Hi Lewm
These are all interesting challenges as you are no doubt aware. Coupling the chassis to the plinth is the trickiest challenge. I like your idea of bolting the chassis right through to the bottom where it can be firmly anchored underneath - good one! The bore holes will need to be precisely aligned and ideally drilled through both layes in one go, which could be tricky. I had considered glueing 3 cabinet inserts into boreholes in the slate that would accept a small machine bolt as I'm not convinced that a good enough thread can be cut into the slate for a bolt/screw to bite into.
I'm not convinced that the two facing layers will be completely flat and smooth, so I wont be glueing them together, also I would like to keep the plinth modular because of the sheer weight. I'm more inclined to try sorbothane between them.
The tonearm hole also presents the same challenge, do you think a threaded hole can be cut into slate that will be good enough for screws to bite into? |
[IMG]http://i230.photobucket.com/albums/ee15/indypepa/newdenon.jpg[/IMG]
I have owned my DP80/dk300 for 6 weeks now along with a Koetsu SA1100 special edition tonearm. I am running a re-tipped and nuded Denon 103, this rig is my last stand at analogue nirvana and I'm deeply impressed so far.
I am looking at developing a new plinth, for reasons that are discussed above, also as the footers on the dk300 are nothing more than threaded alu blocks encased in plastic with felt attached to the bottom. I'm really interested in a substantial slate plinth, but as kcc123 says, it's cost prohibitive. I'm off to some reclamation yards this weekend to try and source some slabs.
My second option is to go for a massive layered plywood jobbie, with maybe a sheet of SDS isophonon as the top layer, although I feel the slightly textured finish of the sheet may be a concern for coupling to the underside of the chassis. My previous deck was a KAB modified SL1210 and for that I built a solid wood plinth surround (box) that contained an inch of silver sand and granite slab for the deck to sit on, this is also an option, but I really want to go all out for the slate solution, however, getting 4 inches depth along with cutouts, coupling holes and finishing is no mean feat.
I have also sourced some butyl rubber speaker damping compound to apply under the 'skirt' of the chassis.
Look forward to any theories you guys may have for suitable solid or cld plinths. |
Thanks for the reply Lewm. I am based in the UK (Wales) where the world's finest slate comes from (apparently) but it's still very expensive here. Hopefully I can source a decent fireplace plinth or something of similar size. I have a local stone mason who specilises in headstones, so he can help with finishing, just need to find someone to cut the holes.
I have inverted the plinth onto an A2 sheet of paper and traced the cut-outs for the motor unit and tonearm. How are you intending on securing your chassis and tonearm to the slate exactly? I was thinking of perhaps some bore holes with an m5 cabinet insert secured/glued inside.
Please post some images of your slate plinth when you are ready. |
My 'finest slate' line was written in jest, it's just a marketing gimmick in my opinion, and I can no-way afford Slatedeck's prices anyway. Yes I agree that the fastening holes are very close to the inner edge of the cutout, and this is a concern, it's certainly a job for a pro.
The person who sold me the DP80 is a dealer in all things japanese dd and he told me that the 80 has a sapphire bearing which is superior to that employed on the SP10mk2. I have the original manual and what looks like a press pack type thing, but it still gives little away in terms of detailed spec for this deck, it really is a somewhat closed book, and that has probably kept the interest in this fine deck to a minimium compared to the SP10.
I was interested in the torque measurements between the DP80 and sp10mk2, but I cannot find anything, what I do know is it is a great deal higher than the SL1210, it takes a fair bit of finger pressure on the platter rim to register on the strobe. |
Hi Raul
Interesting stuff, you are a lucky man indeed to have both decks to play with.
I was under the impression that the DP80 was also designed for professional/studio use, and the DP75/M was the domestic version. It doesn't matter as they (Technics & Denon) are both superb decks and make me wish I had discovered direct drive years ago before I wasted all that time & money on suspended belt driven decks. |
I sourced a nice big slab of slate for just £30 on the weekend from a reclamation yard, it's 2 inches thick and the plan is to cut in in half and double it up, so it will end up being 4 inches deep which is the same depth as the DK300. The upper & lower layers will have different cut-out to refect the shape of the motor unit, with the lower (base) layer having a larger surface area for greater flexibility fo locating footers.
This plinth is going to be monsterously heavy, I would imagine total weight with DP80 motor unit will approach 100kg. I am intending to use Clearlight RDC cones and combi-bases as footers, but I am wondering what to use between the two layers of slate (if anything at all) if the two layers dont sit absolutely flush with one-another. Does anyone have any ideas as regards the best approach, i.e. a thin layer of compliant damping compound to isolate or something solid like small spikes to tightly couple the two layers? |
I've had a look at a similar thread on another forum, and agree with you Lewm that bolts are best for this job! I have decided to bolt both chassis and tonearm through the top layer only, I will drill a rebate/countersunk hole into the underside in order to secure a washer and nut, that will remain flush when placed on top of the base layer. |
Just a quick update.
I've handed over my template to a fella who runs a mill and specialises in slate. I'm going for a monster one-piece 100mm thick 'headstone finish' type slab. The cut-out is tricky (especially at the front where it comes with a couple of inches of the edge, and it will have to be cut with a water-jet, but I'm hoping he'll come through. At the moment I've decided to go for threaded inserts glued into bore holes for the anchoring points. |
Hi T_bone
I spent some time scratching my chin on this one. I was toying with the idea of having a corner piece cut out of the plinth, rounded off and bore it for the arm, whereby it would 'sit' inside the concave rounded corner without actually touching the plinth, much like the Michell Tenodec, this would allow the arm to be moved idependently of the plinth to accomodate different arms. But it would be very costly, so in the end I have decided to commit to one arm (10.5" S-shape Jelco) and have a hole drilled out in the one-pice plinth, so no going back now! |
Lewm
How did you get on with the tricky holes on the edge of the motor unit cut-out? I can't find m4 bolts / machine scews longer than 60mm, so unless I bore slightly larger holes from underneath to a dept of 50mm in rder fasten a nut on each bolt, i'm stuck. That's why I'm going for threaded inserts. Thanks for the heads-up re: surface mount arms, I had no idea such arms existed. Isn't the Terminator a linear tracker arm? there is a guy over here using one of them with an SP10 on a slate plinth, it looks totally brutal. |
A revovable arm-board would be desirable, I did consider trying to get a square or circular hole cut through the plinth with a lip half-way down for the arm board to sit on, but this would depend on the type of kit used to cut, Given what Lewn said about the water jet cutter, I imagine that the cut-out will be quite rough and the 'plug' will be equally rough if not in pieces so a new block of slate would need to be sourced, cut and finished off to sit the arm in. Perhaps a circular hole would be better, as a conventional drill could be used, and I dont see why a 'lip' couldn't be incorporated.
What do you guys think would be the best type of footer to use under these hefty slabs? I intend to use RDC cones, cups and combi bases. Would a solid 'less compliant' footer be better perhaps, The chap who sold me the Denon suggests cerupucs or still points, but I'm looking for a less expensive solution. |
Well it been a while now, but the slate plinth for the Denon DP80 has arrived and I'm getting it together.
It's 100mm deep and a considerable weight. I have managed to drill the 3 fixing holes (m6) up close to the inner edges and glue m4 threaded inserts into the holes, this has worked out easier than expected with the slate being easy to drill, There are twin arm holes with a deep rebate on the underside of the plinth to allow my fingers in to adjust, I am using an ex-broadcast Denon DA309 at the moment, but the other hole will accomodate a Jelco 10" in the near future. I have done the same on the underside with threads to accomodate RDC cones. Once I have cleaned the plinth with WD40, I will be finally rubbing it down with bees wax to protect it and bring out the grain. Here are preliminary snaps.
http://i230.photobucket.com/albums/ee15/indypepa/2.jpg
http://i230.photobucket.com/albums/ee15/indypepa/p1-1.jpg
http://i230.photobucket.com/albums/ee15/indypepa/007.jpg |
Thanks for the feedback fellas.
T-Bone, I took those 'action' shots the other day, however neither the motor unit nor the arm were secured into the slate, and it was sitting on large temporary sorbohane footers, but it sounded rather good considering with more romance in the mids and intimacy and presence in vocals. It's a shame you cant source slate easily in Japan, how about marble?
Lewm
I wanted this plinth to have a smaller footprint than the Denon DK300 plinth, which was hanging over the edges of my rack, I was looking for something a little more compact, although in hindsight I wish I had left a bit more room to try a 12" arm in the future. I need to source a bespoke acrylic / perspex cover for it now, to sit on top. Interesting concoction you have there for sealing your slate, it's a beautiful material isn't it...even if it is just compacted mud, but it scratches so damn easily though. Yes this slab is very heavy indeed, I can hear the rack groan when I first heaved it up there.
Lewn I and Im sure others here would love to see some pics of your effort, especially with those tremendous arms you have lined up for it. Ill post some more in a few days.
Thanks all |
Lewn. I forgot to mention that I have filled the ring or skirt with isodamp compound (blacktac) as used in speaker cabinets, this is actually in contact with the plinth, and has given a deadening effect and added mass (not that I needed any more).
The dp80 is really singing now, I have stunning presence and intimacy to vocals. I cleaned it up earlier with WD40, that brought the natural grain up very nicely, and finshed with bees wax that gave it a nice shine.
Here are some more pics.
http://i230.photobucket.com/albums/ee15/indypepa/dp6.jpg
http://i230.photobucket.com/albums/ee15/indypepa/dp8.jpg
http://i230.photobucket.com/albums/ee15/indypepa/dp5.jpg |
