[MPA] Audio I/O Interface and Other Newbie Questions

Scott Baldwin sbaldwin at san.rr.com
Mon Feb 17 18:20:39 PST 2003

On Monday, February 17, 2003, at 04:00 PM, Steve Shapiro wrote:

> Now that I've gotten that out of the way...Here's my questions:
> Given that the bit rate of an audio CD is 16-bits, what's the reason 
> for getting an audio I/O interface that lets you record at 24-bits or 
> more?

This is a good question, to which there is no simple answer......
There are actually two numbers to consider in digital recording.  The 
Bit depth (16,24) and the sampling rate.  (44.1K, 88.2, 96K...etc).

Think of the bit depth as the dynamic range possible in your 
music(loud-soft).  At 16-bit the dynamic range is about 100db.  Keep in 
mind that in highest quality analog (Tape) recording the dynamic range 
is about 80- 90db.  At 24-bit the range is about 110db.

Do we need this greater dynamic range?  only your ears can say for 
sure.  The cynical point of view is that the companies who build the 
equipment have to keep coming out with "better" equipment to sell us.  
To maintain sales they have to convince us that the 16-bit converters 
that we bought a few years ago are no good now and need to be upgraded 
to 24 bit.
  The irony of this is that most popular music is recorded within a 
small dynamic range.  Compression is widely used in recording and 
mastering, and the dynamic range of the average pop song is much less 
than 100db.  Only in classical music do you see wide dynamic ranges 
within a single piece of music.  Most experts agree that at soft 
volumes that 16-bit is yuck.

The sampling rate is the rate at which the music gets turned into 
digital data. CD's currently use a sampling rate of 44.1K  That means 
that 44,000 times a second, the converter takes a snapshot of the 
analog signal and turns it into digital.  At 96K this happens 96,000 
times  a second.

Over the last 20 years of digital recording there have obviously been 
1000's of hit songs recorded at 16-bit/44.1K.  There are those 
audiophiles who maintain that digital recording is cold and brittle 
compared to analog.   The theory is that only by recording at 24/96 can 
we capture the same warmth as the old analog.  To decide for yourself 
you have to use your own ears.

The general theory is that although CD's are 16/44k, recording at 
higher rates and then downsampling for the final mix gives a better 
result, than if the music was recorded at 16/44 in the first place.   
This is a high subjective theory, with no real objective way to prove 
it, other than by listening.

The other point is that in a few more years we probably will have a new 
commercial product that brings music to the masses at 24/96. (probably 
a DVD).  The thinking is that by recording and archiving your music now 
in 24/96 you can remaster in the new standard later.

Seeing as 24/96 converters are widely available now, it makes sense to 
purchase this technology, even if you record at lower rates.  Keep in 
mind that stereo 16/44 recording uses about 10MB/min of hard disk 
space.  24/96 will use considerably more, so you have to figure hard 
drive real estate into the equation.

> On a related note, does anyone have an opinion of the Midiman 
> Audiophile 24/96?  It features 24-bit 96 kHz multitrack recording 
> (hence its name).  If I'm planning to run Cubase SX on a MDD G4 dual 
> 1.25GZ machine, is this card overkill?  Why or why not?

I'm not familiar with this interface, but it is only a stereo in and 
out, so you can't record more than two tracks at a time.  If you want 
to record more tracks simultaneously you need something like the MOTU 
828.  It certainly is not overkill.
> Finally, I also have a PowerBook G4 Titanium 500Mhz running Jaguar.  
> Is there any chance of doing all my Cubase SX recordings on that?  If 
> so, is there any audio I/O interface cheaper than the MOTU 828 that 
> will still give me similar high-quality/low-latency results?

You can use the powerbook, but your the total number of tracks you can 
record in a single song will be much less than on the G4.  I haven't 
used this machine so I don't know what your track limit would be, 
hopefully someone else has used this powerbook and can tell you.  The 
828 is the best choice for the powerbook.  The only other option would 
be a USB interface.  These suffer from all sorts of problems, and i 
recommend you stay away from them.

Good luck,

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