Testing out a 50mm dynamic headphone driver now and the initial results are very impressive. Most cheap 50mm drivers suck but this is the most neutral fullrange I've found on Ali so far. I've bought 4-5 drivers lately and this is the only one which is fullrange without beeing harsh. Its very detailed but not sibiliant. Bass doesn't go super deep but works for rock and most genres. Since its 16ohms it gives good dynamic and loudness from cheap bluetooth headset chip amps if they are rated for 16ohm. Put this driver into a cheap BT headset and I can assure you that you will be amazed over how much better it sounds. I think you can lower the treble with felt if you feel its too hot, or put a hole in felt backing if you want more bass from it. I haven't tried this since I think its perfect in its stock form 🙂 https://www.aliexpress.com/item/1005003441738083.html?spm=a2g0o.9042311.0.0.3ddd4c4doXfYRI
Seems like you did my research for me. I've been planning on making a pair of headphones with 50mm drivers. I'll check this one out.
It's good that my findings can help someone out! When I started there were little info on current 40/50mm drivers available from ebay/Ali.. As you probably know all these driver have breakup within the audio range unfortunately. So its a matter of finding one that has its problems in a frequency range where its least noticable. I would estimate that this driver has it above the vocal range and under the cymbal range somewhere. To me it sounds like the breakup peaks are very controlled and much lower in amplitude than on the other drivers I've tested. I can also add that this driver has "speed", a word Steve Gutenberg often uses in his reviews. I didnt know excactly what he meant before I heard this driver 😉 . I just noticed this driver is on offer right now so I bought another pair for more fun in the future 🙂