Dimensions

Hailun HL121 - Height: 122cm X Width: 151.5cm X Depth: 60.5cm

Yamaha U1 - Height: 122cm X Width: 152cm X Depth: 61cm
 

Piano string length known as speaking length
(one of the very important part of piano scale design - longer string promotes richer and more powerful tone)

Hailun HL121 - #1 bass string length is 120cm. Middle section (Tenor) is 91cm. German Röslau steel wires for the treble and bass strings - rich singing tone with powerful bass

Yamaha U1 - #1 bass string length is 113cm. Middle section (Tenor) is 91cm. Old treble strings - weak, thin tone. Old bass strings - tubby and thumpy sounding, dead sound
 

Action and Hammer

Hailun HL121 - Full-sized Direct-Blow action type with new Undercovered German hammer felt for durability and promotes better tone quality and power. New action design with premium materials - responsive action with no clicks, no buzzes and even touch - better feel for control

Yamaha U1 - Full-sized Direct-Blow action type with Undercovered Japanese hammer felts that are old and worn - loses it dynamic range and tonal colours. Old felts and leathers harden over the years and action becomes noisy and keys become loose - poor control create poor playing habits
 

Age & Warranty

Hailun HL121 - Brand new with 10 years FACTORY warranty and will last you for the next 50 years

Yamaha U1 - Majority, at least 40 years+, old scale design and materials, with 1-5 years DEALER warranty. Looks new but MUSICALLY dead (tone dead). Major components such as the soundboard, strings, action parts, bridges and pinblock have deteriorate due to wears and humidity. Major rebuilding works needed attention and can cost much more than a new piano
 

Conclusion

Hailun HL121 - Similar height with Yamaha U1 but HL121 have a longer string length scaling (+7cm), which is commonly found only in taller pianos like Yamaha U3. In another words, HL121 have the performance features of a 131cm. Excellent touch and tone with powerful bass. Quality equal if not better than Yamaha U1 and affordable price

Yamaha U1 - Lack of sustain power, weak in tone and noisy action will greatly affect students playing in the long term and most likely to quit piano lessons sooner. Price is equal if not more expensive than Hailun HL121