Altec Compression Driver ID

[kelossus]

Hi

I am considering an Altec build I have been offered a pair of Altec compression drivers. They are missing the back cap so I have no idea what model they are and the bloke selling them has no clue. Any guru's here able to identify them based on the below pictures? Also in the deal is a pair of the horns pictured below? Very little info on the net. Are these worthwhile or would you bin them and source a proper Altec horn?

https://www.stereo.net.au/forums/uploads/monthly_2021_06/450D3CED-DCD1-4B36-A1DC-8D4963CC681B.jpeg.2949589639ce8062ea4371fc91fe9c6e .jpeg
https://www.stereo.net.au/forums/uploads/monthly_2021_06/500D7D81-0B8E-48C5-AB0B-8C374CFBAB93.jpeg.ecfd4379daed0bc050e39a4b51c1561e .jpeg
https://www.stereo.net.au/forums/uploads/monthly_2021_06/10E8C4AE-6BF9-4E2E-9F96-F28745890D29.png.eb3b2fe7e36112184447b87cd90c56f7. png

[Earl K]

That driver is either a 902 , 908 or 909 model .

The 902 and 908 each have a 7/8" exit while the 909 has a 1" exit ( measure the size of the mesh screen , not the cardboard gasket ) .

The 902 has the most HiFi sounding diaphragm in it of the 3 models ( assuming it's stock and not replaced with some ChiCom junk ).

Without taking off that loading cap, there's no actual way to determine which model that driver is ( apart from mounting it a horn a running a frequency sweep >. since the 908 has the least amount of HF ) .

Great Plains Audio ( GPA in Oklahoma ) sell replacement diaphragms ( the 34647 - 8 ohm model for instance ) that are very HiFi sounding.
- GPA's diaphragms are made from the original Altec tooling ( purchased when Altec went bankrupt ) .


:)

[kelossus]

That driver is either a 902 , 908 or 909 model .

The 902 and 908 each have a 7/8" exit while the 909 has a 1" exit ( measure the size of the mesh screen , not the cardboard gasket ) .

The 902 has the most HiFi sounding diaphragm in it of the 3 models ( assuming it's stock and not replaced with some ChiCom junk ).

Without taking off that loading cap, there's no actual way to determine which model that driver is ( apart from mounting it a horn a running a frequency sweep >. since the 908 has the least amount of HF ) .

Great Plains Audio ( GPA in Oklahoma ) sell replacement diaphragms ( the 34647 - 8 ohm model for instance ) that are very HiFi sounding.
- GPA's diaphragms are made from the original Altec tooling ( purchased when Altec went bankrupt ) .


:)

Thanks Earl.

Is the performance of the CD degraded by not having the backing cover? I know the JBL CD's have the foam pad in the back and the Altec's appear to have felt.

[Earl K]

Removing the pictured loading cap and install the normal back cover allows the diaphragm a bit more movement ( iow; it can go a bit lower > at a reduced power rating ) .

GPA might sell you a pair of back-caps ( if you also buy diaphragms ) > just guessing though .

:)