University Adjustable Response Woofer

[Clipped and Shorn]

Anyone ever seen one of these vintage speakers. This one is a C-12, a 12 inch. It has two sets of terminals. There is a set of four on the bell housing around the magnet for choosing various possible crossover frequencies: (A-com, B- 5000, C-2000, and D 700). Then there are two terminals that go to the voice coil: marked 1 and 2.

The way I found it there are two wires coming from an 8 terminal crossover unit, a wire from #7 and a wire from #1. I have deduced that #1 is common, although in this box it is hooked to B-5000.

The wire from terminal #7 of the crossover goes directly to terminal 1 of the voice coil. There is a short jump wire from C-2000 to terminal 2 at the voice coil.

This does not make any obvious sense and I do not have any literature about how these old University home systems were set up. I do know that this woofer sounds liked it is crossed over too high for my ears.

I may do some trial and error alterations. This is dangerous since one's intuition may not jive with the proper circuitry and is based on the assumption that there would have been an obvious logic intended by the manufacturer when they stamped these specs on the unit itself, figuring that someone might have to deduce this without the instructions.

My intuition says that this bell housing gave you several crossover points to choose from before heading to the voice coil. In this case the present hook up as found makes no intuitive sense since the terminal marked Com is skipped altogether.

I would think that the Com from the crossover would hook to the Com on the speaker bell, and then you choose one of the crossover point terminals B,C, or D to jump to terminal 2 of the the voice coil. Terminal 1 of the voice coil hooks directly to the crossover terminal #7 which I assume is correct.

I will try hooking Com from the crossover to Com on the Speaker Bell. then I will choose terminal C from the Bell to go to terminal 2 of the voice coil, leaving terminal 1 of the voice coil still hooked up to terminal #7 of the crossover. You're with me right?

Now the other University Speaker that I rescued from going to the dump looks exactly like this one in the link below, and sounds pretty darned sweet hooked up to my Fisher 800C. I am going to use both this 15" and the 12" in the 3-way box. Together these two speakers cost me approximately nothing, so it is a fun project.

University 15" Triaxial

-c7s