Tonearm for Teres turntable - approx $1000 - ??

As long as you are planning to stay in the medium compliance range of cartridges, such as the ZYX, then unipivots can be a valid choice for a tonearm. As the compliance of cartridges gets lower, it becomes more and more difficult for unipivots to retain proper control over the cartridge. There are some stabilized unipivots which can adequately control low compliance cartridges, but they are generally more expensive ones.

The main thing is to be sure that the tonearm you are considering will be matched to the range of cartridges that you will use. The type of bearing, arm tube, and effective mass, are all things that must be considered into the equation.

The Hadcock is an unstabilized unipivot arm that is known to be a good match with high compliance cartridges such as Grado. Many people consider Hadcock/Grado combinations to be a "magical" matchup. But it would be a far stretch to try to match a Hadcock to a Denon DL103, Shelter, or Koetsu.

It is all "relative" to the cartridge/tonearm matching. Many arms can be very good when matched with the right cartridges, and mediocre or poor when matched with the wrong cartridges. It is difficult to discuss the merits of a tonearm, unless a cartridge is considered in the discussion. Some arm designs are excellent at some things, and poor at others. In many cases of relatively good tonearms, it is the match with the cartridge that will decide what is best to use.

Regarding the "TWL HiFi mod" for the OL Silver, the effect of that mod is only moderate on medium compliance cartridges such as the ZYX, and is much more effective on the lower compliance cartridges that it was designed to work with, such as Denon DL103 or DL103R, Shelter 501 or 901, or Koetsu. Improvement is noticeable with cartridges like the ZYX, but not as astounding as the lower compliance cartridges.

Can't comment on the Morch, except that I would prefer the more expensive dual-pivot DP-6 over the UP-4 personally.

Hi OakIris,

Cartridge compliance is the stiffness of the suspension donut that holds the cantilever assembly in the body of the cartridge. It is the thing that allows the coils to be moved inside the magnetic field inside the cartridge. The compliance of cartridges is rated in units of CU(compliance units), with low compliance being generally considered under 10cu, medium-low compliance typically from 10cu-12cu, medium compliance from 13cu to about 20cu, medium high compliance from 21cu to about 25cu, and high compliance anything over 25cu. These are general ranges and some people may quibble about details, but they are pretty close to being what is generally accepted. Low compliance cartridges have stiffer suspensions, and high compliance cartridges have very soft suspensions, and the spring force of these suspensions has an effect on the interface of the cartridge and the tonearm.

With regard to cartridge/tonearm matching, the rule-of-thumb is that as the compliance gets lower, the effective mass of the arm must increase, in order to have the ability to keep the cartridge stabilized over the groove, and also to make a happy mass/resonance frequency in the desired range of 8Hz-12Hz. Going lower than 8Hz in mass/resonance can cause the system to be excited by rumble frequencies which is not desireable, and going higher than 12Hz can cause the resonance of the arm/cartridge matchup to have an audible effect in the audio range above 20Hz. So, when we look for matching arms and cartridges, we strive to have the mass/resonance match within this range mentioned above. Sometimes the match can yield somewhat higher than desired results, and still sound quite good. But we want to get as close as possible to the desired range.

There are charts available on the web which have matching curves for choosing cartridges which match to certain effective masses of tonearms, but these are general, and don't include all of the information needed for complete matching criteria, but they are a good general guide. You can also use the HFN&RR test record to check the exact resonance in your system.

What they don't tell you is that there is significant energy fed back into the tonearm and bearings, which can cause the tonearm to move in unwanted ways, or make the bearings chatter or break down. This energy is most severe in low compliance cartridges, and this is why I use and recommend quality higher mass gimbal-bearing tonearms for low compliance cartridges. Unipivots can be used on low compliance if there is a specific method of stabilization present on a unipivot tonearm, and if they have the correct mass needed for it.

So, for high compliance cartridges, generally you look for a lower mass(less than 9grams) tonearm to match it. For medium compliance cartridges, you look for a medium mass(9g-11.5g) tonearm to match. And for low compliance cartridges, you look for a high mass arm of over 12grams(and sometimes much higher, depending on how low the compliance is). The high mass arms and low compliance cartridges seem to be the most difficult matches to make because there is so much energy being sent back into the arm to excite everything, that much more than just the mass/resonance issue comes into play. Generally, it is less risky for beginners to start out with something in the medium mass/medium compliance range, because they are less likely to make a big mistake there. But, there are great sonic rewards in the low compliance cartridges, if you make a good match for them.

Typically, I make my matches by the "seat of my pants" because I've had a lot of experiences with many different matchups. But, a beginner should learn the basics first, and then try to fly later.

You can do some Google searches on the key words I've used and you'll come up with a variety of articles with charts and graphs to help you.

And, if you are in a quandary, just email me and I'll help you out.

BTW, the HiFi mod makes the effective horizontal mass of the Rega arms and OL Silver arms high enought to stabilize the low compliance cartridges, even though the effective mass of the standard tonearm is marginally too low for the use of such cartridges. The result is that the shortcomings of the matchup are overcome by the use of the HiFi mod.

With an 11.5gram effective mass tonearm, I get around 10Hz as your calculated resonant frequency in the horizontal plane, and 11.2Hz in the vertical plane, using your listed formula. 10Hz horizontal and 11Hz vertical is just fine. The actual measured frequency on your turntable may vary some from the predicted, but it should be fairly close.

The OL Silver MkII is about 11.5 grams

You may note that the cm/dyne rating is also known as compliance units(cu).

As you can see, this is a combination of a medium-high tonearm effective mass(11.5g-the higher end of medium), and a medium-low cartridge compliance(with 12vert. being in the lower end of medium compliance, and 15horiz. being in the medium). It fits nicely into the general categories that I presented in my earlier post.

However, with the light cartridge mass of 4.2 grams, the counterweight may have trouble achieving counterbalance, so the the supplied ZYX headshell weight may need to be used, and this will change the calculation, but even a 4g headshell weight increase will still yield results in the similar area of mass/resonance, and certainly still be in the target frequency range.

With a cartridge like the ZYX, you may choose from either a quality gimbal-bearing arm like the OL, or a quality unipivot tonearm with sufficient mass(around 11g).