Vinyl Asylum: Incognito Wire Installed in Origin Live Modified Rega RB250 (quite long) by NewbieBaby

This discussion specifically concerns procedure steps for the installation of an Incognito tonearm wire modification onto an Origin Live modified Rega RB 250 tonearm which I conducted myself. This discussion does not directly address the installation of the Incognito modification onto other series Rega arms, though such procedure may in respects be similar. The procedure items suggested below are intended to be used with regard for the instructions provided with the Incognito kit.

The procedure for installing the Incognito Mod is not hard, its just that each step should be thought out in advance. A deliberate and meticulous approach is necessary for each step in the process, especially for successful soldering of the signal wire to the fish wire and to the cartridge clips.

I purchased from Origin Live a new Rega RB 250 arm with the structural modification only. Origin Live chooses yet not to accept credit cards, so I made payment with a bank check to cover costs as confirmed by e-mail. Total time between mailing of the check (US Postal 5 day delivery) and reception of the arm was slightly less than 3 weeks.

I purchased the Incognito wire mod for the Rega arm from the Moth Group. The Moth Group accepts credit cards over a (hopefully) secure internet connection, and total time between placing of an order an reception of the wire was 2 week, but this included a one week inventory back order delay for the Moth Group.

The Origin Live (O-L) Structural Modification for the Rega RB 250 arm consists in replacing the plastic counterweight stub, which is simply threaded onto the arm end, and replacing the counterweight. These are replaced with a rigid metal counterweight stub assembly and a different counterweight with a locking screw. The O-L counterweight is significantly larger diameter than the original Rega counterweight (1.573 inches, 40 mm vs. 1.175 inches, 29.8 mm) but weighs about the same as the heavier of the two standard Rega counterweights. The O-L counterweight is made of a magnetic material, likely a steel (vs. the Wolfram original), and I wonder if a brass material would be more appropriate for this application. Based upon what I have read and have now seen, the design intention for the Structural Mod is to obtain a rigid counterweight structure with as little component surface contact as possible with the arm structure it attaches to. In my opinion, the Structural Mod achieves these design goals. The Structural Mod assembly can be completely, and easily, removed from and replaced to the arm, and for installation of the Incognito mod, the O-L counterweight structure should be removed, as detailed below.

As an aside: I was interested to know if the Express Machining Heavyweight would fit on the O-L stub, and the answer is no. The O-L stub and counterweight hole measure 0.528 inches and 0.533 inches, respectively, while the original Rega stub and counterweight hole (the E-M Heavyweight being assumed to fit onto the Rega stub) measure 0.500 inches and 0.537 inches, respectively. Base on these measurements, the Heavyweight hole is likely too small for the O-L stub.

As stated in a previous post on the subject of the Incognito Mod kit, the quality of materials, assembly, and finish seems very high. A separate grounding wire is installed at the gold plated strain relief plug which affixes at the arm pillar base. The internal diameter of the Rega arm pillar bore measures 0.632 in. and the outer diameter of the Incognito plug which fits into the pillar measures 0.627 in., so the clearance is suitable for an easy fit (this clearance can have an additional use as detailed below). The wire plug is affixed with the existing set screw in the pillar. The 4 signal wires are, I think, a Cardas 33 AWG stranded wire. A single wire is composed of 6 fine wire strands, 5 copper and one silver (or possibly silver plated), and the 5 copper wires seem to be of different gauges. The plastic sheath of the signal wire seems not to be teflon given how it responds to the solder iron heat.

Installation:

The O-L Structural Mod is removed. A metric hex key is used to remove the cap screw in the bore of the stub. Once the stub is removed, the threaded plate can be seen as threaded into the arm end. To remove the threaded plate, find a nut that threads onto the original cap screw, and screw it onto the cap screw. Then thread the cap screw into the mounting plate about 4-5 full turns. Then turn the nut, here functioning as a lock nut, to lightly lock the cap screw to the mounting plate. The mounting plate can then be screwed out of the arm end, and it is not hard to do this because the thread clearance seems to be generous. Re-installation of the O-L assembly will occur in the logical reverse order.

The original Rega wire is removed. Loosen the set screw (no need ever to fully remove this) in the pillar to release the original plastic wire termination plug. pull the plug out and cut the attached wires. Then remove the rubber plug with wires at the head shell end. Removal of the rubber plug was made easy by firmly grabbing the plastic expansion plug fitted in the center of the rubber plug with a needle nose pliers. Pull the entire rubber plug assembly with wires away from the arm. In any case, take care not to damage the rubber plug. When the rubber plug and wires are free of the arm, remove each wire from the plug. During re-assembly, the new wires will be run through the plug and the plug reinstalled.

Remove the original internal arm ground wire. This is a black wire and runs from the previously removed wire termination plug up through the arm pillar hole and terminates on a spring strip fitted in the arm end, Simply grab the spring clip with a needle nose pliers and pull the attached wire away from the arm. Full removal of the ground wire at this stage is suggested in order to make subsequent wire installation easier.

Critical detail: The hole in the pillar through which the signal wires run has a small short plastic/rubber grommet/sleeve pressed into the lower most end of the pillar hole. This must be removed for easiest drawing of wires through the pillar hole. The plastic sleeve can be seen from the bottom and removal can be accomplished two ways: Either push the sleeve up through the pillar hole and out into the arm tube, or hook it from behind and pull it down and out from the pillar bottom.

As an aside: Notice the clean internal surface finish of the Rega arm tube. Is there some nice light substance that could be applied for acoustic damping here?

As background: A "third hand" type device is very useful for convenient and easy soldering of signal wires and cartridge clips. For any subsequent solder work on the signal wires (and new ground wire) there is no need to strip the sheath plastic from the wire ends using mechanical means. The metal fine wires may be suitably exposed using the heat of a soldering iron to cause the plastic to pull into itself away from the heat source. My technique is to bring the soldering iron tip to as near as possible the cut wire end without touching, then the plastic will pull back a little, then touch the iron to the metal wire end to cause the plastic sheath to pull back further. Subsequent soldering may cause the plastic to pull back too far exposing bare wire, and tactful use of clip on heat sinks can be useful here. The 6 fine wires of each signal wire should be twisted reasonably tight prior to tinning with solder. Concerning tinning, the Incognito provided solder should only be used for the final tinning of wire ends for the soldering of the cartridge clips. The Incognito provided solder seems to not have the easy flow characteristics of conventional solders, and not enough is provided for regular tinning of the solder iron for good hot-tip maintenance. For the fishing of wires through the arm, use new conventional solder to affix the signal wires to the fish wire, and also to clean the iron tip for cartridge clip soldering.

From the detail items provided in the Incognito kit, find the fish wire (mine was white and of comparative heavy gauge) and notice that one end is already striped. I suggest the stripped length should be about 1.25 inch minimum.

Notice that the tone arm signal fine wire pairs are soldered together at their ends (red with green and blue with white). For easiest fishing of wire through the pillar hole, I suggest the paired wires be cut free as close to their soldered joint ends as possible (not at the gold mounting plug but at the fine wire ends).

Tin the exposed stripped fish wire end along its entire length with the thinnest layer of solder possible. Tin the twisted ends of each signal wire with the least solder possible. Solder attach each signal wire to the fish wire with the placement of each wire staggered along the full length of the tinned fish wire end. Start at the point on the fish wire furthest from the end and work down to the end with each successive wire, and protect previous soldered joints from melting by using clip-on heat sinks. I was able to attach the wires without additional solder using only the solder already tinned onto the fish and signal wire ends. The signal wires should be attached such that they run parallel with the fish wire using as little solder as possible. If the attachment points of each wire are staggered in this fashion, the drawing of the wire through the pillar hole will be very easy and more likely successful the first time. With a fine wire nipper, trim any solder or wire ends that may catch on metal corners while drawing the wires through the pillar hole.

With the above preparation, drawing the wire through the arm was very easy. At this point, do not yet cut the signal wire from the fish wire. This should be done after a new ground wire is fitted and the gold termination plug fixe to the pillar.

I remounted a ground wire that makes direct contact with the arm tube as the original black wire did. The Incognito assembly makes ground contact only in the pillar. It may be of no significance, but 2 bearings with associated oil films can possibly exist between the pillar contact and the metal of the tone arm structure. I unsoldered the original black ground wire from the spring contact piece and replaced it with the short run of wire provided in the Incognito kit as practice wire for soldering. The short length of wire was first fished through the pillar hole in the same fashion as the signal wires. The spring clip is first soldered to the relevant wire end the clip inserted and fixed back into the arm tube end. The wire end at the pillar bottom is cut with 0.375 inches extending beyond the pillar end. The full 0.375 inches length of this wire end is heat stripped and tinned.

With the ground wire at the pillar end so prepared, the gold termination plug can be inserted into the pillar bore. The tinned ground wire end should be place such that as the gold plug is inserted into the pillar bore, it is friction fit between the pillar bore and plug (there is approx. 0.005 inches clearance here). While the plug is being inserted into the pillar bore, the fish wire should be pulled lightly to take up slack in the signal wires. Affix the gold plug with the set screw before working on the leads at the head-shell end.

The fish wire is ideally removed by cutting the signal wires through virgin wire as near their ends as possible in order that any solder at the cartridge clips be that provided with the Incognito kit. Thread the signal wire through the existing 4 holes in the rubber plug. While concurrently pulling lightly on all the signal wires, the rubber plug is positioned about 0.375 inches from its final position in the arm tube, and the signal wires are affixed to the rubber plug with crazy-glue type instant epoxy. This affixing of the wires to the rubber plug makes subsequent handling of the cartridge leads more convenient and allows a relatively controlled amount of signal wire slack to exist in the tone arm tube so that connections will not be stressed and so any influence of wire twist for the arm pivot resistance is minimized.

Take care to size the needed length of wire for the final cut prior to installation of the cartridge clips. For the attachment of the cartridge clips, In initially tinned the clip end such that the cavity was first lightly tinned to assure good flow of the solder and then the cavity was filled in anticipation of the tinned wire ends. The manual technique is somewhat critical here as there should be essentially no relative motion between the cartridge clips and the signal wire as the solder is solidifying. To achieve this, I fixed the clip in a "third hand" clamp and positioned it such that I could insert the tinned signal wire end into the molten solder in the clip cavity with a very controlled motion. Only a slight finger motion was needed and my hand was resting and braced so there was no shaking. I did not need to add solder during this operation as it was already in the clip cavity. I needed to only touch the iron to the clip and insert the wire. It was actually quite easy once the appropriate preparations were made.

At this time, a check of the mounded and balanced arm idicates it pivots with no obvious binding.It will be a while yet before I can listen to it.

I hope this will be of use for someone.