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Old 6th Jun 2015, 8:51 am   #1
Bobdger
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Default Wireless World Uni-pivot pickup arm design

I am looking for a photocopy or scan of this original uni-pivot pick up arm article. This was when I was at tech in the 1970s. I think the design, with full dimensions and build notes was spread out over a few months.

Did any one build one of these pick up arms?.

Thanks Bob.
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Old 6th Jun 2015, 9:17 am   #2
Radio Wrangler
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Default Re: Wireless World Uni-pivot pickup arm design

No, but I thought about it at the time.

There's a useful listing on DIY arms at

http://www.audioasylum.com/cgi/t.mpl?f=vinyl&m=33675

but I don't see a wireless world unipivot of around the time I thought it was. The arm on sale at that time was the Keith Monks one.

David
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Old 6th Jun 2015, 7:11 pm   #3
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Default Re: Wireless World Uni-pivot pickup arm design

Would this be the one also published in the Wireless World High fidelity designs published in 1974? If so I can scan it.

If it was originally published in WW after 1970 I've probably got the article(s) but they are currently buried under a pile of stuff awaiting sorting out. if I can summon up the courage to sort the stuff I'll see if I can find the article.

Keith
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Old 6th Jun 2015, 10:21 pm   #4
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Default Re: Wireless World Uni-pivot pickup arm design

Hello,

Was this the unipivot arm design by R. Ockleshaw from the November 1971 Wireless Word? If so I have it at hand as I was only last week I looking through it, not for the arm design, but for the PLL Wow and Flutter meter that appeared in the final article of a series of three articles showing the construction of the arm, turntable and finally the Wow and Flutter meter to check the completed turntable.

Terry.
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Old 6th Jun 2015, 11:00 pm   #5
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Default Re: Wireless World Uni-pivot pickup arm design

I thought it might be that Terry but didn't post as David had put up the same list at p2*' ie 11/16/17. The date is a close match!
Dave w
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Old 7th Jun 2015, 10:16 am   #6
Valvepower
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Default Re: Wireless World Uni-pivot pickup arm design

Yes, Dave it’s a match as the articles I have here ran Oct, Nov & Dec 1971 and match the ones in the list in Davids (Radio Wrangler) post.

I was going to scan the Wow & Flutter article for archiving anyway this is as my WW’s are falling apart! And whilst I’m at it I’ll scan the other two articles and put the whole kit and caboodle on the forum.

Terry.
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Old 7th Jun 2015, 11:29 am   #7
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Default Re: Wireless World Uni-pivot pickup arm design

Hello,

Was this the unipivot arm design by R. Ockleshaw from the November 1971 Wireless Word? If so I have it at hand as I was only last week I looking through it, not for the arm design, but for the PLL Wow and Flutter meter that appeared in the final article of a series of three articles showing the construction of the arm, turntable and finally the Wow and Flutter meter to check the completed turntable.

Terry.

That's the articles please can you send me a scan. Many thanks Bob.
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Old 7th Jun 2015, 2:53 pm   #8
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Default Re: Wireless World Uni-pivot pickup arm design

Hi Bob,

I’ve scanned and up loaded the three articles on the Arm, Turntable and Wow and Flutter meter.

I does make very interesting reading, with a great combination of theoretical and practical design, the likes of, which you just don’t see anymore.

At a tangent and for a bit of fun I’ve also scanned the front cover of the December copy, which shows the Sony Trinitron CRT – just because liked the cover. It’s hard to believe its 44 years old though.

Regards
Terry
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File Type: pdf W_and_F_WW_12_71.pdf (363.0 KB, 432 views)
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Old 7th Jun 2015, 5:27 pm   #9
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Default Re: Wireless World Uni-pivot pickup arm design

The arm seems to have conventional pitch and yaw bearings and isn't a unipivot.

The wow and flutter meter is based on some Motorola TTL-based PLL chips from the end of the sixties. They might be hard to get now.

David
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Old 7th Jun 2015, 5:46 pm   #10
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Default Re: Wireless World Uni-pivot pickup arm design

Hello,

Yes, the Motorola parts are long gone. I recon I’d have a crack at using the CD4046 with a bit of redesign - thats if I decide to use the circuit though.

Terry.
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Old 8th Jun 2015, 7:39 am   #11
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Default Re: Wireless World Uni-pivot pickup arm design

Thank you Terry,

The arm as I remember it was on a single pivot using a 78 needle as the pivot. still looking for this information.

Bob.
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Old 8th Jun 2015, 8:33 am   #12
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Default Re: Wireless World Uni-pivot pickup arm design

A pivot and an arm/headshell shouldn't be hard to make.

The fun comes in arranging a damper for the pendulum-mode swinging of the arm on the pivot point, which skews the stylus off-vertical. The usual method was to dangle a downward extension of the pivot cup into a pot of viscous fluid (silicone oil)

The second instalment of fun comes in mounting the counterbalance weight via a lossy elastomer to damp the resonance of the arm's moment of inertia versus the compliance of the cartridge.

The hardest bit is arranging an adjustable amount of anti-skating torque. KMAL used a pair of magnets. Strings and things tend to skew the arm unless very carefully arranged. Anti skating was arranged to increase with decreasing groove diameter.

Whichever way you do it, there's a lot of work in making a useable arm, the alternative I suppose is spoiled by the prices original 3009s fetch nowadays, though the Acos Lustre is also a good arm without the boosted price.

David
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Old 13th Jul 2021, 11:57 am   #13
Dennis W
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Default Re: Wireless World Uni-pivot pickup arm design

I made the WW Unipoise Tone arm in 1971/72

I have a pic of it but unfortunately dont have it.

Their was an error in plans and WW contacted the Author who sent details. He said there had been no other queries so thought I was the only one to make it.
I actually made seven its a long story.
Arm worked perfectly. used it for at least 10 years. then moved house and it got lost in transit!

If anyone wants a pic I can send it if someone tells me how

Regards

Dennis
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Old 13th Jul 2021, 12:04 pm   #14
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Default Re: Wireless World Uni-pivot pickup arm design

There is an excellent guide to posting pictures in the forum here:

https://www.vintage-radio.net/forum/...ad.php?t=77650

Cheers

Mike T
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Old 20th Jul 2021, 2:58 pm   #15
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Default Re: Wireless World Uni-pivot pickup arm design

If I recall correctly the Wright article listed was the one the Audio & Design Unipivot is based on and it was sold by Keith Monks. Arm is MBA-1 I think but i would have to open the box it has mercury bottle this is used for the arm lead contacts its virtually frictionless.

The A & D arm is rated, I think by about 1972-3 they stopped making the arm. Vinyl engine would elicit the information.

I have the arm boxed with all the instructions, mercury I need to make an arm board up for one of my Fons CQ30 turntables to mount it....on.....another one of my projects....on the to do list.....American Broadcast history has the Wireless World magazines on it.....if you use the link to Audio Asylum.....you can find most of the articles listed......
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Old 20th Jul 2021, 8:59 pm   #16
Ted Kendall
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Default Re: Wireless World Uni-pivot pickup arm design

Why not go the whole hog and run it through Ionofane tweeters?
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Old 22nd Jul 2021, 9:01 pm   #17
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Default Re: Wireless World Uni-pivot pickup arm design

This is my take on a unipivot arm. The parts are made from scrap in the "parts bin". Not pretty but it works.
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Old 22nd Jul 2021, 9:10 pm   #18
Stevie342000
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Default Re: Wireless World Uni-pivot pickup arm design

Quote:
Originally Posted by Ted Kendall View Post
Why not go the whole hog and run it through Ionofane tweeters?
Ah well that is simple to answer I have some Dynastatic speakers with a Shackman electrostatic in them so I have no need for added ozone living close to the city centre, pollution in the air is bad enough....besides is that not the one with Quartz crystal in, not like you can get those in Lidl or anywhere else...
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Old 22nd Jul 2021, 10:13 pm   #19
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Default Re: Wireless World Uni-pivot pickup arm design

I seem to remember there were also some ion-based tweeters that needed an argon supply. Avoids the nasty ozone by replacing it with an asphyxiant. They didn't catch on.

David
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Old 26th Jul 2021, 9:29 am   #20
Electronpusher0
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Default Re: Wireless World Uni-pivot pickup arm design

Back to Bobdgers OP the Unipivot design was published in WW 1966 Jan and Feb.
Attached.

Peter
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File Type: pdf Wireless-World-Unipivot-pt2.pdf (415.0 KB, 58 views)
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