Screw-down reflex clamps vs. record weights


Recently we have seen more and more 'record weights' on the market. These are normally lightweight(300-400gr)and simply sit on the record. They do not appear to give priority to bonding the record to the platter.
Two outstanding record weights of this type are the Kuzma Ebony Record Weight and the HiFi Tuning VRO ('vinyl resonance optimiser') - there is a review of this(for those who read German) at www.fairaudio.de.
It appears that these clamps, rather than channelling disc resonances away through the spindle and main bearing and/or optimising contact between the record and the platter surface, seek to absorb them directly (i.e. into the clamp itself).
The Kuzma Ebony is a particularly interesting case since it has been introduced by a company that supplies screw-down reflex clamps as standard on its high-end turntables.
My question is: has anybody had any experience of these clamps - probably 'vinyl resonance tuners' is a more appropriate term - on their turntables as replacements for screw-down reflex clamps? Clearly as a way of dealing with warped or dished records they will not be of much use, but it may be that they do a better job of damping the disc.
I would be particularly interested to hear of experiences involving SME turntables (whose platters incidentally are covered with a bonded layer of 'Isodamp' damping material).
Thanks,
Peter
pgtaylor

Showing 4 responses by dover

Some of the comments above demonstrate a complete lack of understanding of clamps/weights. You have to look at the total picture, in particular what is under the record.
Example
Record weights do little to bond the record to the platter, so they presumably are not in the business of optimising resonance-damping through this interface.
Real answer is - That depends on what is under the record.

Some clamps/weights are designed with a slightly concave platter or platter mat and the downward force couples the record to the mat.
Examples here are
Goldmund clamp/mat - reflex clamp with concave mat
VPI Classic - screw clamp with concave platter
Most heavy weights will help couple the record to the platter if the platter is slightly concave

Some clamps/weights are designed to work with a washer under the record. These will have a peripheral edge that applies pressure to just inside the outside edge of the record label such that the clamp/weight when applied couples the record to the platter/mat.
Examples are -
Sota Reflex Clamp - uses a washer under the record.
Final Audio VSD17 - a 1.8kg weight with a peripheral edge that uses washers under the record.

When I look at most of the clamps or weights on offer, then, unless they are used in conjunction with a concave platter/mat or washer they will do very little or nothing. They might possibly help reduce any slippage of the record during play. If all they do is reduce "resonance or vibration" then a potato impaled on the spindle might be just as effective.

There are some caveats as as been pointed out above -
Use of a heavy weight with a suspended deck may impede the performance of the deck.
Use of a heavy weight may accelerate bearing wear if the bearing quality is poor or not designed for heavy mass.
Dont assume anything here, I have seen bearings on the some much vaunted TT's that are made out of junk metal. Check your oil after a few months - if its dirty, then your bearing is wearing out.

On the subject of mats one of the most ill informed reviews I read recently in an online magazine did a shoot off of mats on a Garrard where they compared leather, copper & carbon mats. Well anyone that has owned a Garrard should know that Garrard platters are slightly concave and unless you have had the platter top skimmed, then any hard mat is only supported at the outside edge and would most likely sound awful. No mention of this in the review. No wonder people in this hobby get led up the garden path.

Pryso - For my Final Audio VDS weight I just made some hard plastic washers of varying thickness and then tested to find the optimum. The Sota Reflex also is adjustable from memory, if you look down from the top there is a screw inside for adjusting the force of the grip on the spindle. I would think about a 1/16 of an inch should be enough for the washer, you want the minimum to minimise the bending on the record.
Peterayer - my Final Audio has a 4.8kg copper mat with an indent for the record label. With the VDS-17 1.8kg gunmetal weight and washer, it is crisp, articulate and very detailed. I tried a 300/400gm weight instead ( with the washer ) and the sound lost articulation and detail - the top end sounded rolled off, lacking extension and detail. We are talking $2000 cartridge versus $10 old Grado kind of difference here, not minor.
I strongly suspect that 300-400gm is insufficient for coupling with a washer type system. It may be insufficient to do much on a concave platter in terms of effective coupling. It may dampen resonances but I would seriously question whether the difference is large in that application.