xEM vs NExT - Any difference in 125 khz performance?

Hi! I’m considering an implant but was more interested in 125 khz RFID than the NFC, though I’d be interested in the NFC capabilities if there weren’t many drawbacks.

My question is if the read distance for the T5577 tag is the same for the xEM tag as it is for th NExT tag. If it’s the same (ie - having the NExT tag and using it for my ID badge would function just as well as an xEM tag) I’d likely got the NExT; if not I’d get the xEM.


Hey buddy, that is a simple decision.

Get a NExT !
Same read range as the xEM
You get the bonus of the HF

Also if you live in North America, The postage is free

I am not sure of what the drawbacks are you are referring to. :man_shrugging:t3:

How have you confirmed your ID Badge is LF?

Beware the range on x series can be pretty disappointing for some

I’ll break ranks on this one,

I have 2 next and 2 xem

Not a statistically significant data set but I’ve found my xem to read a bit better,

They are in different locations so there is a chance that it’s simply that my xem are a bit more shallow

Is that also on the same readers? ( Emulation Mode )
Presenting in the same orientation?
That would make the data a little more significant…

Not having a go, just trying to get a slightly clearer picture.

Same readers, as similar presentation as possible given they are in different locations of my hand

For instance with the XACv2 for my gunsafe project, I initially used my xem in L5 easy 1-2” air gap

Now I use my NEXT in center top wrist, 1/8” air gap max, typically touching

Same NEXT wouldn’t work with work reader, same xEM just barely hits it

I haven’t used the LF on my 2nd for anything yet, but since it’s in em more by default, I can make it chip my XAC, same distance as my first NEXT, about 1/8”, and this implant is my most shallow
(I quietly worry it may reject some day)

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Lol. There’s no biohacker solidarity :fist: on performance, man. Data speaks for itself.

I have a NExT installed and some loose around here. Unfortunately I only have 1 xEM that’s in an injector, and I’d like to keep it that way. Common sense indicates that the xEM would have better range because more of the implant is devoted to the antenna. In this case their performance is balanced out because the tighter antenna in the NExT and the higher quality ferrite necessary to create that smaller antenna cause the chip to recieve more flux from the same field. Basically they should have the same read range, but it’s possible the xEM could be easier to position correctly.

@Equipter might be able to give us some insights. They have both an xEM and (a bunch) of NExT, plus they’re good with a Proxmark. Might be able to do an lf tune or something and give us some numbers with n sheets of paper between the implant and the antenna.

RDV4 Stock antenna: 38200mV/38v

Without paper:

xEm: 37600mV Δv: .6v

NExT #1: 37900mV Δv: .3v

NExT #2: 37800mV Δv: .4v

With paper:

xEm: 37800mV Δv: .4v

NExT #1: 37900mV Δv: .3v

NExT #2: 37800mV Δv: .4v

ProxLF: 26600mV / 26v

Without paper:

xEm: 26400mV Δv: .2v

NExT #1: 26500mV Δv: .1v

NExT #2: 26500mV Δv: .1v

With paper:

xEm: 26400mV Δv: .2v

NExT #1: 26550 Δv: .05v

NExT #2: 26550 Δv: .05v

these are the values i got, things might be different for anyone else who tries doing it obvs values will be different due to placements/skin density etc etc etc, hope this helps!


Thanks for that.

Yeah so it looks like the xEM is in fact getting slightly better coupling with both flat and cylindrical antennas, adjacent to and a small distance away. The difference is exceedingly small though, so functionally from a user perspective they’re probably about the same.

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if it isn’t working, just mash harder!

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AFAIK the NExT EM antenna has been tuned a bit to work better with the HF antenna next to it, so minimal loss was expected and adjusted for. It may be impossible to get closer to perfect.

That sentence both relieves and terrifies me

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