Back to: TD-160 Dept.
The 'Chadwick Mods' revisited.
Above photo: 9/7/2015. Just after the latest restoration.
I've decided to undo some of the 'Chadwick mods' I had carried out on my TD160 several years earlier. After making the listening observations I have, and in consideration of another individual (Charles Trayhorn ) recognized as an Audio Professional, I have decided to take a more conservative approach that employs the best of Trayhorn's ideas along with what I consider the most effective mod carried out by Steven Grant's company known as Chadwick Modifications.
What I'm keeping:
What I'm undoing:
What I'm doing:
Here are some photos of the TD160 C after the 'restoration / modification'.
Above two photos: The subchassis after the cork/silicone removal. Back to standard....., briefly.
Looking at the cleaned up TD160 cabinetry. (aka plinth). In this view we can appreciate that the veneer on the inside is Walnut while the veneer on the outside is Teak. Standard for that period of production. Also in this view can be seen the RCA jacks as well as the ground stud mounted to the jack plate..
Looking at the original bottom cover which I assembled to the cabinet for this photo. The original bottom cover makes an excellent pattern for making the more substantial cover to be used. Otherwise, it stays off.
The new bottom cover installed. Material: 1/2" MDF. I deliberately chose MDF for its audio friendly properties. 1/4-20 thread inserts were installed so that cone feet of choice can be used. Additionally, the rubber feet at each corner is also an option, depending on what one might choose.
Looking at the cone foot. It partially covers the counter-sunk screw that secures the bottom plate to the cabinet. If one wants the four corner screws can hold rubber feet. The screw hole countersink is made deep enough so that the cone foot does not make contact with the fastener screw.
Assembling the Motorboard:
Turntable is inverted again. This time with extra care to protect the exposed tonearm underneath. The cue is operated by a spring loaded flexible steel cable. The knob in front operates the cable which needs to be connected to the knob cams.
Tonearm signal wires are soldered to the RCA jacks. The tonearm body ground wire solders to the ground stud on the jack plate. The chassis/bearing ground from the ,motorboard tab solders also to the ground stud at the jack plate. Original Thorens signal wires are retained. These are extremely fine gage cable and of a low enough capacitance to be used on even the fussiest of cartridges.
trying out Simone Luchetti's precision machined aluminum clutch pulley (more info on this pulley: link)
In this pic the dustcover is installed. This turntable I pampered all its life. Dustcover is free of any scratches. That's rare for a turntable bought new in 1975. (making me the original and current owner)
UK. Charles Trayhorn at Metrosound. Early development of what was to become the Thorens TD160 Super.
Trayhorn mods: circa mid 1970's
Thorens TD160 Super
Thorens essentially used the above list of 'Trayhorn mods' and based them on its TD160 mkII in AB configuration. (Came without a tonearm)
"Chadwick Modifications" was the name of the company. Steven C. Grant operated it in Cambridge, Massachusetts.. And...his middle name was Chadwick, hence the company name.
The Chadwick 'mods' carried out on a Thorens turntable were different from those employed by Trayhorn and Thorens. He used the standard Thorens cabinetry, but replaced the thin flexy masonite bottom cover with a far more solid bottom plate made from 1/2" thick baltic birch plywood. He used silicone damping materials on the undersides of the motor-board and sub-chassis. He used silicone also to damp the inside of the inner platter (hub). See below for a list of mods carried out on a TD125 that was featured in a review by Steven Stone in TAS vol 14, issue 58, march/april 1989 (pgs 102,105). Readjustment of tonearm pivot bearings and selectively dampened the arm tube.
He sold a 'corktone' platter mat and included that in his list of mods. He offered to replace the standard signal cables with a Sumiko PIP rca output box and then the customer could use any interconnect preferred.
End of updates.
Below: Old notes circa 2001 - 2003. I maintain these to this page just for reference. Many mods done then are now considered by me to be obsolete and I won't go there again.
This page documents modifications done to my TD-160 and reports how well they worked.
8/19/2003: Some time has passed since I first wrote this page. Back then I was looking for a project and so thought it might be fun to make improvements to a turntable. As it turned out, it is quite fun and nearly two years later, I'm still at it. What follows is the revised and continuing story of my test mule, a TD160 mk1 that sounds much better than any standard Thorens has a right to. Initially, I just wanted to see whether it was easy or hard to improve on one of these models. Now I can say that much of this work really is simple and, as a bonus, cheap to carry out.
You can't really start a project without a plan. Initially, I looked for a plan, a list of procedures to carry out. What I came up with was the list below. The Chadwick mods. These became my plan. Back in the latter days of the LP era, Chadwick used to advertise in the classified sections of audio magazines. He offered an upgrade service for Thorens turntables. I remember sending for and receiving his catalog. I never did send in my Thorens and, ultimately, lost track of the catalog. Then came CD's and years of idleness for the Thorens.....sigh.
Above scan taken from an audio magazine classifieds circa 1989
I didn't completely forget the Chadwick mods and when renewed interest in vinyl came over me, (circa 1990's) I began looking for information on Chadwick Modifications and exactly what it was that the company did for its customer's tables. The links below offer the best detail I could find. Steven C. Grant died in 1999 and, as far as I know, took the knowledge of his method with him. Otherwise I'd have called him up.
The Thorens is a much discussed turntable on the internet at the audio-asylum, (vinyl-asylum) which can be found at the link below:
Within the archives there I was able to dig up the following scraps of a recipe of Chadwick mods on a TD-125. Here is the link to the full post which refers to a magazine article in the Absolute Sound and an A/B comparison between the modified Thorens and a much pricier VPI table: http://www.audioasylum.com/audio/vinyl/messages/95257.html
9 mods were done:
I have experimented with the above list and have the following thoughts about it.
Below are links to pages that detail the various work to be done.
Tonearm/cartridge alignment definition of terms use info here to align your tonearm.
Finding a proper replacement belt Testing replacement belts from various belt vendors.
TP16 MK I Tonearm, maintaining the cue mechanism Restoring the cue drop time.
Rewiring a TP16mkII with silver wire. Wei Zhu sent in these photos of his experience.
Parking it on a wall shelf Suspended tables like it on the wall.
The result of all this work is well worth the time invested. The transformation is like having a completely different table. Background noise is way down. Signal to noise is way up. A sense of "in-the-room" presence is apparent. Soundstage, imaging. Notes hanging in air that didn't used to hang. Cymbals having more shimmer. Now it's making some music that draws you in.
Most Effective (Important) Tweaks:
1) Correct settings of suspension, tonearm and cartridge. If it were a car, you'd call it tune-up, lube and maintenance.
3) Wall shelf. This eliminated the problem of structural born vibration disturbance that plagued this table when it was placed on a floor standing audio rack . The wall shelf allows the suspension to become stable and then it can react as it was designed to against the forces happening between stylus and groove. Also, life with the player is much better this way by allowing me the freedom to walk by without having to tip toe.
4) Drive belt, renew it with an original equipment replacement. Worn out belts lose grip during the more dynamic moments on a record and in the lower frequency notes. The result is lifeless music. A new belt brings back your dynamics and bass response.
5) Tonearm / arm board upgrade (replacement with SME 3009) The tonearm is important, but so is the arm board it mounts to. Different materials result in different sounds.
6) Phono Cartridge, get one that matches well to your tonearm. (Effective mass versus compliance of cantilever) Basic rule: More money in the cartridge = better sound. The question becomes "where do you draw the line...?" Consider the value of the table, quality of the tonearm. More info to come on cartridge/arm matching.
7) Platter mat. For a long time, I was not a believer in platter mat tweaks. That changed when I tested Malcolm Coulsen's Spotmat. This led to some experimentation of my own and, ultimately, mat #10. This mat allows a more solid lower frequency and a more alive and natural sounding midrange. More musical detail reaches my ears. Yes, mats can make a difference. Have some fun, make your own.
The SME 3009 S2 Improved is a lower mass version of their previous arm. It is also lighter and smaller and fits under the dustcover of the TD160 without interference. However.....
It might be best, when considering a tonearm swap to first choose the cartridge you wish to use. Following that, select a tonearm that will match well. Then, of course, you have the problem of determining if that arm will match well to your turntable. One thing leads to another, then another....etc. With the assortment of cartridges and arms available to choose from, your perfect match is entirely possible. More info about using this tonearm on a TD160.
1/2 inch birch plywood, Grade A. One piece at 12-15/16 x 16-1/2 (note, I had to buy an entire 4ft. x 8ft. sheet.)
4 - rubber feet, hole in center for wood screw mounting. (hardware store item)
4 - #8 x 1 inch brass wood screws
1 - 4 sq.ft. piece Dynamat (can be found at Car Stereo stores)
2 - 36 x 12 inch pieces of 1/8 inch automotive cork gasket material
1 - tube Blue RTV Silicone
1 - package of Blu-Tak (Bostik) available at audiophile vendors
4- packages of Elmer's Tac 'N Stik (Blu-Tak substitute, much cheaper commonly available)
1 - can of talc (available at billiard supply shops)
Link to page for the tonearm details