Wednesday, January 19, 2011

Shift towards active speakers

After bi-amping and tri-amping your speakers, what is next on the audiophile’s list of things to do to obtain sonic bliss?

The natural and logical progression would be to buy active speakers as these would, in theory, create sound that is closest to the real thing.

The main advantage of active speakers would be that they use active crossovers which have components of very small values which are not very detrimental to sound quality. I read somewhere that passive crossovers with higher-value capacitors and inductors can cause some 20 per cent loss in signal strength and can degrade sound quality.

Yesterday, I was at AV Design in Kuala Lumpur for the launch of PMC’s new range of active speakers.

PMC’s sales manager Andy Duffield said more and more people are asking about active speakers these days.

“In the studio industry, people buy only active near-field monitors. This trend seems to be moving to the consumer market,” he said.

But it would appear only the top strata of the consumer market would be interested in upgrading to active speakers. Would someone owning an integrated amp be interested?

I think only those who have tried monoblocks, bi-amping and tri-amping would check out active speakers.

Andy said PMC makes all its speaker units in-house. The tweeter is made by another company to PMC’s design and specs while the mid-dome unit is made in-house and actually doped by hand by an Italian woman.

“Somehow she can do it better than any machine,” he said.


The woofer unit uses a chassis made by woofer specialist Volt, but the cone, magnet and voice coil are made by PMC.

PMC's sales manager Andy Duffield, a six-footer, standing
 beside the PMC MB2-XBD speaker.
The PMC-tweaked Bryston amps and crossover.
The MB2 speaker. Note the Volt-sourced
chassis  of the bass driver and the
transmission line vent at the top of the baffle.


The woofer is unique because it is the only one in the market which has the frame in front of the cone instead of behind it. This is to aid heat dissipation from the voice coil as there can be distortion and impedance change if it gets too hot.

PMC’s active speakers are different from others like ATC’s as the amplifiers are not fitted inside the boxes.


Instead, PMC offers a combo of power amps and active crossover made by Bryston but tweaked by PMC. These are connected to the speakers by proprietary cables which come with the active speakers.

And the speakers come in two boxes - the bottom box is the supplementary bass speaker with its own transmission line and the upper box, which is simply stacked on top of the bottom speaker, has another woofer, the dome mid and tweeter housed in its own transmission line.


It is possible to buy just the top speaker without the supplementry bass speaker, but PMC recommends buying the pair as together they would fill the room with solid bass since the transmission line vents are placed such that the bottom speaker has the vent at the bottom of the baffle and the upper speaker has its vent at the top. Even without the supplementary bass speaker, the bass goes down to 17Hz.


After a short slide presentation on the top-range BB5-XBD active speakers, the group of hi fi bloggers went to listen to the MB2-XBD powered by the PMC-tweaked Bryston 3B SST2, 7B SST2 with the Bryston (PMC-tweaked, of course) 10B electronic crossover.


The MB2-XBD is second in the range and the active version costs RM270,000. Without the XBD bass unit, the cost is RM183,000. A passive version is also available, said James Tan of AV Design.


They are huge speakers as the stacked MB2-XBD are a couple of inches taller than me and I’m five feet eight. The speakers are around 5’ 10” tall and the top-end model is more than 6’ tall.


A wide range of music was played and the speakers sounded great, as they should given their price and the amount of technology (or tweaking) utilised.


The speakers are designed for both the studio and home use and given its studio pedigree, they sound accurate with flat frequency response. Since they are British, the mids are fabulous. But the bass was un-British and was tight and deep.


We played a Nils Lofgren track real loud and that sounded like a concert was held at the AV Design showroom.


The MB2-XBD speakers are now on demo at the AV Design showroom at Wisma Rohas Perkasa.


Friday, January 14, 2011

Another hi-fi shop closes

Audio Impression in Summit shopping mall, Subang Jaya, has closed.


According to one of its owners, Roy, it was closed in December.


He said they will decide whether to reopen it in another location after Chinese New Year.


If they decide not to reopen it would be a sad loss for Malaysian audiophiles because Audio Impression brought in some pretty high-end marques like Kubala Sosna and Stage 3 cables, Coda amps and Eminent Technologies hybrid panel/woofer speakers. 


It is the second hi-fi shop to close in recent times. Late last year, the Hi-Fi Shop in the new wing of 1Utama shopping mall in Petaling Jaya closed.

Wednesday, January 12, 2011

Tweaking the Rega RB300/301 tonearm

Rega tonearms come in two forms - one has vertical tracking force utilising gravity and the other uses a coil spring (for a negative downforce, actually).

In the former group are those based on the RB250/251 while the other group comprises variants of the RB300/301.


Much has been said in various online forums about the coil spring adding resonances to the tonearm and causing the sound to be thick and smeared.


The right tweak, according to this website http://www.tonearm.co.uk/rega-arms-hi-fi-world.htm is to disable the spring by turning the dial to past the ‘3’ mark and move the counterweight forward or backward on the end stub and measure the tracking force with a stylus gauge.


Another website - http://www.tnt-audio.com/sorgenti/analogue_bits_e.html - recommends placing pieces of felt between the coils of the spring after disabling it.



The coil spring.

Turn the VTF dial past the '3' mark to disengage the coil spring.

There are some audiophiles who have actually removed the coil spring altogether.


Since I am now the proud owner of a Clearaudio digital stylus gauge, I can easily check out the tweak to see if it works.


The RB300 of my Rega Planar 3 has Michael Lim’s end-stub and underslung counterweight and it was a matter of setting the vertical tracking force dial to ‘0’ and adjusting the counterweight so that the tonearm was floating slightly above the mat.


Then I turned the dial to around 1.5 and used the Clearaudio stylus gauge to check the tracking force. I can confirm that the dial is not accurate and a good stylus gauge is a must if you want to venture into the world of vinyl. I set tracking force of the Rega Exact mm cartridge at 1.85 gms and the anti-skating at around 1.6.


I spun two test albums that I have been listening to for the past few weeks - Miles Davis’ The Man With The Horn and Bob Dylan’s Together Through Life 180gm double LP.


With the coil spring engaged, the soundstage became narrower and somewhat congested - there was less separation of the voices and instruments, and there was less depth.


Leading edges of music were ‘rounded off’ and the highs were smooth and some instruments like the trumpet, electric guitar and cymbals lacked some ‘bite ‘and shimmer.


Then I reversed the process - I set the VTF dial to past ‘3’ to disengage the spring and adjusted the counterweight to get the 1.85 gms tracing force.

However, the counterweight was a bit further back which increased the effective mass of the tonearm, but there should be no problems with a low-compliance cartridge.


Listening to the same LPs again, I could discern that with the spring disengaged, the soundstage widened and was deeper, there was more space between vocals and instruments, the leading edges became sharper and dynamics improved. The treble had the right bite and shimmer.


All the other audiophiles who did this tweak years ago are correct - with the spring disengaged, the RB300/301 can sing like a bird in spring.



Thursday, January 6, 2011

A New Year's tweak - gel isolation platform

There I was feeling all feverish with inspiration and breaking into sweat with anticipation wondering if the idea that suddenly popped into my neurotic mind would work.



I was all worked up over how to isolate my Rega Planar 3 (with upgraded motor) from vibrations.


I had tried all sorts of footers under a one-inch (2.5cm) thick acrylic platform - cork, earthquake pads, mass-loaded vinyl, soft foam, pumice blocks, steel cap nuts, steel spikes and brass footers.


Each material had its own sonic signature - with soft cork the bass sounded fat and flabby while with hard pumice blocks the treble sounded bright and brittle. The tonal balance changed with the footers used - with some materials it was bassy, with others it was bright.


I needed something that would sound neutral - I needed something that was neither too hard nor too soft, neither too springy nor too pliable.


My neurotic mind was working at a very fiery pace as I knew I was hot on the trail of something feasible. Suddenly I realised I needed something that was neither solid nor liquid and very fluidly my thoughts jelled into one eureka moment - I needed gel.


So I ended up in a pharmacy and spotted some Hot/Cold Packs. These are used to reduce body temperature when you have a high fever or to soothe joint pains and muscle aches. You can put the Hot/Cold Pack in the freezer to turn it into a cold pack or heat it in a microwave oven to turn it into a hot pack. When it is frozen, it turns quite hard and softens as it warms up.


At room temperature its viscosity is like that of thick syrup. Drop the pack and it just goes ‘splat’ - it does not bounce at all. In other words, any impact or vibration will be fully absorbed by the gel.


I bought two packs - they are larger than normal and measure 31cm (12.2") by 15cm (5.9") by about 2cm (0.7") thick and can be used as hot/cold pillows. Each cost about RM30.


Back home, I placed the two Hot/Cold Packs next to each other on an Ikea Lack table and put the acrylic platform on top of them and applied some pressure on it to ensure that the platform was level. I used a spirit level to adjust the platform to be as level as possible.


The Hot/Cold gel packs to be used
as 'footers' for the isolation platform.


The acrylic platform was placed on top of the Hot/Cold gel packs.
The Rega Planar 3 on the gel isolation platform.


Then I placed the Rega Planar 3 on the isolation platform with gel ‘footers’ and spun some vinyl. The Planar 3 was fitted with Michael Lim’s acrylic platter and the RB300 tonearm had his end stub with underslung counterweight (which improves sound quality tremendously) and a Rega Exact mm cartridge. Phono preamp was the Creek OBH-15.


I was pleasantly shocked by the sound quality - the bass went deep and tight, the mids were clear and the treble shimmered smoothly. The tonal balance was just right.


The gel isolation platform absorbed vibrations so well that the cartridge was able to extract lots of musical information from the grooves. I heard plenty of details, but the surface noise remained very low.


I played one of the few audiophile LPs that I own - John Coltrane’s Lush Life in 180gm vinyl - and was transported back to the venue where the recordings were made in 1957-58. It was such a sonic treat.


You can make your own gel isolation platform for a few hundred Ringgit - two Hot/Cold gel packs cost around RM60 and the acrylic platform is available for about RM475 from ATS Rack in Amcorp Mall in Petaling Jaya. ATS Rack’s vinyl platform measures 48.2cm (19”) X 38.1cm (15”). A cheaper alternative is to get the acrylic platform from Michael Lim (http://www.lpturntables.blogspot.com/) who sells it at around RM300, but his is smaller at 45cm (17.75") X 36.2cm (14.25")  which is the same size as the Rega turntable.


The gel isolation platform works very well for turntables without spring suspension like the Rega. I have not been able to confirm if it works for spring-suspended turntables like the Linn or Oracle. If I have the chance to borrow a spring-suspended turntable to test, I will post the results.


In the meantime I will listen to a few more LPs...

Related posts: http://hi-fi-avenue.blogspot.com/2010/10/rm12-tweak.html
                     http://hi-fi-avenue.blogspot.com/2010/02/rm5-tweak.html