Platter mat insanity

I was doing an idler upgrade to my 401 (more anon) and when finished used the Keystrobe disk to ensure speed. I use a 10" EP as a platter mat. I played a bunch of albums and it sounded fantastic. On the 6th side, I noticed I'd forgot to remove the 4" strobe disc. Duh. I took it off and figured VTA was responsible. So I lowered the arm to see if that made it sound so good. Nope. Put back on the 4" strobe disk and raised arm. The awesome sound returned. So air under the record removed haze, smearing, flattened soundstage and muddled bass; and made it so more musical. Comments... 
I'm unsure of "air under the record", is the deciding factor. There's a lot going on there, so, from a distance, I'm skeptical. 

One point to always remember, 50% of lps are/have a raised center. Is this something you're aware of?

I tried the same experiment on my other 401 system. Same result to a slightly lesser extent as it's not as revealing as my main setup. 
Naked platter > 10" vinyl EP > 4" plastic strobe disk.

My wife never listens to the gear but I called her down. Using "The Gifted Ones" / Dissy Gillespie, Count Bassie, Ray Brown, Mickey Roken (Pablo 2310.883), she was amazed at the difference.
This is not a simple case of ringing or undamped vinyl. It is a removal of a pretty thick veil, and a release of the music heretofore suppressed. Please try it.
I have tried several different mats on my G-401, an Acromat, the suspended design from the maker of Trans-Fi Terminator (which didn't seem to work well at all for me), and a solid TTW copper mat (along with TTW brass weight), and I always come back to, and stay with, the copper mat and brass weight.

I don't know what to make of your EP mat, though I could try using the strobe disc from the KeyStrobe speed setting system. May be worth a try, though.

Have you ever heard of the "Resomat", made by Trans-fi in England?  Contrary to most dogma, it raises the LP above the platter on a bunch of rubber tips. This permits the LP to resonate freely.  That mat has a loyal following.  So, maybe you are in a way correct about why the strobe disc effects an improvement in SQ, according to your ears.  Of course, be aware that VTA may play a role, in fact.
@lewm I tested for VTA. While it had some small impact, it was nothing like the improvements wrought from the 4" disk. The Resomat and Trans-Fi have sadly ceased business.
@islandmandan Dan, well aware of your setup! I’ve been wary of the weight of the copper as we’ve discussed a while back. I would be delighted if you can do the strobe disk test - don't bother with adjusting VTA initially. Just dig the opening up of the music!
Yes, noromance (by the way, does your moniker suggest that, like me, you are beyond your prime?), I'll have to get off my lazy butt and spin some vinyl and try your trick out. You never know unless you try, right?

Dan, as a friend told me once when I asked him if he was still interested in women, he may be old but he wasn't dead! Looking forward to your findings.
noromance, you mis-spelled the names of nearly everyone on that record, and to be honest, whenever someone says "even my non-audiophile wife, (daughter, brother, therapist, et. al).heard the difference", alarm bells go off in my head.
@jnorris Hmm... so I did. Getting old is no fun. Whenever I see a comment like yours contributing nothing, I want to punch a wall. In fact, what is the point of your existence? I am detailing an observed phenomenon and passing it on so others might try it for themselves.
@jnorris Actually, my wife is a classically-trained musician and I trust her ears over your suspicions. I played the same track twice without telling her anything. 20 seconds into one of them, she commented on the difference. 
noromance, The intent of my post was not to suggest that you purchase a Resomat.  I was merely trying to point out that possibly the inadvertant effect of leaving the strobe disc on your platter, thereby raising the LP off the surface of the mat, was analogous to the effect deliberately achieved by using the Resomat.  You may be liking that effect of letting the LP resonate freely in air, essentially. 

By the way, the Resomat was not by any means the first and only implementation of the idea.  Decades ago, the Transcriptors platter did the same thing; the LP sat on felt dots mounted on a set of regularly arranged pucks fixed to the surface of the platter.  It was not even possible to use a conventional mat with the Transcriptors.  I am guessing that the Transcriptors idea must have influenced Vic of Trans-fi, in his design of the Resomat.  Vic is English.  Transcriptors was a British product.
While the Terminator arm is temporarily unavailable (Vic builds them in batches), Trans-Fi is still in business and the Resomat currently available.
Noromance, I tried the trick using the KeyStrobe disc last night, first playing side one of "The Blues and the Abstract Truth" (45 RPM Analog Productions re-issue), and, as always, It sounded very, very, good. I then slipped the KeyStrobe disc in, and was surprised at noticing the same phenomenon that happened with you. Why, I don't know. I then played Lee Morgan "Tomcat", another 45 RPM disc, same result.

My strobe disc is brass, so the heavy brass record weight had to be used to keep the record from slipping on the disc. It may have to become a permanent fixture in the playback chain. Good thing you forgot to remove it!

By the way, I purchased, and installed, the Audio Silente idler wheel, and it worked just as well (at least) as the original Garrard idler. I tried to find your review of the Artisan Fidelity idler, but it didn't turn up. Can you direct me on where to find it?
Thanks and regards,
Post removed 
@bdp24 Good to see Vic is hopefully bringing the Terminator back. He did stop building the Salvation and hopes to make the arms in Russia?
@lewm Yes. I’m aware of the Resomat and have been intrigued by Vic’s ideas on no clamping etc. I tried lots of mat ideas a while ago including felt floor protectors but the result was always a softening and muddying of the music. This is the first time trying no mat as such under the LP. I suspect that even the Resomat points may stabilize and damp the record enough to reduce the impact of lable area only support.
@islandmandan Dan, I'm delighted you hear and (perhaps) approve of the strobe disk effect. 
PS... I never got around to doing the AF idler review due to the above. Anon.

I like and agree with all of Victor Pattachiolla’s designs EXCEPT the Resomat. The Salvation turntable, excellent; the Terminator arm, excellent (and a great value). But the Resomat, like the Transcriptors turntable, suspends the LP in air, not a good idea imo.

It was long ago established that an LP groove being traced by a phono cartridge stylus causes the vinyl to vibrate/resonate like crazy, especially if the vinyl is suspended in the air, with no surface below it to absorb and damp that vibration. The vibration in the vinyl created by the stylus travels from the location of the stylus in the groove both out to the edge of the LP and in to the center hole of the LP, that vibration then reflected back from those locations to the stylus, where it is read by the stylus as a time-delayed "echo". How can that be a good thing?! Yes, the echo is a very low-level signal, but the dimensions of the LP groove, and the amount of travel exhibited by the stylus, are extremely tiny, and very vulnerable to any added vibration. IMO, a solid surface in full contact with the LP, the material of that surface intended to absorb and damp the vibrations inherent in LP playback, is the "correct" approach.

I would agree with you if I didn't hear what I hear. It isn't a brightness or an edge to the music masquerading as additional information from the grooves which you might get with what you describe. It is an opening up of the soundstage and a removal of noise and confusion. Bass is much cleaner, yet goes deeper when called for. Audience sounds are improved and dynamics more real and almost startling. The instruments take on more color with piano hammers and cymbals presenting texture where with a mat there is none. I'll give it another test tonight.
Looked at this critically last night. 
1. The LP is not stable at all while perched on the strobe disk. Not that I don't know but as @slaw pointed out, the label recess is absent.
2. I ruled out any VTA issues for certain.
3. I removed all mats (10" EP and strobe disk) and tried 3 tiny 5mm high stone tiles between record and platter. Same result with previously noted improvements. (Music became slightly "harder" as the material suggests)
4. Rooting through the workshop, tried 3  tiny flathead brass bolts with screw heads on platter under the label, thread end up. This was quite stable and gave very good results. I am going to explore this path in more detail.

... It was long ago established that an LP groove being traced by a phono cartridge stylus causes the vinyl to vibrate/resonate like crazy, especially if the vinyl is suspended in the air, with no surface below it to absorb and damp that vibration ...
Please tell us who you believe established this effect that you report as fact rather than theory.
David Fletcher, Marcel Riendeau, Peter Moncrieff, George Merrill, Austin Jackson. There are others, but that’s enough to get the sincerely interested started.
The record to platter interface is a critical design element in a turntable.

While it ranks behind bearing & speed accuracy in the hierarchy of things, it does make a difference and system tastes and interactions will definitely affect your preferences.

I liken the "free air" preferences to folks who prefer a little bit of reverb. There’s nothing wrong with it, but I’ve found this to be recording-specific - something I’m always wary of.

Strictly speaking, you’re trying to drain as much stylus chatter (noise) as possible from the LP, into the platter and the right mat help in this regard.

This is where matching the acoustical impedance comes into play. The closer the speed of sound of your platter surface matches that of an LP, the more absorption (and less reflection) you’ll have.

It’s the reason we like our carbon fiber top plates (and graphite before that). It’s also the reason we’re puzzled by preferences for acrylic over PVC in monolithic platter designs, because PVC is better behaved with respect to absorbing noise from the LP. It’s not as pretty as flame polished acrylic, and many folks buy with their eyes instead of their ears, but that’s a story for another day.

Thom @ Galibier Design
My search stopped with graphite. I use a 1" slab of graphite atop the platter, like Nottingham Analogue (Tom Fletcher design).

Does two things - couples to vinyl, and deadens the platter.
I am feeling much better about the design-intelligence in the 1/4” thick rubber mat on my Technics SL-1700mk2 turntables after this thread of conjecture. Seems Good ole Technics had it right all along, despite less than optimal tonearm geometry. Yet another reason to ditch the archaic SL-1200mk2 derivative. 
" I am feeling much better about the design-intelligence in the 1/4” thick rubber mat on my Technics SL-1700mk2 turntables after this thread of conjecture" 
Okay I'll bite... Where from this thread did you get the idea that a .250 thick rubber mat is a good idea?
Everybody I knew dumped their rubber mat when the Audioquest Sorbothane mat came out. Then companies started exploring, as Thom @ Galibier put it, impedance matching materials like Acetal (Delrin), Graphite, even lead.
Interesting: I have used a ringmat for years after trying just about everything available.

Nothing I have tried has been able to persuade me to make a change. This is probably one of the best
examples of the use of air suspension with minimal ccmtact area.
@terry9 I tried the Boston graphite mat. Beautifully made but killed the sound - sucked the life out of it. Sent it back.
@sleepwalker65 Rubber sounds like rubber. Rubbery and like rubber sounds.
I will preface this post with the disclaimer that I am NOT an engineer and do not have a vast knowledge of the dynamics of a stylus in a groove going around in circles. However, I can't help thinking that this is somehow analogous to salmon fishing in British Columbia. If one is motoring along on a choppy ocean (substitute the grooves in the record) and just sits on a bench, your butt is constantly losing contact with that bench due to the bounce created by the waves. However, if you stand up in the boat and use your legs as mild shock absorbers, everything calms down and you can enjoy the ride. Is it possible the lack of support under the record somehow allows the stylus to stay in contact with the groove by microscopically reducing the "bounce"?
These last few posts sort of illustrate the "dilemma", if this issue could take on the dimensions of a real dilemma.  I cannot disagree in the slightest with what Tom Mackris wrote.  It makes perfect sense.  But then we have to take into account the actual experiences of the rest of us.  Mats with an acoustical impedance close to that of vinyl are preferred by many but not all.  And why do metal mats occasionally sound really good?  Many of us pay many hundreds of dollars for copper mats, because we think they sound great and that copper sounds better than other metals, for example. (In this case, I think part of the mechanism has to do with the copper mat acting as an EMI shield, and maybe copper, being softer than many metals, is closer in its acoustic impedance to vinyl than other metals.) Likewise, I am not going to tell a person who loves the ringmat or the resomat that they are "wrong".  I would agree that some of these choices are preferred because they may generate a kind of euphonic distortion, but that's OK.  Platter mats are like seasoning on food; a small detail that makes a big difference.  Anyway, for noromance, I am convinced that he is liking the undamped sound that arises from raising the LP off the platter.  I think he proved that to himself with his experiments.

Can't agree that any of this pertains to the thick rubber mats that were typically supplied with even the best Japanese turntables of the 70s and 80s.  Almost any alternative will sound better, IMO.
@noromance the 1/4” thick mat that Technics supplied on the SL-1700mk2 and 1800mk2, 1600mk2 and SP-10mk2 and SP-10mk3 is very dense and much more rigid as a result. Its dense rubber compound makes it an excellent vibration isolator, making the above series of turntables second to none for rumble in addition to being second to none for wow and flutter. Yes, they could have better tonearm geometry, but you can’t deny that Technics knows more about turntable design than nearly any other turntable manufacturer  still in that business. 
@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 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?

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.
If the platter rings when you strike it with something don’t strike it while music is playing. Even better isolate the table. Then the platter won’t ring.
@slaw I can't find any info on Sprey's mat. I may try mounting the brass screws to a disk. I don't use clamps as I find they deaden the sound slightly.
@slaw Thanks. 
The actual link is here.
Interesting 5 dot support on small mat with a brass? weight.
I believe this mechanism, like my own efforts above, to yield cleaner reproduction. It may not suit all recordings but it excels on those that do.