Vintage DD turntables. Are we living dangerously?

I also have the Victor pigskin mat that came with the TT-101
but have ever only used it on top.

On top of what Totem❓

Perhaps I need to get out more often.

Hold your horses Totem......I might be able to save you the effort...😎
The Achromat 1200 arrived this morning sporting its rebated underside which fits nicely clear of the Victor edge lip.
Multiple comparisons ensued:-
1) Achromat on its own
2) Achromat plus Jico (thin) on top
3) Achromat plus Jico (thin) below
4) Achromat plus Victor Pigskin on top
5) Achromat plus Victor Pigskin below
Let me warn you....the Achromat is NOT a perfectly flat item and in all cases where it was used, the 'warp' created was obvious with the tonearm rising and falling noticeably....😫

All comparisons are against the bare Victor platter with the thin Jico mat....
1) With the Achromat on its own....the bass became less defined, the midrange slightly less transparent whilst the treble harmonics lost some of their 'shimmer' (and 'shimmer' is good 😜❗️).
2) With the Jico mat on top, a slight degrade to the bare Achromat.
3) With the Jico mat below..it seemed surprisingly worse.
4) With the Victor pigskin on top..not much better than the Jico.
5) With the Victor mat below...not much difference to the bare Achromat.

I then, for reassurance....again compared the Victor pigskin on bare Victor platter with the thin Jico on bare Victor platter and it is very very close...👅👀
I would still give it (just) to the thin Jico...but could happily live with the Victor.

When I receive the glass platter mat...it will be interesting to repeat all these comparisons...😏

Halcro,

Did you use the double-back tape to attach the Achromat to the Victor platter? I ask because my mat could not be any flatter! I've checked it with a straightedge.
BTW: Jico just got a little more of my money! (grin) Place an order

Regards.

Hello,

Agree with comparing apples to apples, viscosity wise, when comparing the two oils.
Here is some data re viscosity of multiple grades oils:
http://www.viscopedia.com/viscosity-tables/substances/engine-oil/
The multiple grade is not crucial in our case because we are dealing with relatively low temperatures (in the 70-80F) but can relate to the viscosity in the chart.
Adding weights and comparing stop times should give some indication but the best proof is in the listening. Less friction will translate to quieter background and lower sound floor.
Hope this helps,

Doron

Minh,

You could use the 5W20 in both oils.
Good enough for this application, in my mind.
Just make sure to clean and dry the bottom plug/oil pan and the spindle/bearing from the RP well as it tends to adhere to metal parts and maintain its lubricity.

Re the formulation of synthetic oils:
For most oil companies, oil is a by product of refining crude to fuels.
It's a thorn in their side. They buy an additive package from companies like Lubrizol who specializes in this field. The additive package will contain, anti rust and oxidation agents, anti foaming, metal deactivators, viscosity modifiers, etc, etc.
Then, oil companies will package it nicely, put a photo of a tiger or a race car or whatever and sell it with all sorts of marketing claims...
Synthetics are a bit different in the sense that the base stock is manufactured by cracking ethylene to a long chain of hydrocarbons which do not contain impurities like in the case of standard mineral oil.
The main advantage of synthetic base stock is prolonged life and flatter viscosity curve (less change in viscosity as the temperature changes, which is desirable).
Both kinds will be blended with the additive package.
Royal Purple started as an industrial oil blending facility with two main advantages:
1. They filter and clean their base synthetic stock to a high level (ISO cleanliness of 14/13/11) - most important in process compressors and rotating equipment in general.
2. They blend their own additive package and in it, they include their secret recipe to a potent anti wear agent which increases film strength and reduces friction to a very high degree.
Of course the world is full of marketing claims, snake oil and $20,000 speaker cables which makes any claim a suspect,
I just have very good experience with RP in the industrial realm, which instigated my curiosity re my audio hobby, specifically my turntable bearing (both my previous Oracle Delphi and now my TT-101).

Btw, I am not an RP representative.
I am a chemical engineer who deals with mechanical seals and rotating equipment in general.

Halcro,
The purpose of a mat is to provide a stable surface with a similar impedance of the record, or so they say. Some think the best mats are forms of acrylic, methacrylate (Delrin), carbon, or vinyl. The trick is in preventing vibrations from reflecting back to the record. Achromat does this with bubbles somehow. Perhaps a lead sheet would be more affective.

Beside the obvious problem of weight, lead is soft and manufacturing a flat sheet might be a problem, but I doubt if any material is more affective at slowing vibrations. A lead sandwich or under mat might be ideal.
Regards,