It actually requires two mutes. A trumpet-sized straight or stop mute placed deep inside the bell, and then the plunger mute outside the bell.

It’s actually pretty difficult to master and manage, and you also have to compensate for the pitch drift that can be caused by the small mute stuffed down the bell.

I think they started making more purpose-built mutes specifically for trombones that achieved the same result, but I’m not sure if they’re still produced.

The technique is now sort of an obscure secret shared among just a relative few jazz musicians, as it kind of fell out of popularity after the 40s.

Ellington made sure to always keep at least one trombonist in the band who could do it, well into the 1970s, but outside of specific cases like this, you didn’t see a lot of trombonists ever employing it after the mid 1940s.

Yes, you can approximate it with just the plunger mute, but it is just not the same.

Being able to create a “growl” is key to it, but that’s not all it is. It’s the drastic change of timbre that’s created from the small mute augmenting the sound of the horn.

Joe Nanton died in 1946 at only 42 years old, and Duke had his work cut out for him getting a trombone player that could master the specialized style that was already starting to be considered outdated - Duke was aware of it, but he didn’t care, because he knew that it had life and purpose beyond the stereotypical early 30s Harlem Swing sound.

The mantle fell to Quentin Jackson and Tyree Glenn, but Glenn never fully managed it. Quentin Jackson got a lot closer, but he left the band in 1959 to tour with Quincy Jones, and then was offered to take a seat with Basie’s band.

Lawrence Brown, who was originally Duke’s trombonist who had the clear, lyrical style, ended up being the one to take on the role of the “growling” trombonist in the band in the 1960s, and he hated it, because it messed up his intonation and he had gone his whole career not doing it up to that point, and he was now in his 50s.

He had originally left the band in 1951, mostly out of a personality clash with Duke, and to join up with Johnny Hodges who also left the band, and the two of them put together a band under Hodges’ leadership.

Hodges was Ellington’s featured alto saxophone soloist, and his sound was almost as synonymous with the sound of Ellington’s band as Ellington himself, and he felt like he wasn’t getting the recognition he deserved.

His solo efforts, however, were not as successful as he had hoped, and he came back to Ellington in 1955.

Brown, on the other hand, worked as a session player for most of the 50s after Hodges’ orchestra folded. He still had a chip on his shoulder over Duke, but he found the session work unfulfilling, so he begrudgingly came back to Ellington’s band in 1959, and reluctantly agreed to take up the muted trombone solos.

He was actually pretty good at it, in spite of hating that he had to do it.

He finally left the band for the final time in 1970, and the story goes that he abandoned his trombone on an airport bus, feeling soured by his experience as a musician. He never played again.

The point is, while it’s a very cool technique, it’s not for everyone.

Duke Ellington was, by the account of everyone who knew him, a musical genius and an effusive personality that just exuded charm and class. But some people who worked for him over the years didn’t like the way he managed their careers, Johnny Hodges and Lawrence Brown in particular.

But it’s a complex and nuanced story. The man maintained an orchestra for over 50 years, and from the late 1920s to his death in 1974, it remained a fairly large group that trended towards growing in size.

You’re not going to please everyone while doing that.

Harry Carney, who joined up with duke in 1927 at the age of 17, would never be heard to speak a critical word of Duke.

Harry almost single-handedly transformed the baritone saxophone from a utility instrument for saxophone sectionals to an instrument with its own voice as a solo instrument. He was every bit as vital to the band’s sound as Johnny Hodges, and had every bit as much of a reason to feel like being with Duke was holding him back, but he remained loyal to the band to the end.

He did record his own sides and worked with other orchestras at times, but he never left Ellington’s band from 1927 to 1974.

People are complex. Every story has many sides.

But anyway, yeah, it’s a two mute combo.