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Topic: Noob wants to digitize his old tapes (for good!) (Read 8949 times) previous topic - next topic
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Noob wants to digitize his old tapes (for good!)

Hello everybody,


my question concerns the digitalization of old tapes (sure, not a very original
question and yes, i have used the "search"-function .

I did accomplish that task a year ago by recording the tapes (all audio-plays,
no self recorded stuff) with a tape-deck (taken and disconnected from a Technics-compact hifi-system), which was connected to an external Soundblaster Mp3+ USB-Box. I used no Phono-preamp (since i heard that a pre-amp is mandatory only with turntables and record-players...). The recording parameters where 16-bit with 44.1khz.

The quality was o.k., but I'm wondering now if i should redo the whole thing with a new and better setup, since high-quality sound-devices are getting more and more
affordable. Would it make sense to use a more improved soundcard (no Creative-Labs, theirs seems to have some technical issues) with a 24-bit resolution and higher sampling-rates like 96khz or even 192khz (maybe the M-Audio Audiophile 192 for internal usage, or the external Terratec Phase 24fw )? I know, i can't
improve a flawed source like tapes to a DVD-Audio level, but does it really make
no physical difference at all to use 16-bit or 24-bit?



You see, many, many questions from a mere amateur and your answers are much appreciated!

Noob wants to digitize his old tapes (for good!)

Reply #1 –
I think you're worrying about the wrong end of the signal chain.  I would pay more attention to upgrading
the cassette playback deck.  Get that right, and a competent 16/44 transfer should be more than sufficient.

The idea would be if you could get your hands on one of the Nakamichi models that self-corrects tape
alignment as it plays.  Good luck finding one!

Noob wants to digitize his old tapes (for good!)

Reply #2 –
Hello krabapple,

I've heard of the Nakamichi-decks. I gather that those are not built anymore,
right (good old ebay then...)?
However, are they really that much superior to a tape-deck bought at my local
hi-fi-shop (for example a Sony TC-WE475  for149 $)? And if the answer is yes,
which Nakamichi-model would fit my demands best? I've heard that the low-
range Nakamichis are not good at all. And if i wouldn't be able to purchase the Nakamichi, which manufacture and model would make a good alternative?

Could somebody give me a model-setup (cassette-deck, soundcard, con-
nectors) in order to help me to get the most bang for my bucks? My tapes are
really dear to me, but i don't want to do the whole time-consuming process
over and over again (I know, love hurts, but one can carry it too far...)!

Thanks in advance

Noob wants to digitize his old tapes (for good!)

Reply #3 –
(Thanks, Marlene, you where great!)

                                        *clears his throat*

                    "Where have all the experts gone, long time passing?
                        Where have all the gurus gone, long time ago?
                    When will they ever reply, when will they ever reply?
                      When will they ever reply, oh will they ever reply?"

or for the more prosaic minded: bump!

Da capo (just kidding...)!

Noob wants to digitize his old tapes (for good!)

Reply #4 –
Quote
or for the more prosaic minded: bump!
[a href="index.php?act=findpost&pid=277154"][{POST_SNAPBACK}][/a]

Well, I'm no expert when it comes to tape transfers (I concentrate on vinyl), but I can just make a few observations:

1. krabapple is right about improving the replay rather than recording side. Even the best cassette tape ever made, in pristine condition and played back with everything aligned perfectly, won't max out the capabilities of 44.1kHz/16bit.

2. As for Nakamichi decks. I have a friend who used to be in the HiFi industry, and he once said to me "cassette decks begin and end with Nakamichi; anything else is second-best". He also thought that Teac made pretty good decks if you couldn't score a Nak. But this was many years ago, before Nak came down-market. So cheap late-model Naks are probably no better than other mass-fodder. If you want to be sure of getting a good-un, restrict yourself to models with three discrete heads. General consensus is that the best cassette deck ever made was the Nakamichi CR7. The Nak Dragon had the reputation of getting the best possible replay performance out of any tape (though not quite such good overall record/replay performance as the CR7), but if you can ever find one for sale it'll require a second mortage.

3. If the tapes are all commercially made (you said they aren't self-recorded), then in theory they should all be properly aligned azimuth-wise and Dolby-calibration-wise. In which case it shouldn't be necessary to get a deck with adjustments in these areas: just find a decent deck and get it properly setup and all your tapes should in theory play properly. But I have no idea how well prerecorded tapes really stuck to the standards, so I may be wrong here. Does anyone else know whether prerecorded cassettes can be relied on to be properly aligned?

Noob wants to digitize his old tapes (for good!)

Reply #5 –
Hi cliveb,

yes, all my tapes are commercially bought ones, mainly audio-books
as well as classical music. You said no tape, however professionaly
produced it may be, could max out the 44.1khz/16bit specs. Well, I,ve
read a lot about the small demandings when it comes to tapes recorded
with "speech", but isn't it a different story with music, especially
classical music?

When it comes to the "Nakamichi"-machines, I'm really wondering why
all the good tape-decks where made twenty or ten years ago (yes,the
market for tapes was huge and competitive then, and the CD pulled the
plug for the tape in the late 80's), us leaving with mediocre crap
from nowadays made machines. Well, that's what i call progress. The
making of good tapedecks seems to be an ancient craft, a perfection of
it's own, forgotten by the CD and MD thrilled industry of today. Is
there really no "contemporary" tape-deck up to the task to do the job
as good as it was done already twenty years ago?

A final question for cliveb. Which soundcard would you prefer for the
recording of the tapes? Internal, external? M-Audio, Emu, or anything
else?

Thanks

May the wisdom of the community show me the way!

Noob wants to digitize his old tapes (for good!)

Reply #6 –
Quote
You said no tape, however professionaly
produced it may be, could max out the 44.1khz/16bit specs. Well, I,ve
read a lot about the small demandings when it comes to tapes recorded
with "speech", but isn't it a different story with music, especially
classical music?
[a href="index.php?act=findpost&pid=277300"][{POST_SNAPBACK}][/a]

Remember I said this about cassette tape: high-speed reel-to-reel with a very wide track and Dolby SR might conceivably surpass 16bit (and will certainly surpass 44.1kHz), but as far as cassette is concerned, the format is simply not capable of this kind of resolution. The most you could ever hope to get from a cassette would be maybe 75dB dynamic range, which equates to about 12.5 bits (and the dynamic range available at high frequencies is considerably reduced due to tape saturation effects). The frequency response of cassette tape is very restricted: although some high-end machines might get close to 20kHz, the vast majority are way down by about 16kHz (and this is only acheivable at low signal levels).

Quote
A final question for cliveb. Which soundcard would you prefer for the
recording of the tapes? Internal, external? M-Audio, Emu, or anything
else?
[a href="index.php?act=findpost&pid=277300"][{POST_SNAPBACK}][/a]

As I've already said, I'm really not an expert with tape, but if we're talking about cassette tape, then any of the well-respected soundcard brands (M-Audio, Terratec, Echo, etc) will be more than adequate. Even a Turtle Beach Santa Cruz would be fine. As for Creative soundcards, I've always steered clear of them for high-quality work, but have not used the Audigy 2, which appears to be regarded as a fairly decent card. I personally don't have experience with the external USB devices, but now they are mainstream I have no reason to doubt that they work.

Noob wants to digitize his old tapes (for good!)

Reply #7 –
Quote
As I've already said, I'm really not an expert with tape, but if we're talking about cassette tape, then any of the well-respected soundcard brands (M-Audio, Terra-tec, Echo, etc) will be more than adequate. .
[a href="index.php?act=findpost&pid=277798"][{POST_SNAPBACK}][/a]


When it comes to the interconnection between the tape-deck and the sound-
card, which type of connectors would be best (RCA, SPDIF, etc...). Are there
any quality-differences with the handling of the signal?

Greetings

Noob wants to digitize his old tapes (for good!)

Reply #8 –
Quote
When it comes to the interconnection between the tape-deck and the sound-
card, which type of connectors would be best (RCA, SPDIF, etc...). Are there
any quality-differences with the handling of the signal?
[a href="index.php?act=findpost&pid=277936"][{POST_SNAPBACK}][/a]

I think it's extremely unlikely that you'll find a cassette deck with SPDIF output - it would need to have built-in A/D coverters. So just use good quality well-screened coax cables to connect the normal output of the cassette deck (usually RCA sockets) to the line in of the soundcard (which will be a 3.5mm stereo minijack or a pair of RCAs, depending on the card - if it's a minijack, adaptors are easy to obtain).

Noob wants to digitize his old tapes (for good!)

Reply #9 –
Quote
So just use good quality well-screened coax cables to connect the normal output of the cassette deck (usually RCA sockets) to the line in of the soundcard (which will be a 3.5mm stereo minijack or a pair of RCAs, depending on the card - if it's a minijack, adaptors are easy to obtain).
[{POST_SNAPBACK}][/a]


Hi cliveb,

is this "pair of RCAs" consisting of two mono-connectors?
Because the soundcard I'm planning to use for the job
(an external FW device) does only have two "balanced 1/4" jacks"
(+1 coaxial digital I/O, 1 MIDI I/O) for analog input.

Do those features (or the lack of them) cause problems when it comes
to the connection of the tapedeck? Would an adapter do the trick?

Here is a pic of the box:
[a href="http://audioen.terratec.net/modules.php?op=modload&name=Sections&file=index&req=viewarticle&artid=21]Phase 24 FW[/url]


Thanks

Noob wants to digitize his old tapes (for good!)

Reply #10 –
Quote
is this "pair of RCAs" consisting of two mono-connectors?
Because the soundcard I'm planning to use for the job
(an external FW device) does only have two "balanced 1/4" jacks"
(+1 coaxial digital I/O, 1 MIDI I/O) for analog input.

Do those features (or the lack of them) cause problems when it comes
to the connection of the tapedeck? Would an adapter do the trick?

Here is a pic of the box:
Phase 24 FW
[a href="index.php?act=findpost&pid=278320"][{POST_SNAPBACK}][/a]

Yes, each RCA connector carries one channel, so you need two for stereo.

If the Phase 24 uses genuine balanced 1/4" jacks for analogue I/O, then each jack will be a TRS (tip-ring-sleeve) type plug carrying a single channel in differential mode. To feed an unbalanced signal from a cassette deck, you'll need to make up some custom leads, using cable that has two separate conductors and an overall screen (eg. microphone cable):

- centre pin of RCA goes to tip of jack (using one of the cable conductors)
- screen of RCA goes to ring of jack (using the other conductor in the cable)
- screen of the cable is connected only at one end, to the sleeve of the jack

I suspect that the input sensitivity of the Phase 24 is likely to be at professional levels, and the output of a domestic cassette deck may not be sufficient to drive it to full record levels. If the S/N ratio of the Phase 24 is very good, this isn't a problem: just record as hot as you can, then normalise later in software. For example, if the noise floor of the Phase 24 is -90dB, you can probably afford to have peak recording levels as low as -20dB without losing resolution.

Noob wants to digitize his old tapes (for good!)

Reply #11 –
One suggestion I'd like to make:  If you can, employ some sort of analogue noise reduction before digitizing.  I've used a Kenwood De-noiser, Phase Linear Auto Correlator, and my favorite is one based on a National Semi Conductor chip.  I realize that none of these are common now, but if you can find one in good shape it would be well worth the money.  The side effects of analogue and digital noise reduction are different.  Carefull use of both can yield almost magical results without noticable side effects.

Noob wants to digitize his old tapes (for good!)

Reply #12 –
Quote
To feed an unbalanced signal from a cassette deck, you'll need to make up some custom leads, using cable that has two separate conductors and an overall screen (eg. microphone cable):

- centre pin of RCA goes to tip of jack (using one of the cable conductors)
- screen of RCA goes to ring of jack (using the other conductor in the cable)
- screen of the cable is connected only at one end, to the sleeve of the jack
[a href="index.php?act=findpost&pid=278399"][{POST_SNAPBACK}][/a]


Hello everyone,

thanks for your instructions, cliveb! But I'm a hopeless dilettante when it comes
to "do it yourself"-jobs, therefore I would like to buy (if possible...) such a
cable in order to save the health of my family and myself  ! Do you now any
company or vendor selling such prefabricated cables?

Thanks

Noob wants to digitize his old tapes (for good!)

Reply #13 –
Quote
One suggestion I'd like to make:  If you can, employ some sort of analogue noise reduction before digitizing.  I've used a Kenwood De-noiser, Phase Linear Auto Correlator, and my favorite is one based on a National Semi Conductor chip.  I realize that none of these are common now, but if you can find one in good shape it would be well worth the money.  The side effects of analogue and digital noise reduction are different.  Carefull use of both can yield almost magical results without noticable side effects.
[a href="index.php?act=findpost&pid=278437"][{POST_SNAPBACK}][/a]

In my opinion, while noise reduction is a good thing, it may also harm the sound (reduce detail etc). Since NR techniques are constantly improving, why not record the sound as-is, and perform the NR on the PC later on, while keeping the original files intact ?

The "ideal" (IMHO) way would be to store audio in flac or wav files, and do the noise reduction on-the-fly, just before encoding to a lossy format. Then you can archive your original files in a safe place 

This way, in a few years when better audio processing techniques come out, you can re-process your original files and improve your sound. Remember, the best noise processing techniques (like wavelet decomposition) are impossible to do in the analog domain.

For some very high frequency signals (radar, radio etc) it is indeed too hard to filter in the digital domain in realtime, due to lack of processing power, but for all audio applications (especially cassette and CD recordings), doing the processing in the digital domain is better practice. For audio signals, with 16+ bits resolution, anything that can be done in the analog domain can now be done in the digital domain, with less distorsion. The only exception is the filtering of above-Nyquist frequencies, which is why any half-decent A/D converter has this analog filter built-in.

Off-topic: in the digital camera world, some sensors include an anti-aliasing filter on top of them, which dramatically attenuates frequencies above Nyquist. This prevents artifacts that happen when you take a picture of a metallic bridge from a very low angle, for example.

It seems to me that the human eye doesn't have such a filter. From inside a train, at steep angles we usually see artifacts in the fences around farm fields and such 

Noob wants to digitize his old tapes (for good!)

Reply #14 –
Quote
The only exception is the filtering of above-Nyquist frequencies, which is why any half-decent A/D converter has this analog filter built-in.

Offtopic: is it possible that this filter does not function properly in my SBLive? It produces some ... remarkable ... artefacts on high-frequency sinewaves (yes, I consistently used a 48kHz sample-rate). I have a bunch of far-fetched theories about this, but the above would be a simpler explanation. Though I personally think it's unlikely. An A/D converter without lowpass does not even deserve to be called an A/D converter

Quote
It seems to me that the human eye doesn't have such a filter. From inside a train, at steep angles we usually see artifacts in the fences around farm fields and such 

As-offtopic-as-it-gets: that's somthing completely different. Overlapping repetitive patterns are prone to produce Moiré patterns independent of your "recording equipment", just as slightly detuned instruments produce "beats" that no lowpass filter or interpolation in the world will eliminate

Type "moire" in google and you get neat stuff like this:
http://www.mathematik.com/Moire/
http://www.sandlotscience.com/Moire/Moire_frm.htm