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Samples from USB Turntables: Audio-Technica AT-LP2D-USB
Knowzy
post Feb 18 2009, 08:22
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Turntable Details
Audio-Technica AT-LP2D-USB
Street Price: $100 (US)
AT3600L Moving Magnet Cartridge
Belt Drive
Fully Automatic
Wow and Flutter: <0.25% (WRMS)
S/N: 50dB unweighted
Platter: Aluminum
Tracking force: 4.54g (Measured personally)
More in turntable guide


Photos











The Sample Clips
For background on the clips, see the "Preparation" thread.

All samples are FLAC and under 30 seconds.
Music
  • CD LP Peg, Steely Dan, Aja
  • CD LP On the Run, Pink Floyd, Dark Side of the Moon
  • CD LP Dare, Gorillaz, Demon Days
  • CD LP Dum Diddly, The Black Eyed Peas, Monkey Business
  • CD LP Rhiannon, Fleetwood Mac, Self-titled Album (Dusty, scratched and skipping album)

Test Tracks


I eagerly await your opinions and analysis on the samples.


This post has been edited by Knowzy: Apr 23 2009, 22:09
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donnie
post Feb 18 2009, 10:32
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The 1 kHz test sample and Dum Diddly (LP) don't work for me
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Axon
post Feb 18 2009, 16:34
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Also the links for the Gorillaz and Black Eyed Peas samples are all kinds of messed up.

I don't have time for a full analysis, but I did just do a quickie frequency response comparison of the Aja samples. Read this graph like a graphical equalizer. Window length is 300ms, overlap is 66%, Blackman-Harris window, L+R and L-R channels (black is L+R, ie the mono signal, red is L-R aka stereo).

Unfortunately I have no idea on how to link to an attachment anymore (mods?), so:

http://www.hydrogenaudio.org/forums/index....showtopic=69618

Off the cuff, the bass boost is pretty shocking, to the point that I'm not exactly sure if it could even be caused by a tonearm resonance problem - it might be a mastering change on the LP. It's around 30db@50hz ish. I'd need a far longer sample (like several minutes) to be sure one way or another. (PM me if you're interested in that sort of thing.) The rising L-R response at the upper treble is probably going to be tracing distortion. I'd guess the drop around 200hz and the generally attenuated L-R signal is a mastering change, but that's always hard to gauge.

This post has been edited by Axon: Feb 18 2009, 16:37
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Axon
post Feb 18 2009, 16:47
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Hey: I looked at one of your close-up pics and that reminded me. While you're at it, could you also be sure to clean the stylus with a Magic Eraser before each play, if you can? Just lightly press the Eraser to the stylus in an up/down motion to get all the gunk off. It's the cleaning method du jour nowadays and it's pretty cheap. It really can improve some of the results.

If you don't have a ME then a useful alternative is a Q-Tip soaked in rubbing alcohol, but you have to be sure not to get the cantilever too wet as it can wick up to the suspension, and some stylus adhesives do not like getting wet (but that's usually a problem with the high-end carts more than the entry-level ones).
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krabapple
post Feb 18 2009, 18:29
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QUOTE (Axon @ Feb 18 2009, 10:47) *
Hey: I looked at one of your close-up pics and that reminded me. While you're at it, could you also be sure to clean the stylus with a Magic Eraser before each play, if you can? Just lightly press the Eraser to the stylus in an up/down motion to get all the gunk off. It's the cleaning method du jour nowadays and it's pretty cheap. It really can improve some of the results.

If you don't have a ME then a useful alternative is a Q-Tip soaked in rubbing alcohol, but you have to be sure not to get the cantilever too wet as it can wick up to the suspension, and some stylus adhesives do not like getting wet (but that's usually a problem with the high-end carts more than the entry-level ones).



Q-tips were too scary for me for stylus cleaning back in the day. I used to use a small, closely-packed brush pad, dosed with alcohol, that I could run the stylus through (like moving a spike through tall grass). I think it was made by the same folks who made the Discwasher fluid...I remember it has a classy wooden handle.

Anyway, a small artist's or touch-up paintbrush could probably serve as well or better today. Every once in awhile I would also check out the stylus under a microscope/loupe -- amazing how much gunk it could pick up from just one play, depending on the disc. (FWIW this was/is a Shure V15TypeV MR, at the recommended tracking force)

I only listened to the Steely Dan clips so far, and it made me not miss vinyl. ;> (To be fair, I think the LP version might sound better with some level-matching to the CD version )

This post has been edited by krabapple: Feb 18 2009, 18:32
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Axon
post Feb 18 2009, 19:12
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Bad news, krab... they're already level-matched. blink.gif
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Knowzy
post Feb 18 2009, 19:28
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QUOTE (donnie @ Feb 18 2009, 01:32) *
The 1 kHz test sample and Dum Diddly (LP) don't work for me

QUOTE (Axon @ Feb 18 2009, 07:34) *
Also the links for the Gorillaz and Black Eyed Peas samples are all kinds of messed up.

I apologize for not double checking the links. It was approaching midnight as I was wrapping up the post. They are fixed now so listen away!


QUOTE (Axon @ Feb 18 2009, 07:34) *
Off the cuff, the bass boost is pretty shocking, to the point that I'm not exactly sure if it could even be caused by a tonearm resonance problem - it might be a mastering change on the LP. It's around 30db@50hz ish.

That was my impression too just by listening to the Gorillaz LP sample vs. the CD. These should be the same masters since the album was put out in 2005.

I will PM you the link to the full Steely Dan song since I know you own both the CD and LP.


QUOTE (Axon @ Feb 18 2009, 07:47) *
Hey: I looked at one of your close-up pics and that reminded me. While you're at it, could you also be sure to clean the stylus with a Magic Eraser before each play, if you can?

Yes, I noticed that piece of debris when looking at the close-up of the cartridge. It's not there anymore. I will take your suggestion and pick up a ME marker and apply it before each play.


QUOTE (krabapple @ Feb 18 2009, 09:29) *
...amazing how much gunk it could pick up from just one play, depending on the disc.

These are all new LPs, so there should be minimal gunk.

That reminds me, though, I still have one more music sample- a dusty, scratched Fleetwood Mac LP. I won't touch the stylus to this record until I finish the test LP tracks.


QUOTE (krabapple @ Feb 18 2009, 09:29) *
I only listened to the Steely Dan clips so far, and it made me not miss vinyl. ;> (To be fair, I think the LP version might sound better with some level-matching to the CD version )

The original plan was to keep match the levels as best as possible. Then I discovered that the USB turntables I'm testing don't allow me to set the levels!

I could normalize after the fact but I don't want to give the impression that the samples have been tampered with.
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Axon
post Feb 18 2009, 19:34
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I only own Aja on LP, not CD. On The Run is a better sample for me.

Magic Eraser is a sponge, not a marker - it's going to be in the cleaning aisle.

Don't normalize - I can normalize the plots myself so that the response at 1khz is set to 0db.
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krabapple
post Feb 19 2009, 16:49
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QUOTE (Axon @ Feb 18 2009, 13:12) *
Bad news, krab... they're already level-matched. blink.gif


Wow.

Well ultimately, that's OK -- I have the CD, not the LP. wink.gif

EDIT: -- hold on -- the Dark Side clips yield the same replaygain value (+1.24 dB) ..but the Dan clips do not

Home at Last LP -0.22 dB
Home at Last CD -2.88 dB

This post has been edited by krabapple: Feb 19 2009, 17:06
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krabapple
post Feb 19 2009, 16:59
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QUOTE (Knowzy @ Feb 18 2009, 13:28) *
That was my impression too just by listening to the Gorillaz LP sample vs. the CD. These should be the same masters since the album was put out in 2005.


It's not unusual for LP versions to be mastered differently than CD versions. Even if the same master tape was fed into the cutting process, EQ can be applied during cutting (and then if that EQ'd feed is saved, that become the 'LP production master' for subsequent cuttings). Or two masters may be made from the mixdown master -- one for modern CD (e.g. highly dynamically compressed) and one for LP.


QUOTE
These are all new LPs, so there should be minimal gunk
.

Vinylphiles IME commonly recommend a thorough vaccuum/clean of even brand-new LPs. Maybe it's just one of their rituals, but isn't there supposed to be some kind of 'releasing agent' on new LPs (artifact of the stamping process)?

QUOTE
QUOTE (krabapple @ Feb 18 2009, 09:29) *
I only listened to the Steely Dan clips so far, and it made me not miss vinyl. ;> (To be fair, I think the LP version might sound better with some level-matching to the CD version )

The original plan was to keep match the levels as best as possible. Then I discovered that the USB turntables I'm testing don't allow me to set the levels!

I could normalize after the fact but I don't want to give the impression that the samples have been tampered with.



That's OK, if I want to I can apply replaygain at the playback end, without altering the actual data.

This post has been edited by krabapple: Feb 19 2009, 17:00
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Axon
post Feb 19 2009, 17:49
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New pics up for Pink Floyd and Steely Dan samples, check the upload thread for the images and details. I'd go this far with the plots:
  • Between 1k-9k the response rolls off by 6-9db. This is a huge, huge difference.
  • The response at 20k is about 15-20db below at 1k. Not as bad, but still crummy in the grand scheme of things.
  • The tonearm resonance is now pretty concretely in the 20-30hz range, which is not as bad as it was looking before, but still not good. It should be in the 8-15hz range, and on many home entertainment systems this may cause audible problems, especially during live playback of vinyl (although many people will like it because it provides a bass boost)
  • The Pink Floyd needledrop has a large noise peak at 19khz, but it doesn't exist in the Steely Dan recording. So it might be cut into the record. Probably not audible to begin with.
  • L-R narrow peak around 21k - this is in both recordings and is probably electrical noise in the turntable, but is certainly inaudible
  • Large (5db) response discontinuity in both tracks at 9.5khz, probably a resonance of some kind? Maybe in the cartridge? Probably audible.
  • ~3db bump at 14k, not audible for most people
  • Large-to-huge peak just after 20k followed by a huge rolloff - possibly the stylus tip-vinyl resonance, or else it could be the LCR resonance of the preamp
It's hard to derive any more from these plots without probably equivalent masters and/or the test record sweeps. Plus, I've already spent way too much time on this on a weekday. smile.gif The plots look really ragged overall, but it's hard to gauge how much of this is the turntable and how much of it is the mastering, especially with the raggedness goes in opposite directions for different records.
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Axon
post Feb 19 2009, 17:54
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QUOTE (krabapple @ Feb 19 2009, 09:59) *
QUOTE
These are all new LPs, so there should be minimal gunk
.Vinylphiles IME commonly recommend a thorough vaccuum/clean of even brand-new LPs. Maybe it's just one of their rituals, but isn't there supposed to be some kind of 'releasing agent' on new LPs (artifact of the stamping process)?
Mold release agents are generally added to the vinyl formulation directly, and I remember a quote (Stan Ricker?) that actually spraying MRA onto the presses almost never happens. That said, there are lots of stories nowadays about brand-new record with chaff and crap inside the seal.
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Axon
post Feb 19 2009, 20:36
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I'd also like to point out that even though an analysis of the frequency sweeps is going to give an authoritative picture of the frequency response of the turntable, the analyses of the recorded music show things that may not appear on the frequency sweeps, such as the impact of stylus shape on the response. They can help explain what you hear on the vinyl, while the sweeps are much less direct in their interpretation.

However, it's important not to read too deeply into it. Excessive distortion may only show up as heightened treble response, and may mask potentially unrelated (but major) linear distortion issues. A certain amount of interpretation is always required.
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Axon
post Feb 19 2009, 20:37
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QUOTE (krabapple @ Feb 19 2009, 09:49) *
EDIT: -- hold on -- the Dark Side clips yield the same replaygain value (+1.24 dB) ..but the Dan clips do not

Home at Last LP -0.22 dB
Home at Last CD -2.88 dB

Yeah I was confused. nm.
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Knowzy
post Feb 20 2009, 05:27
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QUOTE (Axon @ Feb 18 2009, 10:34) *
Magic Eraser is a sponge, not a marker - it's going to be in the cleaning aisle.

Got ya.

You can tell how much cleaning I do around the house. When I brought a couple boxes home, the wife tells me we already have a bunch of boxes in the garage! laugh.gif


QUOTE (krabapple @ Feb 19 2009, 07:59) *
Vinylphiles IME commonly recommend a thorough vacuum/clean of even brand-new LPs.

I seem to have misplaced the LP attachment to my vacuum cleaner. smile.gif

Seriously, though, I looked around at acquiring vacuum system. I'm not a handy person, so the DIY route is not a viable option. Buying an assembled system means forgoing another USB turntable or two.

I did pick up the old, reliable Discwasher system, though. I'll clean the test LP, ME the stylus and then post another sample of the silent groove.





QUOTE (Axon @ Feb 19 2009, 08:49) *
New pics up for Pink Floyd and Steely Dan samples, check the upload thread for the images and details....

The graphs look great. Thanks for that.


QUOTE (Axon @ Feb 19 2009, 08:49) *
It's hard to derive any more from these plots without probably equivalent masters and/or the test record sweeps.

I'm working on test record samples after this post.

That brings up a good question: Which specific tracks make for the best samples? You can read the track list and details for Ultimate and Hi-Fi News are online.

Here's what I'm considering:
Ultimate
  • Side A, Track 1: 1kHz tone (Done)
  • Side A, Track 10: Wow & Flutter test Signal
  • Side B, Track 1: Anti-skating Test, 315Hz sweep to +12dB
  • Side B, Track 4: 1kHz vertical, out-of-phase signal
  • Side B, Track 5: 1kHz to 10Hz sweep at -20dB, vertical
  • Side B, Track 6: Silent groove (will re-do after cleaning)

Hi-Fi News

  • Side B, Track 7: 20Hz to 20,000Hz sweep

Will that do it or are there any other important tracks? Are there any I shouldn't bother with?
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Axon
post Feb 20 2009, 05:53
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QUOTE (Knowzy @ Feb 19 2009, 22:27) *
I did pick up the old, reliable Discwasher system, though. I'll clean the test LP, ME the stylus and then post another sample of the silent groove.
Take that sh*t back smile.gif and surreptitiously suggest to your wife that y'all really, really need a $30 pressurized steam cleaner from Walgreens. Look on several other vinyl forums (Audiogon, Audio Circles, Vinyl Asylum etc) on suggestions on how to use it. Combine that with some decent quality microfiber cloths and you'll probably have RCM-quality cleaning right there, just with some more legwork. Without spending any money on vinyl-specific equipment, too! Use a $10 carbon fiber brush to clean off superficial dust.

QUOTE
That brings up a good question: Which specific tracks make for the best samples? You can read the track list and details for Ultimate and Hi-Fi News are online. Here's what I'm considering:
Ultimate
  • Side A, Track 1: 1kHz tone (Done)
  • Side A, Track 10: Wow & Flutter test Signal
  • Side B, Track 1: Anti-skating Test, 315Hz sweep to +12dB
  • Side B, Track 4: 1kHz vertical, out-of-phase signal
  • Side B, Track 5: 1kHz to 10Hz sweep at -20dB, vertical
  • Side B, Track 6: Silent groove (will re-do after cleaning)
Hi-Fi News
  • Side B, Track 7: 20Hz to 20,000Hz sweep
Will that do it or are there any other important tracks? Are there any I shouldn't bother with?


First of all, IMHO, don't clean the test records unless you can see specific issues with them that require cleaning. You're putting a lot of trust into the cleaner to not negatively affect the test record results, and there are several (admittedly theoretical and unobserved) ways that can happen. Brush scratches record, dirt embedded in brush scratches record, dirt in brush is left on record, cleaning agent leaves residue on record, cleaning agent + brush moves the dirt around without picking it up, etc. For most other records, there is a good enough potential benefit of reduced noise that cleaning makes sense, but most test records are very well manufactured and maintained, and are also more expensive. That said, it's not the end of the world if you clean the records - no results are compromised - but if we hear a hiss in one of the channels on the silent bands and varies based on the position of the record, I'm going to wonder. smile.gif

Second, just post the entire needledrops of Ultimate and HFNRR. I can use almost all of the former and most of the latter. And when you're done with all the tables, please re-record each test record with the first turntable you played it on, to establish how much the results changed as a result of all the plays.

This post has been edited by Axon: Feb 20 2009, 05:54
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Knowzy
post Feb 20 2009, 06:28
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QUOTE (Axon @ Feb 19 2009, 20:53) *
QUOTE (Knowzy @ Feb 19 2009, 22:27) *
I did pick up the old, reliable Discwasher system, though. I'll clean the test LP, ME the stylus and then post another sample of the silent groove.
Take that sh*t back smile.gif

QUOTE (Axon @ Feb 19 2009, 20:53) *
First of all, IMHO, don't clean the test records unless you can see specific issues with them that require cleaning. You're putting a lot of trust into the cleaner to not negatively affect the test record results...

Good thing you were online and stopped me before I did anything stupid!

For the record, I did clean Side A of DSOTM. It was the most crackly of the bunch and I wanted to see if it would make a difference. It sounds exactly the same. The crackles and pops are still there.

Since all the records I'm using in this test are brand new, I will refrain from cleaning any of them and continue simply handling them carefully. I'll touch the Magic Eraser to the stylus a few times before each needledrop.


QUOTE (Axon @ Feb 19 2009, 20:53) *
Second, just post the entire needledrops of Ultimate and HFNRR. I can use almost all of the former and most of the latter.

Will do, with a caveat: We talking about a half GB or more in FLAC files. I will have to monitor my server's bandwidth usage closely.

If it becomes too popular, I may need to make it available on a per request basis (you PM me, I'll give you the URL). Though based on the downloads I've made available so far, we're a long way from that happening.


QUOTE (Axon @ Feb 19 2009, 20:53) *
And when you're done with all the tables, please re-record each test record with the first turntable you played it on, to establish how much the results changed as a result of all the plays.

You got it!
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Axon
post Feb 20 2009, 08:36
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Don't deal with the server - put up a tracker on Pirate Bay and I'll download it from there. Mods, put the guns down! IANAL, but I couldn't imagine that test record transcriptions would be considered a copyright infringement. They are absolutely not a substitute for the original article, you are adding vast amounts of information by transcribing it on your turntable, it only adds to the demand for test records by defining a larger market for their analysis, etc. BitTorrent is absolutely the correct distribution system for this sort of thing.

But of course, I've never done this before smile.gif
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Knowzy
post Feb 20 2009, 21:34
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The Ultimate Test LP FLACs are up. See the original post.

The Hi-Fi News is proving to be a bit trickier. A circular groove follows each track. It forces me to lift the tonearm and scoot it slightly toward the center of the album before I can play the next track. So, when you hear hard breaks in the two HFN FLACs, that's why.

These files are much smaller than my guesstimate for two reasons: The entire album is only 21 minutes and most tracks contain very little audio data- often just a test tone. Side A is 37.2MB and side B is 49.4MB.

Enjoy! I expect to have HFN up sometime tomorrow.
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Axon
post Feb 20 2009, 21:57
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Yeah that was a sucky mastering decision with HFNRR that's been discussed here before. Generally the amount of content on a test record is far less than on a real record to maximize sound quality and make it easier to position the needle on the bands.

I'm downloading the Ultimate FLACs now but I can't promise anything earlier than late next week for results. I'm swamped.
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Knowzy
post Feb 21 2009, 02:14
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I ran the Wow & Flutter test tone through Spectrogram and it exceeded my expectations in revealing deviations from the 3,150Hz test tone. Or maybe I underestimated just how unsteady the Audio-Technica turntable's playback would be.

Either way, I got some great captures! Click to zoom in.




Spectrogram of a 3,150Hz Sine Wave, 2,900 - 3,400 Range
Left: Computer Generated Tone. Right: Audio-Technica LP2D-USB


I created the test tone in Audacity and I believe it matches the Ultimate Test LP tone exactly. The amplitude is .1 in Audacity's units, -90dB in everyone else's.

Here's an extremely close zoom of each tone in Audacity. Audio-Technica is on the bottom.





I'm looking forward to comparing this spectrogram to the Ion TTUSB05 and the Crosley. Audio-Technica lists their Wow & Flutter spec (<0.25% WRMS). The other two manufacturers don't list it at all. Will I need to expand the range beyond 500Hz? We'll see!
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Axon
post Feb 21 2009, 23:58
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Those are pretty, but they're not remotely resolving enough. 99% of that wave might be due to the pressing being off-center - that will be easy to spot if all the other turntables show the same thing. Most of the width of the spectrogram is due to FM sidebands which distract from the carrier wave. Measurable flutter (that we care about) can extend well into the 200-300hz range and beyond. Your frequency and time resolution should both be at least a hundred times more greater to get useful results, and that level of detail is simply impossible with spectrograms.

The reference for interpreting wow/flutter is Poul Ladegaard's legendary 1977 paper on mechanical resonances. Specifically look at Fig. 18 on page 7. Those are the sorts of charts you ought to be displaying/interpreting.

The "right" thing to do here is demodulation of the 3150hz tone into a wow/flutter signal followed by DC removal and amplitude spectrum. Don't spend much time playing with the spectrograms for any kind of analytical use - they're good for visualization but not for analysis. I've been meaning to cook up a good quadrature demodulation program for some time, and now is the perfect time.

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Knowzy
post Feb 22 2009, 04:30
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The Hi-Fi News FLACs are up.

QUOTE (Axon @ Feb 21 2009, 14:58) *
Those are pretty, but they're not remotely resolving enough....Your frequency and time resolution should both be at least a hundred times more greater to get useful results, and that level of detail is simply impossible with spectrograms.

It's never as simple as I hope! smile.gif


QUOTE (Axon @ Feb 21 2009, 14:58) *
The reference for interpreting wow/flutter is Poul Ladegaard's legendary 1977 paper on mechanical resonances. Specifically look at Fig. 18 on page 7. Those are the sorts of charts you ought to be displaying/interpreting.

This is quickly getting beyond my limited aptitude for signal analysis. It's really interesting reading, though.


QUOTE (Axon @ Feb 21 2009, 14:58) *
I've been meaning to cook up a good quadrature demodulation program for some time, and now is the perfect time.

As always, thanks for your contributions and guidance. I couldn't have done it without you.

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Knowzy
post Feb 23 2009, 00:34
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The last sample is up: Fleetwood Mac's Rhiannon from an abused LP.

The cut starts with a skip. We'll see how well the other two turntables handle it.

The sample ends during the fade-out to help make the clicks and pops more apparent.
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Knowzy
post Feb 23 2009, 01:06
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I told you the LP was dusty...




After Playing Entire Side of Dusty Fleetwood Mac LP

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