Benny Audio writes: “In previous publications, I discussed how to measure and evaluate the quality of a turntable drive. So, what distinguishes one drive from another? What types of drives exist, and which excel in specific areas? What is essential and what is not for achieving optimal performance?
Let’s start with a bit of history. Which drives were and still are the best in terms of performance? Unfortunately, with few exceptions, the direct drive (DD) units from the past—machines over 40 years old—still outperform today’s high-end models without breaking a sweat. It’s no wonder they still have so many enthusiasts.
The DD drive operates by integrating the platter as part of the motor or by placing the motor directly under the platter—hence the name “direct drive.”
Pros:
- Absolute control over speed accuracy and stability. Only the best modern belt drives can match DD drives.
- Even distribution of load on the platter bearing.
Cons:
- Motor vibrations directly affect the platter (and the cartridge).
- The ubiquitous magnetic field (due to the motor under the platter) reduces sound quality. The field interacts with the cartridge’s magnets, negatively impacting sound generation.
A variation of the DD drive is the so-called ID or Idle Drive. This is also a form of direct drive but with the motor positioned beside the platter’s rotation axis, transmitting drive through a pulley wheel on the motor shaft.
Pros:
- Decent control of speed accuracy and stability.
- Reduction of the magnetic field, thus no adverse effects on the cartridge.
Cons:
- Significant pressure of the pulley wheel on the platter, negatively affecting the bearing.
- Direct transmission of motor vibrations to the platter.
Belt Drive (BD)
Belt drives were developed during the golden age of vinyl (e.g., top-tier Micro Seiki RX 5000 and 8000 series) as a response to the negative effects of using DD and ID drives. In a BD drive, the motor is often placed away from the platter, sometimes outside the plinth (thus decoupled). The drive is transmitted through a belt wrapped around the motor’s pulley and the platter.
Pros:
- Elimination of the magnetic field’s impact.
- Decoupling the motor from the platter significantly reduces transmitted vibrations.
Cons:
- Like ID, pressure on one side of the bearing during operation, but not as intense as in ID.
- Much harder to achieve good rotational parameters than in DD or ID.
The focus of this discussion will be on the belt drive.
Looking at the specifications of today’s turntables (mainly belt-driven), they can be divided into two categories (my subjective division):
Technology Above All: Here, we find essays on complicated and unique solutions, often unrelated to the drive itself. There is often no information on what the solution is for or its real measured impact on platter rotation quality. It’s as if the method is more important than the result. In some fields, like art, this may be valid, but technological solutions without performance results are just confusing and unnecessarily costly.
Performance Above All: This is definitely where BennyAudio feels most comfortable. The solution used is irrelevant; only the result matters. If the best drive parameters could be achieved using depleted uranium, it would be the only technology used. Fortunately, that’s not the case.
What is Important to Achieve the Best Parameters? Everything! Specifically:
- Power Supply
- Motor
- Motor Controller
- Control Unit: The system controlling the motor (some omit this, simplifying their lives but not necessarily the user’s).
- Pulley
- Belt
- Bearing with Platter
- Oil: Properly selected for the bearing and the entire system.
Selecting the right components is quite a challenge. Only the best-matched elements (not necessarily the most expensive) will yield the best drive parameters. The drive will only be as good as its weakest component. It’s like finding the perfect cake recipe.
A side note: I once read a forum discussion between two DIY engineers. One of them replaced his turntable’s motor controller with one from a much more expensive model. Surprisingly, the change made little difference, causing him to blame the whole world, including the designer of the expensive turntable. Was he right? You decide.
Before describing the individual components of the drive (next article), I admit to a fundamental principle that guides my design process:
KISS – Keep It Simple, Stupid: Make it as simple as possible. I didn’t invent this but gladly apply it. Similar to “Never Assume, if you assume you make an ASS of U and ME”—this philosophy always works, even in my professional struggles in the IT business.
Why KISS? It’s the most challenging construction philosophy. The final solution should be simple, meaning straightforward, clear, understandable, durable, easy to service, and devoid of unnecessary embellishments. There’s no room for pseudo-solutions that can be used as an excuse when the equipment doesn’t meet expectations. Only the simplest solution guarantees the best possible parameters, confirmed by database results (an app on iPhone and SHAKNSPIN). Complicated solutions are far from the top. This should give you something to think about.