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Fosi Audio's Debut Planar Headphones-i5 Launches

Fosi Audio

Fosi Audio

Senior Member
Audio Company
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Hello members!

We’re excited to announce that the Fosi Audio i5 planar magnetic headphones, which gained widespread acclaim at CanJam Hong Kong, CanJam NYC, and AXPONA 2025, are now officially live on Kickstarter!:D


We've prepared an early bird discount for every backer. Let's kick it off!
1745335368233.png

1745335386440.png


Please support and back the i5 via the link below:
 
SlowJim said:
Wow those are big
Click to expand...
One looks a bit like a 60s 'Invasion-style' Cyberman wearing them - and the Jecklin Floats of old were bad enough I remember.

Still, if used at home and if they perform well, they're fair do's :D
 
Fosi Audio said:
View attachment 445993
Hello members!

We’re excited to announce that the Fosi Audio i5 planar magnetic headphones, which gained widespread acclaim at CanJam Hong Kong, CanJam NYC, and AXPONA 2025, are now officially live on Kickstarter!:D


We've prepared an early bird discount for every backer. Let's kick it off!
View attachment 445994
View attachment 445995

Please support and back the i5 via the link below:
Click to expand...
Are there any 3rd party or unaffiliated reviews you could direct us towards? I haven't seen feedback from the canjam threads you mentioned. They look impressive, thank you for posting.
 
Fosi Audio said:
View attachment 445993
Hello members!

We’re excited to announce that the Fosi Audio i5 planar magnetic headphones, which gained widespread acclaim at CanJam Hong Kong, CanJam NYC, and AXPONA 2025, are now officially live on Kickstarter!:D


We've prepared an early bird discount for every backer. Let's kick it off!
View attachment 445994
View attachment 445995

Please support and back the i5 via the link below:
Click to expand...

HKD$ 3,399 = ~$439

~ means approximately
 
"Luxurious", "euphonious"... Simplicity wins hearts. Dubious marketing practices, not so much.
 
Here is my review for the Fosi Audio i5 that launched today (August 15 2025)
diyaudioheaven.wordpress.com

i5

back to Fosi Audioback to measurementshome published: Aug-15-2025, updated Sept-15-2025 NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons f…
diyaudioheaven.wordpress.com diyaudioheaven.wordpress.com
 
This may be a silly question but @solderdude where do you source your felt? I read the review and own an i5, the modification definitely seems worthwhile.
 
In crafts stores.
Online there are plenty of stores selling woolfelt.
For the rear side I used 3mm woolfelt.
Make sure it does not have an adhesive layer on one side.
Have ordered a bunch of the stuff and plan to cut out discs and sell them cheap. (just a few Euro incl. shipping)
Saves people from having to buy a sheet.
 
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AetherDrive said:
This may be a silly question but @solderdude where do you source your felt? I read the review and own an i5, the modification definitely seems worthwhile.
Click to expand...
€ 11,- (this is included worldwide shipping) for 4 pre-cut felt discs + TORX L-wrench and instructions.
Indeed a worthwhile and fully reversible modification.
 
Last edited:
solderdude said:
€ 11,- (this is included worldwide shipping) for 4 pre-cut foam discs + TORX L-wrench and instructions.
Indeed a worthwhile and fully reversible modification.
Click to expand...
After I finish moving in a couple weeks you’ll definitely be hearing from me!
 
solderdude said:
Here is my review for the Fosi Audio i5 that launched today (August 15 2025)
diyaudioheaven.wordpress.com

i5

back to Fosi Audioback to measurementshome published: Aug-15-2025, updated Sept-15-2025 NO SMOOTHING is applied to the shown plots. Most measurement sites have some smoothing applied which ‘irons f…
diyaudioheaven.wordpress.com diyaudioheaven.wordpress.com
Click to expand...
Hey Solderdude, this was a great review. Out of curiousity, any reason why you don't publish it on this site as well? As I see others posting reviews here on cd players and whatnot.

How would you compare the Fosi i5 (after modding) to the Moondrop Para II? They're around the same price here in Aus, so am currently considering both of them, but I kind of like the look and build of the i5 a little more. They both seem to have low distortion, but I would be eq-ing them, so would the Para II handle it better (particularly bass being boosted).
Also, which of these headphones did you feel 'soundstage'/spaciousness was better?
I'm a little sceptical of the velcro attachment of the pad, since it will make replacements scarce, and limits experimentation with different pads. You think this is worth worrying about?
Finally, do you have any of the modding kits left to ship? (really cool that you're offering it!).
 
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My measurements are not made on an industry standard fixture but a cheap DIY fixture so they don't 'fit' in here.

I have not heard/measured the Para(II) so no way to compare.

The i5 is very comfortable (aside from the weight, like all planars) and there is much room for the ears.
One thing the Para II has against it (for me) is the unusually low impedance.
Also I have no idea how deep the pads are.
Out of the box the Para II seems technically a bit better.

The Velcro solution of i5 indeed isn't the greatest idea, indeed if only for aftermarket pads.
Also the hinge kind of rubs into it and aligning it with the headphone isn't quick, also one has to push the pad on firmly to prevent leakage.
Once the pad is on there is no issue.

Fosi told me they will provide pads as spare parts... of course no one can tell for how many years that will be.

Plenty of modding kits left.
 
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