A restoration / transformation for a Thorens TD150 mkII
To see the For Sale Ad page for this turntable, link here 79209FS (sold)
Final iteration: Being readied for sale.
The R7 plinth is a constrained layer Baltic Birch build. At its underside it features three threaded inserts to provide a tripod stance. The heavy rubber feet are fastened with 1/4 - 20 machine screws. The installed inserts will allow use of a wide variety of cone footers. Depending on whether to couple or de-couple to the surface it stands on.
The Arm:Sumiko MMT
Tonearm notes: This arm came to me in need of service. The mounting collar was missing. The arm rest clip was broken. The 5 pin din plug had been removed from inside the bottom tube and the internal wires were hanging loose....but intact. The next inspection required disassembly. What I found within was a very solid framework designed to hold the pivot bearings. A simple, well conceived anti-skate design (using a cam and torsion spring cam follower to increase/decrease anti-skate force levels). Everything looked very good except the pivot bearings had dirty bearing cups. I soaked the ball bearing cups in acetone. Cleaned all parts of the pivot bearings (cones and framework) with acetone.
At the headshell end the spring pins within the coupling joint had good tension and showed no evidence of wear or mishandling. No problems.
Oh, yeah, I took time to measure all physical dimensions of this tonearm so I could model it in 3D cad. Hence the model illustrations on this page.
Knowing that a rather heavy headshell and that low compliance MC cartridges were to be used, I made an auxiliary counterweight out of solid Delrin on a small lathe. This added mass of the installed Aux. weight makes it possible to balance heavier loads out front. The auxiliary weight is secured to the standard counterweight by means of a slip fit over a hub diameter and one set screw to hold it onto the factory counterweight. Install or remove at will.
The mounting collar (to fasten the arm to the arm board) has been, like the auxiliary counterweight, made from solid Delrin, lathe turned.
The collar ID fits the bottom pipe of the MMT with .001 - .003 inches of clearance. Solidly. This, I'm certain, does enhance performance of the arm.
The RCA jack plate is similar to the one used on the first R7 made a few years back. Only this one spans over a different shape of bottom opening. This made cause for some dimensional changes. The jack plate, as it is, offers the convenience of a solid fixture holding the RCA jacks and interconnects. The above series of photos show the jack plate and fine gage tonearm wires and Cardas DIN plug being installed to the tonearm and plinth.
Above: laying out the mounting distance. This is the one reason I keep the Clearaudio tractor-style protractor. In combination with a cad printout of the mounting collar hole pattern, the job is easily done. (as pictured) Next step; drill press.
above: with Sumiko HS-12 headshell. (a very good match with the Sumiko MMT tonearm) Now the turntable is just about complete. The cartridge is a Denon DL-103R with Uwe ebony body. Standard tip. In photos below it is seen that a Orsonic AV-101S headshell has been in use. Now that I've had time to compare between the two headshells (all other things being equal), I'm quite certain the HS-12 gets quite a lot more detail than does the Orsonic. Otherwise, weight, Bass and drive seem similar. I searched for the HS-12 because I knew from previous short experience, and from popular mention around the net, the Sumiko headshell is the natural choice for the Sumiko tonearm.
The armboard is MDF with figured Cherry veneer. I choose the veneered mdf over any solid hardwood because I get better bass with it. The mdf is a fairly good resonance damper and, when used judiciously, does enhance the audio experience.
as of Dec. 26, 2015
Above: Trying out the Zeta tonearm on R7_2. Cartridge is a DL-103R / Uwe Panzerholz body / SoundSmith ruby cantilever/FL diamond stylus
Impressions. Favorable. Both for appearance and sound qualities. The Zeta arm seems to compliment this modified Thorens TD150 quite well. And the Denon LOMC cartridge works well on the Zeta. Sound is meaty, solid in the mid-range. Punchy in the bass and extended in the higher frequencies. I may keep it this way for some time.
(4_22_2015) R7_2 with Sonus Blue cartridge mounted. Golden Sound ceramic footers are blu-tacked to the plinth and stand over 1 inch thick slate blocks. The slate blocks are isolated by cork pads from the glass shelf of my audio rack. The 'cones on slate' produce an effect I like better than the heavy rubber footers being used in other photos of this player. More about that later.
Above and left: R7_2 with Infinity Black Widow tonearm mounted. An ADC XLM II improved moving magnet cartridge is mounted. This is one of 'only a few' cartridges which will mate well with the ultra low mass of the Black Widow.
Above photo: R7-2. (date: March 2014) A Thorens TD150 based project incorporating the R7 mods.
This page is an update to a project I worked on 5 years back. I'm not sure that I'm any wiser for these additional 5 years, but I do have some different ideas about how to approach upgrading the Thorens TD150. For one thing, I recently worked on another TD150 project that went very well. #34259 It went so well that I decided to duplicate those steps for my own project on this page.
Receiving Inspection Note: this linked page was written 5 years ago. It details examination and analysis of the important parts of the turntable as it was then received.
Custom Plinth Design Notes:
R7_2 Concept sketches:
Above: I originally drew this plinth design for project SN#34259. Let's refer to that as R7-1. It was offered to the client as an alternative to my previous concept drawing, R6. While the interior dimensions are compact and allow little space for components, I was happy with the sound of that deck and also the size/form of it, so I am using it again here. This time the color is different and there are some minor changes, but essentially this is the same plinth. I call this one R7_2.
Above photo: The plinth construction is by stacked layer build. 6 layers of 1/2 inch thick Baltic Birch plywood glued/pressed one on top the other. Coating is Acrylic Lacquer. Multiple coats. (10 +) Sanded between spray applications. It awaits final polish as I allow the lacquer to harden over the next few weeks. The heavy rubber feet are from Antique Electronics supply. These fasten by means of 1/4-20 machine screws going into brass threaded inserts that have been installed into the bottom of the plinth. This color (green) is a custom color that I had used 20 years previously on a '69 MGB that I had restored/painted. It is a custom mix. At the time I was going for mid 50's Jaguar British Racing Green. It's probably not exactly the right shade, (there's a bit more blue in it), but it is what I had come up with back then. Having a full quart left over I decided to put it to use. So here it is :-)
Assembly and build method
It has already been established that the motor and platter bearing are in very good condition. Knowing this we can move forward to a simple assembly process.
Above photo: This model is a MKII TD150. It came equipped with with a tonearm cue mechanism that was operated from the front of the deck by means of cable and cranks. Those mechanisms were removed. There is a bracket to support the cue control. This is swaged into a hole in the motor plate. This was carefully removed. See above photo for location and to view the assembly after removal.
Above detail photo: The conical coil springs are replaced with the assembly shown in the photo. The result of this work still offers good isolation from the motor board, and all supporting surfaces. However There is no bounce. Consequently, the hanging sub-chassis holds position rigidly like a non-suspended turntable, yet Isolates from surface borne vibrations like a suspended turntable.
Above photo: The motor capacitor is replaced with a new one. Value is .33uF, 400 volts. The original cap was rated at 10% of stated value. The new one is rated at 5% of stated value.
Above photo: AC input connection. Care is taken to insure that the couplers won't pull off.
Above photo. Looking at the assembly prior to adding platters, belt and arm.
The original decorative facia sheet was drilled for the cue knob, which provided a visual distraction when looking at the deck. I chose not to use the original facia and instead fab another out of thin aluminum sheet metal. It was adhered to the top motor plate with silicone RTV gasket adhesive, then sprayed with a hammerite finish in black. I never did like the look of this. So I removed the facia and did something different.
After experimenting with different attempts at making a top facia cover, I thought about simply polishing the bare plated sheet metal that is the top motor plate. The plating, which in stock form has a foggy gray color, will polish into a shiny surface using Mother's Mag Wheel polish and lots of elbow grease. The cue know hole is covered over with a decal I photo-shopped of a 16th century jolly roger. Hmmmmm. Maybe.
Choosing an arm for 79209
I have used three different arms on this chassis. An SME 3009 S2. A Graham 2.2 and this, an Infinity Black Widow with graphite arm tube:
The Black Widow arm, which is one of the lightest effective mass arms ever produced, is limited to use with high compliance (soft suspension) cartridges. And only a few cartridges remain that can effectively be used. In every case I know of, one needs to find a used or NOS moving magnet cartridge. Presently I have two cartridges that work with the arm; A Shure V15VxMR and an ADC XLM 2 improved. The above photos show the Shure mounted to it. This combination works well. Sound quality is probably as good as I've heard this particular Shure sound. But I prefer this arm with an ADC XLM-II improved mounted. The ADC betters the Shure in all ways.
Using the Graham tonearm on R7_2. Note the black top facia, which later was removed. Also, the Graham 2.2 is far too much arm for this player. If using the original 3 spring suspension per design, the arm is too heavy and bottoms out the spring nearest to it. If using my suspension substitute solid rubber suspension, the arm works fine on this chassis. But I have some other turntables that make a better choice for this tonearm.
Above: using the SME 3009 S2 arm on this chassis. This works well.
Previous notes: (from 5 years back)
The plan at that time:
Play and listen
Begin a systematic modification program
Listen to some records.
Step 1: Receiving
Looking at the TD150 subchassis frame. Some notes and comparisons to its successor, the TD160.
Testing the subchassis for deflection under load. Then comparing to the TD160 subchassis by the same method.
Looking at the TD150 suspension......and what to do about it.
Step 2: Play and listen before the upgrades
Step 3: Making the modifications
Spring Alternatives...? something significant is discovered...!