It Also Doubles As An Apple Peeler.

Buscis2, as I'm sure you are well aware, there are always compromises in designs.

Also, "excessive" effective mass" can be quite relative, depending upon the needs of the cartridge being used.

If you'd like my analysis of the DV507 in a nutshell, I'd say that it achieved its goal of maximum horizontal effective mass and minimum vertical effective mass. However, in the process, the geometry was severely compromised by the very short stub-tonearm which changes VTA-SRA dramatically with only small variations in record thickness or warps, the rigidity was compromised by the additional set of small bearings out there near the headshell, and the amount of wiring connections was compromised by need to bridge from the stub-tonearm to the main tonearm. Also, there were bound to be resonance problems by the multitude of various parts on the arm itself, but I have not done any vibrational analysis of this arm, so I cannot be sure exactly how much impact came from that. Also, back when this arm came out originally, there wasn't much consensus on whether wiring really made any difference or not.

However, they did have a great idea about making different horizontal and vertical effective mass, and that was something worth studying this arm for. I got the idea for my HiFi mod from that. I just didn't over-do the complexity, and made it easy enough for people to add on themselves to the popular Rega and OL tonearms.

I don't think you seem to be missing anything.

Twl, I unfortunately, would have to consider this a very thorough excercise in futility. And, it is shameful the amount of design, engineering, and manufacturing resources invested in a product of this nature.

It's the kind of project in which one design engineer would walk by another design engineers' drafting board and say, "Uh, I think we may have a little problem". How can the topics that Albert, you and I have discussed in this thread not have been recognized by the design engineering staff of a huge company?

Was their design criteria so far advanced that individuals such as ourselves, could not comprehend or understand? Was there an intrinsic value there that we still fail to recognize?

It does however, make you realize the value of quality engineering that contributed to REGA RB series design. That line demonstrates the results of what sound engineering and product execution practices can really accomplish.

Overachievement.

Respectfully, Ed.

Makes me want to dig out my old Rabco arm!

Twl expressed all my thoughts perfectly. The relatively large change in angle of the short arm when tracking a warp would challenge many cartridges. Too many bearings and parts to resonate. Too many connections in the signal path.

I have his HIFI Mod on an OL Silver and it does exactly what he designed it to do, and nothing more. The best engineering is the simplest engineering, and nothing is hard to to - especially for a committee of engineers.