The Scratch-o-Meter

[Wodan]

Ladies and Gentlemen!

I present my latest innovation. The scratch-o-meter!

Inspired by something Chyros did in one of his smoothness propaganda videos, I thought there must be a way to get audio recording that capture the scratchyness of a switch in a very distinctive way. Since I have a very nice&tight steel plate laying around that I got from a faulty delivery, I thought that spare plate would be the perfect base for such an acoustig experiment. I also ordered a cheap pin-on microphone and started some experiments. My first attempt was to press the microphone against the plate and capture the plate resonance. This didn't work out too well. Instead, I put some DSA PBT keycaps (identical) on all switches and started pressing the switches with the microphone. This would give me a great coupling between the stem/keycap and the microphone thus getting me very close to the actual point where scratchiness is experienced. I found out that adding a little bit of foam rubber around the tip of the microphone actually improves the capture quality and most importantly gives the most consistend results.

Here's my current setup:


Here's the old, plate mounted setup:

Spoiler:

And here's the first audio result that I felt was good enough to share it with you all:
What you are hearing is:
3x Gateron Red
3x Cherry MX Red
3x Lubed MX Black
3x Vintage MX Black
3x Nixie
3x Gateron Blue
http://picosong.com/zPPJ/

There is no doubt that the Gateron Red switch is the smoothest of them all from the recording and the MX Red is the scratchiest. It help jumping back and forth between switches to hear the difference. And it helps even more looking at the ware forms
The three MX Black variants all feel very similair. I believe the vingate Black and the Nixie both need some cleaning.

My ideas for future comparisions are:

- Switch cleaning before/after
- Compare MX Black variants
- Gateron vs Cherry
- Parts-swapping between Gateron Red and MX Red to see what makes the Gateron so smooth

Hope you like it

[Chyros]

Awesome! Yeah, I think audio recordings can really help with identifying switch scratchiness . The recordings you put out here are really muffled though, it sounds almost like background ambient noise xD . Is there a way to make the sound louder and sharper? Maybe press it faster or leave out the foam? Especially with regards to Cherry MX and their myriad clones, I think a side-by-side noise comparison like this could be very useful for people to get an indication of relative levels of smoothness, because it's REALLY hard to quantify smoothness numerically.

[Wodan]

Try to open the audio file in a program like Audacity which displays the wave form. The hight and density of the wave form have a direct relation to the scratchyness of the switch.



Without the foam, there is too much distortion created from contact between the microphone and the rough keycap surface. Maybe I can try this on relegendable caps with no top for the smoothest possible surface ... ?

But yeah this foam actually gives the most distinguishable wave forms. I even tried thinner and thicker foam and they both don't work as well The foam also has to cover the full microphone otherwise you do get ambient sounds

[Chyros]

Yeah, the waveforms in my Cherry tests in the videos are HUGELY different as well, almost laughably so. I'll see if I still have the files lying around so I can make a picture xD .

[Wodan]

Bonus switch sound recording:
http://picosong.com/zP4y/

[ohaimark]

There is a better way to do this.

Look into piezoelectric pickups. They'll give you much cleaner waveforms from the steel plate.

I know this because I have one rigged up already.

[Wodan]

The pickups I was getting from the plate were all very similair. It's the wrong end of the "device" i guess and the switch bottoms just don't expecience the scratchiness as much.

I did order one of these acoustic couplers for guitars and will try to attach it to a keycap

[ohaimark]

I mean one of these, Wodan. They translate vibrations from solid surfaces to sound much more efficiently and effectively than typical microphone elements.

[Wodan]

Mhmh ... I got something similair to that but I still prefer the results from my modified pin-on microphone.

Did experiment with that a little more. Now I'm using relegendable Cherry keycaps with no tops so I get a completely blank surface. This has made the measurements a little more consistent. Then I tried to go a little deeper into audio waveform analysis and found a great tool that helped me visualize what I identified as "scratch" in the recordings. Generally speaking, the scratch would show as a tight waveform with a medium altitude. Sounds from the keycap contact, the bottoming out and the keycap "snap back" upon release gave much higher altitudes. But in between those three high altitudes (contact, bottom, release) there you can find the "scratch".

My first example is the archetype of a scratchy switch: Brand new Cherry MX RED:

You can clearly see how the waveform between the three high-altitude waves is very volatile. I am using some kind of filter that - so I figured - visualizes the unrest in a waveform. This makes the difference to the next switch - the mother of smoothness in MX clones - a Gateron Red switch:

You can see that there still is a little bit of unrest between the three high altitude waves but it is much less volatile.

I feel like this is a very nice way to visualize switch scratchyness. I haven't tweaked all the parameters yet but please let me know what you think.

[Wodan]

Did some more sound analysis of linear switches - mainly for the purpose of looking for the magic behind the smoothness of Gateron Red switches (and probably other Gateron switches)

Here's the wave form of three Gateron Red switches:


Compare this to three brand new stock Cherry MX Red switches:


Now I have tried a few different things to make sure neither of the switches are lubed. Put the complere switch assemblies into the ultrasound cleaner and used compressed air to dry them again. That did no affect the wave forms at all.

Next step was swapping integral parts to see how this affects the wave forms. Just looking at the sliders and running my finger nail down the little slope of the slider that triggers the crosspoint contacts clearly shows that Gateron is using a smoother material for their sliders.I was expecting the Gateron Red switch with the MX Red slider to give me the "scratchy" MX Red wave form and the Cherry MX Red switch with the Gateron Red slider to give me the "smooth" Gateron Red wave form. Here's what I got:

This perfectly captures how identical both switches felt after the slider-swap. Neither had the divine smoothness of a Gateron Red switch but both switches felt pretty damn smooth - "Vintage Black" smooth would be the best way to describe it.

How can a scratchy MX Red slider feel and "sound" pretty smooth in a Gateron switch and why does the super smooth Gateron Red slider feel a little less smooth in the Cherry MX switch?

My theory is that there is a difference in the construction of the Crosspoint contacts inside the switch housing. The friction between those crosspoint contacts and the slider slope are the prime source of scratchyness in any MX based switch. If those crosspoint contacts press against the slider with more force/firmness, the impression of scratchyness is further increased. Applying only light pressure on the slider will make the switch feel smoother.

The Gateron switch has a weaker/thinner/softer crosspoint contact construction - that's the only explanation I can come up with. This would explain why a rought Cherry slider feels much smoother in a Gateron switch and why a smooth Gateron slider feels a little less smooth in a Cherry switch.

Based on this theory, I will do futher research into the "break in" effect many Cherry MX users report. Is this effect caused by smoothing the slopes on the sliders or by wearing out the crosspoint contacts? Hopefully I can soon find out Got some badly abused Tipros that I can retrieve some butter smooth non-Vintage MX Blacks from.

Oh yeah here's some more to look at. I took three Gateron Red switches and three MX Red switches and gave each a MX Red, Gateron Red and Vintage Black slider for comparison:

Here you see three different sliders in three Gateron Red switches. From left to right:
MX Red, Gateron Red, Vintage Black
You can clearly see that while the Gateron Red slider in the center is the smoothest, the other two sliders are pretty damn close. Hard to feel a difference here!


Same exercise in Cherry MX Red switches. This time from left to right:
Gateron Red, MX Red, Vintage Black
All the sliders show clearly more scratch than in the Gateron Switch. The Gateron slider is the smoothest, followed by the Vintag Black leaving behind the MX Red slider as the scratchiest. I was expecting more smoothness from the Vintage Black slider since it felt much more like the Gateron Red slider but it doesn't quite deliver identical results. Will do more experiments with Vintage MX sliders vs. Gateron sliders.

As a result of this, I draw the conclusion that Gateron is making the smoothest sliders I tested here. On the other hand, the crosspoint contacts of Gateron switches seem to be weaker than the ones Cherry makes. Since we don't have any long-term observations with Gateron switches, it is difficult to tell what effect that has on the lifetime expectations of Gateron switches. I highly doubt the weaker crosspoint contacts of Gateron switches offer the same reliability and durability we have seen in Cherry MX switches. The way I see it, you trade a smoothness for a shorter lifetime expectation.