While I am certainly not an universal admirer of direct drive in TT-design, I nevertheless would like to give due credit to a highly underrated design of the late 1970ies and early 1980ies.
Mitchell A. Cotters implementation of Technics dd (not that great...) and the bigger Denon dd (much better here) into his B-1 suspended plinth resulted in a work of genius (while pretty ugly looking..).
I am right now restoring a B-1 for a friend and have set-up one at a friends place early last year.
This smart and superbly damped and VERY effectively suspended (with very low resonance frequency !!) TT shows what a dd TT is capable off, if the brain behind is not guided by religion or "visions", but by a clear and logic mind a blue book written by an engineer understanding the physical demands of record playback.
Sonically, the Cotter B-1 w/Denon dd (with its stock Fidelity Research FR-64s or FR-66s..... M.A. Cotter did officially recommend using these 2 tonearms only with his B-1, as they did represent the best in his eyes and ears) is the very equal of ANY TT around today above 80 hz.
At any price.
Fast, very dynamic and with superb transient and low level detail. Its mid and lower bass - while still transparent - is however too low in weight and punch compared to TT's with high platter mass.
But this is the only sonic drawback and it is well shared by the vast majority of all other turntables of our day.
Anyone really interested in TT design and with a mild interest to find out what dd in turntable design can sound like should really try to give this big monster of years long gone by a serious listen. Make sure you listen to it set-up the way it was intended to be used - with FR-64/66s and FR-7 cartridge.
And with a 5-6 mm thick PVC/Metacrylate mat firmly attached to it platter and a good clamp (Sota Reflex or similar).
One of the smarter TT designs of audio history. |
And I absolutely agree with Lewm, T_bone and Johnnyb53 - dd tt's are and very important part of audio history and were THE record playback in disco, home audio and broadcast since the mid 70ies (and still are in 2 of the 3 places..).
Plinth, suspension and smart and consequent applications of physics were and are rare - then and now.
And yes - the platter mass and its fundamental benefits for the "sound" of a turntable.
The one big, inherent drawback of dd turntables. |
Stiltskin, I believe that a high mass (whatever high mass may mean in the individual case...) platter can be fitted only to a direct drive if the heart of the drive - motor and axis - is designed with the respective resulting inertia and pure vertical mass in mind. As the direct control is in most cases an essential design parameter of a direct drive.
I for one wouldn't dare putting a 30 lbs (but I would favor 30 kgs anyway Lewm....) platter on a Denon drive coming originally with a 6 lbs platter. At least not for very long.
A direct drive working with a high mass (and resulting very high inertia) platter has to feature other design parameters in some key components than the average dd from the 1970/80ies.
Aside from that - not the material of the plinth is the core issue, but the internal damping (not bad with Panzerholz, but even better in composite materials) and most important the resonance frequency of the suspension.
I can not stress that point hard enough. Please remember that it was AR with its very first suspended TT which single-handed put in motion record playback high-end (a decade and more later adapted by Linn with their LP-12).
A happy new years eve and a healthy, peaceful and prosperous 2010 to all analog A'goners!
Cheers,
D. |
Radicalsteve, if you include oil-pressure bearing in the same group as air-bearing I would agree with your conclusion (while I would direct slam, air and physical weight to other circumstances than the mere drive principle. |
Steve, agreed. My postulate for heavy mass in platters does include that these platters are composite materials which do dampen each individuals inherent resonance behavior. Metal (gun metal, aluminum, lead, stainless steel, copper - all do have their individual virtues in TT-platter application ) isn't "bad" by nature in platter design, but needs "work" - as all other materials - to produce what is possible.
Cheers,
D. |
Inherent speed stability is one of the indisputable side-benefits of high inertia (i.e. high platter mass - raw mass....).
Stylus drag - while still kind of a nebulous issue - is best addressed by securely clamping, pressing (by means of clamp (sic..), peripherical ring, vacuum - whatever suits you best) the record onto the platter thus that there is no relative movement of the record to the spin of the platter while the stylus moves its way through the groove.
In any case speed accuracy as well as stability should only measured "in action". By following this routine stylus drag won't be any issue any more.
Here again the old principle to avoid the error in the first will always give superior results to correcting the error after it occurred.
In any case - on any turntable: as long as the record has any chance for a relative movement to the spin of the platter, there is no way to discuss speed stability, stylus drag or dd vs. belt/thread, idler wheel drive.
As long as the record isn't clamped down it is all an "orchestra manoeuvre's in the dark". |
Well Raul, sure I am talking in my posts - otherwise they wouldn't exist - but certainly not to the length you are going to. What I have mentioned in my last post are issues and matters which should - due to their simplicity and plain objectivity of facts and their interrelations - be so obvious that they do not need discussion nor controlled tests the way you put it.
None of us has to re-invent the wheel. None has to proof again that our planet encircles the sun. In this audio world there is no such thing clear nor proven enough not to be questioned by some.
That you do not use any kind of clamp anymore - and many others do likely - is certainly not my problem nor does it proof or disapprove anything. Its just a personal preference based on your taste, preferences and the special individual matrix of your hearing.
Just like with everybody else's.
It all comes down to personal preferences and opinions which you have mentioned too again and again.
Hearing and the experience of "sound" in human brain (which is the place where it actually takes place...) is a most individual and not to be quantified nor qualified sensation.
My remarks about trying to come as close as possible to a point where platter and record do form one single mass was purely technical-wise.
The physical benefits in the playback process are so obvious that - sorry - this is far beyond any serious discussion from my point of view.
But of course, you will - and are most welcome to do so - as always have a different opinion. Fine with me.
Enjoy the long journey,
D. |
I agree on the post as a whole Raul.
However - "wrong" or "right" will - in the very end - always be up to the individual listeners taste.
There is no absolute here (which is were...) - not in hearing.
Hearing is always a lone and individual one,- and so will be the final judgement about a certain sound systems performance: - individual.
I guess it is indeed rather a matter of different levels of experience.
The seasoned listener to many different systems with a certain technical background will always have a wider foundation - a more solid ground - on which he can make a "judgement". |
You want to measure stylus drag ? No problem and very easy to perform at home with little more than 5 cent material and 15 minutes time.
BTW, my comment: "stylus drag - while still kind of a nebulous issue - is best addressed by securely clamping" - contains the (obvious....) technical statement that the record should be (if possible...) part of the moving system (the platter... to benefit from energy transmission and a few other aspects) and that stylus drag as such is indeed "still kind of a nebulous issue".
Which it is as it is depending on several periphery parameters.
Anyway - the test (which result will depend on a handful of individual parameters others may list according to their respective set-up...):
Do make a small mark at the outer rim of a record (mechanical scratch, cut of small color mark - whatever - but make it very tiny).
Do make a corresponding mark at the upper outer rim of your platter so that both marks do blend.
Now go and test.
Give it a full length LP side and see what is the result.
The results will differ considerably depending on weight of LP, slippage on surface of platter, dimensions of stylus, VTF, speed and 4-5 other technical aspects in the dynamic process.
Enjoy.
I performed this test 19 years ago in length and detail and decided to simply eliminate the possibility of stylus drag and lived ever happily after. |
