Jelco Arm Stub and Counterweight Set
$249 - next batch available - February, 2023
Mounted With a Lyra Delos Cartridge
This is a complete re-thinking of the energy mitigation strategy for the Jelco tonearm's rear section.
The lossy arm stub is replaced with threaded, 316-stainless steel rod, and a set of three, 303-stainless counterweights is provided (two are shown) for compatibility with a wide range of cartridges.
Also provided is a non-marring (brass-tipped) set screw for the VTA lock, to prevent further divots from wearing into the arm stub.
Read this blog post for background.
Compatibility
We developed this system around the tonearm we collaborated on with Artisan Audio - an OEM Jelco SA-250.
- The new arm stub length is 2" (51mm)
- The diameter of the counterweights is 1.25" (32mm).
- The SA-250's original arm stub is 1.75" long (approx. 44.5mm)
- The stock counterweight diameter is about 1.4" (approx. 36.5mm)
Main Plus Light Weight
Complete Kit
We can't speak to clearance with turntables having dust covers, and frankly, the resonant drone of a vibrating dustcover will negate many of this modification's benefits.
Our primary goal is to ensure compatibility with a wide range of cartridges.
With the lighter of the two accessory weights (shown above), the 9" SA-250 will easily "balance" cartridges ranging from 6.8 grams (Dynavector 17d3) at the light end of the spectrum.
Very likely, a cartridge as light as 5.5 grams is possible (but we make no guarantees).
At the heavy end, the 17.5 gram, Kuzma CAR 40 works with the same weight combination (main plus light), allowing for heavier cartridges with the substitution of the heavier ancillary weight.
Other Jelco Models
We have no experience with other Jelco models or tonearm lengths.
Our understanding is that Jelco has used the same M4 screw fixation method for all of their arm stubs, but this is unverified by us.
The 2" arm stub length (in conjunction with the heavier of the two ancillary weights) was selected in order to anticipate 12" arm compatibility - especially, to balance vintage cartridges with heavy bodies.
Bonus
Non-Marring VTA Set Screw
Included is a replacement grub screw to lock your VTA/SRA in place.
This non-marring screw prevents further "divots" from wearing into the arm stub, so the arm height can be adjusted without the setting "hunting" for a divot.
To repair previous damage, sand the area with 500 or 600 grit sand paper. You will remove the anodizing, but this is inconsequential.
Installation
Documentation to follow ...
