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Comparing Elements of Turntable Construction, Kindly requesting your help in building a turntable comparison chart.
Knowzy
post Aug 19 2008, 03:06
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Greetings HydrogenAudio.

USB turntables, as many around here are aware, range in quality from poor to decent. I'm setting out to create comparison charts detailed enough to find the gems in a sea of lightweight plastic and ceramic carts. Once the guide is more presentable, I plan to give HA an exclusive sneak preview.

What follows are the elements I'm considering for chart #3, "Turntable Construction," along with the possible values.

Is there anything else I should be considering? Are there any elements not worth comparing or combinable with other elements? Am I using correct terminology?

I greatly appreciate your informed input.
  • Drive
    • Belt
    • Direct
  • Cartridge Type
    • Ceramic
    • Moving Magnet
    • Moving Coil (no USB TT's feature these)
  • Plinth/Body (really having trouble succinctly comparing this)
    • Lightweight plastic/No isolation
    • Heavy plastic/Rubber
    • Metal/Rubber
    • Wood/Rubber
  • Anti-skate/Counterweight
    • Yes
    • No
  • Edit: Removed tonearm shape, combined counterweight with anti-skate (thanks for setting me straight Axon)
  • Mount Type
    • Half-inch
    • P-Type
    • Edit: Bayonet (thanks Axon)
    • Edit: Universal (thanks Axon)
    • Edit: Proprietary (thanks Axon)
  • Stylus Type Edit: Added more types
    • Conical
    • Elliptical
    • Spherical
    • Linear Contact
    • MicroLine
    • MicroRidge
  • Dustcover
    • Plastic
    • Cloth
    • None
  • Adjustable Feet for Leveling?
    • Yes
    • No
  • Tonearm cue?
    • Yes
    • No
  • Tonearm Auto return?
    • Yes
    • No
  • Edit: Specs (If Available) (Chart #4: Specifications)
    • Wow and Flutter
    • Signal to Noise Ratio
    • Rumble
    • Dimensions
    • Weight
    Edit: Pitch Control (chart #2) (thanks Axon)
    • +/- X%


This post has been edited by Knowzy: Aug 21 2008, 07:03
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Knowzy
post Aug 21 2008, 03:50
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We're getting way off topic on defining the turntable construction chart but I'm thoroughly enjoying the conversation!

QUOTE (Axon @ Aug 19 2008, 23:13) *
The DL110 is what, a $130 cartridge? That's more than the cost of some USB turntables.


~$150 is where you start finding USB TT's where some manufacturers give you their blessing to BYOC (bring your own cartridge). Forget about it on the likes of the sub-$100 Ion TTUSB05.


QUOTE (Axon @ Aug 19 2008, 23:13) *
3. Doesn't sound completely obviously bad (low ground hum, acceptable wow/flutter, doesn't skip under reasonable conditions).


I'm curious what you all would consider an "acceptable" wow/flutter. Here's what the better USB TT's have to offer:
  • Pro-Ject Debut III USB: 0.12%
  • Numark TTXUSB: 0.15%
  • Stanton T.90 USB: 0.15%
  • Audio-Technica AT-LP2D-USB: 0.25%

QUOTE (Axon @ Aug 19 2008, 23:13) *
So I guess the executive summary of your article needs to be: For the love of God, buy a turntable with a magnetic cartridge, antiskate, and an offset arm.

I think that alone is going to wipe out >50% of the USB TTs on the market, isn't it?


Using that standard, it wipes out 64% of the market as I know it and leaves only three manufacturers.

Here's what we're left with:
QUOTE (Axon @ Aug 20 2008, 12:25) *
...if one is buying a turntable solely for transcription...the lack of antiskate - and potentially even the use of a straight arm - become a lot less objectionable if one is only going to play the record once or twice before putting it back on the shelf.


Using that standard, the following have straight arms/no anti-skate but do have MM carts:
QUOTE (WmAx @ Aug 20 2008, 00:20) *
Because it is a completely mechanical process, I tend to increase the acceptable budget expense on this particular format for playback hardware.

QUOTE (cliveb @ Aug 20 2008, 03:44) *
The bottom line is this: good turntables cost a lot of money. There is no guarantee that an expensive turntable will be good, but it's a pretty safe bet that a cheap turntable will be bad.

Excellent points. Thanks for putting them in those terms.

Certainly I will tell my readers to expect decent sound quality at best.

I think most people don't want bad sound quality or to destroy their vinyl. But I expect only a small percentage are willing to invest the extra time, money and education to achieve great sound quality.

While I'm quoting Clive, I just want to say I've read your LP to CDR Tips from beginning to end and will prominently link it in the "Use Your Own Turntable" section of the guide.

QUOTE (uart @ Aug 20 2008, 06:51) *
The only thing I can think of is that they are just too lazy (or inept) to connect up an analog input.

I have had only challenging experiences getting a clean signal when hooking up any analog input directly to my PC. When I started doing this 15+ years ago, even with nothing connected, the hum and noise would hit -10. I'd hear the hard drive in the signal when it was active and on and on.

Over the years, both PCs and myself have gotten better at keeping unwanted interference to a minimum. But it still takes good equipment and precautions, in my experience, to get an acceptably clean signal even today.

I would much prefer to have the A/D conversion done outside of the PC. USB TT's (and other external soundcards) have that advantage.

QUOTE (Axon @ Aug 20 2008, 12:25) *
Of course, ceramics/crystals are still a crime against music.

Agreed. Any you can't go more than a page in the guide without reading that sentiment in one form or another.
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Axon
post Aug 21 2008, 05:29
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QUOTE (Knowzy @ Aug 20 2008, 21:50) *
I'm curious what you all would consider an "acceptable" wow/flutter. Here's what the better USB TT's have to offer:
  • Pro-Ject Debut III USB: 0.12%
  • Numark TTXUSB: 0.15%
  • Stanton T.90 USB: 0.15%
  • Audio-Technica AT-LP2D-USB: 0.25%

Those sound worse than most turntables I've heard, although I can't quite say whether or not it's going to make an audible difference, having not had any experience with those units, or any sort of baseline to really compare those figures against.

For comparison, the SL-1200 clocks in at 0.025% on its spec sheet (and its speed stability is solid as a rock). My MMF5 clocks in somewhere in the 0.1-0.2% range on W&F (I don't have the exact numbers on me) - the wow is actually pretty audible, but only with long-held notes on instruments played without vibrato, ie solo piano pieces.

That might be something you might want to chime in on - wow and flutter and speed tolerance gets more important when the music gets more "strongly" tonal, and if you want to avoid it, you're gonna have to pay. For direct drive you'd have to go straight into PL120/SL1200 territory. For belt drives.... you might be talking $2000 before it really goes away.

QUOTE
Using that standard, the following have straight arms/no anti-skate but do have MM carts:
Wait. You don't know what I mean by "offset arm", do you?

All tonearms correctly aligned for minimal distortion and record wear have the cartridge mounted at an angle ("offset") against the axis of the tonearm. It doesn't matter whether or not the tonearm itself is straight, as long as the angle is right. The Pro-Ject and AT turntables you mention are definitely not straight-arm tables, they're offset.

When I mean "straight arm" I'm talking about something like a Stanton STR8.
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cliveb
post Aug 21 2008, 10:14
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QUOTE (Axon @ Aug 20 2008, 16:39) *
Again, that $80 jobbie is a crime against records, but if it was offset and had an MM cart, and antiskate, what is there left to complain about?

How about the quality of the bearings (on both platter and tonearm), degree of ringing in the tonearm, etc? Playing a vinyl record can inject a surprising amount of mechanical energy into the tonearm. If it rings, then transients are smeared. If it has rattly bearings, you get all sorts of distortions as the cartridge fails to be held in a consistent location wrt the record. If the platter's main bearing is bad, you get speed variations and lots of rumble.

QUOTE (Axon @ Aug 20 2008, 16:39) *
One advantage a USB connection would provide (which even I would kind of like) is the ability to set gain in a reasonably consistent manner. As cliveb pointed out, 16/44 is all you ever really need to record vinyl, but only if you can keep the peaks between 0dbFS and 30dbFS (which is harder than it sounds due to the 20-30db swing in levels between different records). In some cases, it's physically impossible to get the gain right between the phono stage and the sound card, and when it is possible, it's often a little finicky and requires some technical expertise. There's a win in being able to tell a user "don't worry about gain - just normalize in Audacity and forget abou it" or something like that. And USB tables do offer that possibility.

On the contrary, I'd say that the inability to adjust analogue levels in a USB turntable before the signal hits the A/D converter is a disadvantage. One day a really hot LP is going to get played and clip the converters. The only way to avoid that is for the turntable manufacturer to have set the gain staging so low that on the majority of LPs you'll be losing 3 or 4 bits of resolution. If the converters are 24 bit, that probably isn't an issue, but if they are 16 bit (which I suspect they will be on a cheap USB TT), then it is.


QUOTE (Axon @ Aug 21 2008, 05:29) *
When I mean "straight arm" I'm talking about something like a Stanton STR8.

Just looked up the STR8. That's a really strange arragement - never seen a pivoted arm without offset before. I presume is has no overhang - otherwise the geometric tracing errors would be horrendous. What's the point of an arm like that? Is there some kind of DJ behaviour that it benefits?

I had thought that when you spoke of "straight" and "offset" arms, you were actually talking about the arrangement of the arm bearings. Most arms have the plane of the vertical bearing to be perpendicular to the cartridge main axis. S-shaped arms are the most obvious implementation of this, but J-shaped and arms with straight tubes (but still with an offset) can also have their bearings "offset" in this way. Doing it like this means that when the arm rides up & down over warps, the cartridge does not get twisted (and hence there is no induced azimuth error).

QUOTE (Axon @ Aug 20 2008, 20:25) *
I'd also like to point out that if one is buying a turntable solely for transcription, a lot of the finer issues on wear become less of an issue. The lack of antiskate - and potentially even the use of a straight arm - become a lot less objectionable if one is only going to play the record once or twice before putting it back on the shelf.

I respectfully disagree. Getting anti-skating right is important for minimum distortion (or at least to get equal amounts of distortion in the two channels). Use of a "geometrically-challenged" arm won't just cause wear - it will fail to retrieve a decent signal.

Look at it another way - wear happens when the stylus fails to trace the groove accurately. Failure to trace the groove accurately causes distortion. Anything that causes excess wear also causes excess distortion. Excess distortion is the last thing I'd want when making a one-off playback that will be captured digitally for posterity (even if I didn't care if the record got trashed in the process).
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