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Samples from USB Turntables: Preparation, How do you want your clips?
post Feb 3 2009, 03:01
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As promised, I'm getting ready to produce some samples from USB turntables. Before I put needle to vinyl, I want to get some consensus on the proposed methods and samples. I also want to hear any additional advice you have to offer in terms of producing professional, consistent samples.

I ordered three USB turntables: The Audio-Technica AT-LP2D-USB, the Ion Audio TTUSB05 and the Crosley CR249. I also ordered some brand new albums to sample on 180 gram, virgin vinyl where available.

With your help, we can capture and analyze the best clips these low-end turntables can produce.

The Samples:

Steely Dan - Peg
From 30th Anniversary remaster of Aja. 180 gram virgin vinyl. Note: Using new song.

Play CD Sample (FLAC)

  • Widely considered the best recorded pop album of the 70's (though I don't expect to find unanimous agreement on this at HA!)
  • Instruments sound clear and distinct from each other.
  • Couldn't find a CD to match the 30th anniversary vinyl pressing. "Gold" remaster might be closer but is out of print and runs about $200 used.

Pink Floyd - On the Run
Dark Side of the Moon. CD: 20th Anniversary. LP: 30th Anniversary 180 gram virgin vinyl. See "Cons" below.

Play CD Sample (FLAC)

  • L/R panning of several sounds could make a good test of channel separation and stereo balance.
  • Relatable: Best selling album of all time until fairly recently.
  • Minimal vocals.
  • I believe I hear distortion at points but it could be intentional.
  • I wish I could have ripped the SACD version!
  • Edit: Now using 20th Anniversary CD due to remastering problems on the CD layer 30th Anniversary hybrid SACD. Thanks Axon for pointing out the problem. Next time I will ask for advice on LP-CD master matching. smile.gif

Gorillaz - Dare
From Demon Days. 190 gram vinyl (weighed record personally).

Play CD Sample (FLAC)

  • Fully digital master transferred to analog vinyl.
  • Low, intricate bass that may be difficult to reproduce on vinyl.
  • Light-to-moderate compression that's presumably not present on vinyl version.
  • Nothing comes to mind. Please chime in if you have reasons why this is a poor sample to use.

The Black Eyed Peas - Dum Diddly
From Monkey Business. 140 gram vinyl (weighed record personally). Edit: Now using a different section of the track

Play CD Sample (FLAC)

  • Another all digital master
  • Low, jaggedy (from a waveform standpoint) bass note that should be difficult to reproduce on vinyl (last second of clip)
  • Moderate compression
  • This was my original choice for a digitally mastered recording. However, the LP weighs in at 140 grams. I worry that the inferior vinyl will shift the blame of poor reproduction from the turntable to the vinyl. If you think this would make a better sample than Dare and are not as concerned about the vinyl quality, please chime in. Edit: Now using both this clip and Dare.

Fleetwood Mac - Rhiannon
From Fleetwood Mac. Scratched and Dusty Album.

Play CD Sample (FLAC)

  • Abused, scratched and dusty LP.
  • Nothing comes to mind. Please chime in if you have reasons why this is a poor sample to use.

The Process:

  • Brand new 180 gram, virgin vinyl for DSOM and Aja. 190 gram and 140 gram vinyl for Demon Days and Monkey Business respectively with no pledge of virginity.
  • Brand new turntables. The only playback prior to recording will be the level-setting.
  • Record from best turntable to worst, thereby keeping record wear minimal. The best-to-worst order looks like this:
    • Audio-Technica: "Dual Magnet" AT3600L MM cart, aluminum platter, lists specs
    • Ion Audio: MM cart, plastic platter, no specs
    • Crosley: Ceramic cart, plastic platter, no specs
  • Set levels in the same track but at different point from sample. Make best effort to match the amplitude of CD rip. In the case of compressed digital rips, analog recording should approach peak without clipping. Edit: Or don't set levels at all if USB turntable doesn't allow it.
  • Computer : Three year old, home built PC Pentium / Via MB. Only USB mouse, PS/2 keyboard, DVI out and 100-baseT will be connected during recording. Edit: Forgot to mention headphones.

Any other samples?

  • Useful to take a silent sample form the beginning and/or end of an album?
  • Silent sample of turntable without power connected to test for problems similar to this guy?

Two out of three turntables have already arrived. I'm expecting the Crosley today. Sample clips will follow soon after I gather feedback on the process and clips.

This should be fun!

This post has been edited by Knowzy: Apr 23 2009, 17:27
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post Feb 5 2009, 23:42
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QUOTE (Knowzy @ Feb 4 2009, 20:47) *
Even without WRMS or JIS figures, there's surely a good chart to come from this sample. Maybe a narrow-range frequency analysis where you can see the line straying from 3150Hz over time.

I don't see anything like this in Audacity. Maybe Wave Repair can create such a graph?

I did some investigation and perhaps answered my own question. What I'm looking for is a time-frequency view of the sample's spectrum.

Both Audacity and Wave Repair feature spectrum views of the waveform. However, I found that neither are very good at zooming in on a small range of frequencies.

Enter Spectogram, a free Windows utility specializing in spectrum analysis. With it, I can zoom in on a frequency range as small as 500Hz.

Using Audacity, I created a 10-second sine wave sample at 3150Hz and ran it through Spectogram. Here's what it looks like (click to zoom in):

3150Hz sine wave over 10 seconds

The red line in the middle is exactly 3150Hz.

Of course, the real wow & flutter test tone will not look nearly as clean when played through a turntable. I expect the blue shades (representing lower dB noises) to be all over the place in a real sample.

However, I'm hoping to see that red line move around in relation to effects of wow & flutter on the tone.

Does anyone think this will work the way I'm expecting?

For comparison, here's the first ten seconds of the DSOTM sample in the same frequency range (broken into two panes because it's stereo):

"On the Run" between 2,900Hz and 3,400Hz

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