Just received a pair of Noble Bell's today for evaluation. (Thanks Brannan!)
First of all, MUCH different than the Velvets. The Bells are brighter and more detailed in the highs. But still with lots of bass. I'd say a slightly V-shaped signature.
I prefer a brighter sound, so for me, the Bells are right up my alley. They have lots of air due to the elevated highs. To me that makes them sound more clear and resolving. But I also have no tolerance for any harshness in the highs and the Bells, while bright, are never harsh.
I used to have Noble X's, but it's been so long since I've heard them, I don't know if a comparison is relevant. Sorry.
But I do have a pair of Katana's and Encore's and K10 Customs. To me the Bells are more like the Encore's than the Katana's. The Katanas are more neutral than the Bells. The Bells have more bass than the Katanas and elevated highs compared to the Katanas.
The Bells remind me more of the Encores in terms of frequency response.
No, they're not as good as either the Katana or the Encore's, but that's to be expected considering the price difference. But the Bells are REALLY good for the price. (I think $199? that's unbelievable in terms of the sound quality vs. price!)
Compared to the K10, I agree with
@Kunlun . The K10's are darker, thicker, more bass.
I also tried some Comply foam tips and that seems to smooth out the highs a bit and yields better bass response. But I've always gotten a much better seal with Comply foam tips compared to any silicone tips I've tried. I pretty much always use Comply tips with all of my IEMs.
(And lastly, WOW! These things work great for movies in 7.1. The detail and clarity really help the imaging.)