Large "Voice of the Theater" Driver Chart

                          High Frequency Drivers
Model
Tenure
Original
Impedance
AES Power
Rating
Recommended
Replacement
Diaphragm
Comments

       288

1945-1949 20-22 Ohms 20 Watts 20221 24 ohms
25885 16 ohms
25884   8 ohms
First permanent magnet high quality theater high frequency driver. Magnetic shorting ring must be removed by Altec  factory before installing new diaphragm.
         288B 1949-1959 20-22-24Ohms 20 Watts Same as above Has deeper top plate than 288, otherwise similar to 288. Also must be converted by Altec before rediaphragming.
   288C
1959-1972 24 Ohms 20 Watts Same as above Similar to 288B, has no shorting ring, however ought to be remagnetized.

288D
1959-1970 16 Ohms 20 Watts Same as above 16 Ohm version of 288C
         288-8E 1970-1972   8 Ohms 20 Watts 25884 8 Ohms
50 Watts
8 Ohm version of 288C.

   288G Series 

1972-1979 8, 16, 32 Ohms 20 Watts 34400 32, 20W
25885 16, 50W
25884   8, 50W
Improved larger Alnico magnet models, has 2 db more sensitivity over previous units. Also 2 db more output over 10KHZ.
  288H Series  1979-1980 Same as above 20 watts Same as above Has new radial phasing plug, some increase of extreme high frequency performance over 288G, same magnet. Last of Alnico magnet models.
  288K Series 1980-1987 Same as above 20 watts Same as above Ferrite magnet version of 288H. Same specifications.
  288L Series 1987----- 8,16 Ohms 20 watts 25885 16, 50W
25884   8, 50W
Virtually identical to 288K. Built to more stringent tolerance.
    291-16A


291-16B

1968-1973 16 Ohms 40 watts 25885 16, 50W Composite diaphragm version of 288C. Has somewhat less high frequency performance and less transient response than 288s. Later 291s followed magnet development of 288s. Rediaphragm with 299 diaphragms.

     299A

1987----- 8, 16 Ohms 50 watts 25885 16, 50W
25884   8, 50W
Newest Altec high frequency driver. Has good sound of 288 with 2½ times the power handling. Costs less. Use this unit whenever possible. When rebuilding older 288s or 291s, use its diaphragm. 

Low Frequency Drivers


Model Tenure Original
Impedance
AES Power rating Recommended
replacement diaphragm
Comments

       515

1945-1955 16-20 Ohms 35 watts R515-16G, 75W
R515-  8G, 75W
Original 515, has great midrange, lacks low bass.
       515B
1955-1978 16 Ohms 75 Watts Same as above Has great low bass, impedance drops below 16 ohms in earlier versions at midrange. Later reconed units lack midrange. Recone with 515C series cones for bass horns will solve this problem. Works great in vented bass with standard cone.


515C

1978-1982 16 Ohms 75 Watts Same as above 16" frame version of 515B. has regular constant impedance voice coil, lacks mids in horn enclosures. Great vented box woofer. Same remedies apply as 515B, last Alnico magnet 515.
        515E 1982-1984 16 Ohms 75 Watts Same as above Ferrite magnet version of 515C. Lacks even more mids in horn enclosures. Don't use in larger VOT cabinets (210, 211). Great vented box woofer. Ok for A5, A7.

515G Series
1984----- 8, 16 Ohms 75 Watts Same as above Newest version of 515C. Built exclusively for horn enclosures. Don't use in vented or sealed boxes. Works better than any previous model. Great woofer.