Ammonite Audio Improved Mounting Collar for Jelco Tonearms – Silver


Our very popular Jelco mounting collar, in bright silver anodised finish, specifically to match the new Jelco TK-850 and TK-950 tonearms. Now with a nylon-tipped grub screw as standard. New silver spacer rings also available.  UK shipping included.



About The Ammonite Audio Jelco Collar

Our custom improved mounting collars for Jelco tonearms have been re-designed in and are now even better and easier to use.   The Mk3 collar has rounded shoulders, but is otherwise identical to the Mk2.  Key improvements over our Mk1 collar include:

  • The central pillar hole now has a sharp side-cutout.  This means that the arm pillar is now held gently, but firmly, against two vertical’knife edges’, so there is no longer any possibility of the arm pillar leaning to one side.  If your armboard and platter are aligned to the same level plane, this new collar will guarantee that the Jelco arm pillar will be truly vertical to that plane.
  • The standard grub screw is a large 6mm stainless steel item,  with a nylon tip that grips the arm pillar better than a flat steel screw, meaning that the arm height can be set using minimum force.
  • The overall diameter of the collar is now the same as the standard Jelco collar.  This means full compatibility with any armboard cut for a standard Jelco arm.

Why do I need a different collar for my Jelco tonearm?

Have you ever tried to set the azimuth of a Jelco tonearm correctly?  Just when you think you’ve got it sorted, it’s off again!  That’s because the standard collar, while beautifully machined,  provides very poor vertical support of the arm pillar;  and the tiny set screw typically pushes the top part of the arm to one side, almost guaranteeing that the arm will not be properly set up. The azimuth actually varies as the arm traverses the record, which matters a great deal with modern cartridges and stylus profiles.  The custom collar gets around that problem by ensuring that the arm pillar will always be secured properly vertical, so setup becomes easy and repeatable.  That means better musical reproduction.

Is the collar compatible with other tonearms?

The collar is fully compatible with standard Jelco collar mounting templates, and all Jelco manufactured derivatives with 18mm diameter pillars, including Audioquest, LAD, Ortofon, Roksan.  Some Sumiko variants have a smaller 16mm pillar, so are not compatible.

Key Features

  • The Improved collar is 2mm taller than the standard collar, and longer underneath for much better support of the arm pillar:
  • It is fitted as standard with a large stainless steel M6 grub screw, with flat end stub to protect the soft metal of the arm pillar.
  • A nylon-tipped grub screw is now standard.  The nylon tip grips the arm pillar better than the flat steel version, meaning that the arm height can be set with minimum force.  These nylon tipped screws are expensive for us, but worthwhile.
  • Supplied with a hex key for grub screw adjustment, and stainless steel fixings consisting of 25mm long M4 bolts with nuts and washers and hex key for arm height adjustment.  If you have a thick armboard and need longer mounting bolts (40mm, 50mm and 60mm bolts are available), these can be supplied at no additional cost

Application Notes

The custom collar is 2mm taller above the armboard than the Jelco original.  Look carefully at your tonearm as it’s currently fitted to the turntable – if there is less than 2mm clearance between the top of the standard Jelco collar and the base of the arm rest plate as currently fitted to your record deck, it may not be possible to set the arm low enough with the custom collar, to achieve correct VTA, without recourse to a thicker platter mat or headshell spacers.  It is possible to use thin metal shims between the cartridge and headshell to tilt the rear of the cartridge down a touch, thereby achieving the correct VTA without using different mats or spacers.    Please ask us if you are unsure about this.  In practice, the potential problem only applies to turntables with very low-profile platters, eg the Technics SL-1200; however suitable and compatible armboards are available for the SL-1200 from online sellers which allow the whole arm to be sunk low enough to ensure that correct VTA is achievable without any difficulty.

A matching 10mm spacer ring is available immediately, also in grey and black – it is designed to raise the whole tonearm higher to accommodate really tall turntable platters, such as stacked platter Lencos.  The spacer ring is fully compatible with the standard Jelco collar.

Measurement Information

Our collars have the same mounting pattern as a standard Jelco collar.  Please note that some compatible Jelco-derived arms may have original collars with different mounting patterns, so to fit a standard Jelco collar, or our improved collar, may require alterations to the arm board opening and arrangement of bolt holes.

Overall diameter: 56mm
Height above armboard: 12mm
Bolt Holes: 3 x M4 arranged at 48mm diameter
Centre Bore: 18mm
Armboard Hole:  30mm
Weight: 83g

What Length Bolts Do I Need to Mount a Collar On My Deck?

Please note that only 25mm bolts have full threads – please refer to the product images above, and choose the optimum bolt length carefully using this table:

Depth (Thickness) of Armboard


Collar + Spacer Rings

1 Ring

2 Rings

Up to 12mm Depth




12mm-25mm Depth




25mm-45mm Depth




45-60mm Depth




*we don’t supply bolts longer than 60mm

Additional information

Bolt Length

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