thebes Posted February 17, 2017 Share Posted February 17, 2017 Decided to build a rubber plinth for my Technics SP25 in an attempt to match the characteristics of the factory plinth which used some kind of dense rubber. A discussion of of weather to proceed or not, along with other considerations can be viewed here: I decided to go ahead, found some heavy rubber made from recycled tires, ordered a sheet and spent today building the plinth. First thing was to lay the rubber flat on the floor since it was curled up from shipping. Then I laid it out some scrap wood to cut on, along with needed tools such as razor blades, utility knife, straight edge, measuring tape and some soapy water, which I learned off the internet aids in cutting rubber. Quote Link to comment Share on other sites More sharing options...
thebes Posted February 17, 2017 Author Share Posted February 17, 2017 First you score the top, then make deeper cuts taking care to keep the blade straight . A few passes and some patience, and I have two of three three panels cut. Quote Link to comment Share on other sites More sharing options...
thebes Posted February 17, 2017 Author Share Posted February 17, 2017 I need three panels because the original plinth weight about 20 lbs., which I presume to mean that the original designers favored that approach so I want to replicate it. I need to cut some large holes for the table and my material must not be as dense as the original, because after making two holes, they two panel only weight about 10lbs. Therefore I have added a third panel which does not have a hole, only a small channel for wires, and this brings the weight up over 20 lbs. Quote Link to comment Share on other sites More sharing options...
thebes Posted February 17, 2017 Author Share Posted February 17, 2017 With all the panels in place I test fit the table. It has screw holes under the platter for attaching screws/or bolts. I use those white plastic screw-type drywall anchors to attach some screws. I then drill out the arm hole, and add soem more anchors for an armboard. Quote Link to comment Share on other sites More sharing options...
thebes Posted February 17, 2017 Author Share Posted February 17, 2017 I then drill out the arm hole, and add some more anchors for an armboard. I'll be using a Sony PUA-237 arm which has an effectiv length of 222 mm, with a 15 mm overhang so the measuring has to be be pretty exact. Quote Link to comment Share on other sites More sharing options...
thebes Posted February 17, 2017 Author Share Posted February 17, 2017 Al that remains is to mount the headshell and align everything and it's good to go. Since the table I'll placing it on its very level, I was going to just let it lie flat without legs, however the DIN plug for arm is too long, so I've decided to just lay it on top of the original thing wooden plinth for now. The rubber is to flexible and would sag if I just used feet. A listening report will be forthcoming after tonight listening session. 1 Quote Link to comment Share on other sites More sharing options...
thebes Posted February 19, 2017 Author Share Posted February 19, 2017 Well I spent several hours with the new plinth Friday night. I've been using this particular arm/cart/table combo for several week so I'm pretty familiar with the sound. First, when tapping the rubber plinth I still get some sound through the speakers, but much, much less than while using the one I made out of Baltic birch. So not dead silent, but definitely improved damping. Second, I had expected at best a minor improvement in the sound, but was quite surprised, and pleased at the overall improvement of the sound. The soundstage is a bit deeper, the presentation is more musical and the mids are a bit more magical. I did not, however, notice much change in the upper register which is a bit harsh at times, but overall I'm quite pleased with the experiment which has yielded real sonic benefits, even though this is a direct drive table and not a belt, idler wheel or suspended table. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 19, 2017 Share Posted February 19, 2017 Interesting experiment. What about combining this with birch, either as a final top layer or sandwiching sheets of rubber between layers of wood? Quote Link to comment Share on other sites More sharing options...
mike stehr Posted February 19, 2017 Share Posted February 19, 2017 It seems (to me) that using drywall screw anchors to fix the tonearm and tone board to the rubber base would leave a little slop/wiggle? Like Michael mentions, maybe a top layer (mabbe a 1/4" to 3/8" thick) of like mahogany or maple...wood types used for musical instruments. I admire the just do it and see what happens approach. Quote Link to comment Share on other sites More sharing options...
thebes Posted February 20, 2017 Author Share Posted February 20, 2017 I thought about using the Baltic Birch with it, but I think, (sorry no way to actually run graphs) that the rubber did what I wanted. Aesthetically, I kinda like the rubber. With the little bits of white cordage in it, (its basically chopped up tires) it looks pretty cool. Hence the acrylic armboard. I have to hit the rubber pretty hard to get the arm to move even a bit, so it appears to be pretty solidly attached. This is not the bouncy type of rubber. Later on I may run the bolts all the way through to the bottom, and maybe add some wood. Right now the three panels, plus the base, are not even glued together, but at over 20 lbs weight, it doesn't seem to be a problem. Since this is an experiment it can be conducted in stages with listening in between. Quote Link to comment Share on other sites More sharing options...
Shiva Posted February 20, 2017 Share Posted February 20, 2017 I have enjoyed reading of your design idea and quick follow through. Very cool sound experiment. Do the rubber mats have any aroma of Goodyear to speak of? Quote Link to comment Share on other sites More sharing options...
thebes Posted February 21, 2017 Author Share Posted February 21, 2017 They did the first day or two but now you have to put your nose almost on the rubber to smell anything. I also used the leftover rubber as isolation pads under my cd player and preamp. I was surprised at how quickly the smell went away. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 21, 2017 Share Posted February 21, 2017 6 minutes ago, thebes said: I was surprised at how quickly the smell went away. I find myself thinking that after spending a day with @jimjimbo Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted February 21, 2017 Share Posted February 21, 2017 3 minutes ago, Thaddeus Smith said: I find myself thinking that after spending a day with @jimjimbo Game on! Not long till the end of April..... I'm going to Mexico in March, so I'll have to find an extra nasty gift to bring back for you Michael. 1 Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 21, 2017 Share Posted February 21, 2017 I'll settle for vanilla extract! Need anything from DFW? I can hook up with Brian for sauces if necessary. Quote Link to comment Share on other sites More sharing options...
jimjimbo Posted February 21, 2017 Share Posted February 21, 2017 Yes, we were planning on bringing back lots of vanilla, perhaps some tequila that I can't find here.... I'm good on sauces right now, but thanks. Quote Link to comment Share on other sites More sharing options...
Shiva Posted February 21, 2017 Share Posted February 21, 2017 43 minutes ago, thebes said: They did the first day or two but now you have to put your nose almost on the rubber to smell anything. I also used the leftover rubber as isolation pads under my cd player and preamp. I was surprised at how quickly the smell went away. Glad to hear it. I just had an oil change at my local Pepboys and their waiting room had a few well placed stacks of tires by the seats, very thoughtful of them. potent rubber, the smell did not dissipate, though they were on sale. Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 21, 2017 Share Posted February 21, 2017 45 minutes ago, jimjimbo said: Yes, we were planning on bringing back lots of vanilla, perhaps some tequila that I can't find here.... I'm good on sauces right now, but thanks. I'll find something to bring along that's not easily found elsewhere Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted February 21, 2017 Share Posted February 21, 2017 8 minutes ago, Thaddeus Smith said: I'll find something to bring along that's not easily found elsewhere Back hair? Quote Link to comment Share on other sites More sharing options...
Thaddeus Smith Posted February 21, 2017 Share Posted February 21, 2017 9 minutes ago, CECAA850 said: Back hair? I actually have a fairly hairless back, thank you very much. Quote Link to comment Share on other sites More sharing options...
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