Adjusting A Cart – Part 1

As these days, we face new summits of cartridge price ranges and passionate debates on which cart performs in which way, it is time to discuss one of the most critical aspects of cartridge performance…..THE ADJUSTMENT!!!!!

It might be a nightmare for some high end cart users, if one day a real master of analogue vinyl reproduction would enter the listening room, which is packed with all the bells and whistles, and shows the proud owner that he can adjust an entry level cart to such a high degree, that it sounds better than what is available in this hypothetical Hifi paradise. Be aware that in the world of our stylus tracking the groove an error of one Millimeter is like a Kilometer from the stylus viewpoint…so precise adjustment means PRECISE ADJUSTMENT…which is not something that can be done while having an important meeting 20 minutes away and which can also not be done if our mobile phone is still switched on. Our pandemic times gives us some unknown resources which we can use to evolve to real analogue maniacs. Some of you might be surprised that sometimes it doesn’t require a new toy, instead we just need some hours of good concentrated work and the stuff we already have will blow us away! The difference of a mediocre adjusted tonearm and turntable in comparison which plays at the highest possible level is astonishing. Sometimes it is just a little move….imagine the azimuth is just 1° off and you will correct that….

You cannot believe what such a small move can do for the way the system is now able to render recorded space!

Get prepared:

To work in such small dimensions needs a lot of patience and some good tools. The first tip from my side would be to get some proper loupes normally used by watchmakers. These specially made tools can be fit into one eye so that you have both hands for working on your turntable. They also have the big advantage that they do not distort in such a heavy way – which is important if we want to judge if something is flush in a straight line. Another very important hint implies some feeling for delicate work: The next thing after a tight fit is no fit at all – so excessive force is not what a good analogue tech needs. A good adjustable light source would be the next thing on my list – because you can only adjust things which you can observe… the typical cosy dim light in our listening rooms is not sufficient!!! Besides proper tools like Allen keys, screwdrivers and a collection of high quality tweezers you should invest in a proper adjustment jig. Here we have to think about the geometry we want to adjust – because the jig depends on exactly that! If your record collection is 90% Pop and Rock you might decide to choose a different geometry than someone who is listening to big orchestral music which is normally cut very close to the label. For those classic listeners a Baerwald geometry would be a good starting point while Pop and Rock people would be better suited by something like Lofgren. A proper jig should have both geometries to choose from.

How to start?

Adjustment is done in a kind of circular form – because you cannot adjust each parameter at the same time – but a lot of them are dependant on each other. One little example: if we adjust the geometry as precisely as we can and some minutes later we adjust the VTA in a more drastic way than we thought – the geometry is off again…because the needle will now have a different position than before our VTA change. It is also a good idea to buy a very thin jig – because such a device can be placed on an old record – which helps us to do all the adjustments in exactly the plane the needle would track the groove…

First things first…. we have to mount the cartridge to the headshell of our tonearm and already we face a very important decision regarding the torque we use. This decision depends on the damping behaviour of your tonearm and the energy the cart would transfer. For example a Koetsu wooden cartridge, like the Rosewood or the Urushi range benefits from a really tight fit, it will deliver a much higher resolution in the treble and air frequency spectrum and it will also deliver better macro and micro dynamic. A Lyra cart on the other hand can benefit from a somewhat looser connection to the headshell, which will give the sound some nice midrange bloom, the Koetsu already has in spades. Speaking about torque of the headshell mounting screws, we also must ensure that both screws are tightend as evenly as possible – otherwise we will produce asymmetric tension to the cart. If you handle an unknown cart you normally have no idea which torque figure would be near to the optimum…. It will be a matter of try and error… as the torque you will use has a tremendous influence on the leading edge rendering of the cart as well as the extension of the frequency extremes, you might spend some time with just this single parameter. 

While mounting the cart and applying the four connector wires, we should spend a moment cleaning the contact pins using some isopropanol alcohol to get rid of any grease we might have applied with our fingers to this fragile contact point.

As you opted for a certain geometry which will fit your record collection, take your time and adjust the cart as precisely as possible – do it with both zero points the jig offers…. While performing the geometric adjustment you will put the needle onto the jig a couple of times to align the cantilever with the centric line on your jig. It is a good idea to adjust any antiscating device fitted to your tonearm with zero force, because otherwise the needle could be bent by the antiscating force which will result in a wrong geometry!!! Start by positioning the cartridge housing, if it has a rectangular form factor, parallel to the jigs lines… but the final and most relevant adjustment must be made using the position of the cantilever itself.
One of the most crucial parameters of cartidge adjustment is the correct azimuth – it is as important as the VTA…. And it is not an easy task to get it right!!! It is a kind of self-deception to think that the needle of even the most expensive carts is mounted absolutely orthogonal to the record surface – it is not! With just a 1° azimuth mistake in your cartridge adjustment you sacrifice the whole crosstalk figure between both channels and therefore the phase response of the cart.  To start the azimuth adjustment we align the cartridge parallel with the record surface viewed from the front of the cart. Now we have to listen to a recording where a vocal is placed dead center with a good portion of high frequency energy. Listen to sibiliants like S, SCH, T….if your speakers and the room acoustic is spot on, you will detect the slightest azimuth anomaly. Even if the sibiliants are behaving in a strange way, the frequency mid section of the human voice might be dead center…it is the high frequency spectrum where a misaligned azimuth is first detectable. But what can we do now….?? Experienced analogue cracks will turn the arm or the headshell ohh so slightly and listen again.. they have such good ears, that they manage to get the azimuth corrected in a way that if you measure the cart afterwards with an oscilloscope in X/Y mode, there will be hardly any correction necessary. But if you are less experienced there is some help coming. Take a mono recording, put it on the platter and switch the preamp to mono mode (hopefully it has such a switch or knob). Then you have to swap the connection cables from just one channel of your cartridge connectors… and put the needle into the groove… What you now here is hopefully near to no sound. Or rather a very, very low volume and just some strange high frequency events in the music, like very dynamic sibilants and snare hits or cymbal attacks. The theory behind this technique is: If we listen to a mono record we can be sure that the signal is really mono… (equal level on both channels – be aware – some carts may have channel imbalance of 1dB or more – I will address that in a follow up). If we switch our preamp to mono both channels will now send the exact same signal to our amplifier and therefore to the speakers. By swapping the connection wires of just one channel on our cart we generate a 180° out of phase signal from one channel…. When both channels are equally merged with the usage of the mono function of our preamp, we should get 100% cancellation of sound. If the azimuth is wrongly adjusted we will get more sound level – because our cancellation will suffer as the left or right channel are no longer 180° out of phase. So the technique must be done without touching the volume potentiometer anymore once we found a good setting… We will not achieve 100% cancellation because our cart does not have 90db or more channel separation as a digital source might have. With a cart we will have 30db – maybe a little bit more…so those short sound fragments of high frequency explosive sounds will remain. The goal is to make these the least audible! If you achieved that – you have set the optimum in azimuth adjustment for your given cart! Do not forget to reconnect the cart afterwards in the correct way – and please do not forget the mono switch;-)))) If you have an unipivot tonearm you might become an expert in the above mentioned technique – because the azimuth is normally changed with a slight turn of the counterweight on unipivot tonearms… but to get the correct VTF you also need to move the same counterweight… To do that without turning the damn weight is a special task…Therefore unipivot tonearms have some advantages in other disciplines – so do not bash them – try to get in a special Zen – Mode, try to smile and enjoy the unforced sound they can provide….

The VTA should be set after the geometrical installation, so that the headshell is parallel to the record surface observed from the side. Please do not use the armtube…some are conical, some have a J or S – shaped form factor so it would be very hard to be sure the cart rides parallel to the record surface. For getting an initial parallel adjustment a plexi glas block with some parallel lines engraved is highly recommended (also to get the azimuth initial adjustment right). After you managed that initial position you have to use your ears!!!! For the following listening session it is good to use records of a thickness which are common in your collection – it makes no sense to use the very best high end pressing made from 200gr virgin vinyl if you have just 3 records of that kind. So use the quality of vinyl which is wide spread in your collection. To justify the VTA you have to take some care in picking the right music. As with the azimuth adjustment session a vocal with good high frequency energy positioned dead center is a good starting point. If you use a Koetsu cart the following procedure might be a little bit tricky, because the special line contact cut of the diamond reacts very, very sensitively to the slightest changes. Listen carefully to the initial setup where the cart is parallel to the record surface…now make some slight changes…start by adjusting the arm tail upwards… listen again…. What should happen now, is that the center focus gets better – the mono mid vocal signal jumps more forward – and in the same moment if you have done it to excessively, the width of the stage shrinks. Simultaneously, the presence of the sound will increase slightly… If some Koetsu owners think you can get more treble out of the legendary cart….that is wrong! What you get is more presence – which will mask the highest treble and air performance – so you did exactly the opposite of what would be a proper adjustment. Also Lyra carts will gain in presence to a degree were the sound becomes abrasive…If you adjust a slight amount of tail down position of your tonearm you might be in for a surprise. A Koetsu will now starts perfoming with its typical delicious treble aesthetic. The recorded space is rendered in a wonderful, opulent way while the center focus is still completely intact. With a Lyra cart such a tail down position might not be what the doctor has ordered – such carts in my experience sounds best dead parallel to the record surface – but….try your own experiments ALWAYS!!!

If the tail down adjustment is done in a more drastic manner (more than 1 Millimeter) then the center focus gets more and more unsharp – we have problems to localise the vocal performance in the center – it is widened in an unnatural way. The bass response will get muddy and unprecise – the bass slows down and the tonal Gestalt is badly damaged! ATTENTION!!!!!: If you use a unipivot tonearm please check after any VTA adjustment the VTF….it will change!!!! Switch on Zen mode again……

Antiskating…..the last miracle

With anything other than a linear tracking arm we will have scating forces varying from the start of the record till the last note cut into the vinyl. So there is no such thing as a correct skating force compensation. Some people will tell you, that a test record is necessary with some tracking torture test cuts. Some people are hardcore specialists in this regard and start to increase skating compensation with more than 70 mü testband….that is TOTALLY WRONG!!!! Imagine…if a rotating tonearm tracks one side of a given record there are two points were there is no tracking error…. The arm now travels in segments in which the scating force rises – and drops again… And it is not only dependant on the tracking angle – there are many more parameters involved such as the stylus cut, the modulation density, the chosen geometry and so on. If you use excessive skating compensation your needle will deflect sideways – so all our azimuth adjustment is now obsolete – the whole phase response of the cart is totally off!!!! And even worse – the suspension of your cart will give up some day….If you do not believe me – go to ebay or some other selling platforms and check out some Lyra offerings, carefully observing the „straight“ cantilever….So forget the 70mü torture track adjustment – that is the wrong way – because the maximum with which a record is cut would be 50 mü – and even a 50mü torture test is not recommended. To get a starting point use the space between the last groove close to the label. Set the needle beneath that groove and adjust the skating compensation in such a way, that the arm follows the last groove or stands still without any movement (till the needle catches the groove). That might be a slight under compensation – but it is a very good starting point. From here on use your ears – if you detect decreased microdynamic performance of your cart – the needle might deflect….observe this with your loupe – and do it on different positions of the record surface. Keep in mind – there is no such thing as a correct compensation – it is always a compromise!!!
The next four essays will deal with some method variation to get the azimuth and the VTA correct, we will discuss the VTF parameter in detail and the electrical side of cartridge performance as well as the damping possibilities some tonearms offer to their users…

Stay tuned

E. Strauss

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