DIY Tonearm

[audioflyer]

Not sure I agree with that, as they are equivalent in my mind. As far as I can tell, all that matters is how far the centre of mass is below the pivot point. Basically, the bearing housing cup and counter weight system is like a pendulum, driven by the stylus moving through the groove on the record. For it to be stable, you want the natural frequency of oscillation to be lower than the lowest frequency note you want to be able to reproduce. For small displacements, the time period of oscillation is

That is, it depends only on length of the pendulum and we are fairly tightly constrained by just how far the centre of mass can be from the pivot point, unless you raise it well above the surface of the record which generally is not done. Might be worth trying though!

I did have a very similar thought about making the cup hang below the arm board that would be a challenge.
The only other option to increase the height would be to crank or step the head shell down.

 

[mcai7et2]

I think that the pivot point should be as close to the plane of the record as possible, otherwise any movement around the pivot will exert a lateral stress on the stylus.

 

[John Channing]

I think that the pivot point should be as close to the plane of the record as possible, otherwise any movement around the pivot will exert a lateral stress on the stylus.

Not sure how that works, but I know generally the pivot point is kept close to the plane of the record.

I did a quick calculation and the Aro pendulum natural frequency is well below 10hz, so the basic mechanics would suggest the design is stable in the audio spectrum already.

 

[kropo]

Hi

Sorry for loaning topic. I almost finished my first DIY Naim Aro Look-A-Like today. I had problems with counterweight so finally it got kind of ugly. But at least now I can finally listen NOFX.

Pictures:

Regards

Jake

 

[Pete MB&D]

Nice! How does it sound?

Pete

 

[kropo]

Nice! How does it sound?

Pete

Hi

Not bad at all. I don't have original Aro to benchmark but I have Rega RB300. Some adjustments need to set but at this point this one sounds good.

Regards

Jake

 

[orangeart]

Great work there Jake, you've got further than we managed. Care to share your thoughts on some if the points we discussed here?

Stefan

 

[kropo]

Great work there Jake, you've got further than we managed. Care to share your thoughts on some if the points we discussed here?

Stefan

Hi

Of course I'll share if I got something to share. I haven't follow this thread but I'll read this and post my thoughts.


Regards

Jake

 

[Chops54]

That's a pretty decent arm you've made there kropo. Not sure about the finger lift though I'm assuming that's just a temporary thing?

 

[kropo]

Hi

I looked this topic and I ended up with the result that I need to make another one with arrow as arm tube.

My DIY Aro was made of aluminium and steel. Counterweight, "pivot stick" plus bearing assembly and arm cup pivot was made from steel, other parts are made from aluminium.

This thread has same thoughts that I had.

First I was thinking materials, and ended to aluminium. Second was the arm tube dumbing. I haven't dumbed yet the arm tube, but have thought it. Also covering the hole at the end of the arm tube on the headshell end. At now I have clear hole there, but I was thinking to cover that with some foam or something light material. The arm tube is 10 mm aluminium tube with 12 mm aluminium tubes at the both end.

Arm cup has through and through hole for arm tube and one hole for counterweight tube. Arm tube has aperture at the bottom inside the arm cup and there is mounted the pivot and near that a hole where the inner cabling goes through.

The azimuth setting was easy to decide, eccentric counterweight.


Regards

Jake

 

[kropo]

That's a pretty decent arm you've made there kropo. Not sure about the finger lift though I'm assuming that's just a temporary thing?

Hi

Thanks, yes the finger lift is temporary, this arm is not going to stay at this setup long time. I'm building another turntable to that arm. I noticed yeasterday that this kind of "big/long" finger lift is much harder to use than smaller one, needs to change that.

On the list is:
1. New lift
2. New counterweight

3. New arm with arrow/or something as arm tube


Regards

Jake