GyroDec blog

Fair enough. I will measure it later this week and share the result.

Up early to make sure I didn't miss the delivery which cam at about 11am in the end. That gave me some time to strip down and prepare my GyroDec for the planned changes.

As I feared the 'Rega' arm board measures at 219.5mm mounting distance on my GyroDec. It may be possible that somehow the Michell chassis changed between the 1990's and now but that seems unlikely. It is more likely that they haven't checked their Rega arm board is cut for 222.2mm and not 219.5mm. Odd.

So I decided (well had already expected) to drill and tap some new M5 holes on my chassis so the arm board would be further from the spindle. This meant that the arm board gave 223mm as recommended by Origin Live and used on the Zephyr arm and Zyx R100L cartridge from my SL1210/II.

The new armplate weighed about 380g as did the gold-plated original. I've yet to meet a Rega arm that weighs 620g so I am not sure how the 1.0kg would be met. The OL Zephyr weighs about 570g so I theorised it would be close enough to 1kg. The GyroDec chassis balanced fine and the sound was good so all's well.

The changeover to Orbe screw-down clamp went smoothly. Definitely better than the GyroDec's original friction clamp. I fitted the Densodamp at the same time and my standard 'tap test' (rap with half-knuckles or a handy screwdriver) showed it worked, no ring or resonance after.

Saturday things got in the way like shopping and the Palace vs West Brom game. However I did have the GyroDec turning by the final scores and the altered bearing was being run-in. I checked the Zephyr/R100 alignment matched with a 223mm UNI-DIN arc protractor, VTF scales and crosstalk balance.

I played a few familiar sides. PG4 side one, Lover Over Gold side one, and others I'll spare you. The change to the better MC cartridge and OL arm has brought out the strengths of the GyroDec. It is more lively/dynamic than the SL1210/II and will probably improve as the new bits bed in and I fine tune some settings.

I read on VE or another forum that (apparently) Michell asked what the Rega distance was and were told it was 219.5mm (which is about 8 5/8 inches not an obvious Imperial length). Rega use 222mm (sometimes written up as 222.2mm) and Origin Live use 223mm.

I wanted to move my OL Zephyr across from my SL1210/II with my Zyx R100 on it. They were already aligned to UNI-DIN's null points.

Even 222mm is 0.8mm out is visibly different but I reckoned the arm plate hole would allow me some wriggle room to achieve 223mm. Obviously 3.5mm is laughable to look at, let alone calculate the tracing errors that would result. So I decided to correct the GyroDec geometry by drilling and tapping three new holes that moved my original arm plate away from the spindle.

To be fair someone using a 2 point protractor would not know the mounting distance is less than 222mm. They'd just square the cantilever off at the two null points on the paper protractor. By contrast anyone using a Dennison-type protractor would quickly spot the P2S distance was not standard and a 222mm arc protractor wouldn't work.

After my DIY efforts on a crosstalk amplitude and phase meter I tried a Fozgometer and was hooked. I calibrated mine on its speedy arrival and haven't looked back.

Congratulations Jon. Yesterday I spent the day at a house in Leeds with +20 hi-fi enthusiasts and the main house system uses a GyroDec/SME V and Benz Wood SL, a really nice sounding table and beautiful to behold as well !