A Copernican View of the Turntable System

Chris, maybe it is just me but this seems to be a bit confusing. You said you tried two tts on the side wall, "directly opposite the firing of one of my speakers". Does this mean one speaker is toed-in to such a degree that it is aimed at one of your tts?

Now perhaps a few points were suggested in my earlier comments that were not made clearly.

First, it is not always easy to differentiate between airborne and structure borne vibrations. After I moved my tt, it was then located in a position with less structural bracing (likely bad), yet it sounded cleaner. So in my case I must infer the minimizing of airborne interference was a net gain over the increase in structure vibrations.

Second, I think a lot can be understood about equipment location from the study of speaker interface with the room. It seems to be understood that where three planes intersect (any corner) you will find the greatest build up of bass nodes. (Insert assumption that bass frequencies have more energy, thus are more detrimental than higher frequencies.) While the corner of my alcove may not have been as severe as a room corner with longer walls, my experience (two shorter walls and a large shelf = three planes) still supports this point. Less of a problem with bass node build up may be realized where two planes meet -- two walls, a wall and floor or ceiling. Further reduction occurs with only one plane (along a wall and up from the floor) while the least airborne interference may be away from all walls and the floor, while admitting this may be the least practical.

I believe this also relates to Jim Smith's recommendations in "Get Better Sound" when he promotes side wall equipment locations over front wall between the speakers.

Conclusion: try locating your tt/arm/cartridge where there will be the least bass node build up.

Pryso,

Jim Smith went around my listening room with a mic measuring bass energy and concluded that my rack was in a good location on a side wall behind the first reflection point and not near a corner. I believe his recommendation that the rack not be placed between the speakers has more to do with the mass of the equipment and rack effecting the imaging and soundstaging of the system. Soundstage depth and center-image density and clarity are improved when there is open space between and behind the speakers. At least this is the case in my system and I would think in most others.

Hi Pryso

I agree with what Jim Smith and yourself say. I also keep my TT’s on racks 6” from the side long wall wall in the 12 x 24 ft room.


Speaker Angle

This picture is the regular placement. The only positioning change I needed to do for this experiment was to rotate the midrange/tweeter module and angle the woofer box a few inches inches to point at the TT’s directly.

The front of the woofer is 9 feet from the front wall. The SP10 TT at the rear is actually 7 feet from the back wall – looks deceiving. The Lenco is only 5 feet from the speaker woofer not 6.

Armpod Recommendation

For those of you that use a metal (brass, SS, bronze, other ) armpod have you tried a few drops of oil in the tonearm mount screw holes before you mount your tonearm ?

I’d really like to get your impressions on what this does to the sound for you. I am using some oil in the armpod and the SP10 SS legs.

Cheers

Interesting thread. Reading comments about resonant energy in stands/shelving etc. I was reminded of this "seismic" stand product from Townshend I just read about and which looks very intriguing to me (I love the TT too but that's another topic). Check it out (below the Rock 7 TT) http://ear-usa.com/townshendsinks.htm

The base as an island, I am not sure?

The fundamental objective of turn-table design is to maintain an optimal geometrical relationship between the stylus and the groove in such a matter to allow, as Halcro so eloquently said it (paraphrasing), the cartridge to transmit perfect information by moving up and down frictionlessly to allow for correct VTA as the groove modulates.

This in turn consist of two factors the geometry and the maintenance thereof. Geometry is the initial location (for the lack of a better term) of the tone-arm pivot point, stylus contact point and center of rotation of the disk, such to achieve Baerwald or Stevenson setup (or whichever one you believe to be best) and including optimal azimuth and VTA. Maintenance is the ability to prevent outside factors such as vibration and noise to change the optimal geometry.

Now to separate and isolate the arm pod from the platter, in perfect world, seems to address the maintenance issue. If the arm pod is isolated, any vibration from the motor or bearings will not be transmitted to the tone-arm or stylus.
This raises the question how is the arm pod accurately located in relation to the platter? Many of the systems in this thread show the arm pods simply placed alongside the platters with no means of accurately locating relative to each other (this is an appearance based on the photos) clearly these tone-arms are properly setup, but how accurately (initial geometry) and what prevents them from moving over time?

Ultimately, the arm pods must sit on a surface that is shared with the platter. The platter is isolated from this surface by pneumatic footer or other method, which no doubt prevents the platter vibrations from transmitting through the surface back to the tone-arm. But now since the platter location is no longer rigidly held relative to the tone-arm pivot, other environmental factors, such heavy footsteps on the floor or ambient noise, can cause these distances to change momentarily (vibration) or permanently (until readjustment). Is the arm pod as an island truly ideal?

A rigid location of the platter vs. the tone-arm pivot ensures optimal geometry, and high mass plinth minimizes the impact of vibrations and noise from the platter. Then isolate this assembly from the room. Is this approach not superior?