SP-10 mkII, the next project

[user510]

Originally Posted by Nanook

Some answers to your wondering why the differences or preference of one table to the next:

• In my experience all distortions add to the music. The additive effects can be very good, but are due to energy storage and release. These distortions usually become part of the sonic signature of the table (or almost any audio piece for that matter) because they are coupled to the turntable/plinth system.
• The liveliness apparent in the TD124 could be attributed to the material used for it's plinth, and the total mass of that and/or other materials.
• The same can be said for that of the SP10MkII, if in the Obsidian base vs say a wooden one or alternate material or combination of materials. The total mass whether a combination of materials is still important.
• My thoughts regarding this is that if both tables were placed in similar plinths (same construction and total mass , down to possible constituent materials) you would find the differences to be reduced. If you can minimized the sound of the idler wheel, then the differences should be reduced again
• Based on my experiences with my old Oracle and an old Dual 1214, I can say that the old Dual holds it own, even without minimizing the effects of the idler wheel

from "justaguy"

To begin with my comments were meant as observations. Sentences prefixed with a question mark were offered in the rhetorical sense. And also posed as something for me to address as time goes on.

I am aware of certain dogmatic points of view circulating around the web having to do with turntable drive systems and whether or not said systems contribute to the overall temperament/character of a turntables' output or if it isn't just a matter of matching a given TT to a proper plinth to alter its character.

At this point in time I tend to view the design of the drive to be the dominant feature in determining a turntable's signature sound. And that there will be a signature sound. However it will be interesting to see how much of a character change there is using different plinth designs. I will try at least one more design before committing to a paint job on the plinth.



I have experimented a little bit with my TD124 by listening to it in different plinths. Currently it is in heavy slate. But I have listened to it in a sturdy but open box style plywood support. With mushroom isolators. Without mushroom isolators. Overall, I heard the same signature sound coming out of that TT in any of those 4 configurations. However, I thought there was a slight bit greater musical energy coming from the Thorens when parked in the open box plinth and on mushrooms. But it was also the noisiest in terms of background residual noise. In the slate, it retained 'most' of its energetic output but with improvements in reduction of background noise and improvements in detail retrieval. Etc.

It's early, but I tend to think that once certain criteria are met, like platter and bearing performance, and given equal arms/carts/downstream components, motor performance is a prominent part of any drive train and will contribute --or detract -- from the listening experience in an obvious way.

-Steve

[sq225917]

Investigations we've been doing with the help of Paul R over on PFM would seem to back up that drive and suspension/or otherwise largely define the sound of most decks.

Turntable speed analysis - Page 6 - pink fish media

[user510]

Originally Posted by sq225917

Investigations we've been doing with the help of Paul R over on PFM would seem to back up that drive and suspension/or otherwise largely define the sound of most decks.

Turntable speed analysis - Page 6 - pink fish media

Thanks for posting that. I've been reviewing that thread from page 6 forward. If I understand correctly, they are plotting a constant test tone from a test record and measuring for wow/flutter.

If I'm correct in that assumption, the test results are useful in comparison against different turntables and how they measure the same test tone.

What I'd like to see is a test tone that includes a sudden increase in modulation at a lower frequency. Something in the bass, and then again something in the mids. A sudden increase in modulation in the midrange. This would be to test for the effects of modulated stylus drag on platter speed. Say, compare different turntables for how much, and for how long the speed variation occurs.
But then I don't even know if there is such a test for making that kind of measurement. But the wow/flutter testing on constant pitch tones are still useful.

And they are using Fickert's Ultimate Analog test software?
Adjust+ - Home



-Steve

[Nanook]

I agree with you. I guess I was answering an rhetorical questions or replying to your comments. It seems we are on the same page. Where did you source your slate from? That is currently the largest issue for me: accessing the raw slate. I've tried counter top shops, etc. Another option may be soapstone (if they can make sinks out of it, I'm sure a plinth could be made easily enough).

stew

[user510]

Originally Posted by Nanook

I agree with you. I guess I was answering an rhetorical questions or replying to your comments. It seems we are on the same page. Where did you source your slate from? That is currently the largest issue for me: accessing the raw slate. I've tried counter top shops, etc. Another option may be soapstone (if they can make sinks out of it, I'm sure a plinth could be made easily enough).

stew

Hi Stew.
The slate I have I acquired from J.Weiss at Oswalds Mill Audio. My setup is one of two prototypes from the first slate plinths produced for the TD124 there. As such it does not resemble the external appearance of that firm's current product. But the internal cutouts (by cnc water-jet) were made from a cad file I produced. I believe they still use a version of that file....perhaps with modifications/refinements.

I haven't done any further work on that plinth. One of these days, when certain planets align, I'll rework the surfaces and edges of that plinth into a slightly different appearance. But that's for another day. Right now I'm thinking about the SP10 mkII and how to learn from it what I can learn.

I haven't tried to access slate from any other source. Flooring and roofing pieces that you can find in the home improvement stores won't do. But the same slate quarry that produces those pieces will likely also produce counter-top slate of a much thicker dimension. The limit for thickness might be somewhere around 2 inches....depending on the machinery available to work the raw product at the quarry. At least that was a limit imposed on the two pieces of slate that I have. Maximum thickness available from that quarry at the time. Just under 2 inches. But that was in 2007/2008.

So I would go to the source; an actual slate quarry. Also, some of the guys over at Lenco Heaven have found their own sources for heavy pieces of slate. I would search over there if you are serious about a diy slate plinth.


For myself I don't know that I will do another slate plinth. Other than keeping and perhaps reworking the one I already have. Instead, I intend to experiment with different woods over time. Right now I tend to think that stacked Baltic Birch ply can sound very musical. Just an opinion not verified by any method other than by listening.

-Steve

[Bon]

I recently found this thread and thought I might contribute my experience. I have an extensive background in vinyl replay systems. I owned 2 Garrard 401's in the early '70's and a Linn LP12 from 1975-2003. In between I have owned various Thorens, and currently I am re-plinthing a TD125 mk1. I have owned various tonearms including Decca International unipivots, SME 3009's, Stax UA7, Rega 250, 300, Michell Special 250, and currently 2 SME IV.
Since 1999, my table of choice has been the SP10 mk2. All of my previous tables have been plinthed by me and I feel I have learned a fair bit of useful information about materials applied to plinth systems. To cut to the chase, the three important parameters for a plinth are mass, stiffness and damping. Of these the hardest to get right is damping.
http://qualia.webs.com/dampingfactor.htm
It is best to use materials inherently well damped rather than apply a damping treatment. Densified wood (Panzerholz etc) measure well for all three parameters but it is almost unobtainiun in my neck of the woods and incredibly expensive. I have built SP10 plinths from timber products, engineered stone, Corian and finally, isopthalic fibre-reinforced polyester resin.
http://qualia.webs.com/apps/profile/71866842/
The resin plinth is the best so far but is extremely time and labour intensive to produce. The ply fibre layers are laid down in resin over days. The curing process generates considerable heat, so cannot be rushed.
http://qualia.webs.com/apps/forums/t...ntonite?page=1
Regarding some of the comments from previous posts, in my experience, for mechanical systems (cartridges, tonearms, plinths, loudspeakers), the better the damping, the more natural is the reproduction. Less well damped components can sound exciting, snappy and vivid, but long term critical listening usually reveals an unnatural quality. For example the SME V/IV tonearms are sometimes criticised as boring, but they are just accurate in my experience.

[kevinkr]

Very cool Bon.. Thanks for sharing..

[user510]

Yes. Thanks for posting on an interesting topic; plinth materials.
I was reviewing qualia webs for a damping test on 'fiber reinforced phenolic resin' but did not see that material mentioned. It is an older plastic material available with different fabrics/materials that occasionally gets mentioned among TT diy'ers but....

Have you considered removing the SP10 mkII drive components from the aluminum chassis and into an alternate housing?

-Steve

[Bon]

Hi Steve. My first serious SP10 mkII plinth was the Corian one in around 2000. I discovered the "bearing drain" back then and the TT is bolted through the full thickness and pulled down so that the main bearing is clamped down onto 2 layers of 3 mm lead sheet lining sandwiched with the plinth base. This lasted for ten years when I acquired an SME IV to replace the souped up Rega RB300. The higher resolution of the SME lead me to construct a new plinth from an engineered stone "Caesarstone" commonly used for kitchen benchtops. The resulting plinth was massive (34 kg), stiff but poorly damped by empirical tests. I managed to tame the 20 mm thick base by applying constrained layer damping to both surfaces of the base, with two 3 mm aluminium sheets sandwiching the engineered stone with a polyurethane damping layer on each side. This was an improvement. I discovered the audio qualia site and have a good friend and fellow SP10 mkII owner, who happens to be an expert with fiberglass resins. We did some empirical tests and were very impressed with the results. We went forward with the resin/fiber SP10 plinths, which required mold construction and working with quite toxic materials. A surface filler compound is applied and then sanded to very flat finish. Then a high quality auto spray coat is applied. The results justified the effort. The mass is approx 18 kg. Total thickness is 90 mm. Stiffness is beyond reproach and damping excellent. Where I notice the improvement is firstly in human voice reproduction. It just sounds so natural with the SME IV and various moving coils. All frequency bands are as good as I have experienced in my system and listening room.
As for removing the parts from the chassis, I have always removed the brake. I have three SP10's, two in use and one spare. I have been toying with removing the chassis from the spare and installing the parts in a resin/fiber plinth. Just an idea at the moment. If I carry through results will get reported here.

[KatieandDad]

Very nice.

Have you thought about casting one in pre-cast concrete and then just applying a resin outer skin in order to effect the finish ?