1908年、Wm. Knabe & Co. とチッカリング・アンド・サンズ、ニューヨーク州イースト・ロチェスターのFoster-Armstrong Co. はニュージャージー州法の下でアメリカン・ピアノ・カンパニー(略称Ampico)を設立した。アーネスト・J・クナービ Jr. (社長)とチッカリング・アンド・サンズのC. H. W. Foster、Foster-ArmstrongのGeorge G. Fosterがアメリカン・ピアノCo. を率い、各自はそれぞれの会社とHaines Brothers、Marshall & Wendell、Brewster、J. B. Cook & Co. を管理し、合わせて年間約1万8千台のピアノを生産した[33]。
クナービ・ブラザーズ
アーネストおよびウィリアム・クナービは1909年に職を辞し、ニューヨークでの一連のビジネストラブルの後、1911年にオハイオ州でクナービ・ブラザーズを法人組織にした。会社はシンシナティにオフィスを構え[34]、近隣のノーウッド(英語版)[35]のSmith and Nixonのかつての工場で「木材は平方インチでワイヤーの割り当ては小数点の単位でピアノを理解し、商業主義のくびきから解き放たれ[36]」、アップライトおよびグランドピアノを製造した。アメリカン・ピアノCo. は名称の使用に関して訴訟を起こしたが、結果として下された差し止め命令ではクナービ・ブラザーズに元の看板を使用を止めさせ、兄弟に会社が新しい会社であることを示すことを要求しただけであった[37]。工場は1912年1月に焼けたが[38]、跡地に現代的な工場を建設する前に、一時的な工場ですぐに生産を再開した[39]。会社は1916年の終わり頃に未払いの貸付金のために管財人の管理下に置かれ[40]、兄弟はその年の年末までに破産を宣告した[41]。
^The Baltimore Directory for 1845, John Murphy, Baltimore, 1845 p.80
^advertisement Matchetts Baltimore Director, for 1847–'8 R. J. Matchett, Baltimore. 1847 p.448.
^advertisement Baltimore Wholesale Business Directory and Business Circular, for the Year 1852 I. Hartman, Baltimore, 1852 p.21
^advertisement Adams Sentinel and General Advertiser Gettysburg, Pennsylvania March 29, 1852
^advertisement Baltimore Wholesale Business Directory and Business Circular, for the Year 1853 I. Hartman, Baltimore, 1853 p.28
^advertisement (Erie Music Store) The Erie Observer Erie, Pennsylvania, March 11, 1854 p.4 (issued November 12, 1853)
^David A. Dana The Fireman: The Fire Departments of the United States, with a Full Account of All Large Fires James French and Company, Boston. 1858 p.254; the stock alone was valued at $60,000 – "Large Fire in Baltimore" New York Times November 6, 1854 p.4
^J. Thomas Scharf The Chronicles of Baltimore; being a Complete History of "Baltimore Town" and Baltimore City from the Earliest Period to the Present Time Turnbull Brothers, Baltimore 1874 p.547
^William Knabe vs. Henry Gaehle and Edward Betts. Dissolution of Knabe, Gaehle & Co. C17 Baltimore City Superior Court (Chancery Papers) MSA C168; Accession No. 40,200-5143-1/14, MSA No. C168-747 Location: 2/16/6/14. January 17, 1855 William Gaehle vs. William Knabe, Edward Betts, and Western Bank of Baltimore. Dissolution of Knabe, Gaehle & Co. C30 Baltimore City Superior Court (Chancery Papers) MSA C168; Accession No. 40,200-5371 MSA No. C168-978 Location: 2/16/6/32 August 31, 1857
^advertisement Woods' Baltimore Directory, for 1856–'57 John W. Woods, Baltimore p.179
^"Pianos! Pianos!" The Republican Compiler Gettysburg, Pennsylvania, January 18, 1859 p.2; reportedly Knabe only had seven weeks after the dissolution of Knabe, Gaehle & Co. to prepare his piano for the fair in 1855
^advertisement The Republican Compiler April 18, 1859 p.3
^Spillane p.133; James W. Sheahan and George P. Upton The Great Conflagration. Chicago: Its Past, Present and Future. Union Publishing Co., Chicago. p.354; Julius Bauer & Co. acted as Knabe's Northwestern agent as well as their New York agent from 1862 until 1873
^William Nordhoff "Improvement in Pianos" United States Patent no. 57,257 April 14, 1866
^James Parton "The Piano in the United States" The Atlantic monthly vol.20 no.117 p.93
^"The Piano Forte Manufactory of Knabe & Co., Baltimore" Debow's review, Agricultural, commercial, industrial progress and resources. vol.2, no.1, p. 71-73
^"The Great Southern Piano Manufactory" Debow's review, Agricultural, commercial, industrial progress and resources. vol.1, no. 2, 1866, p. 209
^"Piano-fortes" The Great Industries of the United States: Being an Historical Summary of the Origin, Growth, and Perfection of the Chief Industrial Arts of this Country J. Burr & Hyde, Hartford. 1873. p331
^"The Knabe Piano" The Columbia Spy Columbia, Pennsylvania August 20, 1870 p.3
^International Exhibition, 1876. Official Catalogue John R. Nagle and Company, Philadelphia. 1876. p.265
^"Piano Award – Knabe Victory – Unanimous Award of Highest Honors to William Knabe & Co." New York Times October 1, 1876; all of the awards had equal value, but each included specific comments from the judges that the exhibitors could publish as they saw fit – "The Centennial Awards" New York Times September 28, 1876.
^"A Knabe in the White House" New York Times December 16, 1882 p.5
^Daniel Spillane History of the American Pianoforte D. Spillane, New York. 1891. p.132
^Henry Hall, ed. America's Successful Men of Affairs vol.2 The New York Tribune, New York. 1896 p.477
^Alfred Dolge Pianos and their Makers vol.2, Covina Publishing Company, Covina CA, 1913. p.121.
^"Knabe Company Extension – Bond Issue of $450,000 Made by Manufacturers" New York Times May 2, 1903
^"Three Generations of Piano Manufacturers" McClure's Magazine vol.26, The S. S. McClure Co., New York and London. 1906 advertising section p.16m-16n
^"Inspired Handiwork" The American Monthly Review of Reviews vol.24 1906. advertising section p.41
^"Piano Makers form $12,000,000 Combine" New York Times June 10, 1908 p.5
^"Knabe Bros. Co." The Newark Advocate Newark, OH, May 5, 1911 p.12
^William N. Osborne Music in Ohio Kent State University Press, Kent Ohio 2004 p.494
^advertisement The Newark Advocate February 25, 1913 p.7
^Six, Baer & Fuller Dry Goods Co. et al. v. American Piano Co. (211 Fed. Rep., 271.) 8th Circuit, November 28, 1913 The Trade-Mark Reporter vol. 4, The United States Trade-mark Association, New York. 1914 p.246
^"Fires" The American Library Annual, 1913 Publishers' Weekly, 1913, New York. p.38; the value given is $100,000
^"Knabe Brothers Piano Company" The Newark Advocate February 29, 1912 p.8
^"Receiver for Piano Company" Van Wert Daily Bulletin Van Wert, OH December 9, 1916 p.1; the note was for $100,000
^"Pianomakers in Bankruptcy" New York Times December 31, 1916. p.17; Their combined liabilities were more than $660,000 and their declared assets amounted to $476.38
^"E. J. Knabe Found Dead" New York Times September 28, 1924 p.S8
^"William Knabe, 66, Piano Manufacturer" Special to the New York Times March 1, 1939 p.27
^"Piano Industry to be Converted" New York Times June 22, 1942 p.23
^"Piano Producers Optimistic on Fall" New York Times July 28, 1949
^"Aeolian-American Merger" New York Times May 18, 1951. p.54
^Trademark Assignment Details, Reel/Frame 0053/0478 May 21, 1959; Reports of the Tax Court of the United States Government Printing Office, Washington, D. C., 1969. p.110
^Susan Caust Farrell, Directory of Contemporary American Musical Instrument Makers University of Missouri Press, Columbia MO 1981 p. 2