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Glenn Van Looy ABCs


Glenn Van Looy

Adjustable Bottom Caps for: 

Euphoniums and Baritones

GVL Stills_edited_edited.png

What Is an Adjustable Bottom Cap?


An ABC replaces the 1st or 3rd Valve Bottom Cap on Sopranos, Cornets, Trumpets, Flugel Horns and Tenor Horns. They are the same diameter and thread as the Valve Casing on your Instrument.


1st or 3rd Valve it's your choice. Some players prefer an ABC on the 1st Valve and some on the 3rd, with the BIG advantage being that you can try the 4 Weight options and find the one that works best for you and your instrument.


For Euphoniums the best advantage for Centring and Securing Notes in all Registers is on the 4th Valve and equally so for 4 Valve Besson and Yamaha Baritones. For 3 Valve Baritones, the 1st Valve gives far superior results and benefits.


What Does It Do?

From Students to Professionals of all ages, customers worldwide tell us that using an ABC has a very positive effect in "Centring and Securing the Notes in all Registers, helping to Slot them more accurately".


How Does It Work?

The first diagram details the Waveform of a Note when there is not an ABC weight added to a Valve Casing and shows the degree to which us brass players, as much as we try to keep the note in the centre, can lip the note up and down (shown between the orange lines) from its actual True Centre of the Note shown by the green line. 

Heavy Bottom Caps
Heavy Bottom Caps

The second diagram shows how by adding extra weight with an ABC to a Valve Casing, it Attenuates the Note closer to its True Centre. An analogy of this is when we used to turn the dial on an old-style radio to "Tune it in" and get the best reception, that’s the Attenuation achieved by using an ABC.

The science behind the ABC is that adding Mass/Weight, this Attenuates the Lower Harmonic Partials, acting positively in terms of centring/securing the notes. 


Will It Work for Me?


The evidence from hundreds and hundreds of ABCs sold is Yes and to make sure, you can try one for a Month Without Obligation and see the benefits for yourself - we ship Worldwide.


ABCs are made in the UK to the closest of tolerances by computer-controlled lathes and diamond cutters ensuring the highest quality. Every thread is machined specifically to suit each Make and Model of the various Instruments we mention.


With our unique 1 Month Approval offer you've got nothing to lose and everything to gain.

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

Reviewed by Dave Werden

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.


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 . . . .

Dave Werden and Heavy Bottom Caps
Heavy Bottom Caps

What our customers say about us…

Heavy Bottom Caps

A superbly engineered piece of kit really makes a difference in centring notes in all registers. I have settled with mine on the 3rd valve of my 1980 Sovereign cornet and can't wait to have one on my Stomvi trumpet!! Highly recommended – Sharon M

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