Hi Peter, that is some brilliant planning and beautiful representations of your new Lenco plate!! I would caution that the most dangerous source of noise is the motor/idler/platter interface, particularly the motor/idler as source of noise, then picked up by the platter/tonearm/cartridge. So you don't want the motor island to be TOO decoupled, but indeed bolted securely to the heavy plinth like all the rest (the constant reduction in noise as the mass increases proves this is effective), but disconnected as you have designed it to cut off that avenue of transmission. Though of course orientation of the motor must be perfect.
Speaking of high-mass, we now have some measurements/Empirical Evidence (using ears and a trick to make rumble more audible, that is) in the form of measurements taken as mass increases of noise and its suppression. Have a gander at this, lifted from the Hi Fi World website:
"Just one final tip! In order to check how much “noise” is getting from the motor to the deck chassis/plinth (and subsequently to the stylus):-
1)Take a matchbox (ideally with a few matches in it) and place it on the chassis (NOT on the platter!) next to the platter and within “reach” of the cartridge.
2)Turn the volume control of the amp to minimum. Gently lower the stylus onto the matchbox.
3)Carefully switch the deck on. Slowly increase the volume control. The matchbox acts like a sounding board and amplifies any sound emanating from the deck.
Obviously, this does not show up any deficiencies in the main bearing but it can be very revealing and is useful when fine tuning....Go away for a day and there's a stack of posts to read! Clive, I think clarifying what we are calling everything is a good idea, as my terminology (turntable chassis bolted to a plinth sat on a base) is a little different to yours (turntable chassis bolted to motorboard sat on plinth). Cobblers, I think I have misunderstood some of your comments as a result, apologies if this has caused confusion. Anyway, just been in search of some of the dreaded rumble using a matchbox (thanks John T). Rumble was not something I had concerned myself with in any of my experiments as I had not been noticing it and I had therefore rather forgotten about it. Cranked up the volume to a moderately loud level, sat the stylus on said matchbox and stuck my head against a speaker. Rumble rumble! Next thing I remember, my wife was leaning over, dabbing a cold flannel against my forehead, I must have been out for five minutes, it must have been the shock....But seriously though, I am hard pressed to hear it from my listening position when the room is totally silent and when there is music playing, no way. Out of interest I removed the spacers that separate my two part plinth and bolted all six layers of birch ply together into one lump and listened again. Rumble was quite considerably reduced (I am guessing) perhaps a third. No way I was going to hear this from my listening seat. It would have been interesting to have tried this when it was in its hollow 1970s box, bolted to a bit of warped 12mm chipboard, with no proper feet. Out of curiosity I thought it would be nice to see the rumble, so I hooked up my scope, and there it was, not a simple sine wave, but not far off, by the look of it a low base frequency with two or three harmonics thrown in and a bit of other spurious noise. This seems like quite a good way of "listening" to the mechanical noise of your deck? Incidentally it was also interesting walking across my room. My seemingly solid concrete floor and heavy equipment rack didn't seem quite so solid when I watched the scope go crazy with every step. Anyway, not quite sure where I am going with this, but clearly the accepted high mass approach is doing what we are told it will do. Assuming the mechanical noise my turntable is making is fairly typical, it seems likely then that those of us preferring lighter wooden plinths (motorboards) are tolerating a higher level of rumble, but not one that is likely to be a problem during use."
Now, let's think about this for an instance: how much more effective would the experiment have been if the two stacks had not been bolted but instead glued together? And what effect on the sound is there as the mass increases and allows ever-finer levels of resolution to emerge from ever-reducing noise? My own experiments prove to my own satisfaction that there is absolutely no penalty in terms of PRaT, in fact the reverse, but with the caveat that as resolution increases, more and more care must be taken with set-up.
And using those scientific instruments - my ears (and faith in them and empirical evidence) - again, I have for the first time tried walnut as an armboard material, and was amazed to hear an increase in PRaT and coherence/gestalt over maple!! The midrange seems airier and more natural, as does imaging, and highs seem more natural. Now, the walnut seems more natural-sounding overall, more a midrange material, while maple in comparison sounds more Hi-Fi, with higher highs and perhaps lower tighter bass (not sure yet). But with some tonearm/cartridge combos (like the Denons which can occasionally sound hard) walnut is a an excellent fix/balancer. On the other hand, too-gentle combos might profit from the maple. Me, for the increase in PRaT and coherence/gestalt, I think I very definitely prefer the walnut. Of course, this is only using the SME V/Denon combo so far.
The walnut was such an improvement in PRaT/gestalt, that it raised my ESS/Pierre amp combo up to near the level of my Sony 3130F/AR2ax's in the Kundalini Effect (and don't underestimate either the old Sony amps or the ARs), tipping the ESS combo into producing the Kundalini Effect which it just shy of producing with the same frequency and intensity as the Sony/AR combo. In fact, I now need two sound-rooms, as I can't live without the glorious highs, midrange, clarity and perfection of the Pierre Amp/ESS (Heil Air-Motion transformers) combo, and can't live without the intense Boogie Factor/Kundalini Effect (which is caused by the tremendous coherence/music-cut-of-whole-cloth along with serious PRaT, SLAM and DRIVE, and a good dollop of midrange neutrality) and unbelievable bass of the Sony/AR combo!! And common to both systems is, of course, the Giant Glass-reinforced Direct-Coupled Lenco!
I am starting now on my Giant Garrard project, and am already eyeing my Sony 2250 to see if I can't boost its performance, as I hear something special from this old DD workhorse, and am hoping to bring to light another Giant. Of course, there's the tremendous Rek-o-Kut eyeing me accusingly as well. Perhaps I'll take some time off to get all these projects off the ground, and eventually start a new thread, we'll see. In the meantime, I'm working behind the scenes to get the Lenco and other idlers more exposure out in the mainstream, where the Conquest (of The World by idlers) is continuing apace, even if it is less visible for now. Watch this, or a new, Space!! In the meantime, I hope you all are having as much fun as I am! Vive la Lenco, Vive la Idler-Wheel!!
