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In Reply to: Would a concrete plinth be a good idea for a sprung t/table? ... posted by andyr on October 9, 2006 at 01:36:57:
You really want the resin style concrete rather than plain concrete. It offers a better modulus for resonance control.
For instance on the Kenwood KD-550 that I owned, the owners manual shows that they utilize a CLD approach to resonance control with the plywood bass controlling high frequency and the resin concrete plinth controlling low frequency. In this way they are tuning out resonance before it becomes an issue.
Suspending a table does not require any specific material composition. It is just a way to isolate foot falls for example.
...its massive, resonant "petrified cream of wheat" plinth. These things were very poorly designed, with plenty of resonating hollow cavities and a ringing marble-like cast material that made the TT sound lumpy, inconsistent, and lackluster.
> > > "Suspending a table does not require any specific material composition. It is just a way to isolate foot falls for example."
You're just making this crap up as you go along, as usual. Material selection is of paramount importance, suspended or no. A well-designed suspension isolates the 'table from its motor and its support. More importantly, it allows a knowledgeable designer to utilize light, rigid materials, rather than relying on crude, PRaT-killing, energy-storing mass to "isolate" the TT from its environment.
To answer the original question, massive supports and suspended TTs are a poor match. Try a light, rigid Neuance or Mana shelf, or a cheap Ikea Lack. Stone and thick wood under a suspended TT sounds comparatively dull, warm, slow, and bloated.
And then you discount the Kenwood which actually incorporates actual science to capture and control resonance within its honey-cone matrix below the turntable. They mixed proprietary blends of resin and stone to attenuate specific frequency ranges. They selected specific grades and thickness of plywood to control high frequencies. The ringing of the platter is controlled by the specific rubber mat they selected.
The whole thing sounds awesome with the right tonearm and cartridge and easily beats many expensive turntables.
Actually the choice of a plinth material has nothing to do with whether that material can be suspended or not. You can suspend popsicle sticks if you care to take the time or trouble. Suspension is accomplished to eliminate accoustic feedback from the pick up. Some designers use springy suspensions (SOTA), some taut suspensions (THORENS), some silicone dampened suspensions (BASIS) and others with combinations of springs, silicone, foam or other more exotic materials.
Just what would make any plinth material unsuitable for suspension? Moreover what suspension technology exists that precludes any material from being properly suspended?
Fretless you are spooning out drivel. It is designers choice.
So go ahead and add to the conversation but please list your personal opinions as such. I do not care if you want to attack me for whatever reasons you feel necessary, I just wish you would take some time to actually conduct some sort of professional discourse on an important topic.
By the way HP once wrote that a Kenwood Trio which incorporated that concrete resin base was the best sounding turntable he had ever heard. So do I trust you or do I trust HP?
Thanks for the tip - that certainly sounds promising.
However, I've never heard of "resin style concrete" before ... can you give me a link so I can read up about it?
BTW, I think a plinth ideally does more than just isolate footfalls - ie. external vibrations from getting to the stylus. It also needs to help drain away vibrations produced in the turntable by external and internal means ... and, as my mate's experiemnt with the 1" thick hardwood plinth for his Thorens, certainly makes a difference to the sound of the turntable! :-))
Give him a PM and perhaps he can scan these and send them to you. There might be a manual available on Vinylengine.com.
The Kenwood literature specifies what frequencies they were attenuating and I found a great deal of material such as reviews by googling Kenwood KD500/550.
HP of VPI once wrote that the resin crete Kenwood platform with an upgraded arm and cartridge was the best turntable he had ever heard. He bought it. Of course the high end VPI's pretty much sonically toast a Kenwood table now. Just take a look at Ray O Stat's set up under inmate systems. He has a nicely arranged VPI platform.
But the resin crete material has a superb modulus to attenuate low frequency. Much better than any material I know of from the literature I have examined. There was a great paper in Speaker builder of a guy that used quartz sand, ground rubber tire pellets, and builders epoxy to build a high modulus speaker cabinet.
VE does indeed have the Instruction Manual for the KD-500 ... so I was able to read that! :-)) It only mentions the resin-crete plinth once, though, and doesn't go into any technical detail about frequencies.
But I would just google "KD500/550 reviews" and see what comes up in the search field. Check Yahoo too, sometimes I get better results from one or the other.
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