Plinth Dampening & Other Mods

krameraxeman

Active Member
I picked up a 1975 Panasonic RD-3600 + 27 LPs from a guy on ebay a couple of years ago for $50. I've done a number of tweaks to it, like replacing the cracked dust cover with one from a SL-23 (same cover), replaced the cart with a DL-110 (before the prices went through the roof), replaced the belt, deoxit'd the speed control pots to fix speed issues, and replaced the headshell. All of this was well worth the effort and $$.

A mod that I did recently that yielded really dramatic results was to line the interior of the plinth with Dynamat (ran it like this for 6 mos or so) then stuff 4lbs of Plasticlay in there. The Plasticlay made a huge difference. I've seen threads about doing this on plastic SL-1200 like plinths, but haven't seen anyone doing this with a TT like the RD-3600, so I thought I would share. Oh and I dynamatted my platter too....dunno if that did much as I did it at the same time....

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I did waste, and I mean utterly waste, $50 of a acrylic platter mat. Not only did it not sound better that the OEM mat, it would slide on the platter whenever I started the TT or cleaned a record. I tried sticking the mat down, but then my vinyl would just slide on the mat.....lame. Other than that, every mod I've listed has really turned out well. This has really turned out to be a great performing TT. I especially like that nobody seems to have this model. :)
 
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Nice!

I agree that damping the plinth on many tables will can have a very positive effect, I did similar on a Sonab 85s I had.

One thing that may be worth trying is a length of heat shrink over the arm tube, but not the adhesive kind as you want to be able to remove it latter if need be. It is a smaller tweak depending on how resonant the arm is, this tweak cleared up very fine detail on my Sansui arm.

The other thing is if the signal wires are hard wired to the table, replacing those old ones with new quality ones can make a very noticeable difference IMO.
 
Thanks krameraxeman for the info and feedback. I've been thinking about doing this to my Yamaha TT. I wasn't sure if it would yield very good results. I see it did for yours. So I think I'm going to give it a try.

And yes datafone changing the rca's to jacks on the back. Where you can use custom interconnects. Does help the sound quite a bit. For the tonearm on my TT. I using 4 small rubber o-rings. They do help bring out a little more detail and help quite the surface noise of the records.
 
Nice!

I agree that damping the plinth on many tables will can have a very positive effect, I did similar on a Sonab 85s I had.

One thing that may be worth trying is a length of heat shrink over the arm tube, but not the adhesive kind as you want to be able to remove it latter if need be. It is a smaller tweak depending on how resonant the arm is, this tweak cleared up very fine detail on my Sansui arm.

The other thing is if the signal wires are hard wired to the table, replacing those old ones with new quality ones can make a very noticeable difference IMO.

That's funny, my next tweak was to try out shrink tubing on my tonearm to see if that yielded any further improvement. I don't think I'll go so far as re-wiring the tonearm though (looks like a PITA). My audiophile friends think I'm dumb for not just going out and buying a pro-ject, music hall, etc., but I find tinkering fun and a cheap table is a good thing to experiment on.
 
Nice work.

I would say the heat shrink tube on the tone arm is a good idea also.

Another project that yields dividends is either a wall shelf or a sand box. Build a box that will hold a good portion of sand. Build a top plate that will sit on the sand, and put some heat sink or l brackets that will enter the sand and provide a pathway for vibration dissipation and provide stability to the floating top plate. Don't think I ever met anyone who did not report positive gains with a sand box for their turntable.

Regards
Mister Pig
 
Yea I could go out and buy something a little better than what I got. But I'm too much of a tinkerer. I find it very fun and rewarding to work on lesser equipment and try to bring as much out of it as I can.
 
Yea I could go out and buy something a little better than what I got. But I'm too much of a tinkerer. I find it very fun and rewarding to work on lesser equipment and try to bring as much out of it as I can.

EXACTLY!!!

Is Dynamat & clay mod almost always beneficial?

Well, I did the Dynamat first and ran my turntable for actually almost a year like that. It helped a bit. I noticed a marked difference immediately after the Plasticlay treatment. The combo worked well for me, but I wonder if I could have just skipped the Dynamat. BTW, make sure to use Plasticine modeling clay (like Plasticlay) as it never hardens and doesn't have H2O in it like regular clay.
 
Think you're onto something in that it's the clay really. The intuition tells me the big chunk of wet clay would have more impact too. Tried it on the platter yet?

Sent from my X10a using Tapatalk 2
 
Think you're onto something in that it's the clay really. The intuition tells me the big chunk of wet clay would have more impact too. Tried it on the platter yet?

No, not going to try it on the platter. I don't want to add weight to it and put stress on the motor. It think I'd likely have adhesion and balancing issues as well. The Dynamat on the the platter stopped the platter from ringing when I tap on it.

Also, you definitely do not want wet clay anywhere near your turntable. Water and electricity don't mix. I'd also be worried about corrosion. Actually, if it didn't blow up in your face immediately, clay would eventually dry out and not stick to the plinth anymore. Basically, regular clay is not recommended.
 
My Technics platter rang like a bell so I mixed up a batch of spray vibration dampner (Lizzard Skin) and shot the back of the platter surface. It only added a little less than 2oz of weight but made a ton of difference. Just a nice thud now when I tap the platter. I guess the same as adding dynamat but worked well and the platter still balanced perfectly. I thought about adding something like clay to the plinth as well but this is a suspention chassis table so I don't think I would reap the same benefits.

Sent directly from my thoughts using tinfoil antennas and a stainless mixing bowl helmet.
 
That's funny, my next tweak was to try out shrink tubing on my tonearm to see if that yielded any further improvement. I don't think I'll go so far as re-wiring the tonearm though (looks like a PITA). My audiophile friends think I'm dumb for not just going out and buying a pro-ject, music hall, etc., but I find tinkering fun and a cheap table is a good thing to experiment on.
Oh, I didn't rewire the actually tone arm on my table, it is internally damped so could be too much for me, but the hard wired leads that attach to where the tone arm wires start inside the table I did change, as long as you get decent quality ones that will fit the securing grommet It's not too difficult...as long as you have basic soldering skills :)

I was going to go the way of connections on the rear of the table, but that adds an extra connection that I chose to avoid. Still a good idea if swapping cables is what someone likes to do.
 
One thing to watch for is with suspended sub chassis, if damping them don't go over board (maybe even avoid it), or it could adversely effect the suspension, i went too far with one table and the suspension collapsed :(
 
Is Dynamat & clay mod almost always beneficial?

I say no, not always. I used one pound ofmodeling clay inside the plinth of my Yamaha P751 and it made it sound dead and lifeless. This table is made with a light weight anti vibration resin type material, looks like plastic but it is not. I removed most of the clay and it came back to life.

You can overdo it on these types of tables. The later Technics and many early 80s tables use it.

If anyone tries this do a little at a time. There is such a thing as too much.

Cheers, Bob
 
I did some damping in a Technics SL-5 I used to have. It helped, probably more than I was expecting. The best I can do to describe the sound is to say it "tightened up". Basically it just got more clean sounding. I suppose that was due to reducing feedback effects or something, but it was definitely audible.
 
I ran my TT with shrink tubing on the tonearm for a week. To me, I didn't notice any sonic differences at All's. The shrink tube added a lot of mass to the tonearm. Since I didn't hear a difference, I removed it.
 
5# in the Luxman helped, but the feet are very compressed, so maybe some racquetballs next time I'm in town.

I didn't dynamat or dampen the platter, was considering balance.
 
Since this thread is a big help for those looking to squeeze the most out of their stuff, I'm awakening it.

I had a roll of some type of adhesive, compressy, foamy stuff, not sure what it even was. I ripped little pieces of it and put them on the underside of the plinth of my Technics SL3200 (decent, basic table) and then put a wrap of plumbers tape on the tonearm, and after putting everything back together, was pleasantly surprised at the improvement.

I'm leery of the modeling clay, since it would probably be too much weight for the feet, but damping the plinth with that stuff certainly helped. And funny enough, that plumbers tape really seemed to help as well.
 
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