HELP - tonearm with no offset, overhang or side thrust.

[Nat]

No audio system sounds like live music - they are in two different acoustic spaces, with the first superimposed on the second, and usually the original dynamic range is much greater than would be tolerable in a domestic setting, and it is likely limited by the mics capabilities also.
Some people like expanders to give more of an approximation of the original dynamic range, but most people don't like the audible pumping as the circuitry tries to catch up with the signal. In some ways distortion functions to make loud sounds louder, so a poorly reproduced signal may sound more vivid - this seems to me to explain the fact that many metal heads are perfectly happy with crappy systems (but this may be audio snobbery on my part). Perhaps the underhung arm design sounds more dynamic because of its geometric issues.
The offset angle of tonearms minimizes distortion, but at the expense of requiring antiskating, which causes its own issues. It is pretty clear that there are people who prefer the greater overall distortion of underhung arms to the issues caused by offset angle. I guess it is a matter of taste.

 

[mr_petit]

The offset angle of tonearms minimizes distortion, but at the expense of requiring antiskating, which causes its own issues.

The non offset tonearm also generates a skating force due to the massive tracking error. Not as much skating force as the offset tonearms, but at least about half. And it's not constant, but varies from half negative to half positive. And there's no correction on that what soever (at least, I haven't seen a non offset tonearm with antiskating system that corrects that)
See my post earlier in this topic. The tracking error is that big.

 

[cgallery]

The non offset tonearm also generates a skating force due to the massive tracking error. Not as much skating force as the offset tonearms, but at least about half. And it's not constant, but varies from half negative to half positive. And there's no correction on that what soever (at least, I haven't seen a non offset tonearm with antiskating system that corrects that)
See my post earlier in this topic. The tracking error is that big.

Tracking error doesn't cause skating forces. Overhang and underhang cause skating forces.

 

[ripblade]

Tracking error doesn't cause skating forces. Overhang and underhang cause skating forces.

Actually, it's caused by the lateral displacement (linear offset) of the pivot in relation to the friction vector. The greater the displacement the greater the force. With an offset arm it's displaced to the left beyond the spindle; with a straight arm it's in the playing area directly behind the null. This results in a much lower force initially (or the DJs wouldn't use it) that changes direction at the null, helping to even out stylus wear.

 

[mr_petit]

Tracking error doesn't cause skating forces. Overhang and underhang cause skating forces.

This is incorrect.
Any angle >0deg between groove direction and and stylus tip-tonearm fulcrum line causes a skating force.
So in this case also the tracking angle error.
With a normal offset 9" tonearm this angle is max ~20-24deg, and with a 9" underhang tonearm, this angle is max ~12deg. (So roughly half that, see my other posts earlier in this topic).
So with an underhang tonearm there is definately a skating force created and it's not compensates. With this type of tonearm, on the outside of the record the arm (and cantilever) is pulled to the inside, and on the inside of the record the arm (and cantilever) is pulled to the outside.
Just like on an overhang tonearm, this skating force should be counteracted, but I havent seen any underhung tonearm that does this.
Pretty strang actually if you think about it, considering the price of some of them...

 

[Nat]

I was writing this when mr petit posted, so didn't see it until after he posted, so repetition of his points wasn't intentional.

I actually have a decent grasp of the geometry and force vectors involved in skating and its more complicated opposite, antiskating, and I do know that all pivoted arms, offset or not, will skate - in the case of underhung straight arms there is one point in the middle where there is no skating force, but everywhere else there will be more or less skating, and I suspect, in different directions depending on which side of the middle point. I believe I made these points earlier in the thread.
My suspicion is that exasperation with the variability of skating force (and, I'd note, of expert opinion about what to do about it) depending on groove modulation and stylus type is intense enough to many users that some just ignore it, and others welcome any alternative to dealing with antiskating, so find a lot to like in underhung arms.
I have been trying to get the right antiskating force since the early 70s, and anyone who tried to set antiskating when using a very high compliance cartridge surely noticed that the most obvious thing that antiskating did was cock the cantilever since the skating force was applied to the stylus, whereas the antiskating force was applied via the cantilever's pivot point, so skewing was inevitable. Because very high compliance cartridges have such flexible dampers, the skew was obvious, and obviously completely undid all that careful alignment of the stylus you'd done, since now it was at an angle in the groove - were you supposed to cock the cartridge to compensate? But wouldn't that then affect channel balance? And so on til you tore your hair out.
All you audiophiles who came along after very high compliance cartridges disappeared may not notice any skewing, but I bet its there. I suspect the high regard for Moving Coils, the acceptance of tracking forces above a gram and a half, and the renewed/continued interest in older cartridges, which usually had high tracking forces, may all be related to stiffer suspensions. (And this goes double for Deccas.)
I have thought about an antiskate mechanism that applies the force to the cantilever essentially at the stylus, via a thread (obviously a thread running all the way across the record wouldn't work, and even if it did, it would make playing a record ridiculously challenging, but an arm attached to the main arm pivot but also attached via an adjustable spring or weight system to the plinth might be manageable for the more demented level of audiophiles. But I suspect that market acceptance would be close to zero.

 

[mr_petit]

I have been trying to get the right antiskating force since the early 70s, and anyone who tried to set antiskating when using a very high compliance cartridge surely noticed that the most obvious thing that antiskating did was cock the cantilever since the skating force was applied to the stylus, whereas the antiskating force was applied via the cantilever's pivot point, so skewing was inevitable. Because very high compliance cartridges have such flexible dampers, the skew was obvious, and obviously completely undid all that careful alignment of the stylus you'd done, since now it was at an angle in the groove - were you supposed to cock the cartridge to compensate?

Do you own a Dual Skate-O-Meter? Or are you familiar with how it works?
Because, despite what you're writing seems logical, it doesn't work that way, otherwise those skate-o-meters wouldn't work.
You can look at a skate-o-meter as a cartridge with almost infinately high lateral compliance (there is of course some friction on the cantilever fulcrum, but my orsonics have jewelled bearings, so it's very very little).
When dialing out the skating force with a skate-o-meter, when the proper AS force is applied, the cantilever sits perfectly straight. In other words, there is no force present that can cause skewing on the cantilever, as that is the very effect what would cause the skate-o-meter to point to the left (or right).
Skewing of the cantilever with high compliance cartridges is caused by setting the imporper AS force, not by applying an AS force by itself. If the proper AS force is set, there is no skewing present.
So if you've been struggeling with this aspect for half a century, a skate-o-meter would be an invaluable tool for you
For me they were an eye opener.

 

[Nat]

I haven't ever seen any of these things, but have known about them for years. I am not confident that I understand how they work. Perhaps I put too much faith in my analysis of the forces involved - it may be that the drag of the record in the direction of the groove is enough to pull the cantilever back from the skew that is visible when the stylus is in the groove but the record is not rotating. But I saw the skew all the time even when the record was playing - certainly less, but still visible. This was with a Mayware Formula IV (which has very little friction, so that's not the issue) and Sonus Blue, AKG P8es, and other cartridges, and even with my first turntable, a Pioneer PL 12d with a Shure M91ed.
Have you checked the Skate O Meter results agains what happens with actual very high compliance cartridges?

 

[tabarddn51]

That's very interesting about Under-Hang producing about 45 to 50% on the skating force of over-hang alignment. I take it that the different Off-Set angles produce different tracking error. Which is one of the reasons I only use 12'' arms, as it leasers this even more significantly. However the very intriguing thing I remember when researching the Vivid Float arm was that the manufacturer held a S/Q clinic on the different length of arms. With the results surprisingly (well according to then anyway), their 7'' achieved the highest rating!!
You can never get away from tracking error, even using the various & often over priced gadgets. The only possible way is to change the head-shell/cart angle as the arm traverses the LP. This has been done with some success from various head-shell spring loaded units and some arms notably to Frank S's latest arm which somehow swivels the whole T/A upper body.
As we all know playing vinyl is a sum of compromises and it still amazes me on just how good it can sound, considering all of those compromises.
Later this year I am going to try one of those swivel head-shells in an detachable head-shell arm I am developing. But from what I have read so far they work best with higher tracking weights, which usually means low compliance carts & high mass arms.
I have been using the U/H system for over a year now & am delighted with the increase in S/Q it is giving me, I have no intention of ever going back.

Cheers

 

[drmoss_ca]

I've read somewhere (I think in a review of the ViV Labs arm), that using a grooveless smooth disk, the arm shows a tendency to very slowly wander towards the null point, both from the outside and from the inside of the disk. Any skating force it experiences is dynamic, coming from groove interaction, so there's no point trying to measure it with a WallySkater. The other trick it uses is to set the null point nearer to the label, which means tracking error is greatest at the start of a side, but that this is where the groove information is of highest quality, being less tightly packed. The null point being nearer to the label then means less tracking error where the information in the grooves is more tightly packed. This is said to minimise the effect of the tracking error.
Something we often forget is that underhung arms have been very much a Japanese thing, and when Yamaha came out with the arm on the Reference GT5000 they were not breaking new ground in their home market.

 

[loudnoises]

I've read somewhere (I think in a review of the ViV Labs arm), that using a grooveless smooth disk, the arm shows a tendency to very slowly wander towards the null point, both from the outside and from the inside of the disk. Any skating force it experiences is dynamic, coming from groove interaction, so there's no point trying to measure it with a WallySkater. The other trick it uses is to set the null point nearer to the label, which means tracking error is greatest at the start of a side, but that this is where the groove information is of highest quality, being less tightly packed. The null point being nearer to the label then means less tracking error where the information in the grooves is more tightly packed. This is said to minimise the effect of the tracking error.
Something we often forget is that underhung arms have been very much a Japanese thing, and when Yamaha came out with the arm on the Reference GT5000 they were not breaking new ground in their home market.

What was the response from the Japanese market? One assumes this discussion happened there as well. It's been a few years and they haven't replaced it yet, so I'm guessing it's reasonably good.

 

[Beobloke]

A crappy tonearm. Yes, that's a fair comparison...

I have found most of the Vestax tonearms I've used to be pretty decent. One or two of them are very good indeed.

Out of interest, what didn't you like about the one you tried?

 

[drmoss_ca]

What was the response from the Japanese market? One assumes this discussion happened there as well. It's been a few years and they haven't replaced it yet, so I'm guessing it's reasonably good.

It would be very interesting to know that. There must be Japanese audiophile forums that we don't know about!

 

[ripblade]

I have found most of the Vestax tonearms I've used to be pretty decent. One or two of them are very good indeed.

Out of interest, what didn't you like about the one you tried?

Never tried one, but if it's described as 'dime a dozen' it shouldn't be compared to a standalone arm worth many multiples simply because it is straight. Quality matters big time, much moreso than geometry.

 

[EWarrior]

The other trick it uses is to set the null point nearer to the label, which means tracking error is greatest at the start of a side, but that this is where the groove information is of highest quality, being less tightly packed. The null point being nearer to the label then means less tracking error where the information in the grooves is more tightly packed. This is said to minimise the effect of the tracking error.

The effect of tracking error is tracking distortion. They are not minimizing it, though – or at least not for records cut to IEC specs. That would require a null point around 79mm. Their null points are ~89mm, which results in significantly higher distortion at the inner groove of long records.

 

[tabarddn51]

Interestingly Vestax do a separate tonearms, which according to them, it has a 6 month waiting list. Looks quite a descent design, however is very limited with specs given.
There is also a Y/T video on the arm being played with the T/T positions at about 45degrees, still playing perfectly OK!! Cost around 350 Euro, so quite affordable.

Cheers

 

[Beobloke]

Interestingly Vestax do a separate tonearms, which according to them, it has a 6 month waiting list. Looks quite a descent design, however is very limited with specs given.
There is also a Y/T video on the arm being played with the T/T positions at about 45degrees, still playing perfectly OK!! Cost around 350 Euro, so quite affordable.

Cheers

Interesting! I’d not not heard of those - do you have a link?

 

[tabarddn51]

I just Googled & viewed their photos.

Cheers

 

[Beobloke]

Then all you're seeing is spares for existing turntables, not complete tonearm assemblies.

 

[tabarddn51]

That's true, But if you cannot add a counterweight & head-shell, you should not be fiddling with T/T's. What more do you want for for under 400 Euro's