Your thoughts on linear tracking tt's

[Fishtails]

Hi people

Having just found a kenwood linear tracking turntable in perfect working order on the side of the road I was hoping to get your various opinions on these.

Linear vs standard?

It all seems fine to me with sound reproduction excellent.

What are the benefits of linear tracking if any?

Look forward to your opinions!!

[nat]

If the past is an indicator of the future, you may have stirred up a hornet's nest with this question.
Enthusiasts point to the lack of tracking error and the lack of the need for antiskating, and they point to wear patterns on styli to prove the superiority of linear tracking.
Enthusiasts of pivoted arms point to the complexity (hence expense and possible breakdown) of many linear arm mechanisms, and the need to keep them clean and well lubricated, and they reject the claim of no tracking error, insisting that linear arms are error correction mechanisms, and hence are in error most of the time. In a properly functioning linear arm, the error is pretty low -- lower than peak error in a pivoted arm, but even in a properly functioning pivoted arm error is low.
How low is low enough to ignore? That is a contentious issue (and there is a substantial group of audiophiles who use pivoted arms without overhang adjustment who would argue that tracking error is way over rated as an issue.)
To my mind, a more important aspect of the linear versus pivoted debate is personal taste when it comes to track selection. I like lifting the arm with my hand (or cuing lever) and placing the needle where I want it and lowering (free hand or with cuing) on to the record. Easy and instant gratification. But others appear to like using buttons to toggle the arm back and forth, or hitting the band number. I'm assuming that they like the sense of safety that comes from not handling the arm directly, and are willing to wait for action.
I think a lot of the choice is ergonomic, not technical. But you wouldn't know that from the debates that crop up when this question is asked.

[fscl]

Hi people

Having just found a kenwood linear tracking turntable in perfect working order on the side of the road I was hoping to get your various opinions on these.

Linear vs standard?

It all seems fine to me with sound reproduction excellent.

What are the benefits of linear tracking if any?

Look forward to your opinions!!

Well done ftails.......

Love my linears, love my pivots........ Personally got hooked on tangentials with my first Technics SL-7, when she started to misbehave, ended up here searching for service manuals. Now ermmmm have become more addicted to tts.......

Benefits, in theory, little or no tracking error, the vinyl gets played back like the master's were cut......

This U toob along with Part 2 are in several VE topics.......:

http://www.youtube.com/watch?v=xUGRRUecBik

A recent topic with quick impressions of different linear trackers:

viewtopic.php?f=18&t=46477

And a galaxy of audiophile turntables:

http://www.audiofederation.com/catalog/turntables/

Good luck with the Kenwood and enjoy the sounds......

Fred and what model do you have BTW..... and oogled a Walker at T.H.E. Show.....

[dlaloum]

The good: tracking error reduced by an order of magnitude, alignment relatively effortless

The Bad: much more difficult to engineer, and therefore tend to be more expensive to manufacture to a similar level of quality.

So given a manufacturing budget of $100 to make an arm. a given pivot arm is usually superior to a given linear arm.

But once you get to say $200 manufacturing cost for the arm - things start to even out, and in the multi-megabuck pricebracket, a number of the top arms are linear. (at that level we are really talking price no object)

There are a number of mass produced linears that were excellent - names that come to mind include B&O, Sony, Technics, Revox.
Some of these brands manufactured in more than one category, so Sony had some excellent TOTL linears, but also plastic fanstastic cheapies (most likely the pivoted arms in the same range performed better!)

I love my Revox linatrack to bits - but it was never a cheap table - it was a TOTL table, while still being in the mass produced manufactured category, rather than the hand built boutique audio Jewellery class.

I categorise tables like this:

1) Cheapy plastic fantastic (AVOID!)
2) Basic mass produced quality table (in this category pivoted is usually better)
3) Midrange table (this is where the majority of vintage linears sit - and are very good)
4) TOTL mass produced table (Linears in this category are excellent - competitive with many of the best arms today)
5) Boutique hand crafted & Audio Jewellery (great variation here, some audio jewellery is just that - look but don't use! - others are prefectionist works of audio art that perform as well as they look... droolworthy and mostly performance to match)

[Fishtails]

Thanks for your input and opinions. Interesting reading.
The one I found was a kenwood kd-74f and seems fairly decent.
Not a cheap lightweight:)

I also found a huge amount of mint stereo audiophile gear including
Denon amp
Audiophile Sony cd player
Dual tuner
Sony tuner

Will post models and pics soon.

This has been a good week!!

[goatbreath]

If you got it for nowt,,nice one...that is bargain hunting beyond me,,I tend to try and get stuff for nearly nowt..Of course I am Scottish !!

[Fishtails]

We have council collections every six months in our area where people throw all sorts of stuff out on the street. If you drive past at the right time you can be very lucky as I was and pick up amazing stuff for nothing!!

[dlaloum]

It is a great aussie tradition....

ebay is somewhat eroding it, but it is always worthwhile keeping an eye out during hard rubbish collection week!

Some local councils have tried to get rid of this tradition, and all the locals kicked up a major fuss.... so it stands.

During hard rubbish collection week you see people carrying home furniture, white goods, you name it! - And many people cruise the streets looking for "bargains".

Quite good fun really

bye for now

David

[Alec124c41]

We call it "curb shopping." I've found a few goodies, too.
And the original question: there are some great linear trackers, and some not-so-great.

Cheers,
Alec

[Hanuman]

It should be self-evident that the principle of linear tracking makes sense since it's the only way the stylus could possibly trace the same line across the record as the cutter head. The best implementations, however, have always been very complicated and expensive. You wouldn't expect there to be too many dud examples because getting the thing work at all would surely call for some sound engineering.

[vinylrayk]

Hi people

What are the benefits of linear tracking if any?

Look forward to your opinions!!

It's time for me to weigh in on this, and I realize I'm poking a hornets nest with a stick. I've modified and built several arms since I was a teenager, and I've learned a benefit of linear tracking arms that I have not seen much discussed before. Paradoxically, it is related to offset angle geometry but has nothing to do with tracking error! IMO, the main and not-at-all obvious advantage of linear trackers (LT's) is that the LT produces an order of magnitude lower frequency modulation distortion [FMD] during mass/compliance resonance dynamics. Let me see if I can explain this without hijacking your thread.

Frequency modulation distortion in this case is essentially the same phenomenon as flutter in a tape transport or motion picture projector. Extensive research was performed on the topic in the 1950's and the bottom line is that perceptive sensitivity to flutter is a bell shaped curve with maximum sensitivity in the region of 6Hz. With tonearms, it occurs because of scrubbing of the stylus fore & aft along the groove during resonance conditions. In the vertical direction this is primarily governed by stylus cantilever length and the angle of the cantilever relative to the record surface. In the horizontal direction it is likewise governed by the cantilever length, and in this case by the angle of the cantilever with the TANGENT of the groove, but now the offset angle and overhang become major players in the equation. Of course, damping, compliance, etc., are factors. The basic concepts describing this were very well explained in Shure's literature discussing the dynamics of their viscous damping brush, and readers are encouraged to review that before I proceed further. The document is available on Shure's website here:

http://shure.custhelp.com/app/answers/d ... b0ZiWWs%3D

OK, now that you're back, let's look at the vertical case (From Shure):



Vertical displacement of the head causes scrubbing along the groove. All arms are susceptible to this. Mass, compliance, damping, and cantilever angle are factors. You can't do anything about the tracking angle - that's fixed by the cartridge design. Shure's viscous damped brush is VERY effective on mitigating scrubbing induced flutter in the vertical mode.

For the horizontal case (From Shure):



Horizontal displacement of the head also causes scrubbing along the groove, and all arms are susceptible to this, too. HOWEVER, notice in this case that the angle is the offset angle. You CAN do something about the offset angle. In a linear tracker, the offset angle is zero. Vsin(zero) = zero! Eliminating the offset angle eliminates the scrubbing, which means no FM distortion (no flutter). 12 inch arms with a smaller offset angle do better than 9 inch arms, but not by much. Here's the horizontal case redrawn to the same scale except with the offset angle changed to zero:



Well, no, its not THAT simple. It doesn't totally eliminate the flutter, but linear tracking arms have an order of magnitude less horizontal mode scrubbing and hence, less FM distortion, than do conventional arms with an offset angle. Bruel & Kjaer noted this in their investigations of mechanical resonances in turntables and printed an application note on the subject in 1977. This is available in the VE library:

viewtopic.php?f=46&t=1281#p3544

A detailed mathematical accounting of the correlation of tonearm geometry to the FM distortion phenomenon was published in 1982 in the Journal of the Audio Engineering Society:

http://www.aes.org/e-lib/browse.cfm?elib=3825

To demonstrate the audible difference in FM distortion, or flutter sensitivity, between conventional pivoted arms and LT's you need a test record that has a horizontally modulated low frequency sweep combined with a mid-frequency pilot tone. Unfortunately, the Shure Audio Obstacle Course era 4 & 5 disks use a vertically modulated low frequency sweep, and most other test records that have a horizontally modulated sweep don't include a tell-tale mid-frequency pilot tone. The best test records I have for demonstrating this effect are the Ortofon #0001 and #0002, track #8, which has a 2349Hz and 2960Hz pilot tone superimposed on a low frequency horizontally modulated sweep. Ortofon chose those frequencies because we are very sensitive to pitch variations and flutter effects in that range. Another is Hi-Fi News, Side 2, track 2 which has a 1000Hz pilot tone superimposed on a low frequency lateral sweep. On these tests you hear a warbling or flutter effect on the pilot tone as the arm/cartridge encounters the mass/compliance resonant frequency. The flutter effect in the horizontal mode is much less audible with [servo driven] linear tracking arms than with conventional pivoted arms that have an offset angle and overhang. High compliance, low VTF cartridges are the most susceptible. I suspect that many of the posts I've seen lately on "Jico wobble" are related to this problem, and those cartridges would benefit greatly from a low mass linear tracking arm.

On real records with music the FM effect can be triggered by warps, as well as certain transients that cause a sudden change in stylus drag. Note that preamp subsonic filters can somewhat mitigate amplitude related problems associated with low frequency arm wobble, such as woofer pumping. But, once the scrubbing induced FM distortion is there from the head bobbing around and you hear the flutter effects, you can't filter that out.

I have been using a Rabco SL8E for which I retrofitted a low mass viscous damped unipivot arm and an opto-electronic continuous variable speed servo control of my own design. It is currently fitted with a Shure type 4, and this combination has been able to play anything I throw at it without a squawk. The damping brush pretty much eliminates vertical mode FM flutter, and the linear tracking geometry (no offset angle) pretty much eliminates horizontal mode flutter. Judicious damping at the unipivot stabilizes everything.

Another inherent advantage of this type of LT design is that the stylus drag forces are in the same plane as the cantilever and the horizontal motion pivot of the arm. Forces on the cantilever resulting from variations in stylus drag in arms with offset angle have a tendency to resolve themselves into both vertical and horizontal components. Tracking a warp typically also results in some horizontal movement. With LT's, what happens in vertical, stays in vertical, and vice versa.

I am a big advocate of linear tracking arms. Sorry, I'm not a fan of air bearing LT's.

[dlaloum]

Excellent Post !!!

Would you also care to put on your flame proof suit ( ) and explain your objections (theoretical/objective or subjective, or both) to air bearing LT arms?

Enquiring minds want to know!

My own LT experience is with the Revox Linatrack which is a very low mass (4g) servo linear tracking unipivot with magnetic pivot damping.
And I like to run it with a Shure/SAS and the damping brush - so a relative to your setup in terms of many of the design principles used.

I have read much verbiage, almost all of it positive, about the air bearing linears...
Your comment is one of very few bringing a critical (negative) perspective to this type of arm design - very interested to hear the reason behind the comment.

thanks

David

[bauzace50]

Hi,
just a little observation on my own (long departed) Rabco straight line tonearm, fitted to one AR XA turntable:

It was an inconvenient fit, which looked like a patch-up job.

It did NOT fulfill the theory of tangent tracking I explain: in order to move accross the record, the tonearm HAD to move OUT OF TANGENCY in order to actuate the servo system that moved the tonearm to the following grooves!

Therefore, you had a series of many non-tangent readings along with some tangent readings of the grooves along the record. For me, an unfulfilled wish for tangency.

But the most important Single Criterion (in my view): did it sound any better? I could not perceive any difference.

Not wishing to be an iconoclast, but true tangent tracking is only possible IF the tonearm has no need to move out of tangency to navigate the entire record. THAT would require a perfect coordination between the tonearm movement AND the record's inward scroll! That would be prohibitively expensive and a CALIBRATION NIGHTMARE.

A huge part of the difficulty is the actual record engraving! You see, the grooves in EACH record have a UNIQUE inward spiral scroll Because the grooves are engraved with varying depth and varying pitch (inward travel rate) depending on the program's dynamics! (AND the additional problem of the off-center situation).

You would NEED to coordinate record manufacture and tonearm travel in order to achieve perfect playback tangency at all. THAT would be prohibitively expensive, to make it the province of select few princely practicioners. Matter of fact, it might be more practicable in the mode of the cylinder recordings of the late 19th century.

I'll take pivoted tonearm tracking any day,
bauzace50

[dlaloum]

Heheh ... fire at will then?

All servo arms work on the same principle...

They are basically pivoted arms with a moving pivot point.

So they have some of the same issues that any pivoted arm has, in addition to the advantages of an LT (and the difficulties of an LT).

Regardless of the brand/model etc, they all allow the arm to move on its pivot point, and detect the offcentre position, then shift the pivot to reposition things.

So yes, all these arms go out of tangent one way, get adjusted to a little out of tangent the other way, track across the zero point and the cycle starts again.

Depending on the design, many of these arms do not in fact "stop" the motion just accelerate and deccelerate it as needed, others do in fact stop/start.

The quality of the arm can often be determined by how well this adjustment is made - a tonearm is a VERY VERY sensitive device - some LT's have earned a bad name for audible "crabbing" across the record surface - ie: the motor turns on and shifts the arm, then turns off and the process is audible on the output (NASTY!). But this issue is no more or less common than bad bearings on a pivoted arm (regardless of whether the bad bearings are due to bad/cheap design or wear and tear).

Additionally there are the same differences on LT's as with any pivoted arms - there are unipivots and traditional bearings, static balanced and dynamic, damped and undamped, not to mention low mass and high mass, and even ultra short (gantry is over the record, sometimes in the TT lid) or full length.

In terms of the actual level of tracking error generated when the arm is at its max non-tangent point before being adjusted... any decent LT will keep this at substantially less than half the maximum error that any pivoted arm reaches.

An LT spends most of its time as it moves across the surface of the record at far less tracking error than any pivoted arm.
Even a 12" arm will have maximum tracking THD of circa 0.6% at its max tracking error of around 1%

With a Linear tracker like my Revox, the max tracking error spec is 0.5 degrees, on my own hand adjusted example, I've measured max error at 0.3degrees.
So your worst case Lateral Tracking Error (LTE) on the revox is around 1/3rd that of a 12" arm or 0.3deg vs circa 16deg - that means in THD terms less than 0.05% vs 0.6%.

Audibility and perception are of course a completely seperate issue...

But normally 0.5% THD is considered well within the audible range.

bye for now

David