An Interview with Thom Mackris of Galibier Design

LB: Tell us a bit more about material selection.

TM:    It’s really quite simple.  It’s all about eliminating as much compliance from the system as possible and then damping any remaining vibrations.  The trick lies in the application of this principle.

No conversation about materials selection is complete without paying homage to George Merrill.  To the best of my knowledge, it was George who coined the term “tonearm release energy.”  No one was talking about energy transfer in those days.  George stressed the importance of draining vibrational energy through the tonearm base and into armboard and sub-chassis.

George pioneered the use of acrylic in his Heirloom turntable and he sidestepped the problem of energy transfer from the armboard to subchassis by integrating them into a single acrylic assembly.

There’s always a catch, however.  The vibrations have to transfer from the arm to the armboard, and the typical aluminum (tonearm base) to acrylic (arm mount) interface isn’t quite ideal.  There wasn’t much he could do about it with available materials while keeping manufacturing costs under control in his suspended design.

I obviously disagree with some of George’s design philosophy (suspended vs. unsuspended), but I want to pay tribute to George’s ground breaking thinking.  Modern turntable designs stand on George’s shoulders.  He opened our minds to material selection.

Flash forward to the late 1980’s and early 1990’s, and you see a proliferation of acrylic platters.  While acrylic was innovative at the time George adopted it, I never understood why material research all but halted at this point, or why manufacturers didn’t copy our PVC platters at the beginning of the last decade.  It seems to me that the majority of turntable designers either don’t do their homework, are slaves to fashion, or are luddites.

I suspect the failure to adopt PVC had mostly to do with cosmetics (slaves to fashion), and acrylic was the sexy material du jour at the time.  Remember how, in the early 1990’s everyone was scrambling to copy a well-known, European turntable which was heavy on flame polished acrylic?

PVC is clearly a better choice if you value faithfulness to the recording, however.  The same characteristics that make PVC good for a mat, also make it superior to acrylic as a platter in a less ambitious design.  Although (as I mentioned earlier) graphite and carbon fiber are ideal mat materials, they would not be optimal for a platter because both have too low of a mass; graphite has an additional problem in that it is also too fragile (think – pencil lead).

As far as the “stiffie” philosophy I alluded to earlier, solid aluminum works quite well as a base material.  Our Gavia-II with its solid base proved this to us.  A brilliant speaker designer and friend (Jon Lane of The Audio Insider) pointed out one reason for this.  In a high mass, metal design, the dominant vibrations are upper frequencies, and our good old friend, the RIAA curve helps to mitigate these frequencies in the same way it attenuates record groove noise.

When you reach the Gavia-II  level of performance, small improvements are extremely hard-fought, and the next level of subtle detail retrieval in a Stelvio-II comes from extreme and costly efforts to damp the base (the oil and lead mentioned earlier) – in much the same way we damp both the Gavia-II and Stelvio-II platters.

There’s a lot going on under the hood of the Stelvio-II in order to wring out the next level of noise, which involves a costly machining process to create a complex maze of damping chambers.

Working down the food chain (below the Gavia-II), we’re considering revisiting design concepts we first employed in its predecessor – the Quattro turntable.  This ‘table consisted of a layup of aluminum and MDF.  It’s a cost effective approach to taming aluminum’s resonance.  Of course it’s less effective than the Stelvio-II design, but you have to make intelligent compromises in order to bring costs under control.  Apparently one designer thinks enough of our budget design to use it in his $30,000 turntable model.  I suppose imitation is the sincerest form of flattery.

LB: On a related topic, some turntables — including some very expensive ones — have been described as “sucking the life out of the music,” which some might interpret to mean that a turntable should have a “sound” of its own.  What are your thoughts on this?

TM: We are extremely sensitive to this issue, and frankly this is simply a matter of paying attention and knowing what real music sounds like.

Perhaps the easiest way to describe this delicate balancing act is to describe how I would subvert a Galiber to suck the life out of the music:

1. Install as heavy an oil as I could into the bearing – something like power steering fluid
2. Run the belt tension on the tight side
3. Insert a sheet of paper between the carbon mat and the platter body, as I described earlier

The combination of these “adjustments,” along with a poor material choice (the “paper” experiment) will suck the life out of the music.  You’ll get that “dead” sound which high mass detractors correctly don’t like.  They’re right about what they’re hearing, but they’re incorrectly attributing it to the high-mass architecture rather than its design, implementation and tuning.

Getting it right isn’t about selecting a house sound, but rather about designing the resonant characteristics of the drive system for maximum transient response.  Material choices and drive system tuning contribute to the acoustic and mechanical resonant signatures.  Think of this the way a speaker designer would tune a cabinet’s resonant characteristics for transient response vs. one who would tune it for bass extension.  While there may be a valid reason for the speaker designer choosing one goal over the other, there’s never a good reason for sacrificing transient response in a turntable design.

For you tweakers out there, I’m not implying that thin bearing oil will work for you.  The bearing tolerances on your turntables may require the thicker oil for physical stability – to eliminate the rocking so many designers seem to be experiencing.  I’ve actually heard of people using lithium grease in some turntable bearings.  Similarly, you might require more belt tension than is otherwise optimal in order to stabilize a “loose” bearing.  You can certainly play with the combination of these two parameters to see what works for you, however.

I’ve spoken with owners of belt drive turntables who are employing stiff belts.  They’ve shared my observations – that there’s an ideal belt tension, beyond which the pace and dynamics begin to sound compressed and dull.  There seems to be a universality here across brands and motor families.

This belt tension setting is parallel to the “just enough” philosophy with setting tracking force and anti-skate.  You can go overboard with these two parameters.  With tracking force, you’ll get the best dynamics if you set up for the point where you barely eliminate mis-tracking.  Don’t bump it up by .1 or .2 grams … just for “good measure” – even if this is within the cartridge’s specifications.

LB:      Some turntables use a separate arm pod(s), whereas your pod is integral to the plinth.  Was this the result of experimentation, based on theory, or both?

TM:    A little of both.  Knowing that as little a change in pivot to spindle distance as .001” or .002” raises audible distortion, we’re were much more comfortable that this delicate relationship could be maintained with a rigid tonearm link.

Additionally, with a separate arm pod, you have to think of your shelf as being part of the turntable.  This is not necessarily a bad thing, as long as you choose the right shelf, but it’s something to take into consideration.

Of course, I had experience with the separate arm pods.  In my final days working with Redpoint, I developed an indexing system that fixed the arm pod distance for the scalloped arm pod – the one employed for tonearms with short pivot to spindle distances.  So just like anything else, you can mitigate an architecture’s weak points.  I’m comfortable with that design.

In our Mark II designs, we changed from a pivoted armboard to a sliding mount with fine, Vernier pivot to spindle adjustment.  In retrospect, I wish I had done this earlier, but I suppose you can say this about every improvement.  It’s a fairly significant improvement, and there’s a retrofit version for our Mark I Gavia and Stelvio owners.