[R] Long Speaker and Narrow Lens

A project log for T^2 TyMist [gd0138]

I need some virtual desktop monitors that offer 90PPD at 90Hz.

kelvinakelvinA 02/11/2023 at 22:200 Comments

Speaker system

I was able to find the speaker module I remembered seeing >1 year ago:

There's at least 2 similar speakers that are 85mm and 90mm long, but it seems that this one should fit in the space provided. This 80mm speaker doesn't say, but the other speakers all have a thickness of 12mm so I'm going to assume the same for this speaker. The reviews I was able to scan across listings say that this speaker is "as good as the original", and since these are for Samsung TV's, I'd assume that they're actually pretty good.

If I recall correctly, reproduction of bass frequencies require a good amount of air movement, which can be obtained by a higher cone surface area or higher excursion. It looks like this speaker has both, looking at these video:

For reference, the below speaker looks like the 53mm speaker I found when I first did audio research, and the excursion is drastically less:

It also looks nicer and higher quality. I know the aesthetic of the speaker is of little importance, but it's something I wanted to mention. It just feels like using higher quality ingredients.

I also would like to believe a full-length speaker cone would emulate spacial sounds more accurately than a smaller one.

Audio wavefront passing over hear when: Left - Small / point source,  Middle - Everyday objects, Right - Long speaker

This is the speaker (or one of its similar derivatives) in their enclosures and it sounds like it rip 'n' chews (it sounds good). The test songs are nice because I can hear the response across the enitre range, from bass beats to vocals to violin strums:

Yeah... ok... I know how I said I don't care that much about audio quality in the previous audio log but that was just me trying (and failing) to reduce my expectations. I do need some quality, just perhaps not enthusiast grade. 

Eye tracking system

On the eyetracking side of this project, I think I've found a very good lens for this applicaiton:

As long as the lens MP rating exceeds that of the sensor, I shouldn't run into problems. I believe something like a 16mm lens is ideal for this application because I can just have 2 mirrors inside a tube (see below) and there's less of a chance of the camera picking up the tube walls or the two images having unusably different focus levels (because the light path is longer on one).
I've also found an IR led that looks a lot like the EyeTrackVR recommended one.
This one is rated for 20mA whereas the recommended one is 30mA, so I should be in safe radiation levels.

Exciting stuff!