Ever since a couple of dear friends surprised me with a vintage Conn tuba back in February, I've enjoyed digging into the history of Conn basses - and quite a history it is!
Here is my attempt at a complete list of the bass instruments built by Conn over the years, which is pulled together from various sources, including The Conn Loyalist and Horn-U-Copia websites, the many Conn publications posted by Mark Overton at saxophone.org, and a complete 1921 Conn catalog shared by Mark Jones at C. G. Conn Postcards and Ephemera. At some point, I hope to visit the National Music Museum to complete my Conn research and clean up some of the data below, but that is still a ways off. This at least gets the tuba-ball rolling!
The dates listed are not complete, but represent what I could piece together from the sources mentioned above. TA = top action, and FA = front action. I also included weight and bell diameter, where I could.
Upright Tubas (before the use of factory numbers)
Conic Clear Bore Valve (1878) / Patent Light Valve (1881) / Equa-Tone Valve (1882) / Ultimatum Models (1885)
1881-1885 Eb Bass, Short Pattern (3 or 4 valves, TA, 10 lbs)
1881-1885 Bb Bass, Short Pattern (3 valves, TA)
1881-1885 BBb Bass, Short Pattern (3 or 4 valves, TA, 15 lbs)
New Perfection Models
1885-188? Eb Bass, Short Pattern (3 valves, TA)
1885-188? Bb Bass, Short Pattern (3 valves, TA)
Wonder Valve Models
1886-1889 Eb Bass (3 or 4 Wonder valves, TA, 10 lbs)
1886-1889 Bb Bass (3 or 4 Wonder valves, TA)
1886-1889 Double Bb Bass (3 Wonder valves, TA, 13 lbs, 14.5 in)
American Models (all FA, an innovation)
1888-1909 Eb Bass (3 or 4 valves, 10 lbs, 14.5 in)
1889-1894 Bb Bass (3 or 4 valves)
1889-1909 Monster BBb Bass (3 or 4 valves, 20.5 lbs, 17.5 in)
1899-1909 Giant Eb Bass (3 or 4 valves)
Wonder Models (all TA, with new slides, an innovation)
1890-1909 Eb Bass (3 or 4 valves, 11 lbs, 14.5 in)
1890-190? Bb Bass (3 or 4 valves)
1890-1909 Monster BBb Bass (3 or 4 valves, 20.5 lbs)
1899-1909 Giant Eb Bass (3 or 4 valves)
Wonderphone Models (with forward-facing bells, an innovation)
1908-1923 Standard Eb Bass (3 or 4 valves, TA)
1908-1923 Standard Eb Bass (3 or 4 valves, FA)
1908-1923 Monster BBb Bass (3 or 4 valves, TA)
1908-1923 Monster BBb Bass (3 or 4 valves, FA)
1908-1923 Giant Eb Bass (3 or 4 valves, TA)
1908-1923 Giant Eb Bass (3 or 4 valves, FA)
1910-19?? Jumbo BBb Bass (3 or 4 valves, FA)
1913-19?? Medium/Professional Eb Bass (3 or 4 valves, TA)
1913-19?? Medium/Professional Eb Bass (3 or 4 valves, FA)
Perfected Models (new lead pipe w/tuning slide, an innovation)
1910-1912 Eb Bass (3 or 4 valves, TA)
1910-1912 Eb Bass (3 or 4 valves, FA)
1910-1912 Monster BBb Bass (3 or 4 valves, TA)
1910-1912 Monster BBb Bass (3 or 4 valves, FA)
1910-1912 Giant or Contra Eb Bass (3 or 4 valves, TA)
1910-1912 Giant or Contra Eb Bass (3 or 4 valves, FA)
1911-19?? BBb Bass, Jumbo size (3 or 4 valves)
New Invention Models (similar to the previous models)
1911-19?? Bb Bass (3 valves, TA)
1911-1918 Eb Bass, Standard (3 or 4 valves, TA, 12.5 lbs, 14 in)
1911-1918 Eb Bass, Standard (3 or 4 valves, FA, 12.5 lbs, 14 in)
1911-1918 Eb Bass, Giant or Contra (3 or 4 valves, TA, 16 lbs, 20 in)
1911-1918 Eb Bass, Giant or Contra (3 or 4 valves, FA, 16 lbs, 20 in)
1911-1918 Monster BBb Bass (3 or 4 valves, TA, 18 lbs, 21 in)
1911-1918 Monster BBb Bass (3 or 4 valves, FA, 18 lbs, 21 in)
1911-19?? "Jumbo" Model BBb Bass (3 or 4 valves, TA, 25 lbs, 22 in)
1911-19?? "Jumbo" Model BBb Bass (3 or 4 valves, FA, 25 lbs, 22 in)
1913-1918 Eb Bass, Professional (3 or 4 valves, TA, 13 lbs, 16 in)
1913-1918 Eb Bass, Professional (3 or 4 valves, FA, 13 lbs, 16 in)
1913-1918 Orchestra Grand BBb Bass (4 valves, FA, 25 lbs, 22 in)
1913-1918 Orchestra Grand CC Bass (4 valves, FA)
Upright Tubas (after the use of factory numbers)
Factory numbers begin appearing in catalogs around 1921, and they eventually included a five letter "Code Word," which corresponds to the "J" in the number; those will be included where they are known. Also, LP = low pitch, HP = high pitch, "sa" = short action valves, TA = top action, and FA = front action. Finally, you'll notice that Conn reused many factory numbers, which is confusing!
In Order of Factory Numbers:
02-J 1919-1931 New Wonder Standard Eb (LP, 3v, TA, 12 lbs, 16 in, "japan")
02-J 1971-19?? CC Tuba (4v, FA)
03-J 1919-1931 New Wonder Standard Eb (HP, 3v, TA, 12 lbs, 16 in, "jaunt")
03-J 1986-19?? CC Tuba (4v, FA, 18 lbs, 18 in; replaced 02-J?)
04-J 1919-1934 New Wonder Standard Eb (LP, 3v, FA, 12 lbs, 16 in, "jelly")
04-J 1971-19?? BBb Tuba (4v, FA, 21 lbs, 16 in)
05-J 1919-1931 New Wonder Standard Eb (HP, 3v, FA, 12 lbs, 16 in, "jenny")
05-J 1986-today BBb Tuba (4v, FA, 20 lbs, 18 in; replaced 04-J?)
06-J 1921-19?? New Wonder Standard Eb (LP, 4v, TA)
06-J 1924-1934 "Junior" Model Bass (LP, 3v, TA, 15 lbs, 18 in, "jugal")
07-J 1921-19?? New Wonder Standard Eb (HP, 4v, TA)
07-J 1924-1931 "Junior" Model Bass (HP, 3v, TA, 15 lbs, 18 in, "jyrzo")
08-J 1921-19?? New Wonder Standard Eb (LP, 4v, FA)
09-J 1921-19?? New Wonder Standard Eb (HP, 4v, FA)
10-J 1919-1928 New Wonder Prof. Eb (LP, 3v, TA, 14.5 lbs, 18 in, "jetty")
10-J 196?-1971 BBb Bass Tuba (3v, TA, 16 lbs, 18 in)
11-J 1919-1928 New Wonder Prof. Eb (HP, 3v, TA, 14.5 lbs, 18 in, "jewel")
11-J 1958-1960 BBb Tuba (3v, FA)
12-J 1919-1931 New Wonder Prof. Eb (LP, 3v, FA, 14.5 lbs, 18 in, "jiffy")
12-J 1986-1988 BBb Tuba (3v, FA, 16 lbs, 18 in)
13-J 1919-1928 New Wonder Prof. Eb (HP, 3v, FA, 14.5 lbs, 18 in, "jimmy")
14-J 1921-19?? New Wonder Prof. Eb (LP, 4v, TA)
14-J 1955-1964 Director Bass in Eb (3v, TA, 13 lbs, 16 in)
15-J 1921-19?? New Wonder Prof. Eb (HP, 4v, TA)
15-J 1986-1988 BBb Convertible Tuba (3v, FA, 17 lbs, 18 in)
16-J 1921-19?? New Wonder Prof. Eb (LP, 4v, FA)
16-J 1937-1939 Eb Recording Bass (3v, FA)
17-J 1921-19?? New Wonder Prof. Eb (HP, 4v, FA)
18-J 1919-1926 New Wonder Giant Eb (LP, 3v, TA, 17 lbs, 20 in, "jingo")
19-J 1919-1926 New Wonder Giant Eb (HP, 3v, TA, 17 lbs, 20 in, "joint")
20-J 1919-1928 New Wonder Giant Eb (LP, 3v, FA, 17 lbs, 20 in, "joist")
20-J 1934-1980 BBb Recording Bass (bell front, 3v-sa, TA, 29 lbs, 24 in, "jalit")
21-J 1919-1928 New Wonder Giant Eb (HP, 3v, FA, 17 lbs, 20 in, "joker")
21-J 1957-1971 Artist Recording Bass in BBb (bell up, 3v-sa, TA, 29 lbs, 24 in)
22-J 1921-19?? New Wonder Giant Eb (LP, 4v, TA)
22-J 1934-1941 BBb Recording Bass (bell front, 3v-sa, FA, 29 lbs, 24 in)
23-J 1921-19?? New Wonder Giant Eb (HP, 4v, TA)
24-J 1919-1926 New Wonder Giant Eb (LP, 4v, FA, 19 lbs, 20 in, "jorum")
24-J 1934-1971 BBb Recording Bass (bell front, 4v-sa, TA, 30 lbs, 24 in)
25-J 1919-1926 New Wonder Giant Eb (HP, 4v, FA, 19 lbs, 20 in, "jolly")
25-J 1957-1971 Artist Recording Bass in BBb (bell up, 4v-sa, TA, 30 lbs, 24 in)
26-J 1919-1931 New Wonder Monster BBb (LP, 3v, TA, 25.52 lbs, 22 in, "joule")
26-J 1934-1941 BBb Recording Bass (bell front, 4v-sa, FA, 30 lbs, 24 in)
27-J 1919-1931 New Wonder Monster BBb (HP, 3v, TA, 25.5 lbs, 22 in, "joust")
28-J 1919-1928 New Wonder Monster BBb (LP, 3v, FA, 25.5 lbs, 22 in, "judge")
29-J 1919-1928 New Wonder Monster BBb (HP, 3v, FA, 25.5 lbs, 22 in, "juice")
30-J 1921-19?? New Wonder Monster BBb (LP, 4v, TA)
30-J 1932-1934 De Luxe Recording Bass in BBb (bell front, 3v, TA)
31-J 1921-19?? New Wonder Monster BBb (HP, 4v, TA)
32-J 1919-1931 New Wonder Monster BBb (LP, 4v, FA 27 lbs, 22 in, "julep")
32-J 1932-1934 De Luxe Recording Bass in BBb (bell front, 3v, FA)
33-J 1919-1928 New Wonder Monster BBb (HP, 4v, FA 27 lbs, 22 in, "juxta")
34-J 1919-1923 New Wonder Orchestra Grand BBb (LP, 4v, FA, 26 lbs, 23 in)
34-J 1928-1934 De Luxe Rec. Bass, BBb (bell up, 4v, FA, 32 lbs, 26 in, "jaker")
35-J 1921-19?? New Wonder Orchestra Grand BBb (HP, 4v, FA)
36-J 1919-1923 New Wonder Orchestra Grand CC (4v, FA, 26 lbs, 26 in)
36-J 1928-1938 De Luxe Rec. Bass, BBb (bell front, 4v, FA, 32 lbs, 26 in, "jakpa")
44-J 1921-1926 New Wonder Bb (LP, 3v, TA)
45-J 1921-1926 New Wonder Bb (HP, 3v, TA)
46-J 1924-1926 New Wonder Standard Bb (LP, 3v, FA, 7 lbs, 12 in, "jabir")
47-J 1924-1926 New Wonder Standard Bb (HP, 3v, FA, 7 lbs, 12 in, "jabot")
48-J 1921-1926 New Wonder Phonograph CC (LP, 4v, FA, 18 lbs, 15 in, "juror")
52-J 1926-19?? Phonograph BBb, small bore (bell front, LP, 4v, FA, 16 in)
52-J 1996-2011 CC Tuba (5v, FA, 18 in)
54-J 1996-2011 CC Tuba (5v, FA, 19 in)
56-J 1996-2011 CC Tuba (5v, FA, 20 in)
80-J 1924-1934 Monster BBb Wonderphone (LP, 3v, FA, 25 lbs, 23 in, "jacky")
81-J 1924-1928 Monster BBb Wonderphone (HP, 3v, FA, 25 lbs, 23 in, "jason")
82-J 1924-1931 Monster BBb Wonderphone (LP, 4v, FA, 27 lbs, 23 in, "jaded")
83-J 1924-1926 Monster BBb Wonderphone (HP, 4v, FA, 27 lbs, 23 in, "jerky")
84-J 1924-1926 New Wonder Symphony CC (LP, 4v, FA, 20 lbs, 20 in, "jagua")
85-J 1924-1926 New Wonder Symphony CC (HP, 4v, FA, 20 lbs, 20 in, "jaina")
86-J 1924-1926 NW Symphony Grand CC (LP, 4v, FA, 20 lbs, 20 in, "jargo")
87-J 1924-1926 NW Symphony Grand CC (HP, 4v, FA, 20 lbs, 20 in, "jocos")
Donatelli Model?
Bell-Front (Recording Bell) Tubas Over the Years:
1908-1914
Wonderphone Standard Eb Bass (3 or 4 valves, TA)
1908-1914 Wonderphone Standard Eb Bass (3 or 4 valves, FA)
1908-1914 Wonderphone Monster BBb Bass (3 or 4 valves, TA)
1908-1914 Wonderphone Monster BBb Bass (3 or 4 valves, FA)
1908-1914 Wonderphone Giant Eb Bass (3 or 4 valves, TA)
1908-1914 Wonderphone Giant Eb Bass (3 or 4 valves, FA)
1910-19?? Wonderphone Jumbo BBb Bass (3 or 4 valves, FA)
1913-19?? Wonderphone Medium/Professional Eb Bass (3 or 4 valves, TA)
1913-19?? Wonderphone Medium/Professional Eb Bass (3 or 4 valves, FA)
1921-1926 48-J New Wonder Phonograph CC (4v, FA, 18 lbs, 15 in, "juror")
1924-1934 80-J, Monster BBb Wonderphone (LP, 3v, FA, 25 lbs, 23 in, "jacky")
1924-1928 81-J, Monster BBb Wonderphone (HP, 3v, FA, 25 lbs, 23 in, "jason")
1924-1931 82-J, Monster BBb Wonderphone (LP, 4v, FA, 27 lbs, 23 in, "jaded")
1924-1926 83-J, Monster BBb Wonderphone (HP, 4v, FA, 27 lbs, 23 in, "jerky")
1926-19?? 52-J, Phonograph BBb, small bore (LP, 4v, FA, 16 in)
1928-1934 34-J, De Luxe Rec. Bass, BBb (bell up opt., 4v, FA, 32 lbs, 26 in, "jaker")
1928-1938 36-J, De Luxe Rec. Bass, BBb (4v, FA, 32 lbs, 26 in, "jakpa")
1932-1934 30-J, De Luxe Recording Bass in BBb (3v, TA)
1932-1934 32-J, De Luxe Recording Bass in BBb (3v, FA)
1934-1980 20-J, BBb Recording Bass (3v-sa, TA, 29 lbs, 24 in, "jalit")
1934-1941 22-J, BBb Recording Bass (3v-sa, FA, 29 lbs, 24 in)
1934-1971 24-J, BBb Recording Bass (4v-sa, TA, 30 lbs, 24 in)
1934-1941 26-J, BBb Recording Bass (4v-sa, FA, 30 lbs, 24 in)
1937-1939 16-J, Eb Recording Bass (3v, FA)
1957-1971 21-J, Artist Rec. Bass in BBb
(bell up option, 3v-sa, TA, 29 lbs, 24 in)
1957-1971 25-J, Artist Rec. Bass in BBb
(bell up option, 4v-sa, TA, 30 lbs, 24 in) C. G. Conn with a Wonderphone Monster BBb Bass in 1908
Helicons (before the use of factory numbers)Clear Conic Bore Valve (1878) / Equa-Tone Valve (1882) / Ultimatum Models (1995)
1880-1885 Eb Bass Helicon (3 or 4 valves)
1880-1885 Bb Bass Helicon (3 or 4 valves)
1880-1885 BBb Bass Helicon (3 or 4 valves)
New Perfection Models
1885-1887 Eb Bass Helicon (3 Equa-Tone valves)
1885-1887 Bb Bass Helicon (3 Equa-Tone valves)
1885-1887 BBb Bass Helicon (3 Equa-Tone valves)
Wonder Valve Models (and their successors, up to 1913)
1888-1910 Eb Bass Helicon (3 or 4v)
1888-1900 Bb Bass Helicon (3 or 4v)
1888-1910 Monster or Giant BBb Bass Helicon (3 or 4v, 20 lbs, 19.5 in)
1911-1910 Giant Eb Bass Helicon (3 or 4v)
New Invention Models
1911-1918 Eb Bass Helicon (3 or 4v)
1911-1918 Monster BBb Bass Helicon (3 or 4v)
1911-1918 Giant Eb Bass Helicon (3 or 4v)
1919-1922 New Wonder Medium/Professional Eb Helicon (3 or 4v)
Helicons (after the use of factory numbers)
Factory numbers begin appearing in catalogs around 1921 and eventually came with a five letter "Code Word" that corresponds to the "K" in the number. I've included those, when they are known, along with the weight and bell diameter.
02-K 1919-1931 New Wonder Standard Eb (LP, 3v, 14 lbs, 16 in, "kamis")
03-K 1919-1931 New Wonder Standard Eb (HP, 3v, 14 lbs, 16 in, "kayak")
04-K 1921-19?? New Wonder Eb (LP, 4v)
05-K 1921-19?? New Wonder Eb (HP, 4v)
06-K 1919-1926 New Wonder Medium Eb (LP, 3v)
07-K 1919-1926 New Wonder Medium Eb (HP, 3v)
08-K 1921-19?? New Wonder Medium Eb (LP, 4v)
09-K 1921-19?? New Wonder Medium Eb (HP, 4v)
10-K 1919-1928 New Wonder Giant Eb (LP, 3v, 18.5 lbs, 20 in, "knave")
11-K 1919-1927 New Wonder Giant Eb (HP, 3v, 18.5 lbs, 20 in, "knead")
12-K 1921-19?? New Wonder Giant Eb (LP, 4v)
13-K 1921-19?? New Wonder Giant Eb (HP, 4v)
30-K 1919-1931 New Wonder Monster BBb (LP, 3v, 21 lbs, 22 in, "krone")
31-K 1919-1931 New Wonder Monster BBb (HP, 3v, 21 lbs, 22 in, "kutch")
32-K 1919-1926 New Wonder Monster BBb (LP, 4v, 21 lbs, 22 in)
33-K 1919-1926 New Wonder Monster BBb (HP, 4v, 21 lbs, 22 in)
Helicon production seems to have ended after 1931.
Sousaphones (before the use of factory numbers)
Wonder Models (with upright bells, the original design)
1898-1912 Wonder Monster BBb Helicon Sousaphone (4v, 33 lbs)
1902-1912 Wonder BBb Helicon Sousaphone (3v)
1907-1912 Giant Eb Bass Sousaphone (3 or 4v)
Wonderphone Models (with forward-facing bells, an innovation)
1908-1910 Wonderphone Helicon Eb Bass (3 or 4v)
1908-1910 Wonderphone Helicon Monster BBb Bass (3 or 4v)
1908-1910 Wonderphone Helicon Giant Eb Bass (3 or 4v)
New Invention Models (with either original bell up, BU, or bell front, BF, which came to be called "Sousaphone Grands")
1911-1918 Monster BBb Bass Sousaphone (BU, 3 or 4v, 21-22 in)
1911-1918 Giant Eb Bass Sousaphone (BU, 3v)
1911-1918 Monster BBb Wonderphone Helicon (Sousaphone Grand, BF, 3 or 4v)
1911-1918 Giant Eb Wonderphone Helicon (Sousaphone Grand, BF, 3 or 4v)
1913-1918 Eb Bass Sousaphone (BU, 3 or 4v)
1917-19?? Jumbo Sousaphone Grand in BBb (3v?)
1920-1922 New Wonder Medium Eb Sousaphone (BU, 3 or 4v)
Herman Conrad with Conn's first Sousaphone in 1898
Sousaphones (after the use of factory numbers)Factory numbers begin appearing in catalogs around 1921, and they eventually included a five letter "Code Word," which corresponds to the "K" in the number; those will be included where they are known. Also, BU = bell up (original Sousaphone design), BF = bell front (first called Wonderphones, then, starting in 1913, called Sousaphone Grands), LP = low pitch, HP = high pitch, and "sa" = short action valves. Finally, you'll notice that Conn reused some factory numbers, which is confusing!
In Order of Factory Numbers:
10-K 1962-1971 Artist Sousaphone in BBb (BF, 3v, 28 lbs, 26 in)
14-K 1921-19?? New Wonder Eb (BU, LP, 3v)
14-K 1955-1971 Director Sousaphone in BBb (BF, 3v, 23 lbs, 24 in)
15-K 1921-19?? New Wonder Eb (BU, HP, 3v)
16-K 1921-19?? New Wonder Medium Eb (BU, LP, 4v)
17-K 1921-19?? New Wonder Medium Eb (BU, HP, 4v)
18-K 1919-1927 New Wonder Giant Eb (BU, LP, 3v, 20 lbs, 20 in, "kneel")
19-K 1919-1926 New Wonder Giant Eb (BU, HP, 3v, 20 lbs, 20 in, "knell")
20-K 1919-1926 New Wonder Giant Eb (BU, LP, 4v, 21.5 lbs, 20 in, "knife")
20-K 1935-2022 BBb Sousaphone Grand (BF, 3v-sa, 30.5 lbs, 26 in, "knife")
21-K 1919-1926 New Wonder Giant Eb (BU, HP, 4v, 21.5 lbs, 20 in, "knock")
21-K 1957-1964 Artist Sousaphone in BBb (BU, 3v-sa, 24 in)
22-K 1921-19?? Medium Eb Sousaphone Grand (BF, LP, 3v)
22-K 1941-19?? BBb Sousaphone, lighter in weight (BF, 3v-sa, 24 in)
22-K 1964-1986 BBb Fiberglass Sousaphone (BF, 3v-sa, 23 lbs, 26 in)
23-K 1921-19?? Medium Eb Sousaphone Grand (BF, HP, 3v)
24-K 1921-19?? Medium Eb Sousaphone Grand (BF, LP, 4v)
25-K 1921-19?? Medium Eb Sousaphone Grand (BF, HP, 4v)
26-K 1920-1969 New Wonder Giant Eb (BF, LP, 3v, 23 lbs, 23 in, "knoll")
27-K 1920-1931 New Wonder Giant Eb (BF, HP, 3v, 23 lbs, 23 in, "knout")
28-K 1920-1931 New Wonder Giant Eb (BF, LP 4v, 24.5 lbs, 23 in, "kodak")
29-K 1919-1931 New Wonder Giant Eb (BF, HP, 4v, 24.5 lbs, 23 in, "koran")
32-K 1929-1943 New Junior BBb Sousaphone (BF, LP, 3v, 26 lbs, 24 in)
34-K 1919-1926 New Wonder Monster BBb (BU, LP, 3v, 25.5 lbs, 22 in, "kopra")
35-K 1919-1926 New Wonder Monster BBb (BU, HP, 3v, 25.5 lbs, 22 in, "kitch")
36-K 1919-1926 New Wonder Monster BBb (BU, LP, 4v, 27 lbs, 22 in, "klept")
36-K 1960-20?? BBb Fiberglass Sousaphone (BF, 3v, 17-18 lbs, 24-26 in)
37-K 1919-1926 New Wonder Monster BBb (BU, HP, 4v, 27 lbs, 22 in, "krieg")
38-K 1919-1941 New Wonder Monster BBb (BF, LP, 3v, 29 lbs, 24 in, "kiter")
39-K 1919-1938 New Wonder Monster BBb (BF, HP, 3v, 29 lbs, 24 in, "kinka")
40-K 1919-1931 New Wonder Monster BBb (BF, LP, 4v, 31 lbs, 24/26 in, "ketch")
40-K 2016-2022 New version of previous 40-K (BF, 4v, 31 lbs, 26 in)
41-K 1919-1931 New Wonder Monster BBb (BF, HP, 4v, 31 lbs, 24/26 in, "keeve")
42-K 1924-1926 NW Monster BBb Jumbo (BU, LP, 3v, 38 lbs, 26 in, "kenda")
44-K 1924-1926 NW Monster BBb Jumbo (BU, LP, 4v, 40 lbs, 26 in, "kenot")
46-K 1924-1931 NW Monster BBb Jumbo (BF, LP, 3v, 40 lbs, 28 in, "keros")
48-K 1924-1934 NW Monster BBb Jumbo (BF, LP, 4v, 43 lbs, 28 in, "kilta")
Original bell up Sousaphone design ceased production by 1927, although it was revived again, for the new 21-K, from 1957-1964.
Conn advertisement from 1952, in The Instrumentalist
The large paragraph in the black box in the ad above is incorrect. It is not true that "Conn made the world's first sousaphone," whether in 1908 or any other year; J. W. Pepper did, in 1895, which was three years prior to Conn introducing his version to the world in 1898 (see image above). However, Sousa did prefer Conn Sousaphones, and stuck with them from that point on.
Conn 20K and 40K today, at the Conn-Selmer website