Garrard 301 - Project

@lalitk Sorry to hear you are having issues. It appears you are getting acoustic feedback. I doubt there is any issue with the AudioGrail work. It is most likely caused by your stand and suspended floor. Can you reinforce the floor from underneath? If your plinth is one of the hollow types, you may not have enough mass to damp structure-borne vibrations. I have no issues with big 12" REL subs. 

“It is most likely caused by your stand and suspended floor”
@noromance 

I suspect just as much. I am counting on my other rack which is roughly 3x in width and weight to provide better isolation. The plinth has a cavity / opening to accommodate Garrard motor and bearing. Wil know tomorrow if I need to look beyond the rack to further isolate the plinth. 

A Friend who is a through and through ID TT user has their Audio System Racks on a suspended floor. There has been various methods investigated / tried out to improve the TT from the Floor Up.

The Audio System Rack is mounted on a Sandbox Plinth, which I know has been claimed to have been substantial in improving things and is very little expense to put in place, even if made look aesthetically pleasing.

A simple method such as this is worthwhile investigating.

The alternative Rack being referred to being 3 x the Width, could have Pedestal Sand Boxes produced to be able to take the support legs of the Rack only?

My own investigations and trials for mounting the Audio System Rack. Has Three Tiers of different isolation materials used before the Steel Plate Base Plinths are mounted on these. The racks are seated on the Steel Plates with a separating footer. Additionally, the Racks are rigidly braced. The TT is seated on a Sub-Plinth Assembly with Solid Tech Feet of Silence as the Footer in direct contact with the TT.

1, The Sub-Plinth Assembly under the Rack does create a discernible difference to the Rack being in direct contact with the floor. Speaker users are knowing about the benefits if using various methods to interface with the floor on any floor type.

2, Rigidly Bracing a Rack is in my experience very discernible as the betterment to the Rack left free standing. My Racks are braced together (my method not so aesthetically pleasing), as well as being rigidly coupled to the wall structure. Assessing this is easy as both are easy to release and A/B compare, both coupling methods in my set up have been very beneficial.

3, Producing support structures under the TT can be undertaken at a variety of costs and even more permutations for Plinth Materials and Footers used as separators and then the TT’s Mounting Feet. Working with the various options of permutations is where the real magic occurs. To really get the benefits it is best when done as the last exercise of the three treatments.

There is not a ubiquitous methodology for this one, I have loaned out many materials to be used on other systems, as the Mount for the Source, the differing environments and methods used to support the Rack, as well as the Rack Type creates very different outcomes of how a material is assessed for its impact on the end sound. Perseverance wins through.

If any of the other suggestions offered by other contributors for the TT are followed up on. The benefits that are yet to be discovered will be even further benefiting when experienced on a Mounting System that is addressed from the Floor Upwards.

https://forum.audiogon.com/discussions/turntable-isolation-journey

@lalitk 

Just for clarification, do the issues disappear entirely if you turn subwoofer(s) off?

@mdalton 

I honestly don’t recall, I must have gone through half a dozen configuration. I can’t check again until everything is put back together, hopefully by tomorrow.