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DTMark

Analog To Digital Sampling Rate

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Having got my turntable up and running again I have a number of tracks which I have on vinyl and which don't exist anywhere else - mostly old dance music.

I wanted to see if I could take some digital copies for posterity and as backups and to listen to on my phone.

In the first instance I've plugged in my laptop, plugged the phono stage directly into the laptop via the headphone sockets, and then set the sampling rate to the highest - was something like '88,000 Studio Quality'.

Had to put the inbound volume level right down else it distorted, opened Audacity, set the project rate, and recorded several tracks. Then plugged the laptop into the amp and played them back to compare.

The quality loss is astronomical. Obviously this isn't the highest quality gear optimised for the task. What's the best I can get that preferably involves no more than a sound card and some software - since that sound card evidently can't go higher than what it calls "Studio Quality"?

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Won't be the sample rate, 88k is twice CD sample rate (and even if you're one of the "CDs don't sound as good" types they're not that bad). Perhaps the sound card simply has a bad sampler.

If you've had to knock the input volume down very low that'll give you a lower SNR at the input, is there a recording gain level somewhere turned up very high (so it's maxing out and clipping on all but the quiestest parts)? Try finding that and turning it down.

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I agree the sampling rate is not the problem if it is 88kbit/s.

But there are many other factors - audio levels, equalisation, earth loops, and sampling resolution to consider. Are you sampling at at least 16 bits? Some systems will sample at as low as 8 bits, which is just about OK for recording telephone conversations but no good for music.

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Having got my turntable up and running again I have a number of tracks which I have on vinyl and which don't exist anywhere else - mostly old dance music.

I wanted to see if I could take some digital copies for posterity and as backups and to listen to on my phone.

In the first instance I've plugged in my laptop, plugged the phono stage directly into the laptop via the headphone sockets, and then set the sampling rate to the highest - was something like '88,000 Studio Quality'.

Had to put the inbound volume level right down else it distorted, opened Audacity, set the project rate, and recorded several tracks. Then plugged the laptop into the amp and played them back to compare.

The quality loss is astronomical. Obviously this isn't the highest quality gear optimised for the task. What's the best I can get that preferably involves no more than a sound card and some software - since that sound card evidently can't go higher than what it calls "Studio Quality"?

Er... the headphone sockets are outputs on your laptop, not inputs?

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The output from the (separate) phono stage is going into the microphone socket on the laptop.

The sound card has all "effects" disabled, including the "Automatic Level" one. It's actually Studio Quality 96,000kps I think, and 16 bit is the only option. That might be the killer.

Putting everything up as high as it will go results in a 652MB Audacity project file for a 6 minute 12" single. I'm not sure what I did there.

The quality loss is very noticeable at this point, if you then export that to an MP3, it then becomes laughably bad. But then that has been compressed down to just 18MB.

It isn't distorted as such, it isn't clipping, it's that all the fine detail and clarity disappears. Anything subtle on the original completely vanishes or is almost imperceptible, the stereo imagery vanishes, the sense of separation is gone, vocals that used to sound breath-taking lose so much fidelity that they sound more like someone on the end of a phone line. The high frequencies all mush together like they might on a cheap ferric analog tape recording so you can't distinguish anything in particular, though that's true throughout all the frequency ranges, it just notices most obviously in the upper ranges.

This is why I question the sampling rate - the quality difference between the Audacity original and the MP3 at the max rate of 48,000 is huge, it sounds as though it is "halving" the resolution. Which I guess it is.

On the other hand, DVDs tend to sound quite good to me, and I think the sampling rate of those is more like 192,000 so that might be a good target level to go for. Maybe I just need a sound card with a very high sampling rate and lots of on board memory.

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I don't think what you are refering to as a sample rate is the sample rate.

You are refering to the bit rate ( I think its called).

96k will sound awful, I never used to go below 192k and some tracks would lose a lot of depth at that rate, JMJ's Oxygene for example.

Nowawdays I use a program called freerip and do everything in FLAC.

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Quote:

It isn't distorted as such, it isn't clipping, it's that all the fine detail and clarity disappears. Anything subtle on the original completely vanishes or is almost imperceptible, the stereo imagery vanishes, the sense of separation is gone, vocals that used to sound breath-taking lose so much fidelity that they sound more like someone on the end of a phone line. The high frequencies all mush together like they might on a cheap ferric analog tape recording so you can't distinguish anything in particular, though that's true throughout all the frequency ranges, it just notices most obviously in the upper ranges.

A lot of this sounds like phase cancellation - are you definitely recording in stereo? Are you using a 2phono to 3.5mm jack, or is there a splitter involved somewhere?

If it's not a simple L/R mix up, it may just be the laptop onboard soundchip not being up to spec. What kind of monitor input level is Audacity showing? If it's barely registering (like below -24dbfs) a cheap 2 in 2 out USB soundcard should solve it.

Otherwise it's hard to work out without seeing the whole signal chain - but it doesn't sound like the sample rate's your issue. I sample from vinyl at 44.1Khz / 16bit with no loss of quality, going to 96/24 or 192/32 would be massive overkill - those sample rates are only used in "HD" recordings pre-mastering because they give huge headroom, and mean you can keep the dynamic range when you've got a lot going on - particularly important in film soundtracking.

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I don't think what you are refering to as a sample rate is the sample rate.

You are refering to the bit rate ( I think its called).

96k will sound awful, I never used to go below 192k and some tracks would lose a lot of depth at that rate, JMJ's Oxygene for example.

Nowawdays I use a program called freerip and do everything in FLAC.

Good point. I'd say avoid any compression whatsoever until you're happy with what you've got.

Uncompressed 16 bit stereo, 44 kHz sample rate will have a bit rate of 1408 kbps (talking 1000s there and not 1024s, I'm never sure which one people are using).

Can't say I notice much of a problem with 192k MP3s, but I don't exactly have the most refined ears (can't hear bats making any noise at all any more). I find most music slightly lacking in clarity no matter what the source, which is why I put that down to my hearing.

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I think that taking analogue audio into the electrically noisy environment of a PC is almost always going to give sub par results.

If you can pickup a cheap digital recorder and plug that into the output of a pre-amp (not the actual turntable) then you will get a much better result.

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This is an example of probably the best one I've managed so far. It's not too bad. But then you'd have to hear it compared with the original side by side. This is a really old tune from about 1988 I think.

Those high pitched scratchy noises are supposed to be some kind of cymbals, I think, but all the fidelity has gone. Likewise the low frequencies actually have distinct pitches, but on here, it's just a kind of blurred rumbling noise. It sounds as though a certain amount of fidelity has been lost through all ranges.

Just listening to it now on my PC speakers and it sounds OK on here, though other tracks suffer more - this one's quite a clean simple one. It sounds - well, "compressed", "squashed", "flat" or whatever the adjective is. If you then play back the original side by side the difference is huge.

Does say "bitrate 320kbps" in the properties. Is that as high as MP3 can go, maybe I should try a different format?

http://www.dtmark.info/KonKan.mp3

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Have you tried doing it with some music?

Ooh behave.

Actually, I probably ought to try it with Fleetwood Mac's "Tango in the Night" LP rather than a piece of vinyl I've had for 30 years.

But then Fleetwood Mac's LP is probably still available to buy. These old tunes are long gone :(

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Have a look at this. ..if you fancy either paying for the service, or trying to 'recreate' their method:

http://www.vinyltodigital.co.uk/audio/lp-cdmp3/

P

The key to it appears to be the (I quote) "professional sound card". The laptop, has, to my knowledge, whatever it came with - some cheap and nasty integrated thing I expect. PC has an old SoundBlaster card. I think I need to learn more about them.

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The key to it appears to be the (I quote) "professional sound card". The laptop, has, to my knowledge, whatever it came with - some cheap and nasty integrated thing I expect. PC has an old SoundBlaster card. I think I need to learn more about them.

Have you checked the soundcard settings in the control panel?

Sometimes, there are two sets of controls to adjust...the windows controls and then the applications controls. WIndows Vista had a lot of controls.

some tips here: http://www.native-instruments.com/en/support/knowledge-base/show/1055/windows-8-tuning-tips-for-audio-processing/

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I expect the quality of the phono to mic lead is about level with that of the sound card..

Mind you maybe a better sound card would have phono inputs.

Oddly, the output from the phono pre-amp (it's a Pro-ject one) is so high that the highest recording level on a scale of 1 to 100 is 3. Any higher and it distorts. That said the recordings sound of a reasonable volume, maybe a bit on the quiet side.

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Mark, I'm not a sound buff but have you been running the sound straight from turntable to PC are is there any intermediate kit...equalizers etc?

I tried some home recording a little while ago using a cheap and old PC when I was recording some guitar and vocals. The sound quality was much, much better using something in the middle, even a cheap equalizer...when I ran it directly to PC it was usually horrible. But I did find that using an equalizer lost some of the detail. Don't ask me why :)

I used Audacity too to clean up blips and sand down the rough edges.

P

If you dont have the output from the vinyl unequalised, then you will end up with high level high and low level lows...this was RIAA equalisation, and allowed for reducing S/N ratio and allowed for deeper, louder base. it was done in order to fit the entire bandwidth into the single groove.

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DTMark - I've just listened to your link on post 13 and you definitely have phase issues. If you listen through headphones you'll hear the "lopsided" effect.

It's normally only a big problem on sounds that should be dead center, but early dance music used a lot of multi-tap delays and autopanners at really fast settings to produce pseudo stereo width on high freq stuff (like hats and cymbals) and a double track like effect on vocals. Early digital reverbs did similar things and were applied liberally.

There may well be other issues going on - onboard laptop sound is a likely culprit as people have said.

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Having got my turntable up and running again I have a number of tracks which I have on vinyl and which don't exist anywhere else - mostly old dance music.

I wanted to see if I could take some digital copies for posterity and as backups and to listen to on my phone.

In the first instance I've plugged in my laptop, plugged the phono stage directly into the laptop via the headphone sockets, and then set the sampling rate to the highest - was something like '88,000 Studio Quality'.

Had to put the inbound volume level right down else it distorted, opened Audacity, set the project rate, and recorded several tracks. Then plugged the laptop into the amp and played them back to compare.

The quality loss is astronomical. Obviously this isn't the highest quality gear optimised for the task. What's the best I can get that preferably involves no more than a sound card and some software - since that sound card evidently can't go higher than what it calls "Studio Quality"?

The CD sample rate is 44.1kHz, which was chose as it provides for an audio response unto 20kHz (see Nyquist–Shannon sampling theorem). On that basis you won't get much from 88kHz anyway as you can't hear it. I'd drop down to 44k, as that is basically CD quality and most vinyls don't give frequency response above 20kHz anyway - although there isn't really theoretical limit in the vinyl, but certainly the old amps would have had a response curve that tails off at high and low frequencies.

Chances are 88k may be too much effort to capture correctly if you have an uneven frequency response.

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Mark, the problem is with the integrated soundcard, especially since you are using a laptop. The input you are using is for microphone signal levels (that's why you need to turn it down so much), you would need at least a line level input as you normally get on desktop PCs, but the better option would be a proper semi-professional studio quality USB sound card.

The cheapest you can get away with is this Behringer, which also has phono level inputs so you could plug the cable from the turntable straight into it:

http://www.thomann.de/gb/behringer_ufo_202.htm

Behringer equipment is entry-level, but it's reputation is worse than what you actually get, in other words it's not that bad for home use, certainly better than the built-in soundcard of your laptop (at least for recording purposes).

If you are prepared to spend a bit more this one is a good buy:

http://www.thomann.de/gb/art_usb_phono_plus_ps.htm

It's still not pro quality but pro quality would be a lot more expensive and isn't really necessary for your purpose.

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Oddly, the output from the phono pre-amp (it's a Pro-ject one) is so high that the highest recording level on a scale of 1 to 100 is 3. Any higher and it distorts. That said the recordings sound of a reasonable volume, maybe a bit on the quiet side.

Check you don't have the phono pre-amp set to MC (Moving Coil)!

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I don't think turntables put out a line level signal, so you probably need to run it into the laptop via some sort of preamp.

Has your standard audio amp got a headphone output? If so you'll probably get much better results playing the records on your amp and running a cable from your headphone out to the laptop.

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Behringer kit looks good.

Thanks for the feedback - can I clarify what's meant by 'phase issues'?

I thought that this was what you ended up with if you had one of the two speakers wired up with the poles reversed, so you get a weird gap in the soundstage and uneven frequencies from left to right e.g. all the bass from the left hand side.

I'd thought that the shortest route was the purist one e.g. straight from the phono pre-amp from the laptop but I'll try it via the amplifier.

That track (Kon Kan, 'I Beg Your Pardon', 1988) isn't what I'd call an especially good sounding one anyway. It is 'scratchy' or 'raw' sounding from the source. Someone else has had a go at the conversion here..

Don't know how well YT preserves audio quality but that sounds like it has multiple issues and the processor struggled to keep up.

I'll try it out later with some Fleetwood Mac and also a couple of 12" singles that I know sound stunning to see how they transfer and to get a better feel for what you're hearing.

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