TromboneChat

My student recently came into his lesson with a family heirloom, an early 70s 4B!

I tried it out by my GB NY 5.25 went way too deep which makes me think that the receiver isn’t a typical morse taper.

What mouthpiece would fit into it? I would prefer to stick to a 5G size for him as that’s what he plays on but brand doesn’t really matter.

Doug Elliott makes a special shank that fits King receivers. That would probably be your best bet, because the only other option would be the King 29, and that’s an oddball mouthpiece.
The third option is to have the lead pipe pulled and use a more modern lead pipe, but the Doug Elliott route is probably the best way to go.

A small amount of plumber’s tape wound around the end of the shank can help some mouthpieces fit into a King leadpipe.

King leadpipes are in two pieces, like a trumpet leadpipe. They have a receiver which is soldered to the rest of the tube, which contains the venturi and the taper that leads to the first leg of the inner slide. Almost every other maker uses a one-piece tube.

Congrats to the student who was given a 4B. Classic horn!

A Benge Marcellus mouthpiece with remington-ish taper fits well. I heard that Benge Marcellus comes with a lot of inconsistency,, but I don't know, at least mine fits well and feels good.
Actually, insertion depth-wise, it is in-between normal morse mouthpiece(about 31mm) and Doug's King shank mouthpiece(about 25.4mm), so I ordered from Doug a special shank that is a little smaller than King shank mouthpiece. I'm waiting to try it.
A remington shank mouthpiece is not a perfect match for the King receiver, but maybe provides appropriate insertion depth.
And pulling out original leadpipe is one way, I did it, but maybe I'm going back to original leadpipe. the tightest aftermarket leadpipe(something like MV42 variant) feels a little bit off with King 4B and the original leadpipe is even more tighter than MV42 and feels tighter but it contains some of characteristic King sound.

Doldom wrote: Sat Jun 13, 2026 7:56 am A Benge Marcellus mouthpiece with remington-ish taper fits well. I heard that Benge Marcellus comes with a lot of inconsistency,, but I don't know, at least mine fits well and feels good.

To the OP, I have a couple of Marcellus' laying around if you're interested.

If the shank has the right taper that's a good option. But some of them have a standard taper shank. They were inconsistent, and Benge receivers are too. Some standard, some with the King taper or close to it.

The Benge Marcellus is a little larger rim.than a 5G and a little shallower cup, I think. I don't have one right now but I was studying with Marcellus at that time when he started with the Benge horn and mouthpiece.

Make a piece that sleeves the receiver with a 0.15 mm thick copper sheet. It will make the mouthpiece sit 6 mm less into the receiver, which is exactly what you need. If you want to do a better job, you can silver-solder the piece and cut it to a depth of about 36 mm. I've gained projection and compatibility with other mouthpieces. The trombone sounds much more centered.

All of the advice is awesome but i’m looking for a more economic solution. I’m considering Doug’s set ups as they’ve done me wonders in the past myself and it’s a straightforward solution but this is for a young high schooler who will most likely not pursue trombone post high school so I don’t want his family to drop big $$$ if it’s not necessary.

Then maybe apply some aluminum tape to mouthpiece shank until it inserts about 26~28mm and it will be good.

An unaltered Bach 5GS inserts somewhat more deeply than usual, but plays very well on my 4BF.

Teflon plumber tape works well, won't damage anything, and you can customize how far into the horn the shank goes.

In my experience, if you can find any Benge mouthpieces, which they made for a while in a couple "standard" sizes, where the name on the cup looks like this: BENGE, those have always had the matching shank size for that receiver. They'll probably be pretty cheap if/when you find them too.

For what it's worth, I have a King 4B manufactured in 1975, and it has a standard taper.

I use a Vincent Bach Corp 5G, and have used a number of others over the years, including a Bach 6 1/2AL and a Conn Remington.

I was always looking for one that would solve all my problems...

If you could put a Conn Remington in it, the receiver is not "standard taper."

There was another student at Manhattan School of Music when I was there who played a sterling silver 4B and he used a Remington mouthpiece in that horn. It appeared to fit well, and he sounded good on that combination. Not sure if all King large bores work with that taper, but in that case it was a good match.

Jim Scott

CalgaryTbone wrote: Mon Jul 06, 2026 10:25 pm There was another student at Manhattan School of Music when I was there who played a sterling silver 4B and he used a Remington mouthpiece in that horn.

yes, the remington shank mouthpieces still wobbles when inserted in 4B receiver, but it provides appropriate insertion depth.
I heard that King receiver, and maybe the Benge Marcellus mouthpiece too have something like 0.045:1 taper.
(0.04:1 = Remington / 0.05:1 = Morse )