Mitsubishi LT-5V Turntable

When I was researching, collecting details and objects, and writing the text for the page about the Rabco SL-8 tangential tonearm, I found the Mitsubishi LT-5V tangential turntable on a flee market and the seller did not ask too much. On top of that the condition of this vertically operating Mitsubishi was practically Near Mint. To be sure that it would work all right, I ordered a new drive belt for the motor and the disk and two small belts for the two motors, one taking care of the transportation of the arm and the other for lowering and lifting the arm.

 

I tried the machine for some time and as I had more work to do, the LT-5V landed in the storage room where it was on the shelf ever since 2004 the year my Rabco Page was published.
A couple of weeks ago, in the beginning of April 2017, I had to sort out a few things in the storage room and spotted the Mitsubishi. The belt had a bump because I had forgotten to take it off. I ordered a new belt and also the little belts for the two small motors. I started cleaning the machine following the instructions placed on the web by several hobbyists.

 
I unscrewed the spindle, took off the spring washer, disconnected the platter and disk by holding the platter in the left hand and the disk in the right hand and turned them in opposite directions, then carefully took the shaft (bearing) out of the bearing housing and put the disk on the table so it would not risk any damage. Now it was time to clean the bearing housing with cotton wool dipped in blue methylated alcohol and I cleaned the shaft as well with it.


When dismounting the spring washer it sprang of the spindle so quickly that I could not spot it. The inner diameter is 9 mm. The iron ware shop closeby had a variety of spring washers and also the 9 mm one that I needed for a few cents. Cleaning the pulley of the motors and the circumference of the disk can be done with blue methylated alcohol.
 

The next step was cleaning the bearing with oil and reassembling the platter and disk again, clipping the washer (spring clip) on. Then the platter can be put on and finally the short spindle can be screwed on.

If you own a Mitsubishi LT-5V you know all these steps well.

I had done all these important steps and yet there remained an issue now and then with speed accuracy. After carefully checking once again all the parts, bits and pieces, and playing several records, it became clear that one important step had not been done by me and I also had not read about it on the web. That step was the cleaning of all parts of the record holder.


 

The cavity that clamps on the spindle has to be cleaned thoroughly and the space between knob and clamping bar needs cleaning as well so that there will be no dirt, no dust, no particle obstructing the perfect functioning, which is the complete free turning of the record holder while clamping the record well. Now the wow had gone, accurate speed is the result.

Mitsubishi LT-5V - The Sound

The Mitsubishi LT-5V is not just another turntable. It is a complete system, a well thought over conceptual idea. It was on the drawing board in a time where people had hardly heard of computer programs for designing and for manufacturing products and at the same time thinking about every move and step as we are now so accustomed to when using an iPad for example. The LT-5V is completely thought over down to the minutest details of arm mass, headshell, cartridge, motors, transportation, and the various functions to be selected on the display. And all aiming at a sound performance and it is not just an idee concerning flawless mechanics. Some people have a good functioning LT-5V and others have a machine with less favorable sound performance.

A problematic feature is the functioning of the record clamp. I wanted to hear what the effect is of the record holder at the end of the horizontal arm. So I tried an imitation Goldmund clamp and screwed it on the spindle. The openess of the sound image and the transparancy had gone. I have read with great interest the story by soundofvoid at
http://www.whatsbestforum.com.

 

Soundofvoid upgraded his machine by improving various features and aspects. One of these was the functioning of the clamp. He inserted a spring that excerts more pressure. So I took out the spring of the record holder and pulled it out a little. Now the clamp functioned much better and most certainly as it should. For the first time I heard a firm click when pushing the clamp on the spindle. The sound was more controlled and it was clear that the openess and transparancy experienced before were fake and brought about by the malfunctioning of the clamp (record holder). The question is: What is the best pressure? I plan to do some experimenting later. It is also evident that the long horizontal arm holding the record clamp is only a convenience and not a necessity.

 

There is much to learn from the measures taken by soundfovoid to improve the turntable and let it function at the correct speed without wow and flutter. Speed is the main issue with this Mitsubishi LT-5V turnrtable. Soundofvoid improved the accuracy by attaching a series of round weight on the inside of the disk. To find what the effect would be of placing weights on the disc opposite the platter, I took 3 short bars of aluminium and while improvising I put these on the disk with double sided tape and listened to the same reord again and again while changing the position of these pieces by a few millimeters and thus improving the accuracy of the speed.
Nevertheless after having glued the small weights on the disk, the first and immediate impression was that the speed had already improved and probably could be improved further by carefully determining the position of the pieces. That is what I will have to find out.

It is obvious that Mitsubshi did not take soundofvoid's measure. Maybe it was not necessary in 1980 but after many years of service it is possible of course that the functioning was no longer as it used to be in the early 1980s. I will conduct more trials before ordering similar weights as used by soundofvoid.

 

Rumble

After a month the problem of speed accuracy has been solved completely. Speed constancy is very good. But not all problems are solved. The next problem is the rumble that is produced by records that are not completely flat or - when they were pressed - the vinyl did not heat through and through and did not spread evenly. For such pressings the machine is very critical. Bad pressings give a wobbling sound the level of which varies from LP to LP. This is a phenomenon that spoils the listening experience greatly.

 

 

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Page first published on May 1st, 2017

 

Audio&Music Bulletin - Rudolf A. Bruil, Editor - Copyright 1998-2017 by Rudolf A. Bruil and co-authors