Click on the picture for a larger view.
Click on the picture for a larger view.
(updated March 16th, 2001)
Teres #3 is a work in progress: I put it together somewhat hastily in order to learn more about how my final design would need to go together (as well as to score a nice low serial number!) The result has paid off my eagerness to get started, I have been happily spinning vinyl since September 2000.
Thanks to the Brady brothers and the rest of the Teres team for spear heading this outstanding project, it has been a huge success from where I sit (in the sweet spot.)
Materials used are rather prosaic: the bearing mounts into a rectangular base made of oak-faced plywood. This rectangle is backed up with a plywood "donut" at the bearing in order to make the base thick enough here for the bearing shaft to mount into.
I am at present developing a more attractive, solid, and well-damped base from laminated rubber and MDF, but this is not yet finished.
The arm is an exceptionally elegant tangential air-bearing DIY design by Poul Ladegaard. Construction info is available here: Poul Ladegaard's Air Bearing Tangential Tonearm Page
Construction is extremely straightforward and performance is superb. Thanks are due to Thomas Dunker for translating the Ladegaard article, making it available, and encouraging me to try it out, and to Roscoe Primrose for web-hosting. Special thanks are due to Poul Ladegaard for his brilliant inspiration.
My experience with this arm has been very exciting: once you experience the total freedom from geometry- and skating-induced distortion inherent in a tangential design, I expect you will never again use a pivoted arm. Having the tracking geometry consistent and perfect across the whole side of an LP (or especially a 7" 45!) makes a big improvement, and I was already very happy with the performance of my pivoted arm. In retrospect it seems that this consistency is one of the few advantages of CD reproduction and a tangential design negates this advantage almost completely. (The inner grooves are still moving slower with respect to the stylus so there is still some diminishing of the highest frequency information at the inside of an LP, but the biggest effect you notice with this arm is how badly some used records have been trashed by mistracking of the inner grooves.)
I used an inexpensive aquarium air pump to float the bearing. This is stashed inside a wall soffet near my stereo system to quiet its noise.
I have an inexpensive Grado cartridge installed. The Grado MCZ I also own appears to have a weak suspension, it is old and needs replacing. Meanwhile the cheap Grado makes an awful lot of music.
The plywood base rests on a three-legged stand made of PVC pipe and filled with sand for stability. It has leveling feet as well. The motor mount is also made of PVC plumbing parts and is damped with plumber's putty and rubber gaskets. The drive belt is 1/4" magnetic tape. I have tried dental floss and Kevlar thread as well, the tape seems to work the best and is by far the most reliable.
Upgrade plans:
Base: I have a a laminated MDF-and-rubber base in progress. I want to make
the turntable seperable from the stand. I will also to build a heavy
LP-and-accessories storage cabinet to serve as a stand. (Since I got this
turntable running, I seem to have acquired an awful lot of new LPs, hmmmm, I
wonder if that's a coincidence?) The air arm makes this slightly tricky
because there must be provision for level adjustment in the base itself
using this two-piece approach. But this way I can be more flexible in where
I place the turntable.
I have another idea in mind to use a plastic extrusion, suitably damped with resin and shot, and attached to a sheet of aluminum. I have even entertained fantasies of resin-impregnated carbon fiber cloth over the top instead of aluminum. But I will build the MDF and rubber base first, I have all the materials on hand and the cost of the experiment is basically just my time.
Cartridge: I will either replace the stylus and suspension assembly on my Grado MCZ or try something different, perhaps the well-regarded Denon 103D. -- Jeremy