[TomS]

If you take a look at the very bottom of this page http://www.trans-fi.com/salvationmanual.htm he mentions that for a rim drive the base actually becomes part of the turntable. He used both squash balls and gel pads (like for coolers and such) to decouple a large piece of slate which serves as the support for the rim drive and plinth/arm. I tried my table on a granite shelf and it rang like a bell. As an experiment I put some gel pads beneath it and quieted the whole thing down, no feedback at all. A sandbox serves the same purpose and works well too. Just messier to deal with. All of those are just turning the energy into heat.

[Wayner]

I surprised that John, TheChairGuy hasn't recommended that the outside be covered with plasticaly.......

 

[Delta Wave]

I surprised that John, TheChairGuy hasn't recommended that the outside be covered with plasticaly.......

 

 

[neobop]

To answer some of Neobop's questions:
Are there footfalls that my cause issue?  No, the Salamander rack is on concrete floors
I can jump, drop a 100lbs on the floor and nothing would happen.
Is it top heavy?  Yes, about 200lbs on top of that Salamander Rack.
Is there a problem or do I just want to talk about it.  Well, just want to talk about it.  I haven't notice any issues as of yet.
How is PRAT?  Everything sounds very very good!  Like going from my suspended TNT to no suspended TNT and to this.  Everything is tighter, faster, blacker black, no noise...etc..

See pictures below:


TT on Salamander Synergy 30" rack


TT platform (1.5"MDF) surrounded by walnut butcher block and the brass cones underneath


Plinth/tonearm on MDF shelf....

Okay dokey, now we're getting somewhere, and your pics are on page 2

I'm trying to figure out where you could get some plasticlay in there. I think it would have to be around the outside of the platform. You could sculpt figures and stuff with the clay. If you're not good at sculpting maybe you can find a local sculptor or art student. That might damp the platform and help with the "knock on wood" stationary groove test. 

Is that the Classic platter or a steel TNT (if there is such a thing)?
Ever try a mat with it?
What cart?
Go straight into the Pass pre?
Tell us about your speakers. Scanspeak drivers w/series x-over?
About how many records do you have and what kind of music?
Who painted the pic above the table with the red bushes or trees?

Inquiring minds want to know. 

[TheChairGuy]

I surprised that John, TheChairGuy hasn't recommended that the outside be covered with plasticaly.......

 

The rack, shelf or the turntable....cause I've tried 'em all -  wicked, crazeee me! 

(not to mention speaker baskets, inside speaker cabinet cavities - it's great stuff - but I want to stop thinking about it as in reflection it's really one of the wackier and OTT experiments I've done in this hobby).  All in good fun - but it does either point to my high level of curiousity OR insanity 

[Sonny]

If you take a look at the very bottom of this page http://www.trans-fi.com/salvationmanual.htm he mentions that for a rim drive the base actually becomes part of the turntable. He used both squash balls and gel pads (like for coolers and such) to decouple a large piece of slate which serves as the support for the rim drive and plinth/arm. I tried my table on a granite shelf and it rang like a bell. As an experiment I put some gel pads beneath it and quieted the whole thing down, no feedback at all. A sandbox serves the same purpose and works well too. Just messier to deal with. All of those are just turning the energy into heat.

thanks Tom, but I don't have that platform to engage and disengage the VPI Rim Drive....I just move it to and fro...and it works.  The Rim Drive is sitting on it's rubber feet (stock).

[Sonny]

Okay dokey, now we're getting somewhere, and your pics are on page 2

I'm trying to figure out where you could get some plasticlay in there. I think it would have to be around the outside of the platform. You could sculpt figures and stuff with the clay. If you're not good at sculpting maybe you can find a local sculptor or art student. That might damp the platform and help with the "knock on wood" stationary groove test. 

Is that the Classic platter or a steel TNT (if there is such a thing)?
Ever try a mat with it?
What cart?
Go straight into the Pass pre?
Tell us about your speakers. Scanspeak drivers w/series x-over?
About how many records do you have and what kind of music?
Who painted the pic above the table with the red bushes or trees?

Inquiring minds want to know. 

Plastically...well I can put it underneath the platform as there is about a 7.5" lip from the Walnut to the MDF...where the brass footers are attached...but that will have to be another day.  I just put this thing on last weekend..and with an 8 month old baby girl, I barely have time to write this email! 

The Platter is from the VPI Classic the aluminum platter with periphery ring and stainless steel clamp.  No, haven't tried a mat with it...I've tried mats on the VPI Acrylic Platters but prefer this w/out a mat...but who knows.  I have two carts, a SS Retip Dynavector XX-1 LO and a Shelter 901.  The signal goes from the TT to the DIY Pass XONO Pre then via XLR goes to the X1 preamp and via XLR to the X250 amp.  The painting I got from Vietnam in 2006, in Saigon.

All cables are DIY, XLR and RCA cables, including Speaker cables!
DIY Pass XONO Phono Pre (used with the 901 at 100ohm) and Curcio Phono pre (used with the XX-1 at 479ohm load)
I'll get to the speakers another post, got to give my wife a break and get to baby Annabelle!





Here's a link to the speakers information.  http://www.speakerbuilding.com/content/1104/

[Sonny]

SBR Rubber Sheets....anyone know what these are?
I was thinking of getting something like this to put under my TT plinth, Tonearm and motor...to act as a resonance control over the MDF shelf...what do you all think?  See picture above...
http://www.grainger.com/Grainger/Rubber-Sheet-1MTU6?Pid=search

[Delta Wave]

SBR Rubber Sheets....anyone know what these are?
I was thinking of getting something like this to put under my TT plinth, Tonearm and motor...to act as a resonance control over the MDF shelf...what do you all think?  See picture above...
http://www.grainger.com/Grainger/Rubber-Sheet-1MTU6?Pid=search

I would add to Wayner's idea and go with granite and ditch the MDF altogether. You have that awesome rig, may as well go for broke.

[Sonny]

I would add to Wayner's idea and go with granite and ditch the MDF altogether. You have that awesome rig, may as well go for broke.

Dave, I had Granite under my TT before, though I like it for somethings, I think this TT, already dead quiet and full of details with the 901, I think the Granite may not be a good match!  The other thing I can do is put some puddy underneath the plinth, since I have 20" from the bottom to the solid 2.5 inches of steel....that should work, huh?

[Delta Wave]

I don't see why it wouldn't.
I used some of the wrong putty to dampen the plastic Nautilus tweeter mounts on my speakers... needless to say on one of those nice, hot summer days it got a bit too hot up in my loft and the putty melted a bit on one of my speakers. It's a mess at the moment and not too visually appealing. <-- dumbass move on my part.
I'm not saying that will happen to you though... I'm just rambling and remembering that I need to refinish them when I get home next week... 

[Sonny]

I don't see why it wouldn't.
I used some of the wrong putty to dampen the plastic Nautilus tweeter mounts on my speakers... needless to say on one of those nice, hot summer days it got a bit too hot up in my loft and the putty melted a bit on one of my speakers. It's a mess at the moment and not too visually appealing. <-- dumbass move on my part.
I'm not saying that will happen to you though... I'm just rambling and remembering that I need to refinish them when I get home next week... 

Or I can put some silcone (like the tube silicone from Home Depot) used for sealing underneath.

[Delta Wave]

I've got it! Femo stalactites under the MDF, make an art project out of it. 

[neobop]

I suggest something like this between layers of MDF or even a third material.
http://www.rotometals.com/product-p/leadsheet8pound.htm

It works amazingly well to cancel resonances.

[Sonny]

What about lining the inside of the Plinth, the 2.5 inch section from the bottom up with some of this material (V-Max aluminum dampening sheets), which uses butylene and aluminum....that should help dampen some resonance from the MDF Plinth to the plinth, no?

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=268-287

[neobop]

Look at it this way, the only reason you're able to induce feedback like this is because the mass/damping of the platform is not great enough to be immune to the force of your knocking on it. You've set up a test that's bound to induce feedback. It doesn't matter that your table is nearly 200 lbs, if the whole thing is shaking (moving) from your knocking on the platform. Just out of curiosity, what happens if you do the test with the volume set at normal listening levels? What happens if you play music with heavy bass/percussive content, really loud?

The point is, the car panel damping sheet is probably not going to be enough to pass the test. I'm not saying that it's not a good thing, I'm just wondering if your set-up will sound any better? For that matter I don't know if a lead sheet in there will sound better. I do know that lead, in combination with wood, like in speaker cabinets, works great and adds some mass. Some really high end speakers use lead like that. But, if the force of your knocking is great enough to move the platform.....

[rollo]

  Sonny investigate the Mapleshade Isoblocks or equal. The cart nano mount system is very affective as well against feedback.
   With unsuspended tables there must be isolation from the material below. The brass cones are not affective without a plinth and some sort of isolation below. The culprit IMO is not just isolating the TT from below. Isolating the cart from the arm will help bigtime. Nanomounts work and work well. a small investment and your done. Not a Mapleshade dealer.



charles

[Sonny]

  Sonny investigate the Mapleshade Isoblocks or equal. The cart nano mount system is very affective as well against feedback.
   With unsuspended tables there must be isolation from the material below. The brass cones are not affective without a plinth and some sort of isolation below. The culprit IMO is not just isolating the TT from below. Isolating the cart from the arm will help bigtime. Nanomounts work and work well. a small investment and your done. Not a Mapleshade dealer.
charles

Charles, thanks...I've heard of the nano mount from Mapleshade, but haven't really looked into it.  Has anyone used this in the circle?  If so, could you share your feedback?

Thanks
T

[wroman214]

  I am going to add my own 2 cents here and you can do with it what you will.  In sorting out cartridges to use with my Black Widow tonearm I ran across a few that were very microphonic and some that seemed totally devoid of that artifact.  What you are dealing with is based mostly with the cartridge.  Without the needle on the record what you are getting is feedback into the motor of the cartridge and some cartridges are prone to do this.  I choose to not use cartridges that are prone to this.  It may be amplified by some other factors like damped/undamped tonearms but always starts with the cartridge, it is built in per se.  The cartridge designers are well aware of what they are doing and choose this if it suits them to get the sound they want. 
  To give an extreme example I had two different ADC XLM II improved cartriges that were so microphonic that with the arm locked its holder I could lightly rub the wires leading from the cartridge and the sound from the speakers was almost the same as touching the stylus, a Shure V15 III was also not that great. On the ADC I thought I could mount a stylus on the body of the cartridge and play records. A  Denon 301 II and AT 33EV had no feedback that I could detect.  My Empire 2000/E III is absolutly dead quiet.  I also had an opportunity to demo a Soundsmith Carmen and it was dead quiet also so I ordered a Soundsmith Boheme to get the line contact stylus and ruby cantilever. Still waiting on the SS.
Walt

[Sonny]

Thanks all for the comments...but remember, what I am saying is that with the cartridge on an LP, on the platter at higher than normal listening volumes, I get the "sound" of the knocking on the platform to come through to the speakers.  I don't think this has anything to do with resonance, but rather that the sound of the "knock" as you will, a good knock, is ricocheting through the MDF platform, up the plinth/platter and picked up by the cartridge that is ON the record on the platter.  I don't know of any table, that if you had the cartridge down on the record, turned the volume up higher than normal listening volumes (85db and above), knock on the rack or turntable platform and not hear and "sound of the knock" being amplified through the speakers.  I guess the key here is, with the music playing, with the "pressure" of the sound waves created by the volume of music coming from the speakers, going to make the platform, plinth, platter, tonearm and so forth amplify that through the music???

I think this and if the cartridge skips, that is the issue...

T