TromboneChat

Just because it seems we're on a King bass kick here, I want to see if we can consolidate some more King bass bone lore.

The "Duo Gravis" I take to be the King dependent double valve bass with a shepherds crook F wrap, and a E/D second valve with a double joined thumb set of triggers. It is alternately called 6b/7b/1490, possibly 2106, but always Duo Gravis.

What I want to learn about now is the independent 7b that has wraps more like the Benge 290. Is the tubing diameter through the valves still 0.562 like the DG? Any other light you can shed on specs or playing characteristics or even comparisons to the DG, 8b or Benge 290?

I heard they were trying to name the indy 7B the “ IndepenDuo Gravis” but they didn’t have enough room on the bell for the engraving based on their current jigs.

/s

I make a motion as member of the OnTroComm to adopt that name for further discussion on the horn, and hereby include “IndepenDuo Gravis XL” for further discussion regarding King 8B specific topics. The Benge 290 (a private school-educated 7.5B) is well-named enough to not require a further name/horn confoundment.

I’ll need a second for the motion to pass.

I don't have measurements, but I once tried to swap the G/Gb crook from a Benge 290 onto a King 2107; the Benge's tubing was larger.

I have a 7B. I can confirm the valve wraps are .562.
The .562 f tuning slide from my Benge 190 exactly fits the f slide on my 7B.

As far as comparisons, it has some of the zinginess of the 6B Duo Gravis, but the sound is a bit rounder and slightly darker. It’s not as big as the 290. It’s the same bell as the DG, but the handslide is a bit wider, and the lead pipe is different. Also, all 7B’s came with a gold brass bell, and DG’s came in a few different bell materials, (the later 6B’s came with the same gold brass bell as the 7B) so obviously that affects a direct comparison. The ergonomics of the 7B are much better than the 6B.

Thanks, that's the kind of info I was looking for. Same bell, same dia through valves, probably same tuning slide, smaller than the 290.

Next question is about the Chinese 7b clone. I know there are some people here with that. By most accounts it's not a bad horn, but is it similar to the "indyduo Gravis"?

Having played a few 6Bs, 7Bs, and also having owned a 7B and 7B clone:

the 7B is overall just not as good an instrument as the 6B. It's tempting, but it's just... missing something. The clones actually make a couple improvements but I wouldn't say they are amazing instruments either.

Dunno if it's the valves, or something else in the design, but I find the response and sound to really just not be even close to the 6B.

Speculation, but since it uses .562 rotors, I bet the taper is pretty aggressive in the neckpipe on the 6B. Can't have nearly as aggressive of a taper if you have another 2-3" of rotor ontop of it. Probably makes less of a difference on .593" rotors since they're closer to the tuning slide ID.

Burgerbob wrote: Sat Nov 08, 2025 10:29 am Having played a few 6Bs, 7Bs, and also having owned a 7B and 7B clone:

the 7B is overall just not as good an instrument as the 6B. It's tempting, but it's just... missing something. The clones actually make a couple improvements but I wouldn't say they are amazing instruments either.

Dunno if it's the valves, or something else in the design, but I find the response and sound to really just not be even close to the 6B.

The 7B has a bit more of a generic sound than the 6B. That makes it a better fit into non-King sections, but it doesn’t have the same unique stand-out character the 6B has for sure.

It's definitely more generic, but not in a useful way. It's still pretty light and bright but without the cool color of the Duo Gravis.

hyperbolica wrote: Sat Nov 08, 2025 9:03 am Thanks, that's the kind of info I was looking for. Same bell, same dia through valves, probably same tuning slide, smaller than the 290.

Next question is about the Chinese 7b clone. I know there are some people here with that. By most accounts it's not a bad horn, but is it similar to the "indyduo Gravis"?

I forgot to mention the 7B tuning slide is different as well. It’s a bit wider than the DG’s and it won’t fit on a DG. It’s the same slide as the 8B/290.

I saw these folk at the Edinburgh Jazz Fest last year. The bass player was on a 7B.



A great group!

I did not expect the forum to embed the bandcamp player!

mikerspencer wrote: Sat Nov 08, 2025 1:34 pm I saw these folk at the Edinburgh Jazz Fest last year. The bass player was on a 7B.



A great group!

Wow, they’re great. She writes fantastic charts. The 7B sounds great too.