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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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Axon
post Aug 19 2008, 03:43
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So kind of you to give us a sneak preview of our own submissions.
  • Some turntables might have proprietary mounts (Crowley?).
  • Many turntables do not have antiskate adjustment.
  • Some turntables might not have a preamp out (or might not have an unamplified cartridge out).
  • Tonearms are judged as being "offset" or "straight", not "S" or "straight" (many straight arms are offset).
  • Some tables have 78rpm and reverse speed options.
  • Stylus shapes run a far wider spectrum than those 3 and several of those have radius figures attached to them.
  • "Universal" mount doesn't exist as a tonearm type (it's only for AT carts that work in both P-Mount and 1/2" situations).
  • However some tables use bayonet headshell sockets. Some cheaper models may not though. Some carts actually screw into those directly (Ortofon Concorde IIRC) and there are good uses for that for 78s.
  • Pitch adjustment
  • The basics: wow/flutter, SNR
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Knowzy
post Aug 19 2008, 05:58
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Thanks for the feedback. I edited my original post to include your notes.


QUOTE (Axon @ Aug 18 2008, 19:43) *
So kind of you to give us a sneak preview of our own submissions.

I meant the guide, not the table itself. That's not much of an enticement: The table is already in the first post!

The full comparison guide is already 22 printed pages long and still a work in progress.

QUOTE (Axon @ Aug 18 2008, 19:43) *
  • Some turntables might not have a preamp out (or might not have an unamplified cartridge out).
  • Some tables have 78rpm and reverse speed options.

Thanks. These features are noted in the first two charts:
  1. The Basics
  2. Connections and Features
For chart #3, I'm really looking at the physical components and construction of the turntable.

I could post the first two charts as well but I wanted to keep the scope of this post somewhat narrow!

QUOTE (Axon @ Aug 18 2008, 19:43) *
  • The basics: wow/flutter, SNR


I was going to link the specs if available (many USB TT manufacturers don't publish specs). I suppose I could maintain a few more data points, though. Breaking out these details may very well require a fourth chart!

I really appreciate the help of the TT aficionados here. I've learned a great deal from the Vinyl section of the Knowledge Base (frequently linked in the comparison guide).

Thanks!
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WmAx
post Aug 20 2008, 03:05
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The implementations are so different for each feature on each product, you really have to get down to specific products and compare them.

For example, direct drive can be a noisy problem on cheap executions. But the superb executions, like on a Technics SL1200 have no audible consequence, and offer better speed stability then a standard belt drive unit.

The tone arm is critical, in that is has sufficient adjustments to get the best tracking, IMO.

Of course, the cartridge is critical, also. The Denon DL-110 comes to mind for one of the best cartridges for converting music to files. It has a smaller tip, and made with great precision according to those that inspect such things under microscopes, and it lets you get a cleaner signal from used LPs due it reaching to the inner grooves where normal sized tips don't typically contact well. It is also very flat response cartridge according to the Denon response graphs, with a slight 2dB rise over 10Khz, that you can easily EQ out using the graph for reference, in your digital editing to near total flat response. If you want even better accuracy, you can special high quality test record for $40 that you can use to measure the frequency response of your system so that your EQ correction process can be even more accurate.

Are you actually in the market for one? If so, what is the budget? If it is $500 range, there simple is no better option than the Technics Sl1200. The so-called audiophile TTs in the price range have no where near the level of engineering and build quality. If it under $500, then your options are really limited in new turn tables. But you can turn to certain vintage TTs from the 80's for superb playback systems. Some of these, such as some Denons from the early 80's, have extremely advanced tone arms with active servo stabilization and arm resonance canceling using microprocessors. The only issue with these is if it breaks; it's difficult to get replacement parts or service.

-Chris

This post has been edited by WmAx: Aug 20 2008, 03:13
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Knowzy
post Aug 20 2008, 06:44
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Thanks for the advice WmMax. It's consistent with the deep, empirical insight that's made HA an excellent resource in researching my article.

Creating a comprehensive comparison guide to USB turntables is my goal. The first post is what I'm proposing for one of four comparison charts. This chart focuses on turntable construction and components.


QUOTE (WmAx @ Aug 19 2008, 19:05) *
The implementations are so different for each feature on each product, you really have to get down to specific products and compare them.


There's lots of room for that in the comparison guide. I have identified 25 models from 10 different companies. I plan a three to four paragraph review for each company and a two bullet-point review of individual models.

The reviews are in addition to the four comparison charts comparison charts with roughly 40 data points covering features, connections, software, specs and (what I'm seeking advice on here) construction.


QUOTE (WmAx @ Aug 19 2008, 19:05) *
The tone arm is critical, in that is has sufficient adjustments to get the best tracking, IMO.


By "sufficient adjustments" I'm assuming you mean anti-skate (for offset tonearms) and a counterweight.


QUOTE (WmAx @ Aug 19 2008, 19:05) *
The Denon DL-110 comes to mind for one of the best cartridges for converting music to files.


I appreciate the recommendation. It looks affordable and user friendly. The better USB TT's can accept these cartridges.


QUOTE (WmAx @ Aug 19 2008, 19:05) *
...superb executions, like on a Technics SL1200...


I realize the prevailing opinion in this fourm skews heavily toward connecting an excellent TT line-in to your computer. To be sure, I do plan to spend some time describing this method.

However, the goal of this guide is to create what I feel is a badly.needed resource: An inclusive, independent look at the world of USB TT's. Helping consumers, and technically-inclined friends who make decisions for them, see what they're really getting.

By pulling back the curtain, construction deficiencies like ceramic cartridges, no plinth isolation and no foot levels become apparent, and avoidable (budget permitting, of course).

Jeff
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Axon
post Aug 20 2008, 07:13
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WmAx's comments are very insightful, but I suspect you and he are not quite seeing eye to eye on price points etc. The DL110 is what, a $130 cartridge? That's more than the cost of some USB turntables. The SL1200 is, somewhat shockingly, still considered a luxurious expense for most of the population. That said, Denon carts (or at least the DL103) have the distinct advantage of having phenomenally rugged suspensions, and are good choices for family-friendly setups, I'd imagine.

I've had a similar mind at some points to make a guide similar to what it sounds like Knowzy is working on. Basically, what people need to know, in decreasing order of importance, is how to choose a turntable that:
  1. Won't f*ck up their records of its own accord. This, most obviously, means avoiding ceramic cartridges (I can't understand why the damn things are still being manufactured!). More subtly, it also means the use of an offset arm instead of a straight arm, an antiskate mechanism, etc. Of course, if it's a P-mount and it's completely misaligned or the VTF or azimuth are way off, that's a big deal too.
  2. Preferrably, sufficiently rugged as to not break if a family member/friend/cleaning maid screws around with it. This favors extremely cartridge suspensions that are particularly rugged - DJ carts and Denon carts come specifically to mind - although the high end Shure has a stylus protection device that allegedly works pretty well too.
  3. Doesn't sound completely obviously bad (low ground hum, acceptable wow/flutter, doesn't skip under reasonable conditions).
  4. Finally, the "finer" points of sound quality - environmental isolation, frequency response, distortion, acoustic resonances, tighter SNR and wow/flutter tolerances, etc. I'd argue that most consumers are not going to be caring about this.
  5. Upgradability: 1/2"/SME mounts, modding potential, counterweight adjustment, etc. Again, not a concern for the lower end tables.

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?

This post has been edited by Axon: Aug 20 2008, 07:15
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WmAx
post Aug 20 2008, 08:20
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QUOTE (Axon @ Aug 20 2008, 02:13) *
WmAx's comments are very insightful, but I suspect you and he are not quite seeing eye to eye on price points etc. The DL110 is what, a $130 cartridge? That's more than the cost of some USB turntables. The SL1200 is, somewhat shockingly, still considered a luxurious expense for most of the population.


Because it is a completely mechanical process, I tend to increase the acceptable budget expense on this particular format for playback hardware. I won't spend more then $200 or $300 on a CD player(and that much is only for a nice multi-disc changer; preferably factory refurbished to save more $$), but I consider 2 to 3x this acceptable a near transparent vinyl playback system, and personally, I recently bought a turntable that costs nearly $2000 USD, which I admit was totally uncalled for - but I was partly seduced by it's incredibly good looks as a decoration piece smile.gif . So far, all of the audiophile decks I have seen in the price range of the SL1200 are toys in comparison, when you get down to comparing the finer points. The absolute lowest price new(as opposed to buying used, where you can get some fantastic deals in superb early 80's era turntables) turntable that is any good I suspect is the Denon DP-300F. It even has a built in pre-amp so you can connect it to normal line inputs. I tried one of these, and it has a decent arm, and it has low noise level; I could not hear any rumble or hum in normal use. You can get this deck well under $300. It comes with a cartridge that seems okay.

That being said, my idea of $500 deck and $140 cartridge being 'budget' items may be out of perspective from reality. Sorry.

As for USB decks; I simply do not know of any that yet match the value/quality of the non-USB units currently available. That certainly does not mean they don't exist - just that I am not immediately aware of them. Probably one of the better USB tables is the Pro-Ject Debut III USB; but it's around $500, and frankly, a toy, when compared to the $500 Technics SL1200MKII.

-Chris

This post has been edited by WmAx: Aug 20 2008, 08:28
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cliveb
post Aug 20 2008, 11:44
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QUOTE (WmAx @ Aug 20 2008, 08:20) *
Because it is a completely mechanical process, I tend to increase the acceptable budget expense on this particular format for playback hardware.

WmAx has got to the nub of the issue. Turntables are mechnical devices. Unlike electronics (especially digital electronics), which have benefitted vastly from cost-saving technological advances over the years, mechanical systems are still expensive to build well.

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.

As for USB turntables: like WmAx I haven't seen one that I'd ever consider using. And even if a really good USB turntable did come along, do you really want to be locked in to whatever phono preamp and A/D converter it has?
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uart
post Aug 20 2008, 14:51
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QUOTE (cliveb @ Aug 20 2008, 02:44) *
As for USB turntables: like WmAx I haven't seen one that I'd ever consider using. And even if a really good USB turntable did come along, do you really want to be locked in to whatever phono preamp and A/D converter it has?

This is timely for me, because just recently I've noticed several acquaintances (friends and family members etc) buying really cr@appy quality USB turntables that I wouldn’t touch with a ten foot pole. Apparently for no other reason than the convenience of avoiding analog recoding.

The most recent example was my father (who I have to forgive as he's nearly 80 years old now and getting rather prone to making erratic purchases). I went to visit him and he just bought this $80 USB turntable from an Aldi supermarket. And what a P.O.S it truly was. Straight arm, ceramic cartridge, no anti-skate and no control of needle weight. Predictably the sound was very poor, very lacking in both the bottom end and the top end. What made this all the more surprising is that my father used to be somewhat of an audiophile and already owns an extremely high quality Technics turntable (purchased back in about 1980 but still in perfect condition).

Anyway my Dad's got the excuse of being old and feeble minded, but as for the other people I've seen doing a similar thing, the only thing I can think of is that they are just too lazy (or inept) to connect up an analog input.

Personally I think if someone already has a good turntable but doesn't want the inconvenience of needing a full sized amplifier with phono-in connected to their computer (this is the most often cited reason for wanting a USB turntable in my experience) then they’d much better off to just buy a stand-alone phono pre-amp (even a very cheap one) to go between the turntable and line-in.

This post has been edited by uart: Aug 20 2008, 14:56
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Axon
post Aug 20 2008, 16:39
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QUOTE (uart)
Personally I think if someone already has a good turntable but doesn't want the inconvenience of needing a full sized amplifier with phono-in connected to their computer (this is the most often cited reason for wanting a USB turntable in my experience) then they'd much better off to just buy a stand-alone phono pre-amp (even a very cheap one) to go between the turntable and line-in.
Most people have trouble enough hooking up their turntables to their speakers, let alone to a computer. It's rather bizarre frankly how some extremely technically competent people I know think that connecting a phono stage to line in is some sort of dark art or something. I'm not pleased with that at all, but it does explain rather well the reasons for using USB.

QUOTE (uart)
The most recent example was my father (who I have to forgive as he's nearly 80 years old now and getting rather prone to making erratic purchases). I went to visit him and he just bought this $80 USB turntable from an Aldi supermarket. And what a P.O.S it truly was. Straight arm, ceramic cartridge, no anti-skate and no control of needle weight. Predictably the sound was very poor, very lacking in both the bottom end and the top end. What made this all the more surprising is that my father used to be somewhat of an audiophile and already owns an extremely high quality Technics turntable (purchased back in about 1980 but still in perfect condition).
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? And don't tell me that everybody needs a freaking SL1200 as a minimum baseline for that.

QUOTE (cliveb)
As for USB turntables: like WmAx I haven't seen one that I'd ever consider using. And even if a really good USB turntable did come along, do you really want to be locked in to whatever phono preamp and A/D converter it has?
Phono preamps and A/D converters are the absolute last things I'd be worrying about on USB turntables unless I saw good evidence to the contrary. The electronics involved with this are quite insubstantial in their flaws compared to the mechanics. And I don't think that anybody will be buying turntables like these expecting much of an upgrade path here - if they buy in to all of this, they're probably going to spring for a new table (unless they buy a truly good cheap table, like a PL120 or something like that).

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.
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Axon
post Aug 20 2008, 20:25
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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. While measurable wear can occur after one play in those kinds of situations, it very well may be inaudible. Of course, ceramics/crystals are still a crime against music.
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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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Knowzy
post Aug 21 2008, 08:09
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QUOTE (Axon @ Aug 20 2008, 21:29) *
Wait. You don't know what I mean by "offset arm", do you?


I absolutely do now. How embarrassing!

Well, that's why I'm here- to get to know turntable construction and components well enough to make a useful comparison chart.

I went back through the models and all of them do indeed have an offset arm. Anti-skate, that's another story.

To restate it correctly: If you make anti-skate a requirement you eliminate 60% of the market.

The new list of USB TT's featuring anti-skate includes Pro-Ject's USB:
QUOTE (Axon @ Aug 20 2008, 21:29) *
For comparison, the SL-1200 clocks in at 0.025% on its spec sheet (and its speed stability is solid as a rock).

I see what you mean. Quite a bit better than any USB TT that lists its specs.

I can only imagine the what the wow and flutter are on these belt drives that omit the specs!

Very noteworthy.

Thanks again for the help and being patient while I display how badly I need it!
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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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Knowzy
post Aug 21 2008, 17:36
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QUOTE (cliveb @ Aug 21 2008, 02:14) *
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.

Few USB TT's feature an adjustable gain. It's only found on the Numark TTXUSB and on models that have what I'm calling "standalone" capabilities. These are models like Numark/Ion's LP 2 CD where a CD burner is built in to the unit.

QUOTE (cliveb @ Aug 21 2008, 02:14) *
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.

No models have a 24 bit converter. The closest we get is Stanton's T.90 USB which offers 48khz sample rate in addition to 44.1.

QUOTE (cliveb @ Aug 21 2008, 02:14) *
Just looked up the STR8...What's the point of an arm like that? Is there some kind of DJ behaviour that it benefits?

In doing my homework on offset vs. straight, I came across a good technical article. Here's a notable quote:

"The straight arm has found a new home with Scratch DJ's, because, the needle is more stable in the groove when the platter is being spun back and forth as that artform requires. The trade off is excessive groove wear and distortion."
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Axon
post Aug 21 2008, 19:15
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QUOTE (cliveb @ Aug 21 2008, 04:14) *
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.
At these price and fidelity ranges, it could be argued that losing 3 bits of resolution is acceptable. It's not like many people have systems with enough dynamic range to really point out the flaws in that kind of recording. But this does remind me that I should probably grab some hot 12"s the next time I have a chance - I only have one 12" single now, and it's not cut that loud.

QUOTE
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?
As Knowzy pointed out, it makes scratching far more stable. The tracking benefits of an offset arm go right out the window (and make it harder to track) when the record is spinning backwards.

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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).

Of course antiskating is required for minimum distortion, but again, that is of a minimal importance at this price point. Customers of these kinds of tables already know that they're getting what they're paying for, and decency is a ways up from here. What's most important is avoid record wear while providing a basic level of fidelity.

I agree that mistracing/mistracking - as defined by the record leaving contact with one of the groove walls - is a really bad thing. But the lack of antiskate does not necessary mean that's going to happen - it just makes it a bit more likely (and it also increases the tracking force on the other side of the groove, also increasing record wear over time). The same goes for straight arms too. Until that happens, the only real effect is low order harmonic distortion, which, as we all know, is rather inaudible.

More abstractly: Record wear occurs due to plastic deformation of the vinyl, which occurs when the contact pressure exceeds a certain amount on one side of the groove. This can occur regardless of the tracing situation (continuous contact of the vinyl on both sides of the stylus) or the tracking situation (optimal geometric pickup of the signal). But obviously losing tracing/tracking ability vastly increases the risk of damage, and the specifics of the deck can cause the forces on the stylus to be higher than they need to be. The use of a straight arm, and to a much lesser extent the lack of antiskate, means that the stylus force is higher on one side of the groove than another, increasing the risk of plastic deformation (but not necessitating it). It also raises the risk of mistracking in general, potentially requiring a higher tracking force to counteract (which can also increase the risk of plastic deformation).

It could be argued that bearing deficiencies could increase the forces impinging on the stylus, but it's a stretch to establish any sort of meaningful magnitude to that effect. Some people, in fact, have argued that whatever natural slip-stick effect the tonearm bearing has is negated by the vibrations coming from the cartridge...

A much more subtle issue is acoustic impedance, especially at high frequencies, which has been fingered as causing stylus "chatter" and immediate record wear. Unfortunately, that's dreadfully difficult to quantify. It's not the same thing as compliance.

Maybe I'm just suffering from a lack of perspective here, being a young sprout and all, but my impression of record wear is that it has been intimately correlated with how many times people have played their records. And that back in the 60s-70s it was extremely common to wear a record out - but "only" after perhaps +200 plays, on a crappy record player. One play on a table like one of these seems pretty inconsequential to me.

I suppose this issue will only get resolved when one of us buys said cheapo USB turntable and does a before/after comparison: playing a record first on a hifi table, then the USB table, then back on the hifi table. That can tell us pretty quickly what the record wear is like.
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