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The Wonders of a USB Microscope

P

Phack

New Member
I was hearing some sibilance in my beloved and $$ AT150MLX after only a few months of use. I borrowed a jewelers loupe but it wasnt high enough magnification. I found this on deal extreme and a few weeks later (today) it arrived. http://www.dealextreme.com/p/digimicro-200x-zooming-usb-digital-microscope-11743

After learning how to use it I was relieved to find out that my AT150 was in fact fine. I also was able to fix some pretty serious setup issues with my Grado that I have been using as a backup. For starters, I was able to measure the stylus rake angle with the included software and it showed my I was quite a bit off. I had previously tried to eyeball a level tonearm but I needed to raise it almost a full turn (I have an SL-1200 so it was simple) to bring the point of the stylus perpendicular to the record. I have to say the improvement is quite dramatic! I recommend picking one of these up for how cheap they are and quit guessing!

Here are some pictures I took

At150MLX

at6-4-12.jpg


Grado Blue

grado6-4-12.jpg


SRA measurement. Reads 90.57.

gradosra.jpg
 
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see, eyeballing that stylus, I'd have said it was way high in the back. Apparently the tip isnt mounted quite perpendicular to the cantilever. Kind of cool that the scope comes with software to actually give you the angle so you know its correct.
 
I've been thinking about buying one of these to examine albums with although it may be too much. I just ordered a loupe so I can take a good look at the grooves, attempt to smooth out skips, find other damage.

Thanks for the pictures, they came out very nice. I'm going to consider picking up one of these, especially at that price.
 
There's a 'fancier' one on the 'Gon for $500! I'm sure it's not much better than this one!


Ben aka MacKat
 
that thing is pretty cool, think I'll get one.

BTW I assume you did not use the first view there to determine stylus wear on the AT 150mlx.
 
kirk57 said:
that thing is pretty cool, think I'll get one.

BTW I assume you did not use the first view there to determine stylus wear on the AT 150mlx.
Click to expand...

USB microscope is nice tool, but it is not useful to see stylus wear. The best (out of cheap ones) has 200x magnification, which is not enough for that purpose. But it can be use for other purposes. It is fun for kids too (if you have them) - they like to explore things using it.
 
for_p1 said:
USB microscope is nice tool, but it is not useful to see stylus wear. The best (out of cheap ones) has 200x magnification, which is not enough for that purpose. But it can be use for other purposes. It is fun for kids too (if you have them) - they like to explore things using it.
Click to expand...

Agreed. I built a stylus scope from the Sparky's sticky on this forum, and it works great for determining stylus wear, but can't do some of the things this USB scope does.

Guess I need both!
 
Contrary to that thread, it is quite possible to gauge wear, albeit fairly coarsely, with a 200X digital scope. With the stylus in the correct orientation and sidelit properly, the flats are very apparent from the light reflected by them.

Well worn:
attachment.php


Fresh:
attachment.php


Even with low resolution, coarse differences in size and shape of the reflected spots is apparent. The setup is very useful to get a gauge of the stylus condition of cartridges with unknown history.
 
mackat said:
You want the SRA at 92º exactly.


Ben aka MacKat
Click to expand...
This is the target, but I'm finding it's a little tricky to set up statically. Ideally, you want to measure the SRA under real conditions when the record is turning. Unfortunately, at a magnification close enough to measure the angle the image is hopelessly blurred.

What might work (though I haven't tried it yet) is to measure the SRA with respect to the cantilever up close, then measure the cantilever VTA from a great enough distance that focussing becomes less of an issue.

The success of setting up the SRA statically, as depicted here, seems to depend on the static compliance of the cantilever suspension. My first trial with a 10x5 produced an amazing increase in midrange detail, along with a more natural timbre and a more solid bottom end. The same approach with a Benz Wood L2 didn't work at all, just made the cart sound muddy. The 10x5 has a stiffer suspension than the Wood, as measured using a LF response sweep off a test record.

I would say if the cart is very high compliance, this approach to setting SRA may not be successful.
 
ripblade said:
This is the target, but I'm finding it's a little tricky to set up statically. Ideally, you want to measure the SRA under real conditions when the record is turning. Unfortunately, at a magnification close enough to measure the angle the image is hopelessly blurred.

What might work (though I haven't tried it yet) is to measure the SRA with respect to the cantilever up close, then measure the cantilever VTA from a great enough distance that focussing becomes less of an issue.

The success of setting up the SRA statically, as depicted here, seems to depend on the static compliance of the cantilever suspension. My first trial with a 10x5 produced an amazing increase in midrange detail, along with a more natural timbre and a more solid bottom end. The same approach with a Benz Wood L2 didn't work at all, just made the cart sound muddy. The 10x5 has a stiffer suspension than the Wood, as measured using a LF response sweep off a test record.

I would say if the cart is very high compliance, this approach to setting SRA may not be successful.
Click to expand...

Wasn't aware 92 degrees was actually the target. It sounds so good at the current setting I'm afraid to touch it again. I can understand what you mean about dynamic vs. static SRA settings. Fortunately, the Grado is pretty low compliance (at least in comparison to my AT150MLX). It might only ever be possible to be +/-1 degree or so at best since the suspension flex will vary the SRA as it transits the groove on its journey around the record.
 
Phack said:
Wasn't aware 92 degrees was actually the target. It sounds so good at the current setting I'm afraid to touch it again. I can understand what you mean about dynamic vs. static SRA settings. Fortunately, the Grado is pretty low compliance (at least in comparison to my AT150MLX). It might only ever be possible to be +/-1 degree or so at best since the suspension flex will vary the SRA as it transits the groove on its journey around the record.
Click to expand...
If it sounds good, it is good.

Yes, the VTA (and thus SRA) is continually in flux, that's why it's very difficult to measure while in motion. I thought a video might work (the USB scope has video capture as well) but how to average the angles presented in all frames? Never mind that, but how to measure (productively) the angle in each frame??

What we hear is truly an average, but the brain seems content with that. I'm content to leave it at that, too. At the end of the day, it only has to sound good.
 
for_p1 said:
USB microscope is nice tool, but it is not useful to see stylus wear. The best (out of cheap ones) has 200x magnification, which is not enough for that purpose. But it can be use for other purposes. It is fun for kids too (if you have them) - they like to explore things using it.
Click to expand...

HI for p1,
Actually, 200X is ideal for checking stylus wear as is presented in my sticky "Sparkys Fabulous DIY Stylus Microscope". The main problem with USB microscopes is the lighting. And most of them do not have sufficient magnification and optical quality. If you can solve that problem the USB microscope will be a useful tool. I have never seen one that has solved the lighting problem.

Most (all?) of the USB microscopes I have seen are useful only as toys and not serious tools.

Sparky
 
Karma16 said:
HI for p1,
Actually, 200X is ideal for checking stylus wear as is presented in my sticky "Sparkys Fabulous DIY Stylus Microscope". The main problem with USB microscopes is the lighting. And most of them do not have sufficient magnification and optical quality. If you can solve that problem the USB microscope will be a useful tool. I have never seen one that has solved the lighting problem.

Most (all?) of the USB microscopes I have seen are useful only as toys and not serious tools.

Sparky
Click to expand...
Though your thread was an inspiration and light that guided me through my own diy stylus m'scope, I must take issue with that last statement. The USB scopes are crude but effective at examining VTA (or SRA) as well as azimuth. Neither can be done with a quality optical m'scope.

Agreed on the lighting, but a sheet of paper placed in behind the object does help with the exposure.
 

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  • Benz Wood L2 SRA.jpg
    Benz Wood L2 SRA.jpg
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^ That one looks fine.

The main issue with these scopes is how the stand connects the unit...this one looks about right. The one I have has a sleeve that allows one to rotate the scope, unfortunately in some positions it interferes with the focussing wheel.

The other necessity is for the clear shroud around the led lights to be removeable. This is needed in order to get the objective close enough to the stylus. Don't know if this one will allow that easily...some are glued on and must be cut...mine just slips right off.

Other useful accessories include a decent camera tripod and 4 way focussing rail.
 
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