Some Cartridge and tonearm input please

Earlier I had asked for some suggestions on a cartridge for getting my old Thorens back in action and the information was very helpful (thanks everyone!). I am refining my plans and would like to run some thoughts by the experts.

The TT has what appears to be a pretty massive, straight tonearm (see attached photo) with no antiskate. Based on what I have read the most appropriate cartridge would seem to be a fairly low compliance model with spherical stylus ala disc jockey. What do you think of using a Shure M35x as an economical starter cartridge and trading up to a better tonearm-cartridge combination as $$$s permit?

It appears that the only adjustments are the pivot height and tracking force. However the headshell is held on with the single knurled screw on top and it can be moved in and out and maybe turned a little bit that way. I need to read up on proper adjustment a bit before I try to get it set up.

Do you think that it would be possibly to set up this tonearm with a DIY antiskate system using some fishing line, a little pulley and some small weights?

mike

thanks for your patience.
 

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Guess I understand that

Well I suppose I understand why you say that but unfortunately it is either that one or build the wooden Altmann. :xeye:

There is no budget for a tonearm at this point. Are you saying that the existing arm can not be used without damaging my records or just that it will sound crappy? I can take crappy but I don't want to ruin the recordings.

mike
 
Are you saying that the existing arm can not be used without damaging my records or just that it will sound crappy?


I don't really know what that arm is but yes, it looks frightful. As it may well have high bearing friction it might eat your records.

If your funds are limited why don't you sell the TT on ebay and buy something simple but proven (Rega 3, Thorens 160 etc) which comes with a real arm?
 

SY

diyAudio Moderator Emeritus
2002-10-24 10:19 pm
Chicagoland
www.SYclotron.com
Some good points- check for pivot friction and play. If there's any hangup, rattling, or "sticky" bits (especially when initiating movement), you don't want to use that arm. Even if not, at its age, it will probably need disassembly, cleaning, re-lubrication, and re-adjustment of the bearings. That's do-able, but there's a high "sproing" factor involved.

If all is smooth and lovely, you can get by with a cheap Grado.
 
Thank you for all of the informative posts.

I took the thing off to get a closer look and it looks like salvaging it is not practical. It is a General Electric TM-2G by the way. It was originally installed as a mono unit and rewired for stereo. I don't know how heavy it is since I can't put my hands on an appropriate scale right now.

There is a crack in the frame from over torqueing the rough balance adjustment knob, a broken pivot pin, and quite a bit of side to side slack where the support goes through the mounting flange.

The crack would probably be easily repaired but the other problems are, I suspect, more involved. Am I right in assuming that the wobble would be a major flaw?

Dnsey: Thanks for the offer but it has rather substantial sentimental value and the platter and bearings seem to be in excellent condition.

Sy: Interestingly other than the above mentioned slop it seems to move quite freely with no scraping or binding. There was some resistance due to the hookup wires being rather stiff (looks like 20 gauge plastic insulated).

I considered saving up a little to get one of the radio shack $99 belt drives but this is a DIY site so I probably ought to at least consider a more hands on approach.

Just how rediculous would it be to try something like This ?

mike
 

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EC8010

diyAudio Moderator Emeritus
2003-01-18 7:57 am
Near London. UK
You have exhausted your one minute with that "arm". Bin it. Then, nip down to a model shop and buy some balsa wood. Then kludge together a unipivot bearing out of a ball point pen tip. Throw some really fine (multicore) wire at it, strap on a counterweight, and you'll have something far better for peanuts. It won't be pretty, mind, but it'll sound much better. I'm sure there's a balsa arm design floating about on the net somewhere.
 
Have started to do some reading

I have started to do some research on this new and exciting project. I suppose that I can use some parts from the old tonearm to make my job easier.

I suppose I can use the old flange and mounting point and just make the arm length proper for that mounting point (easier than making arbitrary length arm and cutting a new mounting board). I could also incorporate the existing headshell too.

I assume that a rigid material is best for the arm but I am not sure that I could explain why I think that. It could just as easilly be the case that the tonearm should be designed to dampen certain vibrations. What say you? Is it even an important consideration?

Should I aim to have the pivot point above both the counter weight and the headshell?

mike
 

EC8010

diyAudio Moderator Emeritus
2003-01-18 7:57 am
Near London. UK
No, you want the pivot height at record height. To make the arm stable, you want the counterwieght below pivot height so that the arm's centre of gravity is just below pivot height. I suggested balsa because it's light and has good damping. Oh, and it's easy to work. I posted a thread about unipivot arm design together with pictures of my arm on this forum, but I can't quite remember where...

Ditch the headshell. You want minimum mass (but not at the expense of rigidity) at the business end.
 
mashaffer said:
EC, I think you have it right. I'll add it to my history collection (rather than the round file) and start studying up on rolling my own.

mike

Don`t get rid of it yet put some oil on the pivot and the rest of the joints. Then put a old cartrigde in it and a not so good lp if sound ok that will do . Untill u buy a new or make one

Remember if you don`t listen to it you won`t know how bad it sounds or good maybe. One TT is better than no TT


:)
 

EC8010

diyAudio Moderator Emeritus
2003-01-18 7:57 am
Near London. UK
No, no, no! A poor arm/cartridge can damage an expensive collection of LPs in short order. I've always had much better cartridges and arms than the rest of my system, and as a consequence, the LPs I bought as a student are still perfectly listenable. It's just not worth taking risks with your LPs.
 

EC8010

diyAudio Moderator Emeritus
2003-01-18 7:57 am
Near London. UK
Charity shops can be a good source of LPs. I picked up a pressing of the Cantelli Beethoven Symphony No 7 the other week...

The thing is, a flat LP with low recorded level won't stress an arm much. Put a warped LP with high levels on and it won't move as it should, forcing the cartridge to mistrack and wreck an otherwise OK LP. Worse, the friction could easily be different from day to day and at different angles (probably is). I made my first arm when I was 14 in a double period (80 minutes) one morning at school and have never looked back.
 
Plans in the works

I went looking through my scrap bins and a plan is beginning to form. I cut a section of 1" motor shaft on the horizontal band saw for the bearing cup. I dont have access to drill press or milling machine right now but I think I can find someone to true the ends and cut a pilot hole for me.

For the post I could grind a proper point on an old drill bit or I have an extra dimond tipped grinding wheel dressing tool (used to level worn grinding wheels). The dressing tool might be overkill but it would be kind of cool to say I have a diamond bearing. ;)

I have some flat copper rods (about 1/16" thick, 1/4" wide and 3+" long) that look like they came out of a motor arm. I figure on using one of those for the outriggers for azmuth stabilization (with suitable weights attached). The idea is to notch the top of the bearing cup so that the rod fits on top between the cup and the tonearm itself.

Here is my idea for antiskate. The bearing cup will be drilled half way through so I was thinking that I could cut a groove around the cup that was even with where the tip of the post will be and then cut two vertical grooves 180 degrees from each other. Each vertical groove would have a small screw installed just below the circular groove. A fishing line is then attached to one screw, fed up the vertical groove to the circular groove and wrapped around the bearing. The fishing line is then slung over a pully with appropriate weight attached. I don't know if this will work but the idea is to apply the torque in such a way as to not upset the arm balance or dynamics as a line to the arm itself would.

Any thoughts on these plans?

mike