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Product: Laminated acrylic arm-boards for Michell Gyro/Orbe
Manufacturer: True Point Audio - UK
Prices: Available in black or clear acrylic for Rega RB250/300 UKP300 (top right); for SME IV/V UKP250; Heavier arms not needing brass weights do not cost as much. Other arm fittings are available, this test on Hadcock GH242SE (top left); extended armboards are available for longer arms at UKP50 extra.
Author: Mark Wheeler - TNT-Audio UK
Published: September, 2024

Introduction

“The Old Scribe is still tweaking turntables in the 21st century!” whine plebs, stage left

Plenty has been said and written over the years about the pickup arm - armboard - subchassis interface on suspended subchassis turntables. Here at TNT-audio.com there have been several Gyrodec/Orbe users over many years for good reasons. These turntables are reliable workhorses capable of modest high end performance at their top specification. Like any product long in production with few changes over many years, owners and third party manufacturers have spotted some shortcomings and proposed solutions. The pickup arm - armboard - subchassis interface is an obvious place to start tweaking.

First among these Gyrodec/Orbe shortcomings is the tendency of the subchassis to resonate particularly when coupled with rigid high mass pick up arms and low compliance cartridges. The distinct sub chassis bloom is over a different octave from that of the steel subchassis Linn Sondek for example. This may explain why this phenomenon is particularly obvious to those who often switch between these two turntables. Our own Geoff Husband wrote about this when introducing the 1 cent fix.

Armboard Isolation

Orbe/Gyrodeck armboard isolation was taken to a new level with the Pedersen arrangement that actually decouples the armboard from the subchassis. This was prompted by Gert Pedersen's own experience with the SME V on his Gyrodec. Finally, catching up like Harley Davidson do following aftermarket innovation, Michell subsequently introduced their very own arm board isolation pillars. Meanwhile, True Point Audio have been creating laminated acrylic armboards for Michell turntables, alongside their established Pink Triangle and DC motor activities. Today we are comparing the True Point Audio laminated acrylic armboard with Michell original arm board mounted on a Pedersen armboard isolator.

Your Old Scribe's Orbe subchassis had been extensively modified with Pedersen bearing reinforcement flange, Pedersen sand chambers (now filled with sand loaded twopac resin) and Pedersen suspension. Therefore an alternative unmodified 2 pickup arm subchassis was obtained. A suitable version of the True Point Audio acrylic armboard was ordered. Every TPA armboard is made to order so these are not instant gratification products, with a 2-3 week lead time for popular arms. The Rega fitment is by far the most popular option, with Michell's own arms being Rega based, and so many others too.

Who are True Point Audio?

True Point Audio (hereafter TPA) have been ploughing a very particular pair of furrows for many years. Noted for their Pink Triangle aftermarket parts and, not unrelatedly, acrylic products. They're also suppliers of alternative motor power supplies for PT & Michell turntables and their manufacturing of Pete's Pylons. They also make competitively priced universal accessories like Sorbothane® Hemispheres priced from £0.80 to £5.00 each depending on size. TPA make lightweight carbon fibre sandwich armboards for Pink Triangle turntables, so this seems to be an area of expertise. So TPA also manufactures and supplies Acrylic arm-boards, also designed for for them by Pete of the Pete's Pylons for Michell Gyrodec/Orbe. They claim that these acrylic arm-boards give superior acoustic performance because the acrylic material will attenuate transient vibrations, whereas the aluminium arm-board exaggerates them into the subchassis. They can supply weight matched armboards for 9-10 inch arms and extended armboards for 12 inch pickup arms. Each board is machined to suit one tonearm and replace the Michell aluminium original and the Michell stand offs.

Mass is matched by 12 brass weights which echo aesthetically the Gyrodec platter weights. These brass weights balance the subchassis to be similar to the mass of the original Michell aluminium arm-board in combination with the arm fitted. The acrylic is dry laminated construction to increase rigidity while improving vibration control properties. They proved very easy to fit with the supplied lightweight nylon bolts which are part of the isolation system.

The GH242SE TPA board with 12 brass weights weighs in at 425g. The acrylic alone is 235g enabling some fine tuning to achieve the perfect Michell subchassis centre of gravity at the platter bearing spindle. The Hadcock GH242SE Super Silver used for this test weighs in at 420g with approximately 25g extra for cable loop before the clip.

Sound Quality

The Hadcock GH242SE Super Silver is not an arm that dumps vast amounts of spurious energy into the armboard. Hence your mileage may vary with more energetic arms like the SME V, Fidelity Research FR64 or Rega. Owning two complete samples of this arm, your Old Scribe can simply transfer the arm tube assembly from one pillar to the other and swap which lead is plugged into the phono pre-amp. The cartridge is the Dynavector XX2 Mk2.

The Michell Orbe Densodamp was omitted from the first round of listening to exaggerate the differences. Both stainless steel (in the picture above) and the supplied nylon bolts were tried. The nylon bolts were slightly preferred. There is only a bit more difference between the TPA and the full Pedersen armboard isolator when the latter is used with a genuine Michell armboard. Given how much of an improvement the Petersen isolator makes over the standard Michell arrangement, this is remarkable. Readers who still own the original solid Michell armboard fixings will notice the most substantial difference.

The TPA seems to reduce a little more of the subchassis bloom. The TPA seems to have slightly dryer bass and incresed clarity but this could merely be 2 ways of interpreting the same phenomenon. The original Michell plus Pedersen Isolator seems to have a little more bass weight. Installing the Densodamp reduced both these perceptions. Replacing the Densodamp with laminations of glass-fibre mat reinforced resin and Plastic Padding Chemical Metal further reduced differences. Either the Pedersen Isolator or the True Point Audio dry laminated acrylic armboard are a noticeable step forward from the original Michell arrangement.

An alternative pickup arm tube loaded with the walnut bodied Decca London cartridge produced a remarkably similar comparison. Handling noise was a little more papery with the TPA and a little more clunky with the Pedersen isolator but as soon as the stylus hit the groove the differences were minimal. Whether one prefers the TPA with its little brass weights or the Pedersen acrylic disc between aluminium armboard and subchassis is a matter of taste, both sonic and visual. A quick experiment with stainless steel Allen bolts and with titanium Allen bolts in place of the nylon screws demonstrates that the nylon bolts really are an essential part of the TPA armboard system. Playing around with different torque settings did not prove audible.

Conclusion(s)

The True Point Audio laminated acrylic armboard works effectively and looks good to me. It seems to control energy while keeping the arm fulcrum exactly positioned in relation to the turntable spindle at all times. This is essential for information retrieval in the domains of time and space, which is what we need for enjoyable music.

Either the Pedersen armboard isolator or the True Point Audio will elevate performance of the Michell Orbe or Michell Gyrodec. With the Hadcock GH242SE your Old Scribe would not be able to identify reliably which was which in a double blind test. Michell are closing the gap with the compliant armboard mounts and coated springs but the TPA would still edge ahead. Personally your Old Scribe loves the look of the clear TPA Laminated Acrylic Armboard on a silver chassis Michell Gyrodec with a silver arm; black is so 80s.

At the price, compared with a cartridge or pickup arm upgrade the True Point Audio Laminated Acrylic Armboard represents good value. Your Old Scribe paid for this sample at the point of ordering it and is pleased with it.

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Copyright © 2024 - Mark Wheeler, The Old Scribe - mark@tnt-audio.com

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