Alps Plate Spring vs. IBM Beam Spring

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12 Jul 2017, 08:57

Alps Plate Springs have been experiencing a hype bubble that I'm going to partially pop, as they are regularly compared to IBM Beam Springs. I'll go over my subjective experiences with them and note the single objective issue that cropped up.

Later Alps Plate Springs, in my opinion, are a cross between Beam Spring switches and Futaba clicky switches (I'm working from memory in terms of Futaba switches). I can't give a definitive opinion on early APS, but I think they will share some of the fundamental characteristics I explain below.

Subjective Impressions:

• Their friction-feel (slider against housing when pressed) is slightly rubbery, but not very rubbery. Alps SKFL and SMK Alps Mount switches (Monterey Blues) are much worse in that regard. Futaba switches don't have that characteristic, which is worth noting. Beam Springs do not have a rubbery friction-feel.

• They have minimal tactility. Upstroke tactility is sharper and heavier than downstroke tactility, so one's fingers are pushed up. APS switches are much less tactile than Futaba switches, but they share that unmistakably "pushy" upstroke. Beam Springs seem to have longer tactile ramps on the up and downstroke. The downstroke bump seems more noticeable than that of APS switches, which have a slightly shorter (but not really sharper feeling) tactile event.

• APS switches have a cushy feeling near bottom out. I like hard bottom outs.

• The sound is disappointingly one dimensional, as the frequency of the click is laser focused and "poppy" sounding. Some people enjoy its milder click (quieter than Beam Springs), but I think it sounds like the mechanism is being muffled by a cardboard sheet. The switches almost sound rattly when typing rapidly, and there is an evident upstroke click. There is a Futaba-ish pop to APS' sound, but Futabas are rattlier and lower pitched overall. Beam Spring clicks are sharper and fuller. I tend to like music that uses a wide frequency range, so my beam spring preference makes sense. They seem to have more authority... And that's actually backed up by a slowed down listen to APS' recording. APS rings at a single harmonic for a good long while, whereas IBM's mechanism has one secondary spike that settles down into random noise.

You will find two recordings, screenshots of relative amplitude, and a spectrograph below. Both were taken with the same desk, distance, and gain.

Alps Plate Springs | ... sp=sharing

Beam Springs | ... sp=sharing

Spectrograph - APS left, BS right

Note the upstroke clicks at the far left of the spectrograph. I used a slow down-up pattern for a moment.

Objective Issues:

• I think the APS design is inherently weak to off-center key presses. Some binding, but not enough to bring the switch to a complete stop, will occur during serious off-center presses. If presses aren't all that far off-center, the rubbery feeling mentioned in the subjective impressions section will increase to a moderate level. I am quite sure that this is design / materials related and not dirtiness related. I PTFE dry lubricated a single switch in my 5576-002 and felt no change in performance. PTFE lube typically mitigates dirt to an extent.

• Binding can be reduced by using a flat keycap profile. I tested it with the keycaps from my Panasonic KX-E8283 / Electronic Typing Station keyboard (Bondwell Uniform Profile).

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12 Jul 2017, 09:28

I don't think anything compares very favourably when compared to beamsprings :p . That said, I really like Alps plate spring switches, and I feel that their pros are a consequence of their beamspring-like mechanism. Of course, in truth, they are still conductive metal switches, rather than a capacitive switch. They were also designed for low-profile operation, while this was not a consideration with beam springs.

As for the sound, that's of course a hard thing to pin down, but I think their sound is really pleasant and uniquely funky.


12 Jul 2017, 09:30

I like the feel of Alps plate spring quite a bit better than beam spring. (Beam spring boards have nice keycaps, but are above-average-but-nothing-to-write-home-about typing switches. I’ll take Model F, Alps SKCM, Clicky SMK, Alps plate spring, etc. over beam spring. Come at me.)

The sound is crap though (relatively; also, to be fair, beam spring sound is also crap). Clicky Alps SKCM switches sound a lot better. This obviously depends a lot on case and other context, as well as personal taste. The plate spring switches are at their worst in the IBM P70 type “portable” computers, which are the flimsiest plastic construction you can imagine, with ridiculously thin keycaps. I would recommend removing the case entirely from such a keyboard and just setting the bare PCB on a rigid piece of wood (assuming you don’t want to build a better keyboard from scratch or whatever), and then also replacing all the keycaps with thicker ones. I don’t have any experience with the IBM Japanese standalone keyboards.

I don’t know what a “rubbery friction feel” is. Plate springs are generally very smooth (low-friction) switches.

They tend to wear out by getting the little plates pushed out of their original shape, still functioning but becoming much less tactile. I think this is probably their biggest flaw.

While we’re at it though, flaw number 2 is that if you don’t like the switch weight, there’s pretty much nothing you can do about it, unless you want to get into business manufacturing your own click plates.

I type faster and with fewer errors on Alps plate spring than on any other type of switch I’ve tried.

If you like a “hard bottom out”, then you are typing the wrong way to use these switches. The “cushy” bottom of the stroke is the whole point, and combined with the pop on the upstroke is the reason that typing on these switches is so fast and accurate. You need to hold your hands, wrists, and arms up off the table, relax all of your muscles, and type in a light, springy way. Try to imagine that your fingers are dancing across the keys, not stomping.
Last edited by jacobolus on 12 Jul 2017, 09:56, edited 3 times in total.

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12 Jul 2017, 09:53

To be clear, I dislike them but recognize why other people like them.

I actually spent more on my APS keyboard than I did my beam spring keyboard, so I'm not biased due to cost or rarity. It really comes down to personal preference.

They're smooth, sure, but the rubbery feeling is real. There is always some friction between the slider and housing, even if it is minimal. You'd need to try SKFL Alps to really get what I mean, as they're the switch that makes it most obvious.

I also tried floating on the keys, which was meh for me. I need heavier switches to float properly. So yes, I may be "typing the wrong way" on APS.


12 Jul 2017, 09:57

ohaimark: you probably want to try a Marquardt “butterfly” switch, if you like heavier switches and a beam-spring type feel, with a sharper tactile snap and louder click.

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12 Jul 2017, 10:24

Sounds a bit underwhelming...

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12 Jul 2017, 10:34

jacobolus wrote: I like the feel of Alps plate spring quite a bit better than beam spring. (Beam spring boards have nice keycaps, but are above-average-but-nothing-to-write-home-about typing switches. I’ll take Model F, Alps SKCM, Clicky SMK, Alps plate spring, etc. over beam spring. Come at me.) . . .

Try to imagine that your fingers are dancing across the keys, not stomping.
Blue Alps and Capacitive Buckling Springs rank equally to Beam Springs in terms of typing satisfaction, but Beam Springs are definitely below other switches in terms of speed. Accuracy isn't an issue for me. I enjoy the Beam Spring sound and feel so much that a slight WPM loss isn't really a big deal.

As for proper typing style, I know how it's done. I can dance on the keyboard. I just don't do so on a regular basis. There's something satisfying about hammering a document into submission.

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12 Jul 2017, 14:46

jacobolus wrote: Try to imagine that your fingers are dancing across the keys, not stomping.
I'm not sure I could ever manage to type like that: I have some degree of dyspraxia so that style will probably always remain elusive. I also play bass, which doesn't necessarily encourage a delicate touch: I mean whenever I pick up a gu*tar I manage to break the high E-string within seconds. :D

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12 Jul 2017, 16:05

I'm also one who finds beamsprings to be a bit underwhelming, and I don't particularly care for the sound they make either. Their key cap profile is also quite good, but it's still not a favorite. I'm a hard man to please, I suppose, and my favorite spherical profile lies with the exotic Alps SKCL/SKCM sculpted spherical profiles.

I think beamsprings and plate springs are both more of an acquired taste, with APS likely being more divisive, though I know not everyone enjoys beamsprings, but the weight of the IBM name and legend behind them, along with their rarity, gives them a sort of mythical status among many.

I should also note two things:

1) IBM P70 keyboards can come with thick PBT caps (standard Alps Electric thickness) if you find an early model.

2) There is also an early variant of the Alps Plate Spring switch, which has a different top housing (colored grey) and a distinctive black bottom housing, which is disparate from the later and more common variants.

The difference in weight is 10g.

With nickels, I measured bottoming out on "earlies" (as I call them) at 60g.

I measured bottoming out on "lates" at 70g.

For fun, I measured beamspring switches too, and at least in my case, they bottom out consistently at a 60g stack of nickels with a penny on top, so 62.5g~.

I can't say much about earlies, as I have a single switch from a friend who made the discovery after purchasing a P70, but I have a Canon AP500 (I believe you have one as well, jacobolus) coming in with early plate-mounted APS switches, so I can look for more consistent differences.

So far, the most significant difference is in weight, and the click seems to be a little lighter sounding.

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Offtopicthority Instigator

07 Jan 2018, 13:39

Thanks for your work ohaimark! Since I just got my P70 the other day it may be a bit early for me to get into details but I agree with most of your findings. I just updated our P70 wiki page a bit, anyone have anything to add go for it or let me know.



09 Jan 2018, 19:58

Hi, new here, not sure if this is off topic, though it seems fairly close.

How do the Alps Plate Spring switches compare to the the Alps Buckling Springs?

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