Decca London Super Gold Compatibility Question

As stiff an armtube as possible benefits ALL cartridges, but the Decca/Londons, having no rubber damping suspension (and no traditional cantilever; the stylus is attached to a V-shaped metal plate, which goes straight up into the cartridge) benefit most of all. The D/L’s transmit a LOT of mechanical energy into the arm, exacerbating any armtube flex and/or bearing "rattle" present in any given arm. The Zeta is known specifically for its’ strengths in those two criteria.

The front-end damping provided by the Townshend Rock is exactly what makes that table so appropriate for use with Decca/Londons. A damped arm has long been recommended for use with the cartridge, and I have had a few; the Decca International, the Mayware Formula 4, and a modified (with damped bearings) SME 3009 Improved. The Rock makes a damped arm unnecessary (and in fact the front-end damping afforded by that table is a better way to damp than applying it at the back end of the arm), allowing armtube stiffness and superior bearing design & build to be prioritized. The Rock comes with a metal arm mounting plate drilled for the Linn/Zeta arms, which share the same pivot-to-stylus distance. The plate even has the six holes required by the Zeta’s arm mounting collar---very handy. I added a layer of thick acrylic under the metal plate, as that plate is a little too ’lively" for my liking. Yes, I believe in damping resonances!

@noromance, you make a good point. A heavier counterweight closer to the bearings can produce the same effective mass as a lighter one further away, plus create less moment-of-inertia, a good thing say engineers (I take their word for it ;-). The Zeta arm has a counterweight that has it’s rear plate bolted on, with two internal steel washers which can be added or subtracted as needed or desired. Mine was missing one of the washers, so I substituted lead weights bought at a hobby store.

I needed the extra mass to compensate for 1- the missing Zeta counterweight washer, 2- the extra mass of the Decapod on my London Super Gold Mk.7 (it doesn’t weight much more than the standard mount), and 3- the outrigger that is integral to the Townshend Audio Rock Elite table I have the arm mounted on; it gets bolted on to the cartridge end of the arm. The Rock/Zeta/Decca-London combination, a true classic!

The Decca/London is tricky because its’ lateral and vertical compliances are very different, the lateral being about 50% higher than the vertical. Schizophrenic! Of course, the effective (moving) mass of all arms is partially determined by the distance of the rear counterweight from the arms’ bearings. To increase an arms’ em, move the counterweight further away from the bearings. To keep the tracking force the same, additional mass is then added to the headshell, thereby further increasing the arms’ em. Serendipity! An arm with medium lateral mass and high vertical would be optimum for the Decca/London. Is there such a beast?

A good way to add mass to the "classically"-styled Decca/Londons (the Maroon/Gold/Super Gold, etc.) is to order it with the optional Decapod top plate/mount. A second benefit to the welcome added mass of the pod is the far superior mounting of the cartridge to the arm it affords. The stock cartridge holder/mount is a flimsy joke, completely unacceptable. Owners of stock cartridges can have the Decapod installed at the factory at the same time retipping is done. Well worth its’ modest price.