Turntable technology for Millennials or everything you wanted to know but afraid to ask

Straight tonearms

A straight tonearm is exactly as described. These are usually low- to moderate-mass designs with an angled head assembly. The Infinity Black Widow pictured to the right is a great example of an ultra low mass straight tonearm. Examples of moderate mass straight tonearms include the Rega RP-300and the DaVinci Grandezza. This style of arm is ideal for cartridges with high or moderate compliance. Most straight-arm designs use a fixed headshell for mounting the cartridge, but there are many designs that use replaceable headshells as well.

S– & L–shaped tonearms

Pro-Ject Signature 10 turntable

Curved arms are designed to accommodate moderate to low compliance cartridge designs. The one real advantage of most S– and L–shaped arms is they use an EIA detachable headshell, which makes it faster to change cartridges.

Pivot variations

Basically tonearm pivots are either gimbaled, knife-edge or unipivot.

Gimbalpivot

Gimbaled designs are the most common. With gimbaled arms the vertical and horizontal pivots use a needle point in contact with bearings, which allows the arm to move freely at the axis points. Shown is a cutaway of a Dual tonearm from a CS1237.

Knife-edge pivot

Knife-edge designs generally use a gimbal for lateral movement but a use a knife-edge bearing for vertical movement. The SEAC to the right was a dual knife-edge design. If you can, imagine a sharp edge sitting in a V-trough that the arm pivots in.

Pictured is a single pivot design.

Some examples of knife-edge arms are SME, SEAC, Jelco and Infinity.

Unipivot

I have to admit I have a personal bias in favor of Unipivot arms. In fact, up until the development of the Clarify suspended tonearm, Unipivot arms were my favorite. A Unipivot arm uses a needle point as the thrust point in contact with a jewel to act as the veering. The advantage of this design is there is almost zero friction and and minimal resonance passes through the arm. The Audiocraft AC-300 arms pictured above also used oil damping in the pivot to eliminate tonearm resonances. Later designs also used replaceable arm tubes, both straight and S–shaped.

Exotics

There are also what I call “Exotics,” designs that fit in their own categories. A great example is the Kuzma air bearing linear tracking tonearm. It uses air under pressure to isolate the arm from the tubular track it runs on, therefore eliminating friction.

A much simpler exotic at a much more affordable price is the Clearaudio Clarify tonearm. This unique design uses a nylon thread to suspend the arm as a pivot, held in place vertically with a magnet. If no parts of the arm touch, then there is virtually no friction. Also, it prevents resonances from affecting the performance of the system.

There are also a number of strange and exotic designs like fluid drive turntables, laser cartridges and who knows what else. But because of the fact that most of these designs were more experimental than practical, I don’t think spending time on them is of any benefit.

Conclusion

I hope this article is somewhat helpful in explaining many of the fundamentals of turntable, tonearm and cartridge design. I need to apologize for the brevity of the article;I could spend pages and pages on just one of these topics. But the intent is to enlighten you, the reader, on the basics of design and, to that, end I hope I was successful