I have definitely lost my sanity. Here I am reviewing a slab of slate for its audio properties. Even worse, my conclusion is that I cannot do without it. Yet more surprising is my wife, on seeing the slab, offered to buy it for Christmas! Believe me when I tell you that such an offer from my wife is totally unprecedented. I must be dreaming.
Color me one of the growing number of people who have forsaken belt drive turntables for idler drives a.k.a. rim drives. The turntable is a cream Garrard 301 with oil bearing. There are still some who believe idlers rumble, shake, rattle and roll. They will misbehave if you mount them in flimsy resonant plinths and worse still give them a spring suspension. Rigid mounting, especially with high mass, is part of the idler drive recipe. Typical makes are Garrard, Thorens, Lenco and Rek-O-Kut. Prices for these decks dating back to the 50s and 60s have been increasing over the last few years, there are few low-priced Garrard or Thorens idlers available now but given the enjoyment these decks deliver they are still a bargain even at today's prices.
When you get hold of one of these decks you will usually need to mount it on a plinth and match it with a suitable arm/cartridge. So what do we need for the plinth and what effect do they have on the two supposed failings of my cherished Garrard 301?
Rumble prevention is quite simple, as mentioned previously you do not mount the deck on a structure that will resonate and amplify any vibration. You want material that will absorb or "sink" any vibration. Typically, using a mixture of materials that filter out differing frequency vibrations. This is termed Constrained Layer Damping or CLD for short. Most people use birch ply sheets contoured around the motor and main bearing such that there is little open space within the plinth. Alternate sheets of ply and MDF can be applied... even lead is sometimes used. There are many variables to be tried when building such plinths and for most people life is too short to compare all the options and conclude which is the best configuration. Birch ply on its own as a contoured plinth is well accepted as a safe and sensible route.
Slatedeck are based in Wales and they have recently launched a range of plinths following four years of development. Much of this centers around how to cut the slate without it cracking. Their research shows that it requires access to unbelievably unaffordable equipment. Slatedeck manufacturers, essentially, three models.
The Slatedeck Range
30mm Single-Layer: This is just the same as the 20mm version except that it is 50 percent thicker and therefore 50 percent heavier. These 30mm plinths require long mounting screws that are well polished and look totally authentic. This 30mm version is the subject of today's review.
30mm Dual-Layer: two 30mm slate layers are each supported by adjustable spikes, the armboard is larger than the circular ones and is itself supported by 3 spikes sitting on the lower layer. This looks to provide a very well decoupled armboard. This armboard being 30mm thick would not suit my Origin Live Encouter arm, the thread on its base is not long enough to pass through a 30mm armboard Most arms are compatible, there is also a good looking slate spacer for SME mounting arms. If you have an arm similar to mine and want a dual-layer plinth, then I suggest you consult Slatedeck as there may be ways to fix the small compatibility issue.
The dual-layer is quite costly. There is a doubling of materials and the work required is more than double due to the curved corners that require a lot of hand finishing time.
Prices vary somewhat by turntable model, a 301 plinth (with removable armboard) in 20mm slate costs £470, 30mm is £520 and the dual-layer 30mm comes in at £1,200. Shipping is not exactly cheap as these plinths weigh 6.3kg, 9.75kg and 30.1kg respectively.
Slatedeck will develop custom designs for both currently listed decks and those not on their normal list. An SP10 comes to mind here, and they can use other materials such as granite or marble. The Slatedeck range will soon expand, as there will be a slate-based equipment support. For Garrards, there will be a new main bearing and platter. Slatedeck feels that Garrard main bearings, whilst very solidly built, vary significantly in their tolerances and there are also some improvements to be made to the design. I will be very interested to give these items a listen.
To get a great sheen the plinths are hand finished with special oil. The plinths come with a bottle of this for you to top up the sheen from time to time. Just make sure you protect your stylus when polishing, as you really don't want your polishing cloth snagging your cartridge's cantilever! When you see the plinth in the flesh, it does look very attractive, I have not seen a photo yet that does it justice. My wife was immediately impressed, this is a significant complement to Slatedeck.
"Traditional" CLD Experiences
Next, I went down the Loricraft path of mounting the top 36mm layer of the plinth on squash balls that are half sunk into the main plinth. The effect of this was to bring the bass more under control and the overall balance became much more acceptable. I decided to exchange the squash balls for 3 ball bearing supports. The ball bearings are contained within metal enclosures. The ball bearing supports had a big impact on taming the remaining bass issues. This was working quite well but I was still short in the treble department. Taking advice from some idler veterans (or should that be idle veterans?), I decoupled my aluminum armboard from the motorboard. De-coupling armboards is common industry practice but I have not seen it so much with diy CLD plinths. Some production deck examples with decoupling are the wooden armboard on a Linn LP12 attached using short screws and Michell Gyro plastic spacers which can be further improved by Gert Pedersen's upgrade kit.
It does seem that arms with gimbal bearings, knife edge bearings and unipivots may have differing requirements for de-coupling so there is some debate about the subject. My gimbal bearing Origin Live Encounter arm is inherently de-coupled in that the arm is a 3-piece design and the bearings are purposely loose. Even with this design I found that a rigidly attached armboard killed most of the treble so I used rubber washers between the armboard and plinth. The screws securing the armboard were short and not tightly driven home. I used o-rings under the screw heads and between the arm and armboard. This brought the treble up to an acceptable level even though the last element of "air" wasn't quite there. I then found useful improvements from making armboards out of oak, chestnut and mpingo.
Lastly I attached the motorboard to the main plinth, this is pretty much where I started out. Now though I used the ball bearings under the whole plinth, as ever these brought the bass under control. The choice of solid plinth vs ball bearing decoupled motorboard was mainly down to how much bass I wanted and how this related to the mid-range.
I settled in the end for the solid plinth on the ball bearings. The ball bearing supports and armboard decoupling were vital ingredients, without these bass would have been less controlled and treble would have been AWOL. At no point was rumble ever present. It seems you have to try really hard to get your idler to rumble. Does all this experimenting sound like a lot of work? It was. Maybe there is a better way.
A 301 Plinth - The Easy Way
The first revelation is that it looks great. Visual impressions from photos had left me feeling the dimensions of the dual-layer would suit the 301 much better. Whilst I've not seen the dual-layer in the flesh, the single-layer looks really good. My Kontrapunkt B stylus hit the groove, the first few notes played and I already knew the result of this contest. It was no contest. Sure my CLD is very good but it's not this good!
Everything that makes the 301 special is further enhanced. I feel that Slatedeck simply extracts the maximum performance out of the 301, and I am sure it would do this for any other idler or direct-drive deck too. I would love to hear what more the dual-layer plinth could do. So how on earth do I describe what I am hearing? Well, here goes...
With Slatedeck the top-end is quite simply right straight out-of-the-box and better than I'd managed to achieve previously, even with all my armboard de-coupling efforts. Overall the sound of the Slatedeck, relative to my CLD, is bigger, bolder and richer with more top-end. There's a more breathy natural acoustic around vocals and air around instruments. Detail exhibits itself by appearing almost anywhere in the room, my open baffle speakers no doubt help here too. Bass has tremendous weight and power. Remember when you were converted from belts to idlers? This is a change of similar magnitude.
I am no doubt upsetting those who have built their own CLD plinths. I don't make these comments lightly, remember I put many hours into building my own CLD plinth! Did not expect to hear such a comprehensive improvement. In some ways I didn't want to hear such an improvement. Not only does this tell me of all the hours and effort wasted, but also am now going to have to buy the Slatedeck. The review plinth was due to be returned so it could be sent elsewhere. This plinth is not going anywhere!
Here are some comments following my listening sessions:
On U2 / Joshua Tree at the start of "I Still Haven't Found What I'm Looking For" plucked string dynamics are staggering.
Doors / Spanish Caravan – there's a puttering bass in the background, it's normally a low drone or simply not there – now it's well defined giving a gentle and tight foundation to the song.
Diana Krall / The Girl in the Other Room – title track, the plucked bass strings are very distinct and accompany but not overpower the music. Playing this after The Doors is a bit of an ear-opener. The Doors were fine to listen to but the production of the Krall recording is in a different universe. Krall's vocal intonation is subtle yet clear producing tremendous atmosphere.
Freddy Redd Quartet / Music from The Connection (on Blue Note) sounds vibrant, open and very well balanced. Where the music is supposed to be fast it is and comes across with great exuberance. Hi-hats are well presented, with no treble veiling at all.
Spinning Brubeck's Time Out, Blue Ronda a la Turk is first on, hi-hats left, double bass centre with piano on the right. Great separation of the instruments is enhanced by wonderful interplay between them. Take Five was of course wonderful. On both tracks treble was vibrant and sparkling, bass was thunderous when it was meant to be and sax was mesmerising.
My very flawed pressing of Beth Orton's Comfort of Strangers is at last rendered listenable such is the drive to the music, somehow the stylus just ploughs through all those imperfections, casting them aside.
Playing one of the hi-fi test standards, Jennifer Warnes / Famous Blue Raincoat was a wonderful experience. This wide-range recording was really impressive, especially with Bird on a Wire. The frequency extremes were fantastic but what really stood out for me were Jennifier's vocals. I don't personally know Ms. Warnes but after listening with the Slatedeck I felt I did. Magnificent.
Fleetwood Mac / Rumours, exhibited very powerful plucked guitar strings on Never Going Back Again. The Chain was particularly dramatic. This album is not exactly the last word in clarity and presence but this was the best I have ever heard it sound.
Moving onto Goldfrapp / Supernature, there is subtlety between the pulverising bass lines which are very well defined and in no way mask the rest of the performance. The sound here is spectacular, if a little menacing at times when I let more than a watt or two lose on the 100db Prometheus open baffles.
Pink Floyd / The Wall is deeply impressive, especially the deep bass with explosive dynamics.
Even poorly recorded music sounds better than expected! The 301 with slate plinth is not brutal with such records, but the good cuts sounds really great. This 30mm slate plinth seems to maximize the great attributes of the 301 and it banishes foibles that the 301 is sometimes accused of. This shows how important the plinth is and highlights how most 301s and other idlers out there will not be delivering anything close to their full potential. Consistency is important here; the sound across the entire frequency range is consistent, no specific areas are disadvantaged at all. Bass timing & speed are exemplary.
With the single layer plinth there is scope to experiment with decoupling the armboard. I expected this would be necessary, it turned out it was not. It is possible that introducing a non-slate material between armboard and plinth could offer some benefits. Maybe there is a way to support the armboard from underneath, rather than have it rest on the plinth. The option is there for you to experiment if you wish.
Rumble? Veiled treble? Something has to be seriously wrong for these decks to rumble. Veiled treble is easier to achieve. If you want to be sure to slay these myths then get a Slatedeck. It is hard to put into words just how profound the improvements achieved by the Slatedeck. The effect is immediately noticeable, it is the sort of improvement you would hope for, but is rarely achieved, even if you go for a very expensive whole system upgrade.
How About A Dual-Layer?
CLD or Slatedeck?
I need you to do me a favor. Forget I ever told you about Slatedeck. Do not tell your friends. Garrard 301 and 401 decks are expensive enough already, Thorens 124 too. If you spread the Slatedeck secret around prices will skyrocket again, Lencos and Rek-O-Kuts will loose their low-budget status.
Anyone want to buy a lovingly crafted, but recently obsolete, birch ply CLD plinth?
301 plinth (with removable armboard) in 20mm slate costs £470, 30mm is £520 and the dual-layer 30mm comes in at £1,200. Shipping is not exactly cheap as these plinths weigh 6.3kg, 9.75kg and 30.1kg respectively.