Tuesday, February 22, 2011

Fly-wheel tweak

I had been comparing Michael Lim's vinyl platter with the stock Rega glass platter on my modded Rega Planar 3 and I noted that the vinyl platter delivered a steadier pace and rhythm.

This is due to the fly-wheel effect of the vinyl platter since it is thicker at its rim. 

This fly-wheel effect provides speed stability which results in a steadier pace and rhythm. I decided to tweak the Rega glass platter to get the fly-wheel effect.

Despite the fact that the glass platter rings (and this manifests as harder and 'splashier' high notes), the material actually has some advantages - it is quite heavy and is very flat. Many platters made of other materials are not that flat and they can wobble a bit.

To achieve the fly-wheel effect, I had to increase mass along the rim of the platter. So I bought some rubber footers from the DIY shop. These weigh 0.75gm each and I stuck 16 of them around the rim of the glass platter. Total weight = 12 gms.

I played an LP and after a while I felt that the pace and rhythm were still not as good as when I used the vinyl platter.

So I bought some rubber bumpers, which are heavier at 3.5gms each. I stuck eight along the rim. Total weight of bumpers = 28gms. Total weight of bumpers plus footers = 40gms.

The glass Rega platter with the rubber footers
and bumpers stuck along its rim.
If I could do it again, I would just use the heavier bumpers.

Actually if I could start all over again, I would just buy the bumpers and paste 16 (56gms) of them around the rim.

I played an LP again and I felt that the music finally had the steadier pace and rhythm that I wanted.

Also, the leading edges of music became more dynamic and 'sharper' and bass notes had more 'thump'.

This relatively cheap (a pack of footers or bumpers cost around RM6.90) tweak will result in better rhythm and more dynamic-sounding music.

Friday, February 18, 2011

Removing bad vibes

There I was feeling all feverish again with my neurotic mind working non-stop thinking about the limitations of the Rega Planar 3 turntable's design.

Suddenly, it struck me that almost all turntable designers had never bothered to solve the problem of vibrations caused by the bearing. Not just Rega, but almost every other manufacturer out there.

The bearing makes some noise and vibrations because the spindle revolves in the bearing housing and sits on a ball bearing if the spindle has a flat bottom or if its end is spiked, the sharp end spins on the bearing housing base.

Turntable designers just use oil to lubricate the bearing and also to dampen the vibrations.

What happens to the vibrations? The thin film of oil may absorb some of it, but the rest will just travel up the bearing housing to the plinth and then to the tone arm and stylus.

Some vibrations will also travel up the spindle to the sub-platter and then the platter and pass through the mat (which will absorb some) and to the LP to the stylus.

Two strips of Dynamat wrapped around the bearing
housing at the bottom of the Rega Planar 3.

Some designers use heavy plinths or platters to dampen the vibrations from the bearing and the motor.

I decided to absorb the vibrations at the source - the bearing housing itself. Since I had a sheet of Dynamat Extreme - a dampening material comprising a black sticky compound with aluminium sheet backing which is widely used in the car industry - at home, it was just a matter of cutting a strip to wrap around the bearing housing jutting out at the bottom of the Rega's plinth. I used two pieces of Dynamat.

Then I played an LP and noted a lower noise floor.

Since I was already in a tweaking mood, I decided to go one step further - I unscrewed the plastic cover of the motor to see what else I could mess around with.

The Premotec motor. Note the
square piece of double-sided tape.

Dynamat strips were pasted on the motor and plinth.

The Premotec motor (I had upgraded the motor many years ago when Trikay was still in business) was simply stuck to the top veneer of the plinth with double-sided tape.

So I pasted Dynamat on the motor, the plinth and the veneer. I also pasted some on the small plastic cup that houses the spring-loaded thrust bearing of the motor.

I listened to the LP again - the noise floor was lowered some more.

It appears that the performance of a turntable will improve progressively when increasingly more vibrations are removed from the equation.

So if you have some spare dampening sheets lying around, you can improve the performance of your turntable simply by pasting them at strategic spots.

Thursday, February 17, 2011

Roger Wang's showcase

Guitarist Roger Wang will have an album-launching-cum-mini-showcase at Loud+Clear record shop on Feb 25 from 8pm to 9pm.

Roger Wang is one of the best guitarists in Malaysia.

Roger Wang will be releasing his first compilation album after 10 years in showbiz. Recently, his career was given a huge boost when Cantopop's Heavenly King Jacky Cheung used one of his compositions in his Private Corner album.

Roger has also collaborated with Leslie Loh in the audiophile recording 2V1G which has sold some 20,000 copies since it was launched in 2008.

Roger's showcase will be held at the latest record shop to open in Kuala Lumpur and it is located at the hip and happening Solaris Dutamas.

Admission is free. Please call Caffee Wong at 012-3698169 to book a seat.

Tuesday, February 8, 2011

Rega RB250 revisited

For the past week or so I have been experimenting with the Rega RB250 tonearm with the aim of trying to confirm if all the vinyl experts out there, especially the Origin Live folks, were correct when they said the RB250 when modded can outperform the top-end Rega tonearms.

The RB250 has vertical bearings on both sides of the armtube which makes it inherently more stable compared with the RB300 (and its variants) which has the vertical bearing only on one side while the other side houses the coil spring to control the VTF.

My Rega RB250 tonearm is not from an old turntable; it is a newly-made model from a special edition issue for Malaysian vinyl addicts (read: http://hi-fi-avenue.blogspot.com/2010/11/limited-editions-of-rega-rb250-rb300.html)

Since I was on leave for Chinese New Year, I had some time to spare and I took my old Rega Planar 3 to the 'workshop'. First I removed the RB300 tonearm, which was surprisingly quite an easy job.

Then I took the RB250 tonearm and inserted the cables and then the steel base through the hole in the plinth. There was some play and I thought the base of the RB300 was bigger, but when I checked with the RB300, I found out that there was some play with it too.

So, I screwed the RB250 with the supplied thin nut. With my finger and thumb I turned the nut as tightly as I could and then with an adjustable spanner, I screwed it tighter with just a little turn.

Getting the tonearm to be parallel to the edge of the turntable is actually quite difficult as it tends to shift its position when the screw is tightened. After some struggling I managed to get it more or less parallel to the plinth's edge.

The limited edition Rega RB250 tonearm.

The RB250 about to be fitted into the hole in the plinth.
Note the plastic end-stub

The old Rega Planar 3 with RB250 tonearm.

The RB250's plastic end-stub and counterweight.

The RB250 in action.

Michael Lim's steel end-stub and underslung
counterweight fitted on the RB250.
After that it was a matter of removing the Rega Exact cartridge from the RB300 and fitting it to the RB250. I used the third screw so that the cartridge would be set up according to Rega's alignment which is the easier solution. It may sound simple, but the entire operation took me one and a half hours to complete.

After screwing in the plastic end-stub and the counterweight, it was a matter of using the Clearaudio digital stylus gauge to set the VTF to around 1.8gms. Setting the anti-skating force is quite tricky as even at the '0' mark the tonearm swings back. Thus '0' is not exactly '0' with Rega's magnetic anti-skating system.

Then I chanced on a pretty reliable way to set the anti-skating force. I simply placed the stylus on the glass platter. Since the glass has a smooth surface, you can see the tonearm skating outwards when the anti-skating force is set too high.

I reduced the anti-skating force till the stylus did not skate when it was placed somewhere between the spindle and the edge of the glass platter. The cartridge seemed to track quite well when I played an album and the sound seemed quite balanced between the left and right channels.

After playing a few albums, I can confirm that the audiophiles who said the weakest part of the RB250 is the plastic end stub - which by the way is hollow - are correct.

The stock RB250 sounds more transparent and clearer than the stock RB300, but it also sounds rather lean.

I replaced the plastic end-stub and counterweight with Michael Lim’s steel end-stub and underslung counterweight. There was a dramatic difference - the low bass went deeper with more definition and the mid and upper-bass filled up to give the music lots more body and richness while retaining the RB250’s inherent transparency.

I have also been using lead-vinyl mats and a carbon fibre donut mat from sLam Audio with Rega’s glass platter and the combination creates music with a neutral balance and great clarity with deep and solid but tuneful bass. The listening sessions were carried out with the turntable on my gel isolation platform (read: http://hi-fi-avenue.blogspot.com/2011/01/new-years-tweak-gel-isolation-platform.html).

I have not tested my modded RB250 against the RB700 or RB1000, but I can safely state that the modded RB300 - even with the spring disengaged - does not outperform the modded RB250. Yes, the Origin Live chaps are correct - a modded RB250 can really sing and I am not sure why the Rega folks did not bother to improve the design.