Under his adopted French name of Jean Henri Hemsch, he and his younger brother Guillaume gained a high reputation in Paris as makers of instruments. Jean Henri Hemsch died in 1769.

Five of his two-manual harpsichords are still preserved. J.C. NEUPERT made a copy, true to the original of the harpsichord built by Johann Heinrich Hemsch in 1754, which is today in the possession of the Bayerisches Nationalmuseum in Munich. The instrument is one of the few left in its original state and is still in playable condition.. 

Mr. C. Mercier-Ythier, the former owner of the instrument, describes the sound of this instrument as follows: "It possesses a well-rounded sonority in the bass, a warm tone in middle range and very clear treble, which never sounds aggressive. This makes it one of the most beautiful harpsichords, both in the tonal and in the aesthetic sense..."
 
 

Technical details: double manual harpsichord compass: F1- e3 (= 5 octaves) lower manual: 81', 4' upper manual: 82', lute to 82' shifting coupler length 228 cm (7'6") width 89 cm (2'11 ") net weight 68 kg	XL-picture naturals covered with ebony, sharps covered with bone wooden jacks , Delrin plectra case: solid lime, painted in the colours of the NEUPERT samples, gold-coloured bands; stand style: Louis XIV Additional options transposing device (a1 = 440/415 Hz) compass extended to f3 gold leaf bands painted soundboard stands in different styles benches and covers matching the instrument
deutsche Version	clavecin à 2 claviers étendue de clavier: Fa1-mi3 (= 5 octaves) I. clavier: 81', 4' II. clavier: 82', luth pour 82' accouplement à coulisse longueur 228 cm, largeur 89 cm, net 68 kg
2 manuali estensione della tastiera: 5 ottave (Fal -mi3) I. manuale: 81', 4' II. manuale: 82', liuto a 82' accopiamento scorrevole lunghezza 228 cm, larghezza 89 cm, netto 68 kg	2 teclados extension del teclado: 5 octavas (Fal -mi3) I. teclado: 81', 4' II. teclado: 82', laúd a 82' acoplamiento de corredizo largo 228 cm, ancho 89 cm, neto 68 kg