What is a Compensating Brass Instrument?

The term compensating is one that is often referred to but not always fully understood. It is normally used with reference to lower brass instruments (eg. Euphoniums & Tubas) which are either 'compensating' or 'non-compensating' models. There is a common misconception that if an instrument has a 4th valve* it is compensating, but that is not necessarily the case. I'll try to explain exactly what it means as clearly and concisely as possible, although that's easier said than done!
The term compensating is one that is often referred to but not always fully understood. It is normally used with reference to lower brass instruments

Brass Euphonium High Grade Euphonium 4 Pistons Tone Bb

Available in gold lacquer or silver plate with gold trim., The Cambridge Classic non-compensating 4 valve Baritone Horn is the perfect step-up for 3

Cambridge Classic 4 Valve Non-Compensating Baritone Horn

XO Professional Brass - 1270S Compensating Euphonium - Silver Plated w/Gold Plated Trim

Find many great new & used options and get the best deals for Brushed Brass Bb Compensating system Euphonium Horn with case at the best online prices

Brushed Brass Bb Compensating system Euphonium Horn with case

BAR905 Non Compensating Euphonium — RS Berkeley Musical Instruments

Immaculate compensating euphonium For Fascinating Sound Notes

Brass Instruments Music Shop Europe

1897 Boosey & Co Cornet Patent Compensating Pistons brass

Bb Compensated Euphonium 'Dolce' - EP100 – Wessex Tubas

Cambridge Classic 4/4 BBb Compensating Tuba - Euphoniums, baritone

Euphonium /Brass Instrument/ Compensating Valve Euponium (EU-432S