A Copernican View of the Turntable System

I thought that this J. Carr is the smartest guy among us.
But he is as crazy as the rest of us:'Surrounding the turntable ( but not contacting it) would be a double -wall acoustic shild '(08-24-11). How about asking the Russians
for the permission to install our TT in the Mir?

Regards,

In my current home, room and speaker interactions are a source of some real problems. When the gain is turned up i believe this excites the built material of the walls ,ceiling ,suspended floor causing many problems.

With my sources 13 feet away from the closes speaker i decouple my stand from the floor the best i can for now and then decouple the turntable from the stand, it's a job still under construction.

Our previous home listening room was so much friendlier and a real joy to listen music in, concrete slab on grade timber framed home with open vault ceilings.
The living / listening room simply had excellent acoustics.

One experiment listening for feedback problems in our previous home by placing an lp on the platter then resting the stylus on a stationary lp ,turning the gain up full i would be hesitant to try in our new home yet.

This may sound all bad however using a Placette active preamp with a Hell of a nice headphone section and Sony R-10 headphones immediately solved all my room related problems, I think.

I believe that Pryso and In_shore are correct in the fact that the air-borne sound pressure levels, affect the room's fabric to different degrees depending on their materials and structural means of support.
This transforms into 'structure-borne' feedback affecting the turntable depending on it's construction and isolation.
'Sprung' decks, because of this, are more susceptible to this feedback than 'mass-loaded' ones.

Hi Halcro/Pryso/In_shore,

I have for a long time thought that new equipment needs time for the room to settle into it. This is most obvious with changes in speaker systems but seems applicable to equipment more generally. However, this is all dependent on my challengable tools of assessment: my untrained/self-trained ears!

What you've all said does provide food for thought.

Observations of Direct Sound Pressure on a Tonearm

The recent posts have been great, informative and enlightening for me. Thanks guys. TBone - looking forward to your results as well …

Sorry for the long post.

I was curious, so I tried to create a direct air borne problem before it became a structure feedback problem just to see if possible. Two TT’s together on the side wall directly opposite the firing of one of my speakers. Everything u wouldn’t want to do to get direct airborne feedback with a TT I did. The first TT is no more than 6 feet away from the drivers of my speaker. Before I tell u what happened let me say I have played around quite a bit already with this air pressure phenomenon but from the other end.

I have experimented with my air bearing arms to see how the air pressure affects them as it comes out of the air bearing. I learned what their maximum PSI threshold is. Go past this point and they start to resonate from not being able to handle the PSI. Keep just under it and you have magic happening. Anyway above this threshold they resonate and can’t hold the cartridge/stylus in the groove properly anymore. A loss of detail happens. Your $$$$$ TT rig starts sounding like a $$ rig. No surprise right ?

So I thought what the hell, this is going to be more fun than yelling at the cartridge so I let loose on them hoping to make the tonearms/cartridges show some signs of sonic deterioration. I played big music at well over 100 db. What happened?

Well first thing is not what I could hear but feel because my listening chair was vibrating. I then went over to one of the speakers and felt the sound anchor stand holding up the 110 lb speaker. The heavy metal SA stand was resonating. They are spiked to the basement concrete slab. My room is closed 12 X 24 FT. with speakers in nearfield firing down the length. The side walls were also resonating. But what about the music ?

Nothing – NADA – the music and tonearms were fine as far as I could hear. So in my case with this little experiment I heard no direct sound pressure effect on the tonearms. If you don’t believe me.

Ask this Audiogon member if he is worried about Direct Sound Pressure from the Speakers ?

So based on this I agree with what Henry said. The airborne feedback is changing (mutating) into structure feedback. Its going into the walls, the floor, the racks the gear. Everywhere. Structure Feedback is the audiophiles version of “VIRUS” movies. Go ahead put up a shield - its going there too - now u will have something resonating next to your precious $$$$$ tonearm - does this make sense ? I dont know I didnt try it but I'm also not going to Home Depot to buy plexiglass or something else to surround the TT either. I've heard enough.

Structure feedback is there but until you discover it no matter how small a problem it may be and correct it as Pryso's experience tells, you may not even realize its there. This has to be one of the leading causes of why gear may sound good at the dealer, but then people bring it home and it sounds different ?

This experiment was good for me because it gave me a better idea on the limits of what my room are. My racks isolate ok to well above 100 db so below that where I actually listen I am fine for now. Could they be better - definitely - maybe I will ask Don to build me a nicer rack ?

But I think I need a new listening chair first?

Thoughts ?