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Choosing the ‘correct’ workflow to import vinyl/minimising signal loss, Moved from Audio Hardware
shmick23
post Feb 26 2012, 16:54
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hi,

i'm predominantly versed in the field of photographic film capture and digitised images. But when it comes to a workflow for vinyl audio importation, i would really appreciate some advice.

i already have a workflow, but i would like to improve it (hence it will cost more money, always a compromise).

currently i have a TT with reasonable stylus (20-22kHz freq. response), reasonable phono stage (20-20kHz), good RCA interconnects but an average sound card with 'claimed' 24/96 IO which does not have RCA inputs.

i want to upgrade my vinyl source one day to something that supports 20-30kHz, and then match a phono stage and finally a sound card...

what are the best practices when selecting a sound card, or destination device to capture this analog source given my setup requirements?

which inputs produce less noise in an electrical sense - USB based, PCI sound cards, RCA inputs, TDM sync buses, particular product brands, amount of money spent, etc ?

IE. what is the most appropriate method of importing vinyl by losing the least amount of signal information at the destination ?

the only sense i could make of all these workflow questions is to match all components relatively, ie. price, specs. I don't know which audio companies/manufacturers are highly rated without spending a lifetime reviewing brochures and white papers...

i would appreciate some advice.

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christopher
post Feb 27 2012, 02:45
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How long's a piece of string? ;-)

Remember this first: many vinyls are cut using different gear, calibrated differently, almost never the same twice. Stampers wear out and DMMs are wont to suffer from a greater propensity toward sibiliance (they're less forgiving if cut hot). If you want perfect tracking and reproduction every single time, you have to know a: how the master was cut and b: how to reproduce the cutting lathe's setup on your own TT. There's more chance you'll win the lottery than ever knowing this information, so be pragmatic. If you TRULY want perfection, you'll need the engineer to cut you a dub from source tapes for a one-use playback. ;-)

Audio has parallels with video; you want to achieve best possible SNR throughout. A clean, few-steps-as-possible route is preferred. This doesn't need thousands of £/$ spending but some careful TLC will avoid common pitfalls. In my humble opinion, the best things to sort, in this priority, are:

0) GET YOUR TT PROFESSIONALLY SERVICED!
I spent ~£400 having my 1210s professionally serviced recently and it was money well spent - their SQ now is mindblowing. Paired with even a decent everyday cart (Shure Whitelabel) and with a correctly adjusted tonearm the sound is marvellous, much better than before.

1) Pick your stylus and cart carefully.
You may prefer an elliptical styli for superior groove read even though the wear rate is marginally higher. Don't stick to clinical decision making though, investigate 'musical' combinations because heck, ultimately you have to like what you're hearing (more on this later).

2) Get your tonearm balance right!!! and double, triple, quadruple check azimuth, VTA, SRA, antiskate. The last thing you want to do is introduce excessive wear to your groove which will permanently damage it.
There's much FUD around this and only so much you can achieve with the gear you have so do your reading carefully and always second-opinion yourself. Consider buying (or making) an alignment tool. Quick reference #1: http://www.gcaudio.com/resources/howtos/cartbasics.html

3) Get a preamp which has low self noise and, ideally, >80 <=100 dB dynamic range.
Earth point is important, no AC hum is handy wink.gif and balanced outs are also nice - but I rock a cheapo Behringer PP400 mini phono preamp which just has RCA in and out (plus 5.25mm jack) for most of my casual listening / archiving, and... y'know what? It's really not bad. Not superb, but not bad at all. REMEMBER: Vinyl has an estimated DR of 80 dB (average, good quality) to 120 dB (best case on high gsm PVC) - the HA wiki discusses this at length. You do not need the world's most expensive pre to get a good sounding recording!

4) The quality of your audio interface will really help.
Get something nice if you don't already; budget for £150-300 - something outboard with a nice sounding ADC stage that can work natively at 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz etc, by going outboard you can often avoid most of the sources of RF and EM interference that plague internal and onboard soundcards. There's many manufacturers who produce affordable gear in this range; M-Audio, Focusrite, RME, MOTU, PreSonus, Apogee... (I love Apogee but it's realistically out of the budget I set earlier).

Chances are even if you have one of those "HD" on-board soundcards it won't actually be any good at capturing above 20 kHz (bar one or two, all of them are useless). If I had quality outboard audio interface that could ACTUALLY do 192 kHz sampling, and my preamp was decent, I think I'd definitely want to try it to compare results with an 88.2 and 44.1 kHz cap although I'd probably still settle on 88.2 kHz at 24 bit... You are NOT going to get an advantage capping at 24/96 or 24/192 unless your source is an ELP Laser Turntable ;-) plus the additional noise you add by dithering 24 -> 16 bit just isn't worth any negligible increase in SNR IMHO. Remember your source material likely has a SNR well below 80 dB and a well mastered CD decoded with oversampling can have upward of 140 dB but we're talking lab conditions here.

5a) Run everything off a common ground.
I cannot overstate the importance of this. Make a sacrificial multiway if necessary (unplugging earth pins FTW) or get an EMO PDU if you have money sloshing around in a spare Cayman Islands bank account.

5b) Run audio and power cables perpendicular; avoid crossing them if at all possible. If you run them parallel the audio lines will act as lovely long pickup aerials for your 50/60 Hz + harmonics.

6) If wiring your own cartridge, check the wiring schematic. Nobody likes a partially inverted audio signal.

7) make sure your deck's level and it's not inadvertently picking up rumble from traffic or you thumping around in the room whilst the record plays.
I've used piles of t-shirts and pillows in the past as quick 'n dirty isolation from the desk; nowadays I use a mattress and VERY CAREFULLY move around the room. I have a mini Draper spirit level which has both flat and diagonically-mounted levels so I can quickly check the deck on its surface. To avoid picking up bumps and super low frequency sound I'll usually sit and watch the deck whilst it plays if I'm archiving in. Don't believe me? Sit the cart in the groove of a record without it spinning, hit record and walk around the room. Gently hit whatever surface the deck is on a few times, even tapping it should transmit audio through into the recording. You'll need good monitoring or a keen eye for the spectral / waveform view in your DAW to see it, but it'll be there. If you have nearfields, you can gently rest a finger on the cone to feel really low end energy. Now you know that LF stuff is there, avoid creating it in the first place! ;-)

I almost bought some Freefloat Turntable Stabilizers a few years ago but didn't due to their cost at the time... Now reconsidering them but must do more research to see how well they actually do, whether they work well or are more a gimmick than anything else. Also been wondering if inflatable camping pillows would work comparably. Many people come up with their own DIY isolation solutions, c.f. http://www.audiokarma.org/forums/showthread.php?t=204628 and http://www.avguide.com/forums/turntable-is...platform?page=1 (Google is your friend.) Some may also suggest Vibrapods, my personal opinion is these are cone-shaped snake oil holders.


If you want to go crazy, you could even try recording a turntable's output direct without deemphasis, and then apply the RIAA curve in software after you've digitised. This can be tricky though as it's obviously a curve and most plugins won't accommodate for a nonlinear cut/boost across a wide frequency range; I'd also bet that my Behringer PP400 probably does a better job than 95% of the EQ plugins out there so I'd recommend you only try this with 'mastering' level (or at least some seriously good) EQ plugins.


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cliveb
post Feb 27 2012, 12:58
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I concur with some of Christopher's advice, and but disagree with some other things he says.

To start with: yes, make sure your turntable is properly setup. Geometric alignment to minimise tracing distortion and setting the tracking force and antiskate are critical. But I don't personally believe VTA is worth chasing down, for the simple reason that optimal VTA varies from LP to LP. If you happen to have a pickup arm that allows you to easily adjust VTA, then by all means tweak it for each transfer. But if not, it's no big deal - just make sure the top face of the cartridge is parallel with the LP surface and you should be OK.

One thing Christopher didn't mention was the need to clean your LPs properly. This can really help to get a clean transfer. Ideally use a vacuum machine (Nitty Gritty, VPI or Moth - the Keith Monks is the best but costs thousands).

The whole strategy should be to get the very best analogue signal you can from the turntable - no amount of software fiddling after the event will fix an initially bad signal. And using a decent phono preamp is certainly part of that, but there's no need to go to town. Let's face it, the signal that comes off vinyl is hardly the most accurate in the world, and any minor amount of distortion or frequency response inaccuracy introduced by a phono preamp will be vastly less than what is already in the signal. And vinyl has very high intrinsic noise, so any phono preamp with a S/N ratio above about 70dB will be fine.

Here's where I will start disagreeing with Christopher:
QUOTE (christopher @ Feb 27 2012, 01:45) *
Vinyl has an estimated DR of 80 dB (average, good quality) to 120 dB (best case on high gsm PVC) - the HA wiki discusses this at length.

I seriously doubt that anywhere in the HA wiki does it suggest vinyl DR is that high. A typical vinyl LP has a DR of about 50dB. A good pressing will probably achieve about 60dB. Getting up to 70dB is a major achievement. I have no idea where you got your 80dB and 120dB figures from.

QUOTE (christopher @ Feb 27 2012, 01:45) *
Get something nice if you don't already; budget for £150-300 - something outboard with a nice sounding ADC stage that can work natively at 44.1 kHz, 48 kHz, 88.2 kHz, 96 kHz etc, by going outboard you can often avoid most of the sources of RF and EM interference that plague internal and onboard soundcards.

There are in fact plenty of modern PCI bus soundcards around that are NOT plagued by RFI and EMI. Anything from the likes of M-Audio, Echo, Terratec, etc will be just fine. And cards like the Lynx2 and DAL Card Deluxe make genuinely studio-quality recordings. Even modern Creative soundcards are probably more than good enough to record vinyl. The days of interference on internal soundcards is history, except for some on-motherboard stuff.

That said, I think an external USB device is often the sensible choice, as they are so much more flexible and you can easily move them between PCs if needed. Spending more than the price of, say, an E-MU 0202 is pretty pointless for vinyl transfers.

As for what resolution to do your transfers, I am strongly of the belief that 16/44.1 is more than adequate. Vinyl's noise floor is about -70dB at very best, so the 96dB DR of 16 bit gives you masses of headroom. And although some sort of signal above 20kHz can come off a vinyl record, it's pretty much all noise and distortion, so using a higher sample rate is fairly pointless. There is an argument that recording at higher resolution protects you from degradation introduced by post-processing, but you'd have to do a heck of a lot of that to bring the quantisation noise up above the very high vinyl noise floor. Sticking to 16/44.1 will give you access to the greatest number of processing tools (because some useful ones don't support 24 bit and/or higher sample rates).
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shmick23
post Feb 28 2012, 17:37
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thanks christopher, i very much appreciate the analogy of the engineer and single-use-playback - how i wish this could be possible in my lifetime ;-)

i hope for your sake this was a copy and paste - otherwise thank for the mass of information and time spent on writing

i will go through some of the brand recommendations & some very useful facts i neither knew of nor considered

thanks clive for the follow-up too - certainly noted regarding clean vinyl - although i must admit i don't have a vacuum machine, only spray and cloth. When i record, I do a spray and brush off the stylus in the opposing direction to playback each LP

i just don't have the knowledge to comment whether recording at higher/lower bit rates will make a discernible listening difference - it may be just one of those arguements for hearing the difference BTW a $10k or $50k setup

(i wish could afford either) ;-)

thank you again
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