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Review: Adjustable Bottom Cap (ABC) - Heavyweight 4th Valve Bottom Cap

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On my forum and other places euphonium players have discussed the benefit of replacing the standard bottom cap of the 4th valve with a heavier version. The first I heard of this is when I was a Sterling artist. They sent me one for my Sterling Virtuoso and I liked it. The tone and center seemed a bit better for most music. For music that was light and "bouncy" I tended to prefer the standard cap (but that may have just been in my head). Regardless, it was easy to change the cap when I wanted.

More recently I learned of a line of heavy caps made for most valved brasses: the HBC (Heavy Bottom Cap) product. It was designed by musicians and beautifully made. They had a couple different weights available, and I enjoyed using each. My choice seldom brought me to the original cap.

The clever folks who brought us the HBC have created a new, improved cap that is adjustable. Now, in one slick assembly, you have a choice a four different weights. At its "worst" changing to the heavy cap is no harder than before - just unscrew the bottom cap and screw on the new one. But for some of the adjustments it is not necessary to uncap the bottom of the valve.

The assembly consists of four pieces. The top piece screws onto the valve and must always be part of the mix. That piece by itself adds enough weight to be noticed by a perceptive player and may be what some people would use. The next piece to be added must be the bottom part (gold in the photos below), because it has a threaded shaft to fasten to the top piece and to help secure the middle pieces. The options with this assembly are:

Top only: 56 grams
Top and bottom: 114 grams
Top, bottom, and 1 middle: 157 grams
Top, bottom, and both middle pieces: 200 grams

The weight with all pieces is heavier than the previous HBC heavy cap or my heavy Sterling cap. Here is what they look like in an "exploded" view:

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Here is a sequence of photos showing the options on my own Adams E3:

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(Even though I show it on my Adams, you can order one to fit almost any euphonium model. See the website link at the end of this article for more information.)

Below is a video where I play excerpts back to back between my standard Adams cap and the ABC (fully loaded). As I was editing the audio I thought I would use some graphic examples to show the output differences. Here is a graphic that tells a little story. I changed Audacity's colors to help make this clear. This is my first excerpt from the video, mixed together from the standard and heavy cap. The dark blue shows the peak "measured" level (as far as I understand it). Normally there is an inner part that is lighter blue. Audacity says: "The light blue part of the waveform displays the average RMS (Root Mean Square) value for the same group of samples. This is a rough guide to how loud this area might sound... I take that to mean the light blue area is most important to the human ear.

I re-colored the light-blue area to red. Then I overlayed a different sample with yellow. Red is from the ABC full cap, and yellow is from the standard Adams cap. (FYI, the dark blue areas are identical visually.) The difference between red and yellow represents the added sound from the ABC.

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Obviously the difference is small, but it is still audible. However, an even larger difference to me is the way the horn plays. It feels more solid with the ABC cap. The ABC arrived the day before I left for my recital at GPRTEC. The previous week I had put on the heavy HBC because I was doing a couple pieces that needed all the energy I could put through the horn. That is where the difference is most noticeable. So when the ABC arrived I put it right on the horn with no hesitation. I can't swear I noticed the little bit of extra weight over the HBC, but it surely felt nice and held up to whatever I fed into the horn.

It has been established that mass affects sound and response on a brass instrument (or mouthpiece). The effect could be either good or bad, I suppose, but in this case I see no downside unless you just want a lighter feel in some specific cases. If so, removing some weight is a 15-second job with this product.

The ABC people are know for outstanding quality and customer service. I urge you to try one of these caps. The investment is not large (cheaper than most mouthpieces), and there is a 30-day period to decide if it's a keeper.

In my own case, I'm sure I will keep the ABC on my horn in one configuration or the other. I'll keep the top piece on - it's lighter than the heavy Adams cap I usually had on the horn, so it should not prove too heavy for any use. And then I can quickly and easily add 1, 2, or 3 extra pieces depending on my chops and the music I'm playing.

The website's euphonium ABC page is here:

And this is my video with the comparisons. As usual, I played all excerpts with the standard cap and then all excerpts with the heavy cap. The I used my video editor to alternate caps with each excerpt. That ensures that I am not continually adjusting to a different setup with each excerpt.


  1. daruby's Avatar
    Mine is on order!
  2. Chris Waters's Avatar
    Thanks for your order Douglas!
  3. Chris Waters's Avatar
    All ABCs are in-stock and ready for shipping; same day order/shipping service. Why not take advantage of the advantage Exchange Rate!! * ADAMS * BESSON * BOOSEY & HAWKES * BOOSEY & Co * EASTMAN * GENEVA * HIRSBRUNNER * JOHN PACKER “JP” * JOHN PACKER "JP STERLING" * MACK * MIRAPHONE * THOMANN * S E SHIRES & Co * STERLING VIRTUOSO * WESSEX * WILLSON * YAMAHA * YORK * We now have ABCs available for Baritones by Besson, JP Sterling, Sterling and Yamaha
  4. Chris Waters's Avatar
    A recent ABC delivery!! . . . . . . . .
  5. iMav's Avatar
    I ordered one of these for my newly-ordered Adams E3 (recommended to me in a personal email from another member here). Figured it was cheap enough that I wouldn't worry about waiting for my horn so I could take advantage of the 30-day warranty. HOWEVER, to my surprise, the ABC rep told me that I could start the "timer" on my 30-day trial after my Adams horn arrives!

    Now that's above and beyond customer service!
  6. Chris Waters's Avatar

    Following-on from the worldwide success that Chris Waters’ company “Heavy Bottom Caps” (a Division of Ray Farr Flugels) has had with the Tom Hutchinson Adjustable Bottom Caps (ABCs) for Sopranos, Cornets, Trumpets, Flugel Horns and Tenor Horns, the international Euphonium virtuoso Glenn Van Looy has also enthusiastically endorsed the Euphonium and Baritone ABCs and like Tom, uses one on his instrument.
    Glenn said “The ABC just works. From the moment I put it on my instrument I felt the difference. All the notes are so centred and it gives a very full dark sound”.

    From Professional Players to Students and Young People to Senior Citizens Customers consistently tell say that using an ABC on the 4th Valve of a Euphonium or Baritone or the 3rd Valve on a three valve instrument always has a positive effect in Centring and Securing the Notes

    All details about how an ABC works are on the website

    The science is interesting, but actually Trying an ABC is the Real Proof and that's where ABC’s 1 Month Approval facility Worldwide with a full refund policy really helps. Nothing to lose and everything to gain.

    All ABCs are made in the UK at Heavy Bottom Caps’ manufacturing facility in Aldershot, Hampshire.
  7. iMav's Avatar
    I have purchased three sets. One for the Adams E3 and one each for a John Packer 274 and 374.