Johann Heinrich (John H.) Koehnken (1819–1897) was an American organ builder in Cincinnati, Ohio who worked under Matthias Schwab (1808–1862) and with Gallus Grimm (1827–1897). Their organs remain in use (with restoration work) at the Isaac M. Wise Temple (formerly Plum Street Temple) and other locations. Koehnken was born on September 14, 1819 on a farm in Altenbuhlstedt in the Lower Saxony area of Germany (not far from Bremen) and was apprenticed to a cabinetmaker. He worked as a cabinet maker for two years in Germany and two more in Wheeling, (West) Virginia, before coming to Cincinnati, Ohio, in 1839 with his older brother, Johann Koehnken (1812–1872). Both brothers worked in the organ building trade. Johann Koehnken, the older brother, variously went by the surnames Conkey, Konkey, and Koenke and built organs in Cincinnati through the 1840s before relocating to Louisville, Kentucky. The younger of the two brothers, Johann Heinrich Koehnken, had worked under Matthias Schwab at his factory in Cincinnati. He obtained ownership of Schwab's factory on Sycamore Street in 1860. Here he was assisted by Gallus Grimm and the firm became Koehnken and Grimm by 1875. The two worked together for twenty-one years until Koehnken retired in 1896. In 1897, both Johann Heinrich Koehnken and Grimm died. The firm continued under the name of Gallus Grimm's son as Edward Grimm and Company until 1908, when it was purchased by Alfred Mathers. ==Koehnken and Koehnken and Grimm Organs ==