Altec Lansing EQ networks

[bonosurf]

I found these two networks in several 9846B cabinets: 391039 & 391226. They are esentially the same components and both networks appear to be HF "boost" shelving filters. Anyone have the specs on these assemblies?

[Art J.]

The 9846 used the 30904 attenuator equalizer network as shown in the diagram.
The 9846B used the 30923 with the amp.
Your serial numbers mean (Manufacturer number) (year) (week of manufacture)
-391-(Altec) -0-(1970)-39-(39th week)
& 391-(Altec)- 2 -(1972) -26 -(26th week)

Its purpose was essentially to make a smoother match between the 411 and the horn.
Its also known for taming down the horn in close quarters...........

[bonosurf]

Here is a plot of the filter network - assume an 8 ohm load and F=500 to 20000 Hz