How do I get a digital recording to sound like the original?

September 15, 2005 8:11 AM

How do I get a digital recording to sound like the original?

I am converting cassette tapes of my voice lessons to mp3 for storage and use. This means a recording of spoken word, piano, and opera singing. Because the tapes are instructional, I am listening for nuance, it is important that they are as close to identical to the original as possible.

On my first try I recorded with Audio Recorder and edited on Audacity. That turned out impossibly quiet and crappy. I recently tried recording directly into Audacity and that resulted in a totally flat sound quality. I am not an audiophile in the least, and even I can see that the digital file lacks any resonance at all. Since there is such an obvious difference to such an amateur, I assume there is something wrong in my methods.

What could I be neglecting to adjust in my equipment? What is causing the sound difference?
Is this just what the difference between film and digital? Even if I recorded directly to mp3 wouldn't I get the same result?
I am poor so I couldn't really pay someone to convert it for me; do people do that?
What are my options for getting digital files that are identical to the original tape recordings?

Please don't tell me I am condemned to accumulate drawers full of tapes for the rest of my life. Please help!

posted by scazza to technology (12 comments total)

Are you listening to both sources using the same speakers/headphones?

How did you connect the cassette player to your computer? Did you use the line-out port or a headphone port?

If you do line-out on your player to line-in on your computer, you should not be able to tell the difference at all. If you have to use a headphone-out port on the cassette player, well, you're going to have to do a lot of fiddling with levels in your recording software to get it to sound "exactly" the same.

Make sure you do the recording in a lossless, full-sized format like AIFF or WAV at first. Then you'll have a reference to compare it to when you convert that down to MP3--you'll be able to listen to both and decide if your MP3 converter is compressing it too much, etc.
posted by bcwinters at 8:42 AM on September 15, 2005

Recording is always tricky, particularly if you want to mix voice and piano. I suspect your problem is in incorrect miking.

Transom.org has an excellent guide to doing recording. I'm not sure what you mean by "Audio Recorder" (a program? a device?), but you can use a MiniDisc recorder or many MP3 Players for portable audio recording, as well. Be sure that the sampling rate is adequate for music (at least 96kbps).

It is important, also, to get initial recording levels right.
posted by curtm at 8:45 AM on September 15, 2005

If you're original is "playing through" the software, it will double up on the recording and screw up the sound. In Audacity this is a simple setting, but I can't remember where it is. It says something about "software playthrough"... make sure that's turned off. (Quick fix is to mute your computer speakers or plug in headphones).

Other than that it has to be (1) Quality of your line-out, (2) Quality of your line-in, (3) Volume level of source or volume level set in Audacity, or (4) Too much compression.

I doubt if it's number four.
posted by crapples at 8:50 AM on September 15, 2005

It's almost certainly something with your analog setup, not the digital part.
posted by delmoi at 9:12 AM on September 15, 2005

I've never used audacity but I converted a lot of tapes to digital audio using Cool Edit (which I this is/was free at some point? I paid for mine).

Any kind of recording faces the same basic problems. Recording from a tape is a little easier than many recording situations since the source is already properly mastered in most cases.

You want to use the right outputs and inputs. If your tape players has a line out this would be preferable to a headphone out. If you use line out, you should use the line in input on your computer. If you must use the headphone output, I am not sure which is the best input on the computer. I'd probably still try line in first.

You want the volume coming into the computer to be as loud as it can be, without clipping. Cool Edit and most other recording software I've seen have some kind of monitor function, or a loopback function that will show you the level of the audio input. You want the max peaks to be right in the -3db to 0db range. This is extremely crucial. Too loud and you will get audible distortion in the digital version. Too soft and you will get a very poor dynamic range.

Cool Edit, and some others, have the ability to let you listen to either the source material, or the version it's actually recording. Try to set it to the version it's actually recording. Cool Edit calls this "Monitor" or something like that. This is the only way to tweak the settings by ear. Monkey with the output level of your tape player (if you're using the headphone output. Technically the volume should NOT affect a true line out) and the volume on the RECORDING options of the sound input.
posted by RustyBrooks at 10:05 AM on September 15, 2005

If you do line-out on your player to line-in on your computer, you should not be able to tell the difference at all.

This is not really correct. For a start, the analog signal from your cassette player will be converted to digital by an ADC - an Analog to Digital Converter - in your soundcard. If you have a spectacularly crappy soundcard with an ADC which has a low sampling rate of the analog signal, your digital capture will not be a great copy of the analog signal and so yes you will be able to tell the difference.

Furthermore, of course if you're converting to mp3 you'll be able to tell a difference. As noted above, converting to mp3 is "lossy" compression - data is removed in the compression process - so again you won't have a carbon copy. Somehow, somewhere down the line people lost their heads and forgot this - possibly in their eagerness to snap up iPods. Don't get me wrong - I'm not railing on mp3s; I'm just re-asserting that they're not the same as wavs (uncompressed digital audio).
posted by forallmankind at 10:49 AM on September 15, 2005

As forallmankind says, it certainly could be a crappy ADC... What sound card do you have? What sample rate and resolution are you setting it to (this might be hard to find if you are directly converting to mp3)?

I am all for lossless formats, but bcwinters' suggestion is ripe for propagation losses. If you record from tape to wav and listen for perfection, then from wav to mp3 and listen for perfection, it still might be possible that there are some differences from tape to mp3. Not that bcwinters' is wrong, and the suggestion will speed things up a bit, but you really should be comparing back to the original source at least some of the time.
posted by Chuckles at 12:24 PM on September 15, 2005

Thank you everyone for your responses. First off, I am an amateur. Many terms here have been bandied about that I am not familiar with. Requests for clarifications follow:

Are you listening to both sources using the same speakers/headphones?
Yes.

How did you connect the cassette player to your computer? Did you use the line-out port or a headphone port?
Headphone port. It's a small player, not a deck.

you're going to have to do a lot of fiddling with levels in your recording software to get it to sound "exactly" the same.
That's what I'm getting at. Walk me through this?

Make sure you do the recording in a lossless, full-sized format like AIFF or WAV at first.
Check. Audacity only records in a big file exportable as WAV.

Recording is always tricky, particularly if you want to mix voice and piano. I suspect your problem is in incorrect miking.
I don't have a problem with the original recording, it's the digital conversion that sound like ass. So the miking is fine with me.

I'm not sure what you mean by "Audio Recorder" but you can use a MiniDisc recorder or many MP3 Players for portable audio recording, as well.
Audio Recorder is a mac program. Does minidisc record to mp3? Why minidisc? Will recording to mp3 directly sound the same as recording to tape? Won't I have the same sound problem, as one person has said, that it's inherent to mp3 compression?

If you're original is "playing through" the software, it will double up on the recording and screw up the sound.
What is "playing through"? And what do you mean by "Quick fix is to mute your computer speakers or plug in headphones"? I listen to the playback through headphones, while it's recording there's no sound.

Other than that it has to be ... Volume level of source or volume level set in Audacity
Furthermore, of course if you're converting to mp3 you'll be able to tell a difference. As noted above, converting to mp3 is "lossy" compression
My source volume seems to be fine, but I can't get the level in Audacity to get set very well. But why does volume affect resonance? I listen to the tracks before converting them to mp3, so I should have been more specific. Mp3 is the goal, but they still sound flat in the recording files.

It's almost certainly something with your analog setup, not the digital part. posted by delmoi
Can you expand on what an ideal setup would be? Or are you just referring to line-out?

You want the max peaks to be right in the -3db to 0db range.
Anyone know where this is in Audacity? Otherwise Cool Edit sounds like a superior program. Can someone basically compare the two?

What sound card do you have?
I have an iBook, so um, I have whatever came with my computer.

Ok so, I'm scrapping the mp3 thing and will probably keep the files in WAV. That has left line-out, sound card, levels, right?
posted by scazza at 3:04 PM on September 15, 2005

Since you're using a laptop, you might want to consider barging in on a friend with a proper tape deck and doing your analog to digital recording their. That would take one more variable (shitty amp circuitry in the portable player) out of the equation.
posted by Ptrin at 4:23 PM on September 15, 2005

I don't know enough about macs, but some PC sound cards sample at a native 48kHz, resampling to 44.1kHz is bad - somebody with mac knowledge should be able to resolve this.

In any case, you have to know the sample rate and bit depth you are using, 8kHz/8bit sounds a lot like a telephone for example... You probably want to stick with CD quality 44.1kHz/16bit unless the sound card doesn't support that clock rate (as I said above about some PC sound cards).
posted by Chuckles at 4:44 PM on September 15, 2005

I'm no expert at this sort of thing, but part of what you said sounds familiar. There was a step I don't understand, called "normalization". Whatever its doing, it turns lifeless recordings into something that resembles usefull.
posted by Goofyy at 12:12 AM on September 16, 2005

So then does anyone have a tape to digital file conversion service to reccommend?
posted by scazza at 9:50 AM on September 16, 2005