|Last modified: 14-11-2012|
This short article sums up information I found while learning how to digitize some K7 tapes I had, and converting the whole thing into MP3.
"Why useCDex? Well CDex can extract the data directly from an Audio CD, which is generally called an Audio CD Ripper or a CDDA utility. Of course you can do that also by recording through your sound-card However, recording by sampling the signal with your sound card implies that the signal is first has to be converted to an analog signal by the CD-ROM, which is fed into the sound-card and digitized by the sound-card. In practically all situation the quality of the recording will be deteriorated (unless you have a CD-ROM that has a digital output of course). CDex on the other hand, is reading the digital audio data directly from the disc, which can be stored in either a WAV file or a MPEG (MP2 or MP3) sound file.
Dec 19 2000, 12:55 pm
> So here are a few questions for
> you experts out there after some background info.
> I am about to transfer some old cassettes and LP's to digital media
> (CD's). Other than using commercially made CD's and getting exposed to
> mp3, Real Audio, etc. on the net, I do not know much about digital
> media, especially about quality issues.
> The material I will be transferring is rare music. I would like to
> retain as much of the quality as possible. However, the tapes that I
> have are, in some cases, 30 years old, and the LP's I have probably have
> quite a few scratches. In other words, the quality may not be there to
> start off with
Well.... That's one of the nice things you can do with a computer. Scratches can
actually be manually removed using (for example) the pen funtion in Sound Forge.
Just use the <Find> routine to find the offending glitch (or, use your ears and
a set of good headphones OR speakers).
> While I am investigating what format to use (comments on that also would
> be appreciated), I have a question about hardware:
> * Perhaps the general question is if the quality of the soundcard
> matters. I currently have a Creative Sound Blaster PCI 128, which I
> consider to be a low-end one.
It actually is quite sufficient for the use you have for it. It's A/D converters
(only part of soundcard which is interesting for this purpose) is fairly good
and quite probably outperforms the equipment connected to it (cassette or TT).
> * If the soundcard matters, is there anyplace on the net that ranks the
> quality of the various sound cards? I am curious as to how much it
There's always Arny's site: www.pcavtech.com which goes into great detail about
the technical side of soundcards (S/N, various distortion types, freq.
> * What else matters in terms of the computer equipment I will use?
What matters VERY much is the OS used. I have done quite a few (as in several
hundreds of hours thusfar) analog recordings (transfering the Vinyl part of my
(quite substantial) collection to a more portable medium (CD)) and one of the
biggest problems I encountered was missing frames. This is NOT due to the speed
of the harddrive (the 172k stream can hardly be considered "state of the art"
(and every newish harddrive has delayed calibration nowadays)) but it's actually
due to the piss poor interrupt handling of Win9x. This goes for Win95 as well as
for Win98 (no idea about Win ME, lost appetite for these Win versions).
So, as mentioned, one of the first problems I encountered were the missing
frames (parts, chunks) in the middle of the music (pretty much at random, once
every 4 recordings or so (average 5 minutes per recording)). I at that time
decided to audit every piece of recorded audio which was quite tedious. Someone
(don't remember who) pointed me to the fact that Win9x suffers from poor
interrupt handling whereas WinNT doesn't so I switched to WinNT (4). Problems
were GONE (with same harddrive BTW!!!) and never EVER surfaced again (not even
when the harddrive was being defragged at the same time). So I would suggest you
either audit every recording OR go for WinNT (or Win2000 which also works like a
charm (successor of Win NT 4)).
BTW: This problem is also NOT related to the recording software used since it
appears with: Cool Edit 96, Cool Edit Pro, Sound Forge 4.5, Wavelab 2.0 and
Goldwave. This problem CAN be related to the soundcard used. The cards of which
I KNOW they exhibit this problem (under Win9x) are: SB 16, 64, 128 and SBLive!
> Another factor here of course, is the quality of the analog equipment I
> will be using. I currently have a home stereo, nothing fancy. I have two
> Sony portables (TC 153 and 158).
There are a LOT of different things that can turn your effort into a mess. One
of the most often seen problems is groundloops. Someone hooks up his Hi-Fi
system to his computer and everything turns into "hummvile". Reason for this is
that Hi-Fi systems are grounded through the CATV connection. Quick check for
removing "hummvile" is to remove the CATV connection (BOTH video and radio).
Lasting fix is to insert a groundloop isolator in both the radio and TV feed (be
aware of problems when you use your cable for say Internet connection).
Then there is the quality of the RIAA(A) amp used. Quite often, the quality of
the RIAA(A) pre-amp inside a Hi-Fi unit suffices but if they don't suit your
needs, you need to go shopping for an external RIAA(A) amp.
Connections: Keep them as short as possible. Especially in the case of the 1/8"
jack plugs, do insert/remove them at least several dozens of times before
leaving them in the appropriate hole (for their connection (and cleaning action
during insertion) is piss poor).
Recording: Open up the software mixer of your soundcard. Be sure to select the
RECORDING mixer (looking at the playback mixer is quite useless ;-). MUTE
everything except the input which is going to be used for recording.
Now fire up your favorite wav recorder. We're first going to set the level. Put
on a record and play the thing. Now adjust the appropriate slider in the
software mixer (recording panel) until the level peaks during the loudest
passages at -2dB (Cool Edit and several other packages have an internal VU
meter). The 2dB is to allow for some headroom.
You have now set the recording level. No press stop on the TT (while keeping the
needle on the record) and with Cool Edit, record a few seconds. Now select these
few seconds and use Cool Edit's FFT (Fast Fourier) utility to analyse the
content. There should be NO big bumps in the spectrum (especially around 60,
120, 180.... Hz) and the level should be around -100dB (lower is better).
If all that is OK then you have set-up the computer end of your recording
Now consider a few other things: Use a FRESH needle. It might be worth
considering to increase the needle pressure to the highest limit as suggested by
the needle's manufacturer (since that will result in the lowest distortion).
Record wear is a non issue here since you're only going to play it once.
Remember to also readjust the anti-skating accordingly.
The simple way is to use the reading on the anti-skating dial, the nice way is
to use a test recording and look with a spectrum analyser (like the one inside
Cool Edit) at the output. Set anti-skating so distortion is lowest in BOTH
channels (too high and left channel will distort, too low and right channel will
Clean your Vinyl THOROUGHLY. I personally use a carbon brush for that but there
are various other items worth considering as well (just don't go overboard).
Playing wet might be someting to consider IF you know the downsides of wet
playing. I don't, so I don't.
OK, now you're ready to record. After finishing your recordings, listen to them
(for starters because of the Win9x interrupt flaw) for pops and ticks. I
personally use Sound Forge for this part since Sound Forge has a very nice PEN
function. With the pen function you can literally draw a wav file (or apply
corrections to them). If you hear a pop/tick, move the cursor to the offending
part, zoom in (using the zoom function) and, using the pen function, redraw the
offending tick part (quite often only in ONE of the channels) with a shape which
you think MOST resembles what it should have been. You'll be AMAZED with what
you can get away with using this function.
NEVER rely on automated features for pop/tick removal. They'll always degrade
the ENTIRE recording (and often don't discriminate very well between transient
signals and actual ticks/pops, thus resulting in a dull and tediously bad
If you want to apply noise reduction, the one inside Cool Edit PRO works like a
charm (don't know about CE2000). You DO have to look at the settings first BTW
(and of course get a "fingerprint" from a quiet part).
For CD-burning, I would recommend using Feurio. It's about the greatest audio CD
recording software out there (on a WinTel platform that is).