[coverto]

Hi All,

I'm finally taking the plunge into vinyl, due in no small part to what I've been reading on this forum about the virtues of a well-damped JVC table. Picked up a QL-A7 on eBay a few weeks ago and love it, although I recognize that its MDF plinth may be a bit more challenging to damp than the metal and wood veneer plinths of some of the other models. I'm plowing ahead and have purchased some PlastiClay and some RAAMmat sound damping sheets.

As you can see from the attached pic, I've opened up the housing below the tonearm and have lined the entire compartment with RAAMmat (hoping the soft aluminum doesn't create any problems). My next plan is to fill in this compartment with PlastiClay, although it's a good deal shallower than the QL-Y5F that David has been tweaking of late.

My question is - in addition to that compartment being shallower, it's essentially the only compartment that's closed in other than the well that houses the motor. Accordingly, I'm thinking I might just wrap some more RAAMmat around the outside of this ringing metal chassis and be done with it, and then perhaps line some of the MDF nooks that are exposed surrounding the metal well, as seen below. Does that sound like a plan, or is there room to be more ambitious with the clay and damping mat?

Thanks,
James

[Wayner]

I hope you understand that aluminum is a conductor and that you have taken great strides in preventing the aluminum from contacting any voltage (like 120) so you don't have smoke and fire (or worse) and the likes of that.

I think I would have rather seen you stuff that area with plasticlay, avoiding the electronics, but filling in voids and damping internal vibrations.

Wayner

[coverto]

Wayner - I was concerned about that and was pretty careful about keeping it away from any metal surfaces. If that's the case, you think it's safe or would it be better to take it out?

[Wayner]

If your sure that nothing will come loose and touch any solder lugs or stuff like that. The lower right looks like a 120 volt solder lug that the 120 is coming into. Is that correct? If so, I might keep the aluminum foil facing away from that as they are open terminals. Also keep it away from any circuit boards. I'm sure you were careful, but think of it in terms of "what would happen"... and then you may want to cut away some of it or remove it. Maybe I'd pack some plasticlay over the rest of it to fill the void up even more. Tho plasiticlay may not be electrically conducive, it may be slightly conductive as it seems to perhaps have a slight moisture content to it (maybe). This I have not played with, but I think it's good policy not to have anything come into contact with (at least) the higher voltage content. Stuff after the transformer is probably 24vdc so there is no issue with that.

Wayner

[Wayner]

Oh, after looking again, that lug to the lower left looks like it's from the interconnects, so I guess you should be OK. Still, just take a look to make sure nothing of the aluminum is going to touch a connection. You may not get hurt, but something may not work, or work properly.

Wayner

[Wayner]

Is that gold thing in the upper middle a transformer coil? If it is, the transformer needs some 'air" around it to keep cool. I'd cut that back, too.

Wayner

[coverto]

Wayne - I think the gold-looking thing in the upper middle you're referring to is simply a block of wood to brace the bottom faceplate.

So, having been careful with the soft aluminum and planning to stuff the area with Plasticlay, I'm wondering what you think about the rest of the bottom of the plinth - I'm thinking I should leave the inside of the metal motor well alone, correct? Maybe wrap the outside of the well in RAAMmat and maybe try to fill some of those open nooks around the well with Plasticlay if they can stay in there?

[TheChairGuy]

coverto,

Constrained layer damping, which is what I think you've used on your deck, works by converting 'energy' into harmless heat

You may want to check with Dynamat or the maker of the particular brand of damping pads used, but I'd think that use of that might not be a good mix with plast-i-clay packed on top of it.

It may or may not, I'm not certain (which is why you may want to ask better qualified technical people where it was made), but laying plasticlay into the damping pad may not allow the harmless heat to escape or, worse, send the heat back into the pad again creating a resonance loop.

It may well be fine, but the general recommendation for plasticlay damping is it and only it to be used.  The use is twofold: it lowers 'energy' into lower frequency (generally beyond the threshold of hearing it) and the effect of mass damping deflects unwanted energy, too.  Please note: I'm no purist and like to tinker, so for all I know the two together MAY be fine.

Energy can only be turned into something different; it cannot be eliminated.  Plasticlay and constrained layer damping work on a different basis and may not be compatible with one another.

In my experience having tried constrained layer damping on turntables...it was far and away inferior to the positive effects that plasticlay (and rope caulk like made by Mortite and Dennis brands) offered.  fyi.

John

[raysracing]

I just added two pounds if plastelline under my Denon DP-62L. I would have added 6, but my wife and I had a miscommunication. I am using an Ortofon Ref and the results were well worth the money and time. I feel piano, trumpet, cymbals, etc. are better revealed is the best I can subscribe it. I tried to record before and after, but I don't have my best recording equipment at home right now.