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Truly straight underhung tonearms for hifi use

muovimies

muovimies

Super Member
Straight tonearms are common in DJ tables because of getting rid of skating force tracking is better and less prone to skipping when scratching etc. heavy duty use. Tracking distorion is obviously highly increased because the underhung geometry can reach only 1 null point over the course of the record. This is why there really haven't been many arms aimed at hifi use with this sort of geometry, the two commercial examples I'm aware of:

http://audio-heritage.jp/YAMAHA/etc/ysa-2.html
( http://www.audiokarma.org/forums/showthread.php?t=661904 link to a japanese blog in this thread by Theophile)

http://www.stereotimes.com/post/viv-lab-rigid-tonearm/

Skating force and compensation for it with antiskate is a compromise of course, but one that is necessary to obtain the geometries with two null points and the lessened tracking error. Now it is arqued by some, that the skating force is actually more detrimental to sound quality than the increased tracking angle error of an underhung tonearm.

I find this very interesting and would love to hear a high quality truly straight tonearm with this sort of geometry. Since that is unlikely, I decided to pursue a project of some sorts to modify a tonearm for underhung geometry with zero offset angle.

As a proof of concept I mounted a Shure M75 with EVG stylus on a Thorens headshell in this manner, I used the TP-60 headshell but mounted the cartridge in the holes that are not meant for cartridge mounting. It's very slightly offset, but underhung and the geometry is such it reaches a null point around 75mm from the spindle or so.

This is far from optimal but sounds better than I expected. Worth noting is the TP-16 arm has magnetic antiskate, and even when the dial is set at 0 there is still some little antiskate present, so this is less than optimal arm for this test, since on of the keypoints was to get rid of skating forces and the need for antiskate.

I can say it seems that taking skating out of the picture, cartridge alignment is not nearly as sensitive - if the arm was overhung and there was this much tracking angle error, tracking would be very poor in the inner grooves and distortion would be lot more prominent. Needless to say I've been spinning only beater records at this point, but as a testing of the waters this was a success. There is no obvious increase of mistracing / mistracking nor any nasty side effects like inner groove distortion. There is something quite punchy about the sound, but at this point I'm inclined to think I'm probably hearing increased harmonic distortion.

I think the next step is to modify (in a reversible way) a Connoisseur SAU2 tonearm for completely straight geometry, I could accomplish this quite easily by replacing the headshell with a wooden mounting block for the cartridge and wiring the tonearm externally, there's no timeframe for this but I expect it to happen some rainy day :) When I get something more feasible than this M75 setup put together, I'll try to do some comparisons and hopefully put up sound files as well.
 
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I would imagine that with the total lack of off-set angle (unless you angle the cartridge), the only stylus you could use with this type of straight arm is a conical one.
 
Currently waiting for the glue to settle... Esoter Azzurra (Glanz moving flux with 0.5mil spherical diamond) on Connoisseur SAU2 tonearm. Initial impressions with the "headshell" fixed using copious amounts of bluetack and tape were promising enough. I listened to some vinyl from the crap box were I keep records in bad shape - I haven't dared to let these setups come anywhere near good vinyl yet. The alignment will be such that the null point is around 80mm from the spindle, perhaps a bit further away from the inner grooves that would be optimal, but for testing purposes it'll be fine and will also highlight any issues with tracking inner grooves.

This goes in the crazy category, but it's been a bit of an epiphany - for one thing even with elliptical styli alignment seems to become largely a non-issue which is puzzling. There's really an 'immediacy' and certain drive to the sound, I don't know yet what it is, if it's a good thing or just a lot of harmonic distortion that tricks the ears (or phase anomalies), I think I'll know more once I dare to spin some discs I know better. Also at some point a reality check using conventional setup will be in order... Whether this turns into anything 'real' or not, it's a learning experience for sure.
 
CONICAL ONLY! Still won't perform as well as a correct tonearm design with offset angle, correct length, and correct geometry. Alignment is key, even with conical tips. Tracking error with the discussed arm too high.
 
I've been planning a similar investigation. I happen to have a Kenny 770d with a straight arm and removable headshell that has a standard fitting. Only problem is if I substitute a straight headshell I can't get the proper underhang. It's supposed to be about 5mm in from the center of the grooves.

The contention is that side forces on the cantilever are more sound killing than alignment error. All pivoting arms have some degree of alignment error. Why doesn't a 9" arm tear up records when it's about 3° out? What's the max alignment error for a particular stylus?
That ViV arm (2nd link) is over $4K and won two product of the year awards. I doubt if they were limited to a spherical tip. Funny thing is, they say the shorter one sounds better!

On the other hand, you're bound to get more phase error between channels, but how much can a tip rotate? Would the distance be much greater than "normal" alignment error. I don't have answers here, but it's an interesting question. I wonder if the Yamaha arm was before or after the P2 and P3 linear trackers.
neo
 
All I can say at this point the problems with tracking angle don't matter nearly as much as they would with an overhung setup. The tracking error in the current setup is ridiculous on the first track, yet music sounds good. Worth noting I'm using a spherical stylus, but the same thing with happens with elliptical styli.

Unfortunately there's too many variables that changed for meaningful sound quality comparison, since my setup also fixed the weakest link in the stock Connoisseur SAU2 arm which is the headshell. It's a press fit to a plastic plug in the arm tube, that can't be good for rigidity. Now I have a wooden block glued to the arm tube as a headshell, to which the cartridge is attached with bluetack and tape (really tight and more solid fit than bluetack and tape maybe sounds like). Still, from this test I'd say an underhung truly straight setup is not nearly as ridiculous idea than it sounds at first and a good implementation would probably surprise many people.

I'm wondering if minimizing offset and overhang would have any benefit, to get the least amount of skating force while still having two nullpoints, I'm thinking the inner one perhaps around Baerwald and the outer one could be beyond the record area, it would still keep the alignment error far less than my current setup, with the compromise of having some skating force, but less than usual.

I'm spinning records as I'm writing this and just about reached the nullpoint now so I know I'm not listening to increased harmonic distortion at the moment :) Compared to how this table sounds stock the sound is more punchy and 'fast' or 'tight', it sounds 'effortless' and really transparent. Hard to put it into words but it's a really apparent change.

I'm thinking next step is to revert to stock, and I'll try to make that headshell mount more rigid somehow to see if I can carry some of this over to the stock setup.
 
muovimies: "Getting rid of skating force" is a bit of an exaggeration, though, because one still doesn't really get rid of that with a short, straight DJ style arm - it's just reduced quite a good bit...

Greetings from Munich!

Manfred / lini
 
Muovimies,
Thanks for posting the Yamaha link. I didn't notice that it says 1985.
This is after the P1, 2, and 3 linear trackers were discontinued. Here is a google translation of the description:
Yamaha GT series limited production straight tone arm, which has been developed to emphasize the expressive power in record playback. Needle and cantilever of the cartridge overlap on the straight line and the center line because it is a pure straight structure of the offset angle zero, has maintained a constantly stable balance during the tracing. Also, because the overhang is negative, an arm effective length more than 30mm can also be reduced, and has realized the high rigidity and low-resonant. Furthermore, coupled with the 2 ball and radial pivot bearing, it is suppressing the left and right direction of rattling. The brass pipe of non-magnetic chrome-plated direct high rigidity, we have adopted the straight arm pipe of the double structure to tighten brass cutting arm pipe holder of high rigidity. This has reduced the occurrence of unnecessary vibration. Ritz line of 8 Honkyori the shell lead, OFC wire diameter 1.2mmφ is in the arm, the PU cable I have adopted ITK3000. This we have realized the round trip resistance value 0.15Ω. GT series options are installed of Otorifuta YAL-1 can not be.


The YAL-1 is an auto arm lifter available as an option on the GT-2000 and other GT series (750). The GT2000 had 3 arm options, the YA-39 S arm, the YSA-1 straight arm, and the YSA-2 upgraded straight arm!
http://www.thevintageknob.org/yamaha-GT-2000.html

More recently (I think), there was another high end straight arm - no offset from another company. I'll have to find the name.

I believe the underhang null point should be about 100mm from the spindle. That would be around 5mm toward the spindle from the center of the grooves (60 to 150mm). If you have a lot of records with grooves closer to the spindle, maybe a 90 or 95mm null would avoid pinch effect on inner grooves? Using a spherical tip to test, would disadvantage a no-offset pivoting arm. Its weak point is alignment error and a spherical is more likely to pinch. As long as you're using non-collectable records?
Regards,
 
FWIW, I don't believe skating force per se is the real problem. My guess is it's the constant variation in skating force, combined with the inability of any anti-skate system to deal with it, that causes some kind of cantilever "dance" that degrades the music. Think dynamically. Considering the static geometry will only take you so far. Straightening out the tone arm will help, but IMO you really need to move the pivot point, either a traditional linear tracking arrangement, or an arbitrary path like the Schroeder arm, for everything to work right. Or, make the arm l-o-n-g! I remember another Japanese straight arm with a very high pivot point that followed the straight arm approach. It had very good reviews.
 
Another straight arm

The Nottingham Ace Space arm is another straight design. I have one which I haven't mounted yet (planned for the B-12H when it is done), but I've heard one on a Nottingham table a few times and it was wonderful. Of course in this case the cart is skewed on the head to get proper alignment so in fact the geometry is still fairly normal.
 

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If this seems too far off topic then ignore it, don't want to derail the OP's thread.

What are the benefits of a straight-arm with skewed cartridge over the standard layout?

I think if I understand this I may understand what the OP is trying to achieve too, even though they are very different approaches to a problem.

If this seems too far off topic then ignore it, don't want to derail the OP's thread.
 
The one thing that is very different is of course the offset angle, by nature.

The offset angle means that tracking a sine freq will be very different for the inner wall in the groove compared with tracking the outer wall. The tracking will be so much more difficult at the inner groove wall. When the needle is happily tracking at e.g. 20deg groove radius at outer wall, at inner wall it is not just as happily tracking more than 40deg.

This difference is eliminated with a straight arm. Instead we are getting tracking error. Tracking error means some harmonic distortion and skating forces, but harmonic distortion might not be easily detected. And this is just depending on how long we would like to make the arm.
There is a German maker that makes long straight arms, but I can´t remember the name right now.
 
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I reverted the setup back to 'standard' meaning offset angle, overhang and two point alignment geometry. I recorded some samples to make A/B comparison possible, but there's too damn many variables as always in vinyl playback to make meaningful conclusions. For one thing after I had already recorded the samples, I realized the ones with the offset geometry had higher VTA, so trying to dial that in at the moment.

It seems to me the offset geometry makes alignment much more critical - with the straight setup it didn't seem to matter much - sure, there must be more distortion, but it's harmonic and hard to notice and because the greatly lessened skating force the stylus seems to have so much more easier time navigating the grooves, even at the parts where the alignment was most off, there was no nasty effects like you'd get in a offset setup when alignment gets very wrong. The biggest problem was channel balance and extraction of fine detail at the outer grooves, where the alignment was most off (we're talking multiples of a worst case scenario with a two-point alignment).
 
" The product page from the Sakura Systems website, U.S. importer of RS Labs, says, “most of today’s tonearms come with the offset angle to minimize tracking error. The distortion caused by tracking error can easily be explained geometrically and easy to solve geometrically by giving an offset angle to the arm, but the actual effect of the tracking error on the sound is less serious than that of the strong inside force caused by the offset angle. The inside force changes dramatically by the frequency and amplitude of the signal, and a static canceling system is not effective enough. Overly concerned on tracking error, arms with offset angle and forget the forest by just focusing on the tree. Straight arm has tracking error, but it is far less damaging to the signal than the strong inside force caused by the offset angle "

IMO there's some truth to what's said above, I just don't know which is the more damaging compromise in the end. I'd still be inclined to prefer getting the geometry right, but I'm not so sure anymore :)
 
ConradH said:
Why compromise? Both problems can be solved in several different ways.
Click to expand...

I was referring to simple single pivoted arms, though it does seem to me there's always compromises in analog playback, because one problem is rarely solved without adding another problem to solve :) And perhaps more importantly there's the personal compromises in system building due to funds...
 
gusten said:
The one thing that is very different is of course the offset angle, by nature.

The offset angle means that tracking a sine freq will be very different for the inner wall in the groove compared with tracking the outer wall. The tracking will be so much more difficult at the inner groove wall. When the needle is happily tracking at e.g. 20deg groove radius at outer wall, at inner wall it is not just as happily tracking more than 40deg.

This difference is eliminated with a straight arm. Instead we are getting tracking error. Tracking error means some harmonic distortion and skating forces, but harmonic distortion might not be easily detected. And this is just depending on how long we would like to make the arm.
There is a German maker that makes long straight arms, but I can´t remember the name right now.
Click to expand...
Thank you; I understand what you wrote so you clearly kept is simple :thmbsp:

Fascinating subject indeed.
 
I had a Vestax PDX3000

It had a straight underhung tonearm.

The manual was quite specific about cartridge mounting and achieving the correct underhand etc..

It always sounded better than my correctly aligned SL1200

I tried an elliptical stylus as an experiment, Ortofon OM10, despite the fact that the alignment was visibly WAY WAY off at the beginning and to a lesser extent at the end of a record it sounded good, no discernible distortion or any other obvious artefacts.

I'm not saying that it was a HiFi table or anything, just that the sound did not seem suffer due to the funky arm.
 
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