Asymmetric 5-String Necks...

I discovered this years ago when I bought my Tobias. I found it amazingly comfortable, and have mimicked this carve on everything I’ve built. (I’m an amateur player with questionable technique. )

 

I made my first asymmetrical neck years ago based on seeing one and wanting to try it on guitar. I followed what someone else had done and made it thicker on the low E string side, and thinner on the high E side, then moving to the opposite as one moved up the neck. I ended up feeling more comfortable higher on the neck and less so near the nut. I then made one with no "change" in the asymmetry, just thicker towards the high E side all the way up. I liked it more, and I've done it on several personal instruments including my Special Edition Build Off which is just about finished. It's not much change, pretty subtle, but I like it.

 

because it helps players wrap around the treble side easier.

 

Over the years, I've shaped a couple of customers' custom necks with an asymmetric profile, because they wanted it. My own main experience with asymmetric neck profiles is that I own a '91 Carvin Bunny Brunnel BB75F, fretless 5-string. An amazing bass all around. I consider it to be the best ergonomic-design bass that I've played. The best you can do ergonomically with a relatively standard form bass.

The Bunny Brunnel series Carvins have an asymmetrical neck profile. Basically, the high (thickest) part of the profile, which is normally right down the center, is moved over about 1/4" to the bass side. So, the treble side of the neck ends up flatter (larger radius), and the bass side rounder (smaller radius). The explained reason for this is that your thumb should normally ride on that high spot. Moving it over to the bass side rotates your wrist toward you, making your fingers more outstretched and flatter, rather than curled up. If you are playing fast soloing, lots of notes and patterns, keeping your fingers flatter is generally considered better hand form. That's how Bunny and Carvin explained it in the sales literature.

Me, I'm an old-school style bassist. I pluck hard, don't play many fast notes, and like to keep my fingers curled. So for me, the asymmetric neck profile wasn't comfortable or useful. I won't say that it was uncomfortable, but it's not my preferred neck shape. But I can appreciate why many players may like it, if you are into fast soloing and want to develop the flatter fingers hand form.

 

asymmetric neck profile, J spacing... (hard to illustrate with a pic)

 

No, on the BB75 Carvin, the center is tilted toward the bass side. Unless I'm misremembering.