standard counterweight vs drop counterweight

What's the advantage of a drop counterweight over a standard counterweight.
I tried one of these on a Rega Planar 25. Wow, more detail, more quiet, just plain better. It's not subtle either, it's very noticable. For the money, it's a good upgrade. Less that $80 I think I paid.
I also had a WOW! experience after putting a Gregory Kerry F-2 Titanium Heavyweight Counterweight onto my Rega RB-300 tonearm. Although it is a little more expensive, at $129, the improvement is so great that it easily competes for the best value analog tweak award.
To me it was a no Brainer, even though I have heard a good set up(Nottingham Horizon, Shure V, Rb250) without the endstub upgrade. Between the two mentioned above I would have to go with the F-2, from Kerry Audio.
OK, you have heard the benefits, here is the reason. First and most important the counterweight hard mounts to the Rega stub. Normally a tension fit the hardmounting cuts back on resonances. Second the low center of gravity provides for better tracking (less teetering).
Actually, hardmounting does just the opposite- it restricts the reactive energies of playback a means of termination and are thus stored and re-released, feeding back down the arm to the pick up where it's often perceived as an increase in dynamics and detail.
On my OL Silver I've used the stock (concentric) C/W clamped to the arm stub and Twl's DIY suspended C/W, which hangs a weight from the stub on a silk or nylon thread.

The suspended C/W obviously decouples the mass of the weight from armtube resonances nearly 100%. The sonic benefits were increased clarity/reduced bloat, particularly on the trailing edges of all notes at all frequencies. Removing that big hunk of mass from the resonating armtube clearly fed less energy back to the cartridge end of the arm.
What is the best counterweight for the Rega 300B?

I have a Grado Sonata and would like to tighten the bass and keep the beautiful midrange. I presume all counterweight upgrades do this but which does it best? Has anyone tested more than one?


I had both the Express Machining and the Kerry Audio counterweight at one time, I kept the Kerry F2. I tried both on a Rega P3 before I got rid of it and the Heavyweight. The listening test was b/w a RB300 w/ the EXpress Machining Heavyweight vs. the RB 250 WITH Express Machining 2xtreme endstub with a Kerry Audio counterweight. Do not take this as a TRUE test since they were on diff. arms(another debate entirely) I felt and heard more extended highs with the 250 arm, though. Now, was this the endstub, counterweight or the 250 arm(lack of spring) who knows? I hope this muddies up the issue for you.;)-~ The F2 from Kerry does have ridges that the counterweight rides on while attached to the counterweight, tightened by a plastic? screw down bolt, instead of metal(at least where it contacts the endstub). This may help with the resonance issue?