
 
 
 Gary R. Jones 
 
 1000 W. Wilshire Blvd. Suite 360 
 Oklahoma City, OK 73116 
 Tel: 405-848-3108 
 Fax: 405-848-3217 
 
 LARGE FORMAT HF COMPRESSION DRIVERS 
Early 288 and 291 series high frequency drivers used Alnico motors, most with a 
circumferential phase plug. Later 288, 291, and 299 series drivers used ceramic 
motors with Tangerine® phase plugs. All use 2.8" voice-coils and the diaphragm 
assemblies interchange. (The 290 series diaphragm will not interchange) 
 
Three types of diaphragm assemblies have been manufactured. You can verify 
which diaphragm you have by inspection. The "Symbiotik" diaphragm has a 
Kapton (plastic) surround with an aluminum dome (500Hz - 12kHz). The 
aluminum and “Pascalite” diaphragms (500Hz - 16kHz) are all aluminum or 
aluminum alloy. The "Pascalite" diaphragm has the sonic quality of the aluminum 
diaphragm and handles twice as much power. 
 
Part #25884 (8 ohms) or Part #25885 (16 ohms) are recommended as 
replacements for all drivers listed below . . . 
 288B Aluminum, 24 ohms. Direct replacement not available, 
a modification can allow current diaphragms to fit. 
288C Aluminum, 24 ohms. Original Altec part# 20221 
288-8E,G,H,K,L Aluminum, 8 ohms. Original Altec part# 23763 
288D 
288-16G,H,K,L Aluminum, 16 ohms. Original Altec part# 23834 
288-32G,H,K Aluminum, 32 ohms. Direct replacement not available 
291-8K,L Symbiotik, 8 ohms. Original Altec part# 25692 
291-16 
A,B,C,K,L Symbiotik, 16 ohms. Original Altec part# 21531 
299-8A Pascalite, 8 ohms. Original Altec part# 25884 
299-16A Pascalite, 16 ohms. Original Altec Part# 25885