The Korf Blog

The inside story: our research,
development and opinions

19 September 2023
Our Audio Priorities
The Korf blog took a long break over this summer. Why? We are working on so many things that we will gradually introduce over the autumn months:

  • Not just one, but two new tonearms!
  • Some cool accessories
  • New home page
  • New webshop
  • Dealer network
  • and many other exciting things!
In the meantime, please enjoy our 100th blog post!
Summer is the time of letters. We have received a lot, and are very grateful to you for keeping in touch and sharing your thoughts and concerns. Lately, we couldn't help but notice a common thread in many of the letters we get. For example,

It's actually quite a complex series of questions to answer. To understand why, we need to dip our toes into philosophy a little bit.

Theory of Constraints
The Theory of Constraints is a very interesting (and useful) way of looking at complex systems. It postulates that the performance of any complex system is constrained by its bottleneck, and by the bottleneck only. Any improvement that does not address the bottleneck will not result in any improvement of the whole system's performance.
Yep, that's a bottleneck
Any improvement other than to the bottleneck does nothing
Once we get rid of the bottleneck, we are good to go
It does sound too obvious because it is so deeply ingrained into us on the subconscious level. Mostly, we don't even think about it.

If our car is running out of petrol, the impending lack of fuel is the bottleneck. Unless we address it ASAP, the car will stop. No other improvement—washing the car, inflating the tyres, topping up the oil—will prevent the coming immobility.

If we want to make pancakes but we are out of flour, it also does seem obvious that we need to go to a supermarket and buy some flour. Not butter, not sugar, not oil, not a better pan. Lack of flour is the bottleneck. Once we address it (and only it), we are good to go.

Unfortunately, this kind of clear thinking goes right out of the window when people are trying to improve their home stereo systems. Why?

Audio Bottlenecks are Hard to Pinpoint
Audio system bottlenecks are much harder to uncover. You hear that something is off but can't quite pinpoint what is wrong, let alone why. Remediation is often reduced to randomly changing things in order to see what works. It takes a lot of experience to reliably identify, say, an amplifier or a speaker cable as the source of dissatisfaction.

Then there is an emotional unwillingness to see and address obvious bottlenecks (we'll come to that later).

And audio bottlenecks are sneaky. With our car example, it's all very clear. Top up the oil while the petrol tank is empty—no change, the car will still not start. With audio, you can replace something that isn't a bottleneck, and experience some change, or even a slight improvement.

Let me give you an example:
You own a mass market receiver driving a pair of JBL L100 Classic speakers. It all sounds a bit disappointing, and you itch for an upgrade.

You really like your receiver, with its zillion buttons and its clever digital features. And you are comfortable in your knowledge that it is excellent—after all, it's a product of the year of the "Why Hi-Fi?" magazine. It has been praised to the heavens by the press, and the audio forum you frequent can't stop talking of how good it is.

So you decide to upgrade your speakers instead, and exchange your L100s for a pair of B&W 702's.

Will there be an improvement?
I am certain that yes, there will be, at least in some areas. But overall, once the excitement of newness wears off, you will still be disappointed and feel that a lot is missing from your sound. The receiver is the bottleneck. Until you address it, no change will bring overall improvement, or lasting satisfaction.

Many listeners spend decades in "audio hell", changing things that are not bottlenecks while ignoring the real constraints.
Many listeners spend decades in "audio hell" (using Peter Qvortrup's term), endlessly changing things that are not bottlenecks while ignoring the real constraints.

Some cling to well reviewed speakers, or to a supposedly "perfectly measuring" turntable of their youth. Some believe their shoddily mastered CDs will one day sparkle, if only they find the right transport and DAC. Some are imprisoned by limiting beliefs like "all well measuring amplifiers sound the same". And some simply do not know any better.

How This Applies to Tonearms?
Just like the system as a whole, the analogue front end is a chain of constraints. Again, some are pretty obvious. If your turntable's drive belt is worn and the wow is intolerable, changing the cartridge will not help. Same for the worn stylus, realigning it will do no good.

But not everything is so clearly cut. The typical remedies often do not address the real constraints. We have touched on it in our FAQ on inner groove distortion. People tend to focus on what is easy rather than on what matters.

We spent decades trying to understand and perfect analogue audio. Armed with a pair of Mk.I ears, a dB millivoltmeter and an oscilloscope, we bumped around in the darkness for quite a while. Then we understood we are not getting enough quality data. 1960s tools and methods were not giving us any real insights.

Accelerometers followed. Measurement microphones. Signal conditioners. Spectrum analyzers. FEA software. It took a sizable investment and a lot of education to get closer to what's really going on.

What follows below is our philosophy, our hard-won set of priorities we follow when we build things. It is based on gigabytes of real data, and on many thousands hours of listening.
Quality of Motion
In our book, the first and the most important constraint is the tonearm's quality of motion. The combination of

  • the quality of tonearm's bearings
  • tonearm's effective mass
  • and cartridge's compliance

defines which deflection of the stylus will be handled by the cartridge, and which by the tonearm. Which part of the stylus motion becomes music, and which will be discarded. Stiff or erratic bearings will overload cantilever suspension, causing mistracking and distortion. Loose bearings will add random movement (noise) to your music. They will also resonate ("chatter").

Until the tonearm's quality of motion meets a minimal standard, no other parameter or setting matters.

The tonearm should provide a stable platform for the cartridge to work against. Quality reproduction is impossible if this platform flexes, bends and twists in response to the vibration of the cartridge.

This floppiness is not readily visible (save for FEA analyses like the one on the right). It's also hard to pinpoint in the usual downstream signal measurements, unless you know exactly what to look for. This is why it is usually ignored or outright dismissed.

Until rigidity meets some minimum standard, everything else is a footnote. This standard is surprisingly high. The typical ⌀10 thin wall aluminium armtube falls far short of it. Any incremental improvement in rigidity is instantly and clearly audible—we are yet to reach the plateau of diminishing returns.

In tonearms with replaceable headshell, such headshell is often the bottleneck. Few headshells are competently designed, and it's hard to tell a good one from a dud just by looking at it.

Also, a rigid platform is good, but if it is so light that the slightest cantilever deflection moves it, music will suffer. Remember, effective mass is a part of the balance which dictates what becomes music and what is discarded.
Transmission of Vibration
The tonearm's ability to route the vibration away from the cartridge. It is closely related to rigidity, but also includes the connection to the plinth and the energy storage in the tonearm itself (or, better, lack of it).

This includes any form of elastic damping. On close examination, most damping elements in tonearms don't work as intended. Instead of dissipating the energy as heat, they store it only to release it back later.

We advocate extreme caution in use of elastomers and polymers in general. Something as tiny and seemingly inconsequential as a plastic isolator in a headshell connector can have a significant impact on sound.

Signal Integrity
You will never hear "cables do not matter" from people who actually design small signal analogue electronics themselves. Be it in medicine, scientific data acquisition, remote sensing, or even in audio. Things like shielding density and contact quality matter. Triboelectricity matters—remember, those tiny headshell/tonearm wires are subjected to the same vibration as the headshell and armtube.
Stability, Longevity, Ease of Use
There is very little sense in specifying premium bearings if in half a year they will lose their alignment. Or in a miracle new material, if it will eventually deteriorate and require replacement.

And what is the point of having any precision setting if it drifts? It's nothing but an illusion of precision. Same goes for any setting that is too hard to do. It will never be checked, and probably remain less than optimal.

Korf tonearms are designed to never need servicing, and to solidly keep any adjustment until the owner changes it.
Everything Else
Exact antiskating force, precision alignment, etc etc.
Answering the questions asked at the very beginning of this article, is using Stevenson rather than Baerwald or Löfgren a bottleneck? Maybe, if you are setting up a multi million dollar system. But even then chances are, other constraints will limit the system's performance before. Having a 0.3 degree less "tracking error" when a typical cartridge assembly error is 3 degrees hardly ever matters.
This is probably the reason for recent proliferation of tonearms that completely eschew any attempt at "correct" alignment—Yamaha GT 5000, Rigid Float, Yuki AP-01 etc. Might their makers surmise that other constraints of their design will kick in long before alignment becomes an issue?

Features Don't Fix Problems
The theory of constraints tells us that we cannot compensate for one deficiency by improving some other unrelated area. If the tonearm is not rigid enough, VTA on the fly will not help. If the bearings stick and chatter, easy azimuth adjustment is pointless. It's impossible to compensate for an inadequate part by perfecting something unrelated. Adding more features is a waste if fundamentals aren't taken good care of.

We move forward by solving the actual bottlenecks instead of piling on the features
This is why our tonearms do not have the most bells and whistles. It is at odds at our goal of building things that sound great. We move forward by solving the actual bottlenecks instead of piling on the features.

In general, choosing analog equipment on features is a bad idea. This also applies to most things in life, from lab equipment to travel. The oscilloscope you'll enjoy using the most is never the with the most tick marks in the spec sheet. And the most awe-inspiring places on planet Earth seldom come with a free continental breakfast.

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