Platter mat insanity

@noromance ,

Yes there should be room for the lp label, but what I was referring to is that at least 50% of all lps have a raised center right around the spindle hole at around 1 & 1/4" in diameter.

I’m not sure if your original post diagnoses the difference you heard properly. There may be more going on?  Your 10" lp as a platter mat seems like a good idea on paper and it may have provided good results on some lps but I'm skeptical of it going forward.

Steve, I have done some more tests using different recordings (including my aforementioned spouse in the listening session). The results as you suspect do vary depending on the recordings. Older live recordings sound excellent. Newer mixed recordings sound "messy" and "more 3D" and "echoy" according to my spouse. She preferred most well-recorded live jazz with the vinyl off the platter and other recordings on a soft rubber mat (with consequently softer presentations) Now, one could argue that what she was hearing was more insight into poor recordings. I don’t know. We compared many of the tracks to Tidal.com hifi equivalents which was another story.

Sleepwalker, Please tell me how a platter mat can affect wow and flutter.  Maybe there would be an effect on measurable rumble, depending upon where and how you measure it, but I am straining to understand your comment on wow and flutter. 

Also, I have owned two SP10 Mk2s and now own an SP10 Mk3.  In all cases, I could not fall in love with the factory-supplied rubber mat(s), thick and heavy though they may be, once I compared them to other options. I am using a Boston Audio Mat2 on my Mk3; this is consonant with the belief that the mat should be acoustically "like" the vinyl LP.  I tried a BA Mat2 on my Victor TT101 and liked it but since then have come to like an SAEC SS300 metal mat, better.  (There's surprisingly very little difference, but I favor the SAEC for better transient response.) On my Kenwood L07D, I have absolutely fallen in love with a custom made copper "platter sheet" that replaces the OEM stainless steel platter sheet.  (Here is where EMI shielding may well play a pivotal role.) These experiences have caused me to throw out the rule book when it comes to mats, except I always have found any sort of rubber mat to be inferior to the other approaches.  That's just me and my experience in my systems.

@noromance ,

Your last approach, the brass screw heads, may be similar to Pierre Spray’s mat with teeny brass points? Also, are you, or anyone else posting here, using a weight or clamp in your testing?

@terry9 ,

Although I haven’t looked to see if you have a virtual system, I was wondering about your 1" graphite mat. Does this mean, the spindle doesn’t protrude from top of the mat?

@slaw 

I use a custom spindle for the air bushing (thrust and radial air bearing), which supports a cast iron platter and the graphite mat on a machined stainless taper. Part of the design is an extension of appropriate length to serve as a record-centering spindle. I daresay an extension could be made to accommodate any TT for a few hundred - but it does need precision machining.

The reason for a two-piece spindle is simply experimental uncertainty - I didn't know what would work. By itself the cast iron rang, by itself the graphite rang, but together on the spindle they are as physically dead as Archimedes.