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Recently I had the receiver of my Rudy Meinl 4/4 CC replaced. The original had seen an impact at some point and it left edge of the receiver only 99.8% round with a very noticeable external impact mark. I opted to have a Dillon Adjustable Gap Receiver installed. Here are some pictures. Katy Jacobson at Katix Music in Pinson, AL did a great job.







These adjustable receivers seem to be pretty rare these days. When I ordered mine, Dillon Music had 3 in stock.

Anyway, I watched a video David Werden put together on the adjustable receiver on his Adams euphonium. It has a different appearance but appears to do the very same thing. I'm curious how many people out there have a Dillon AGR installed on their horn and what "setting" do you keep it at. Seems like David Werden recommended about 2-3 full rotations out from all the way in. I'm not sure how that translates to the Dillon device as I'm sure the threads are probably different. So far, I've started with 2 full turns and it plays very well. I'll have to keep tinkering to see what I like.

tubatodd wrote: Sat May 02, 2026 6:56 am Katy Jacobson at Katix Music in Pinson, AL did a great job.

I know Katy. She's a champ!

I have one here, originally intended to put it on either my 2165 or Holton 345, mostly because I wanted to be able to stick whatever mouthpiece in the horn that I wanted, until I decided to just have both American and Euro shanks for those Houser manufactured 3 piece models.

So… To not answer your question, I have one but haven’t put it on anything

Primary use for me.was always to use either Standard or Euro shank mpc. Otherwise, I'm not able to perceive much difference. I'm sure it varies a lot from horn to horn, since some tubas seem to be naturally mouthpiece agnostic.

Sousaswag wrote: Sat May 02, 2026 9:04 am So… To not answer your question, I have one but haven’t put it on anything

Funny! Back in 2001, I had an AGR I got as part of a trade.i never got it installed and ended up selling it. Finally bought this one and finally got it installed

When you find your right setting, it will be night and day...

bisontuba wrote: Sat May 02, 2026 11:43 am When you find your right setting, it will be night and day...

Again, I think it depends on the instrument. I had one on my Willson 3050, and any mouthpiece shank, receiver, and distance combination didn't seem to make much difference -- all had consistently excellent response.

bort2.0 wrote: Sat May 02, 2026 12:44 pm

bisontuba wrote: Sat May 02, 2026 11:43 am When you find your right setting, it will be night and day...

Again, I think it depends on the instrument. I had one on my Willson 3050, and any mouthpiece shank, receiver, and distance combination didn't seem to make much difference -- all had consistently excellent response.

Thank you for your feedback. So I would assume how the mouthpiece fits in the insert makes somewhat of a difference. What is the proper fit? What if it fix it either insert but it is just a matter of depth?

I am perpetually confused about gap on tuba ..

On trumpet the effect of the gap was immediately obvious to me... Larger gap tighter slotting and brighter sound but more resistance... Smaller gap felt much more open, more responsive but farther and more difficult to center. It didn't take me long to figure things out.

On tuba it seems much more nebulous. I've done some testing with different mouthpieces on my tubas where I've put some electrical tape around the shank to widen the gap and haven't really felt any difference... in contrast I remember a comment from Wade about using a paper shim to lock in intonation on one of his instruments...

Then there is the euro/fake euro receiver on the King 2341 and Eastman that can supposedly take either American or Euro shank and the P shank Mouthpieces designed to split the difference.. If gap made a significant difference how the heck does so that work at all???

If it was a cylindrical versus conical things... why is the Adams euphonium AGR so well received??

Color me confused Batman....

Firstly, it doesn’t affect mouthpiece fit in the receiver. It just adjusts the tip of the mouthpiece shank with respect to the joint between the receiver and the lead pipe. If the shank is too large it won’t go in far enough, etc.

Secondly, some (German) tubas don’t have a joint between the receiver and the lead pipe. The receiver is an oversized sleeve that fits over the lead pipe, which is then expanded to fit tightly. An AGR creates the joint, because the lead pipe is trimmed off where it goes into the receiver sleeve. I saw them used most often on American-style frankentubas out of the shop at Dillon Music.

The idea was that it affected response and the sound of the articulation. I think Kelly O’Bryant had the most to say about it back on Tubenet more than 20 years ago.

The instruments I tried out that had one did not seem to make much difference, but what do I know?

Rick “considered it once for the York Master, but was dissuaded by MW because it was a sleeved receiver” Denney

Whatever happened to Kelly O' ?

The difference(?) is that some tubas are decidedly Euro receivers A standard mouthpiece might fit in, but it might bottom out as well. When it does fit, it's way up near the cup. And on some horns, it just plays a little different with a standard mpc in a euro receiver. The standard might put your head closer to the bell than you're used to, as well, which sounds silly but when you're used to hours and hours of it being one specific way... You notice the difference.

For a standard receiver, the Euro mpc might not fit in enough to be stable. It might have some wiggle, or might not fit at all. Might play a little differently, might not. Your head will be a little farther from the bell.

Sleeved lead pipe ends have no gap at all.

Older Alexander tubas had enormous mouthpiece receivers that required a huge shank mouthpiece. You'd either have to track down an old Alex mouthpiece, or get an adapter, or a small number of other options. The AGR was great for that to be a universal "fix" to let you use whatever you wanted. Regardless of the whole gap thing, it was hard to simply find many options that would fit.

Looking at the Standard and Euro AGR receivers that screw in, a standard mpc in the standard, and a Euro mpc in the Euro will both go in the same distance to the sleeve. But you can dial it in (1/4 turn a time) until you hear the grass grow just the right way you want.

Again, I think the gap makes a bigger difference in some tubas than others. Some tubas are just squirrelly like that.

I think the overall length of the tuba makes a difference. A trumpet is a lot shorter tubing, so the gap represents a bigger percentage of the overall system. Compared to the much-longer tuba and the infinitesimal gap distance compared to the rest of the horn. All of these are really small differences though. Then there's also the difference in bore, distance between mouthpiece and valves, blah blah blah. Small differences can make a difference to the physical side of things. None of it has anything to do with being musical though.

I forget who said it, but the phrase is something like "a pinhole in a trumpet makes more difference than a bullet hole in a tuba"

Rick Denney wrote: Sat May 02, 2026 3:24 pm Firstly, it doesn’t affect mouthpiece fit in the receiver. It just adjusts the tip of the mouthpiece shank with respect to the joint between the receiver and the lead pipe. If the shank is too large it won’t go in far enough, etc.

Exactly! An American shank mouthpiece and a P shank will go into the receiver different amounts... so the gap will be significantly larger... I had a RT-88 with both Small (American) and Regular (P shank) and I really didn't notice a difference in play feel.

Maybe I am just not sensitive enough or my tuba just didn't care.

I also wanted to add, none of this is said with any disrespect to Matt Walters. I've owned a few tubas that he's "whispered at," and whatever he did or didn't do, those tubas were fantastic. So if he made the AGR, got Dillon to sell it, and helps to market it, I'm not doubting that it has some real purposes and effects for some people and some tubas.

You *do* have to cut the receiver to fit it, so it's a one-way street. That's a bit of a deterrent in some cases as well.

Overall, I just think some tubas (and some tuba players) just don't need (or want) it. Which is fine, because even within our niche among niches, none of use the exact same thing as each other. We laugh at trumpet players for being picky, but jeez aren't we the same..

bort2.0 wrote: Sat May 02, 2026 4:44 pm You *do* have to cut the receiver to fit it, so it's a one-way street. That's a bit of a deterrent in some cases as well.

Katy called me when she removed the stock receiver and realized the leadpipe went all the way to the end. She said "I am going to have to trim some of this leadpipe. Before I do I need your blessing. If you decide you want to reverse this....it will be expensive." I trusted her and I trusted the product. So I gave my blessing.

She sounds like a good repair person.

The tubas that I’ve played have no “gap”. The mouthpiece goes into the leadpipe, which is reinforced with what I’d call a ferrule that attaches to the bell by a brace. I’m sure there is a proper term for that design. If you know, please share.

With that out of the way, I do believe that there’s something there in addition to/beyond what others have said about shank fit, wobble, and head placement relative to the bell. I say this because I have three nearly identical mouthpieces, different only in shank size—same taper with different insertion depths, which affect the intonation. As expected—longer = lower. But, the longest one seems to improve the intonation of one problematic note on my 822—Eb below the staff, which is otherwise flat even with the first slide all the way in.

Now, I don’t know why this might affect one note so disproportionately: maybe it moves a node/antinode relative to a bend in the tubing and that either directly raises the pitch or makes the note “slot” just a bit more loosely and I’m (unconsciously) able to move the pitch down?

I suspect that there’s more going on in our horns (and heads) than we can ascribe to any one thing. However, I’m reminded of the fabled “dent” that apparently tamed a tuba in the past. The more I learn about how the waves we propagate through these unusually shaped instruments are affected by their geometry the more I wonder how anyone ever plays any of them in tune (i.e. tempered tuning, which doesn’t really match the physics, after all). Far fewer complaints about intonation in trumpets—a lot fewer hard bends and turns. Ditto for horns that are made up largely of one continuous bend. Tubas seem to come in just about any shape imaginable, which must (?!?) have an impact on how waves are reflected internally?

I don't think I've ever heard of anyone discovering a true gap - if you define it as I do,

• a space in the receiver
• between the end of the mouthpiece shank, and the beginning of the leadpipe
• where the diameter of the space is larger than the leadpipe and shank interior diameters.

As illustrated in this image from Warburton -


I mean, as far as I know, when people manage to look inside the receiver, they find a smooth joint between the receiver and the leadpipe, and there isn't that step. In the diagram above, the receiver was bored out to make a flush fit with the leadpipe, and bored out again from the other end to accommodate the shank; my impression is that in tubas, the shank end isn't bored out to a larger diameter, it just runs straight to the leadpipe diameter. (Don't know for sure about those German tubas, I didn't follow what "because the lead pipe is trimmed off where it goes into the receiver sleeve" meant.)

That doesn't mean there aren't any interesting acoustic phenomena in there, but it at least seems like it would be a little more ambiguous to calibrate it.

donn wrote: Sun May 03, 2026 12:48 pm Don't know for sure about those German tubas, I didn't follow what "because the lead pipe is trimmed off where it goes into the receiver sleeve" meant.)

The lead pipe is one piece of tubing, and the end of the tubing is where you put in the mouthpiece. There literally is NO receiver, it's just the mouthpiece in the end of the pipe. There is a sleeve over the end of the lead pipe to protect it and give it some stability (and maybe for looks too), but it's just a sleeve.

Very easy to see if you look straight on at it. My Marzan was like this, but I'm not sure if I have an old photo of it.

I had my first concert with the Rudy since having the AGR installed. I dialed it in at about 2-3 turns out. The horn played well. I didn't experiment with any other settings. I was more concerned about the fact that I had the 5th and 1st valves start to stick....even though they were well and properly oiled. I believe this was actually what @bloke warned me about. I think some of the mineral oil worked its way from the slides down the tubes and into the valves. I tried to use a light amount and remove excess but it seems like the mineral oil still migrated.

You might have a scale build up starting to occur.

This is another uninformed guess, but sawing on and thumping on the mouth pipe to install that device may have shaken loose some scale in the mouth pipe tube which migrated down into the rotors.

If you tag me, you're going to get some sort of rhetoric, whether it's useful or not.