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As a designer you could turn your back on a ball race bearing system and go unipivot. What will happen here is that if it’s a pure sharp needle unipivot that is properly coupled to the arm, the point or coupling will quickly wear and we will end up with microscopic chatter as well as the wobble which is inherent in the one-point balancing act of a unipivot. True, designers such as Graham and others have attempted to remedy this problem but that is a story for another time. The Hadcock ingeniously tried to get around this problem by inserting four small bearing balls into the cup that makes the female side of the unipivot bearing. Sadly all that is a solution that compounds the problem in that the bearing will be subject to both chatter and wobble.
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You could opt for a magnetic bearing and open up a whole world of incredibly complex eddy current forces that operate in a completely nonlinear disruptive way and which will cast a nontrivial magnetic influence over the magnets in the cartridge. The only situation where the bearing will remain relatively undisturbed is in a high-pressure high-quality air bearing such as those used by the Kuzma Airline. But in that case none of the energy is dissipated in the arm-wand/bearing interface and it will travel on, shaking against the counterweight and bouncing back again. One of the things I like so much about the design of the Mission 774 [right] is the internal Delrin ring on the counterweight, which is one of the most effective ways I’ve come across to dissipate vibrations. I’m surprised that more designers haven’t adopted that system.
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Audiomods MK V.
As its name implies, this is the fifth iteration of an arm that started life as a Rega RB300. The designer took to exploring the (numerous) strengths and (relatively few) weaknesses of this arm and learned many things. One of the first that becomes obvious to anyone who has dismantled a Rega is that the quality of some of the components is pretty crude indeed. Frankly, you wouldn’t let the anti-skate mechanism anywhere near a high-end table. The fact is, given how little Rega earn from each arm sold wholesale, we should be grateful that they are capable of giving us anything more than a toothpick and a rubber band. On the other hand the coupling between counterweight and arm wand is shockingly bad and would probably be improved by using a thread tied to a toothpick. The quality of the main bearing itself is best described as agricultural. It’s astonishing how much absolute crap quality there is in what is arguably one of the greatest piece of audio equipment ever made. We all know though that as an arm it can dance the dance. It’s great-ish. On the other hand everyone who has owned one knows that at the best of times that dance involves a lot of pirouetting between one Barishnikov leg and one wooden peg. I used to think this was largely down to the wiring but then having had a lovely one with Kondo wiring and Tungsten counterweight, it was clear that there were still issues that needed to be addressed. |
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So Jeff Spall of Audiomods began a process of research, substituting parts of the original arm with improved designs of his own. Out went the anti-skate, out went the bearing, pillar, in the end pretty much every part except the arm wand (which we know is the actual magic part of the Rega). By mark V though even that was being altered. First off, this one is the redesigned Rega RB301 which is gaspably exciting in the first place. Second he takes this arm wand, adds internal damping, drills large holes in it and removes the paint. This makes it a lighter leopard with very different spots from the original.
Audiomods is not the first company to have started by hot-rodding Rega arms. Origin Live is one of the more established along with Mitchell, Audio Origami and others. But I do suspect it is one of the more radical. The idea of incorporating a micrometer on a sub £1000 arm (let alone one that costs £650) should tell us a lot about the seriousness of intent of this artisan manufacturer, about the arm’s performance expectations, capabilities and pretensions. My Kuzma Airline has one but that’s thousands of pounds dearer. The SME V—still the sonic standard bearer in my neck of the woods—certainly doesn’t.
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Arm intro. So what else do you get when you open the rather elegant stained wood box this V comes in? Well, this is an arm that wants to be belle of the ball. Finished in matt silver, the two counterweights and counterweight shaft are gold plated as is the base of the lift mechanism and the micrometer pillar. Even the knurled vertical bearing’s retaining bolts are gold plated. Nice touch indeed. The wiring is one continuous piece of silver Litz right down to the Nakamichi phono plugs. Even the lugs are silver. The build quality verges on the excellent and exudes the kind of pride that tells you without having to ask that each component, each solution was arrived at for sonic choices, not because of manufacturing exigencies or marketing compromise. This is one of the key advantages of this new type of ‘artisan’ based company. Without the overheads and complex supply chain issues of large companies, the artisan is able to go where they want and charge far less than many large-scale companies who have hundreds of employees and their pensions schemes to worry about. |
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Construction. The counterweight itself is very unusual and a thing of beauty. It’s made in three pieces as a sandwich of steel and lead and hence will work as a constrained layer damper where energy is converted into heat. It is fixed via a grub screw, a simple system which does mean there are only two contact points between counterweight and arm shaft. Obviously this is a huge improvement over the crude threads of the Rega but some of us do want more contact. I’ve added bits of Blutak inside. The more you get in there the more the Blutak will act as constrained layer damper and turn some resonances into heat. Very worthwhile. Ideally in an all-out luxury version of this arm I’d like to see a Delrin ring or other solution similar to the Mission 774 (which I think Audiomods also admires).
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