DIY linear tonearm

Springs - we're probably getting old, dear friends
This is also an already discussed topic
#5314 ... i made an attempt on LC1 (on Walter advice),

Look at #2441 -Walter advice - and #2448-2452 drawings+test mockup - my attempt on the B version of Lil Casey at #2470. (+ comments)
c
Quote all you say friend Doug, not only becoming old, but maybe stoned
Blue tape? interesting hint...
 
This is a plot of pink noise from the Ultimate Analog test LP so the plot is not flat because it's raw with the 3dB/oct fall. Y
@warrjon
Just a heads up. The side 2 pink noise tracks on the Ultimate Analog Test LP are unreliable. There is a 5 dB dip in the region below 1 kHz. This will not be of concern with the demonstration of the effect of capacitance on the HF peak, but makes the tracks useless for checking overall FR flatness.

https://www.diyaudio.com/community/...est-lp-aapt-1-vs-hfn-001.303100/#post-6089468
 
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Blue painters tape, I couldn't live without it. It gets used for all sorts of markups and scratch prevention when machining. it also comes in various widths.
I need a technical answer please, is there a difference between the blue painters tape and the green type i use?
If there is, and it warrants it, i will seek out the blue variety, otherwise you will soon see some green painters tape in my constructions, its sure to enhance the sound.

By the way, the variety i have here is Frog tape which i believe will resonate with some builders.

Electrical tape came to hand when wishing to make these modifications temporarily.
And that's become rather useful as so far it doesn't work properly! - maybe i used the wrong width tape.
Components are on order to try to get back on track........
M
 
For some of you who may not have enough to do, please have a look below at my latest iteration.
It has a new lighter carriage, carbon crossmembers and lighter rear carriage rail, shortened also to remove unnecessary rail length.
It is now playing with the cartridge wires directly into my phono pre, neatly taped to its stand!
I always admire other posters construction standards!
It played its first side while i typed this up, all went well.
Auto suggestion kicks in here and tells me it sounds better.
Anything that takes a few days to make must sound better, mustn't it?
Sether may notice this has allowed removal of the front ballast weight, because of the lighter back end.
Horizontal and total mass are over 5gms lighter.
I cannot pretend i expected an audible difference, but very clean bass lines and tunefulness, clear top end are noticeable to me.
I will do some measurements at some point.
This will also allow me (eventually!) to lower the CW arm which will remove a small rising VTF in warp, a couple of 10ths in 5mm of warp, totally irrelevant (imho) in real life but i will do it anyway!
M
Sorry Mike, for some reason I’m not getting this thread pushed to my email anymore. Your new iteration looks excellent I like your design a lot. I glad you posted images of the parallelogram CW mock up as I was intrigued by this from your video a while back. Also, all the information recently about wiring will be invaluable soon as I’m close to getting something which resembles a LTA! Regarding the capacitors mentioned in the RCA leads/DIP box, forgive my ignorance but do these have to be ‘audio’ grade as in the case when I build crossovers?
I also attach progress to the sapphire wheels
S.
 

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Hi again Sether, good to see your progress as well.
I have been advised to look for good quality caps with various recommendations including polypropylene which are on order.
The amp designer says;
G0G/ NP0 ceramic are one of the best you'll get. Some people like silvered mica or polystyrene, but you won't hear a difference.
I will update if i make progress!
M
 
I spent some time over the past few days experimenting with loading. Here are the results. I guess the point of this post is to demonstrate you need to verify results as most of these test LP's have some error and quantifying this error as best we can is key to verifiable results. The uncertainty is still quite large because we have no verifiable reference.

Test LP's used
HFN Pink Noise L then R channels modulated
AP Vertical Pink Noise
Vinyl Check Frequency Response sweep 20Hz to 20kHz used to verify cartridge FR, results not shown as I only wrote them on a bit of paper.

None of the Pink Noise tracks were perfectly flat when compared to the VC Frequency sweep. The VC showed FR between 600Hz and 4kHz varied less than 2dB. Which correlates well with the HFN Pink Noise above 1kHz but the AP is off. Note that there was a difference in FR between channels above 4kHz using the HFN which is the tracks on the LP as there was less than 0.5dB difference in levels using the sweep, and there was no difference using the AP vertical Pink Noise.

These are identical loading showing the Left Channel, the only difference is the LP. The tracks are vertically modulated so I would expect the plots to roll off at about 300Hz. But here we're looking at cartridge loading so we're only interested in the plot above 1kHz.

AP test LP
1006.jpg 1007.jpg

HFN Test LP
1009.jpg 1008.jpg
 
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"The tracks are vertically modulated so I would expect the plots to roll off at about 300Hz. But here we're looking at cartridge loading so we're only interested in the plot above 1kHz."

I assume this is below 300Hz Warren, as one can see in the plots, for interest why does vertical modulation do that please?
M
Plots are intriguing, do you also hear the differences in those results clearly?
 
Hi Warren, no that first picture is just me roughing out the wheel and checking for flat spots. Total mass 1.395g before shaping and polishing. I’ve got the wheels as circular as possible with my equipment and surface polished to 0.1 microns, the same process as with the TC rails. They’re not on the axle/hubs yet as need to make a centring jig as per niffy’s instructions.
S.
 
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