I feel i have to chime in on this, even if it's old. Sentell Pickups....At least the set I have and use, are amazing Jazz pickups.
My only two complaints would be that he used a shell that is not very rounded around the edges, and if I smooth it out, it will be noticeable...However, I didn't request otherwise, so I guess that complaint is moot.
Second, I wish the lead wires were a little thicker, but again, something I could have asked for, so keep that in mind if you are interested?
Now, after mentioning the "bad", these pick ups are awesome. I had them in an Epiphone Toby (My first purchased bass)....initially, with it's stock preamp, but that preamp sucked...I took it out and went passive with these and wow.....The Neck (P-Jazz sounding pickup) sounds deep and thunderous like a quarter pound, but not as scooped.
I bought the neck pick up on Ebay first to go along with Fender N3 bridge I had got for like 30.00. I would never have thought to even look him up, but it came up as a close out (Apparently someone ordered it but didn't pay), so I got it for 35.00. Once I put it in and played for about 3 or 4 days, I called and asked him to make the matching bridge. He quickly got the supplies together and let me know he was working on it.
The Fender N3 would have been fine for me. It sounded great. I eventually took out the N3 and replaced it with the Sentell Bridge pickup and this set was really nice and it complimented the neck great.
In the end, I always wanted to put Bartolini pickups and a bart preamp in the Toby (I guess hoping for some authenticity of the original M Tobias design....don't laugh, but this a great bass for the money), so I did. and am I glad that I did that? Hell yes..The Barts are killer. This bass sounds the way I envisioned it originally. However, I always longed for that Sentell Neck pickup again.
I ended up putting the n3, along with the neck n3 I got later in a Jazz and to be honest, the N3 neck sucked. The bridge was absolutely amazing. I ended up selling the n3 set to get my barts. This Sentell jazz neck with the Fender N3 bridge was such a great sound. The bridge he sent me was great as well, but there was just something about the combo of the sentell neck and N3 bridge that sang to me. And with it being "noiseless", I could play the bridge alone, almost, without any noise. But I don't regret selling the N3 set because the neck sucked that bad.
Now, I am looking at a fretless to re-home these sentell Jazz pickups. Will be a great way to add wonderful tone to a thin sounding bass. Worth every penny. Haven't even begun to tackle any of his wacky tone options.
My jazz set was as straight forward as he probably gets in his designs, but they are great. My little brother, who has amazing pitch and tone recognition, immediately, asked me what the hell he was playing. I told him, dude, those are "Sentell's" (in a heavy metal voice and devil's ears). He had no idea what I was saying, but he knew he loved them too.