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-   -   DIY parallel tracker air arm - another one (http://www.diyaudio.com/forums/analogue-source/157206-diy-parallel-tracker-air-arm-another-one.html)

Speedysteve7 22nd December 2009 09:54 PM

DIY parallel tracker air arm - another one
 
It started out as MkI as proof of concept.

http://inlinethumb60.webshots.com/42...600x600Q85.jpg

http://inlinethumb62.webshots.com/43...600x600Q85.jpg

it did work reliably but did not sound too brilliant - not surprising really.

Then I got a Terminator home and was using it and thought - naaa I could make one of those.

Here's my Terminator copy. Spent some time making this out of the right materials and it sounded as good as a borrowed Terminator arm I tried.

Here it is early on with a headshell made out of a door bolt

http://inlinethumb21.webshots.com/43...600x600Q85.jpg

Then some more work on a headshell from billet aluminium

http://inlinethumb63.webshots.com/35...600x600Q85.jpg

http://inlinethumb41.webshots.com/29...600x600Q85.jpg

http://inlinethumb12.webshots.com/43...600x600Q85.jpg

http://inlinethumb41.webshots.com/43...600x600Q85.jpg

I even put it on my PL-71 - sounded good but looks kind of wrong IMO

http://inlinethumb12.webshots.com/44...600x600Q85.jpg

It was a fun project but I use the PL-71 arm and mat on a modded Technics SL-1210 deck as my normal use set-up. I just love that arm and that decks locked on precision...

marekst 23rd December 2009 11:56 AM

Great work, congrats!
I always admired this kind of tonearms, but my room is so quiet I can hear silverfish fornicating in the records’ sleeves so the slightest hiss would drive me nuts.
Marek

Holger Barske 23rd December 2009 12:07 PM

Very nice work!
I sometimes wonder why we do not see more Ladergaard tonearms around, the concept is simple and works really well.
One thing about your headshell: It seems to be really heavy, and this will result in high effective mass. You will have to mount a really stiff cartridge.

Speedysteve7 23rd December 2009 01:02 PM

Quote:

Originally Posted by marekst (Post 2022304)
Great work, congrats!
I always admired this kind of tonearms, but my room is so quiet I can hear silverfish fornicating in the recordsí sleeves so the slightest hiss would drive me nuts.
Marek

The hiss is pretty quiet. I had more problems with the fish tank air pump.
Even in the cupboard under the stairs (adjacent to the lounge) it disturbed me.

I build a 18mm thick MDF box with foam and carpet tile lining and 5 6mm drill holes for air in - that shut it up completely.

Speedysteve7 23rd December 2009 01:06 PM

Quote:

Originally Posted by Holger Barske (Post 2022311)
Very nice work!
I sometimes wonder why we do not see more Ladergaard tonearms around, the concept is simple and works really well.
Once set up it stayed in trim very well.

One thing about your headshell: It seems to be really heavy, and this will result in high effective mass. You will have to mount a really stiff cartridge.

it does work well - easy to see where you are in a record from the chair too!

The headshell is pretty small really.
The Terminator shell has two large screw in brass grubs to allow massing up for lower compliance carts and an extra counter weight.

I only used my arm on the AT 33 PTG which is med to high compliance and it worked fine. With the SPU Royal N I now have I would need to mass up both the headshell and counter weight and the carriage. As you can see from some of the pics I have an extra bit of ali angle on top - that improved the bass.
Something to play around with to get right.

livemusic 24th December 2009 09:53 AM

Air hiss
 
"...slightest hiss would drive me nuts"

Audible pump noise and air hiss is the only one part of the problem (more or less manageable). Do a simple test with your air tracker:
1. Lower the cart on static (non-rotating) record,
2. Turn the pump off.
3. Crank your pre-amp all the way up (let's ignore electronic hum and buzz).
4. Swith on the pump.
What do you hear?
The air flow couples considerable noise source straight to the arm slider, degrading weak signal, even if the hiss itself is non-audible.
This is one of the major drawbacks of Ladegaard design.

Geosto 24th December 2009 03:31 PM

Hi Speedsteve7,

That is a very nice Terminator style tonearm.
Can you post some pics from your air supply?
I have Build myself a Terminator style arm bud i still have trouble make the air supply quiet.
Now it is in a room next to my listening room.
Here you can see mine creation http://www.diyaudio.com/forums/analo...ml#post1882753

Regards George

Speedysteve7 27th December 2009 11:22 AM

Quote:

Originally Posted by Geosto (Post 2023627)
Hi Speedsteve7,

That is a very nice Terminator style tonearm.
Can you post some pics from your air supply?
I have Build myself a Terminator style arm bud i still have trouble make the air supply quiet.
Now it is in a room next to my listening room.
Here you can see mine creation http://www.diyaudio.com/forums/analo...ml#post1882753

Regards George

Hi,
Been away a few days - These are pics taken from the cupboard under the stairs. I forgot I even put the box on Foculpod feet but an felt or wadding would do.

http://inlinethumb28.webshots.com/43...600x600Q85.jpg
http://inlinethumb23.webshots.com/45...600x600Q85.jpg

The box is jsut 18mm MDF lined with 10 or 15mm sheet foam and then that is lined with carpet tiles cut to fit (carpet side facing inwards).

The pump is here

http://inlinethumb09.webshots.com/39...600x600Q85.jpg

How poeple with fish tanks would put up with something like this in their living room (or any other room) is beyond me - says Quiet operation on the box - yeah right!

Anyway the box completely shuts it up - you strain to here it in the confined space of the cupboard - no way it would disturb the music or between tracks if I mounted it behind the hifi.

Forgot to say George; that is a very nicely made arm. I'd have to do some polishing to catch up there.
Mine is made of B&Q (hardware store) building brackets - no nice solid riser like yours.
You have mounted it very far forward. On my SL-1210 I have a Rega arm board adapter. On the Pioneer it is farther forward and sounds better for it.
The shorter the wand the better I think.

I used a carbon fibre Kite spar/rod for the wand.

I have not considered putting the SPU Royal N on my air arm yet - would need to mass up the headshell and the counterweight too (easy enough). The carriage - just add ali angle strips till it sounds best. I would make another arm board (trust 1/2" ply) I think to get the wand shorter too.

Have days spare now - might try it all and see how it sounds.

Geosto 28th December 2009 06:22 PM

Hi Speedysteve7,

Thanks for the pic's.
I think i would make a box to.
The noise in the room were the pump is located is now is not pleasant.

I use a carbon fiber wand also bud the head shell comes from an old AKAI turntable.
If you are making a new wand you may try this to.
Because of the weight from the tonearm wires the pressure on the tip of the needle was not stable.
I did solve that by drilling a hole behind the hinge.
http://i246.photobucket.com/albums/g...o/P1040119.jpg

Regards George

tinitus 28th December 2009 06:36 PM

Regarding air noise
It helps to have a small "buffer" airbox, filled with light acoustic material, like a muffler on a car
Also gives a more smooth airflow
One major problem is to get all connections 100% airtight, not to loose pressure


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