Vinyl and subwoofers

I'm almost going to guarantee your problem is acoustic feedback from the sub. I know, because I had the exact same problem, and the way you're describing it was exactly how I would describe it. (And my turntable was also on a very stable surface, a granite countertop.) The way to know for sure is if you have another source besides analog (like digital), if the muddiness is there with both, then yes you may need to look into proper EQ for the sub, but if it's only the vinyl, then its feedback.

The solution is simple: get a 12x12 (or 18x18) stone tile from any building materials store, and put four sorbothane feet on the bottom. Put your turntable on top of that. For me, the bass boominess and rumble disappeared immediately. I have a lot of second hand vinyl, and I never see a rumble issue unless the record has serious warpage. Improper setup can also increase rumble. I have no filters in my system, and it plays everything just fine (even with subs) after doing the fix above. Good luck!

Since you are experiencing this with two different turntables and multiple cartridges, acoustic feedback and physical set up in the room must be part of the problem. Can you try wide frequency response head phones capable of very deep bass with the speakers and sub turned off to see if you get the same muddy bass?

That said, my first thought on reading about your problem is that you have a cartridge-arm compliance mismatch as stringreen suggests. I have a sub that can make noticeable pressure in the room below 10hz, and I am getting real sub bass/woofer pumping problems with certain high compliance cartridges on my medium mass Thorens arm playing certain vinyl recordings. Note that I never get this with digital recordings. Turning off the sub or listening to headphones that drop off below 20Hz seriously reduces the "rumble" with vinyl, but since I am using the sub with monitors I miss the bass extension with the sub out.

My solution is going to be to experiment with cartridges with very different compliance ratings to try to find the right match with my arm. Maybe also trying a phono amp with sub-bass filter. Curiously two different Grado cartridges with the same compliance ratings have noticeably different susceptibility to this rumble problem on my table.

The first thing that should be addressed is the compatibility between the ARC PH8 and the Strativari cart?

There was never any mention of the OP's room dimensions, or what, if any treatments? Subwoofer placement or any info regarding this. Room treatments. For that matter, the rack's construction...?

For a small room, especially, I find my Vicoustic Super Bass Extreme Panels to work very well. Others have mentioned GIK. They failed to say that these treatments work best in a closed environment.

I can only assume that since the OP stated the TT was 4' between each speaker that the Op's set-up has the rack in the center of the room. The rack... we aren't told what sort of rack, only it's 5' tall.

My fix? Ideally, your tt should not be in the center of your speaker placement. I can only assume that you have limited options on your system /room by either your WACF or your budget. To eliminate the effect of the center position of your rack in your room to a more appropriate place.. this would be a cost factor that you don't want or need? Right?

Try the springs from Machina Dynamica to place under your tt support/platform. A very modest investment. A very important/relevant return for that investment. This will be the best option in terms of value for the dollar you will likely spend in any instance.

Good luck!

Dear @golferboy : As @erik_squires  pointed out the subs set up is not an easy task for say the least.

Problems are not that we need a ruble filter because we need not or bass traps because we need it either.

First than all we need not one but at minimum two active subwoofers wired in true stereo fashion and crossing at around 80 hz-90 hz with the main speakers playing from 80 hz-90hz and up.

You have only one sub that if using two subs we have a hard task to integerated with only one it's a lot harder.

When two subs are well integrated no one can detect not only its position but that we are using subs in the systems other than with organ music or the Telarc 1812.

Seamless integration is the name of the game but really difiult to do it. I took over ayear to arrive " rigth there ".

In the other side we need subs with a very low THD figure. No where we can read your Thiel sub THD.

The best subs for stereo music are Velodyne with a ridiculous 0.5% on THD where the highly touted JL Audio subs has over 5% !!!!!!, maybe your Tjhiel was over that JL Audio figure and this is a deep problem too.

Here is something that I posted years ago on subs:

 https://forum.audiogon.com/discussions/do-you-think-you-need-a-subwoofer/post?postid=310058#310058


Btw, JBL made an extensive scientific studies on subs using mathematic models and true and real tests where they find out that for a home enviroment and for stereo music the ideal number of subs must be four and the minimum two units. In that studies they told that as more subs in the room each one sound waves compensate in between disappearing room bass nodules and standing waves and bass excessive vibrations ( of course that the SPL in the set up must be according. ). They did not recomend the use of only one sub.

Regards and enjoy the music,
R.

gloferboy,

My speakers go down the 30hz flat. Yours go a wee bit further.  Did you really need a sub?  If you install the sub and your bass is suddenly exaggerated then you probably didn't need it in the first place. You will have to room tune the wave lengths or E.Q. them to correct the issue..
I personally have found that when one adds a sub to a system that already covers the last octave of usable program material that making it work seemlessly is more headache then it's worthq.  If you do get it properly tuned you've pretty much ended up with what you already had in the first place.
Subs are effective when used with speakers that don't reach further then 50hz or so.  Keep in mind, there is very little usable program material below 40hz anyway.
The Theils are first rate, and in my opinion certainly don't need a sub.  They are powerful below 30hz when the program material calls for it and that is exactly what you want from a speaker.  
Norman