Yet more play

[Gordon Steadman]

The uni-pivot is working but not finished as I'm waiting for some 'proper' Parker metal refills to use as the pivot. The plastic ones flop about too much. Mind you, even with that the arm sounds very good indeed so whilst I'm playing with long arms, I thought I'd try another more conventional type.

I have a load of hard disks that have failed over the years and as I stripped them out to destroy the disks, it occurred to me that the motors would make terrific vertical bearings. I also have a load of scrap bits of boxwood about so another good excuse to actually use some. Ronnie is very impressed with all this activity, especially as she wants me to finish a headboard and other stuff around the house. Must get her priorities sorted out:)

Need to turn the bottom support but the bearings are in and the headshell on.

https://farm9.staticflickr.com/8633/16655752716_c6f97e1888_o.jpg

https://farm9.staticflickr.com/8609/16681688735_0147a2b43d_o.jpg

[Gordon Steadman]

And a base

https://farm9.staticflickr.com/8609/16656596896_c7b09f3415_o.jpg

[struth]

Quality;)

[DSJR]

That looks superb and what a great idea for a really good high tolerance horizontal bearing :)

I'd love you to customise a Lenco L75 arm this way, retaining the already good bearing block, but making a long beam as you've done there (so the original counterweight could still be used) with a V rod driven through as per the original, and with a lovely wooden shell as you've made. Absolutely gorgeous job that.

[Gordon Steadman]

That looks superb and what a great idea for a really good high tolerance horizontal bearing :)

I'd love you to customise a Lenco L75 arm this way, retaining the already good bearing block, but making a long beam as you've done there (so the original counterweight could still be used) with a V rod driven through as per the original, and with a lovely wooden shell as you've made. Absolutely gorgeous job that.
Thanks Dave,

I'm still looking for my Lenco!! The aluminium tubes are quite thick walled - ex kitchen support bars - and seem very rigid. I've just collected a couple of parker refills so can test the uni-pivot properly. This one feels much better though, I guess its the nice solidity of the bearings that make it feel secure. We shall see which sounds best. Plus is in my comfort zone as it involves a bit of turning. Somehow an arm perching on top of a parker pen doesn't feel quite HI-FI:)

The boxwood is superb for the headshell, quite light but very stiff indeed, lovely wood and polishes up superbly.

[karma67]

i dont suppose you have a small bit of ebony laying around do you? lovely work on the tonearm!

[Gordon Steadman]

i dont suppose you have a small bit of ebony laying around do you? lovely work on the tonearm!
Sorry but none at all. I used the last supply I had for a fretboard repair last year.

Thanks for the comment on the tone arm. I've fitted a rest, have figured out the anti skate device and await another wiring kit. The arm lift is the one thing I haven't sorted in my head. The uni-pivot just had a cam which is a bit crude. I wan't to make this one a bit more professional. I might have to get my brother in law to put his planet size intellect to work. That's if he has time in between designing our parallel tracker and a bunny stunner my wife wants:eek:

[Gordon Steadman]

I gave up on the uni-pivot. It sounded terrific but there was no way I could control the feedback. Not sure what it was but it's too late to find out now because it's been converted! It is now a 10" arm with the same bearing system as the 12".

Here it is sitting on the Garrard SP25 and making noises that it has no right to make at all. The bass is outstanding. I can't wait to get the big one going as well. That already has a rest and an anti-skate device. I will probably do a string and weight arrangement on the 10". Strange thing, when you polish aluminium, it goes white!! Sadly, the superglue shows as it sinks into the surface and polishes to a mud colour!! Might have to spray it black or something. These arms are seriously good value for money. I only have one more hard disk motor to go - what can I make?

https://farm9.staticflickr.com/8562/16083682784_c6df71ccd4_o.jpg

[Gordon Steadman]

Bugger! I had tried both my new arms on my AR testbed and I thought they were picking up the noise from the motor at a particular frequency. The sound of the 12" was really good so I fitted it to the OL TT this afternoon.

It sounds fantastic, better than the Dual 1019 and better than the OL modified RB250, this with a cheap AT cartridge. Dead chuffed I was. And then.......I turned the sound up and agghhhhhhj....horrible feedback. As it happens with both new arms (10" too) it must be a resonance somewhere, either the aluminium tubes or boxwood or something else maybe.

Very frustrating but I don't have the knowledge or equipment to test where the problem is. I'll just have to try some damping to see if I can tame it. The tubes are already filled with foam, the bearings have zero play - maybe it's the hard disk motors that seemed such a good idea.

Back to the drawing board then:(

https://farm9.staticflickr.com/8640/16729724586_a8e75744f9_o.jpg

[struth]

Maybe try mounting the base of bearing on sorbothane

[Gordon Steadman]

Maybe try mounting the base of bearing on sorbothane

Sounds a good idea. I was lying in bed thinking.....only place I can do it as normally, the energy it takes stops anything else working ....and by a process of elimination, it seems likely it is the tube. The same thing happened when I listened to the uni-pivot. I thought it was the bearing arrangement and changed it to bearings but the same thing happened. As it is the same for both the 10" and 12" arms, it has to be the tube I reckon.

First step is to damp the arm some more and then I'll try your solution.

[paskinn]

Do you need a more thorough solution? If the armtube is getting serious feedback then the whole deck is suffering from vibration. You surely need to isolate the whole thing. My suggestion would be a wooden base fitted with a few small inflatable tubes...which you can level to suit the mass of the deck. Or a simple wallshelf. All decks need good isolation because, at heart, they are vibration measuring machines.

[awkwardbydesign]

Well, the deck in the photo is sitting on a lovely resonant shelf, and the arm is on the end of a long resonant board, so I would look there, especially as you say the problem occurs when you turn the volume up.

[Gordon Steadman]

Well, the deck in the photo is sitting on a lovely resonant shelf, and the arm is on the end of a long resonant board, so I would look there, especially as you say the problem occurs when you turn the volume up.

The top of the cabinet is isolated from the main carcase. It sits on spiked feet into cups. Neither of the other decks show any sign of feedback. However it's fixt:) I just wrapped the arm tube in insulating tape:doh:

So it is now playing away at ear splitting levels and nary a sign of feedback!! It was the same no matter which deck I put the arms on. The test deck is a lump of old worktop and weighs a ton. I have now played the 12" arm on both the test deck and the OL and it is feedback free!!

Simple solutions for simple minds.

[Gordon Steadman]

I have just spent an entire day buggering about.

You might, if you knew me, think that was nothing unusual. However, I have been fiddling with a new arm that my brother in law has put together. He made the mechanism and I made the arm. It's a linear tracking arm. I can't show any pics yet as he seems convinced it has commercial possibilities. It may well have if only I can get the bloody thing to perform consistently.

It seems fantastically sensitive to minute adjustments. The BIG problem is......its the best sounding thing I have ever heard in my system. I always suspected that linear trackers would be the way to real high fidelity.

This thing has the most fantastic, tuneful and controlled bass I have ever heard. I very much prefer it to my OL modded Rega. So, tomorrow will no doubt be a continuing story. The sound it makes is well worth all the agro of sorting a prototype. Most of the time, it tracks beautifully but then hangs in one place and needs a nudge. It is frustratingly close but so often, a small adjustment is in the wrong direction.

So close but so far........:steam:

[struth]

No Pain, No Gain Gordon....Good luck;)

[Gordon Steadman]

The linear tracker has gone back to the UK for some more development work. It's so close but prototypes are always the source of some frustration no doubt.

To make myself feel better, I've fitted the 12" arm to the OL properly. Very good indeed, gives the OL Rega a very good run for its money indeed and is better in the bass. I'm waiting for some brass to come so I can make some proper balance weights, the old bolt stuck on the end doesn't do much for the aesthetics. It's ugly enough already what with the electrical tape stuck round it to damp the arm resonance.

https://farm8.staticflickr.com/7600/16211971713_a2150bd762_o.jpg

[awkwardbydesign]

The linear tracker has gone back to the UK for some more development work. It's so close but prototypes are always the source of some frustration no doubt.

To make myself feel better, I've fitted the 12" arm to the OL properly. Very good indeed, gives the OL Rega a very good run for its money indeed and is better in the bass. I'm waiting for some brass to come so I can make some proper balance weights, the old bolt stuck on the end doesn't do much for the aesthetics. It's ugly enough already what with the electrical tape stuck round it to damp the arm resonance.

Two possibilties for less ugliness. Heatshrink around the tube, or a balsa cross shaped inner damping piece (the 4 wires would run in the spaces). However both would require disassembly of the arm.

[Gordon Steadman]

Two possibilties for less ugliness. Heatshrink around the tube, or a balsa cross shaped inner damping piece (the 4 wires would run in the spaces). However both would require disassembly of the arm.

Disassembly is no problem. Everything is an interference fit apart from the headshell and the horizontal bearings which unbolt. May look at it if I can stop listening for a bit, All this playing the same track over and over to assess the effect of changes has left me a bit bereft.

[Gordon Steadman]

I've been sat transfixed most of the day. The more I listen to this 12"er, the better it gets. I'm almost coming to the conclusion that there is more difference in the ways the arm work than the way they are built (OK, within reason)

Apart from the JVC linear tracker, I now have one 9" - Rega RB250 with OL mods, one 10" and one 12" - home made and the linear tracker that we are developing. (I am ignoring the Dual1019 as all the other arms have been fitted to the same deck to compare them directly)

The Rega and my 10" sound very similar but are both beaten quite comprehensively by the longer arm. Our prototype sounds better still. The idea that the stylus should follow as near as possible to the cutting lathe just makes sense to me. Considering that the JVC is a lightweight plastic jobbie, that sounds not far short of the Rega.

So I reckon my future plans include a linear tracker as my main toy. If our prototype proves too difficult to get 100% reliable, it looks as though I will actually have to spend real folding money:eek:

What a terrible thought.

[struth]

Theoretically you should get lower distortion with the longer arm, if you get it set up correctly.But theory and practice are different babies. If your ears say it continues to sound better in a few weeks then it will remain that way. It's a great thing you've managed to achieve.

[Gordon Steadman]

I've just reduced the clutter around the Mac. Replacing all the boxes (Quad 34/303/FM4 and a Project headphone amp) is this 'ere NAD 7020. I swapped it for an original Arcam Alpha, Denon TU260 and quite a reasonable wedge of folding stuff. The woman that bought my Teufels has a terrible tremor and finds the manual tuning impossible so the Denon has solved that problem for her. As I used the Arcam when voicing the speakers, it seemed the obvious choice.

Makes life a lot easier for me without all the wires etc as well. I only listen casually at the Mac in the evenings and frees up the Quad stuff for somewhere more serious.

Soundwise, it's quite a surprise. Very good in general but a fraction bloated in the bass. Seems to be quite happy driving the KEF101s too.

Ronnie reckons I can afford to feed her something special tomorrow now. Have to see what I can get for 50 centimes.

[The Barbarian]

You need a 160.. :eyebrows:

[Gordon Steadman]

You need a 160.. :eyebrows:

Now that is pretty. What does the yew ball on the top do?

[Gordon Steadman]

Still experimenting with different lengths and pivot points.

This one is offset which means the stylus traces an arc which, in theory, is closer to a straight line than the usual arms, and that is with a straight headshell. It sounds very good but crucially, seems to create a more solid image, much like the parallel tracker. The horizontal bearing is just a push fit so needs the balance weight, which, I guess, would be necessary anyway to even out the load on the bearing.

I'll keep this one in reserve to develop in case our little problems with the new design of parallel tracker are beyond us - with my BIL's talents, I don't really expect that to be the case.

https://farm8.staticflickr.com/7285/16270131984_e4197d5ba9_o.jpg

https://farm9.staticflickr.com/8710/16891294372_7994782d00_o.jpg

[struth]

Heath would be proud Gordon

[Gordon Steadman]

Heath would be proud Gordon

Yeah, poor old Ted was into music:eyebrows:. Especially the organ of course, so he would have loved the bass on this arm.