 1999
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posted
Eli- Umm... The signal, going from CD to hard drive to CD burner... It doesn't change from digital, dude....
At least, it shouldn't... Then it would have to go DAC to ADC.. and that would induce noise.
ShadowStar
BTW- if you do a bit-by-bit copy, or RAW read, you should be able to copy the CD onto your hard driver and then copy it onto the CD burner with no conversion... And perfect copy, or close..
Posts: 2578 | From: Somewhere In the Northeast | Registered: May 1999
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posted
The only degredation I've heard on burned cds is small "ticks" which seem to be induced by burning them on a computer and using a speed that is too fast for the processor. If done slowly enough, I've never heard a difference. I don't know about dedicated burners (Philips etc.) as I don't know anyone who has one.
------------------ inno73@hotmail.com
Posts: 490 | From: Fort Frances, Ontario, Canada | Registered: May 1999
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posted
We have a dedicated copier here at work. I've used it uncounted number of times. It works beautifully! I've used it on old CD's that I've found badly scratched and what not, to make a working copy of them. If you can get a cd to play in a regular player reasonably well, the copier should be able to make a good copy of it. It is all SCSI based, and nothing ever goes through DAC's or ADC's in the process. Ours (dont remember name) can make 3 burns at one time, and cost about 7,000.00 a year ago.
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
posted
Well, I just had an opportunity to try a burner, copied a disc, and tried them both on the same system, same volume. I did notice some slight ticking noise on the burnt copy as Inno mentioned, and also noticed some "tighter" soundstage and Dynamics. Harmonics seemed to die off a tad quicker, but barely noticeable. Might be because it's an "inexpensive" burner? I will try another copy with an Allsop CD ring on it, see if I get a better copy.
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E.C. Wuz here
Posts: 1057 | From: Vancouver, British Columbia, Canada 'eh | Registered: May 1999
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posted
I have noticed on some of the more recent cds I've had burned that the soundstage kind of pops in and out, kinda like it's going from mono to stereo and vice versa.
------------------ inno73@hotmail.com
Posts: 490 | From: Fort Frances, Ontario, Canada | Registered: May 1999
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posted
Discovered not all music CD's are copieable. Might be the burner? Some PC discs seem to have some kind of copy-guard preventing proper installation from burnt copy.
Posts: 1057 | From: Vancouver, British Columbia, Canada 'eh | Registered: May 1999
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posted
Eli, use a newer, SCSI based system!!! I HATE ide cd burners for the very reasons you have come across! An IDE burner simply cannot get the data to the disc in the most efficient way possible. Use either a dedicated cd copier machine, or a very fast computer with SCSI drives. My computer is a 333 PII with 128megs ram, 4.3gb A/V SCSI drive, 6x SCSI Writer, 40x reader, Adaptec 2940UW2 SCSI card, and I've not had a single issue like your having. One other suggestion, record your CD to .WAV format, then burn your CD from that, sometimes that's the only way to copy a CD.
------------------ STILL waiting to hear a GOOD pair of HLCD's!!
If it dont fit, force it... if it breaks, it needed to be replaced anyway...
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