Progress report here on replacing the crossovers and adding the Altec 30923 attenuation equalizer network as an option. I knew I would be building the crossover from scratch but wanted to be sure of the makeup of the original crossover, plus I wanted to maintain use of the l-pad for authenticity.
Below is what you see after drilling out the spot welds on the crossover can. That is firm yet slightly flexible black something in there and I had been told here to try 200 degrees for a couple hours. I did it on the BBQ in a tin pan and never got to the melt point. After about an hour the cardboard surround allowed me to pull out the whole thing and peel it apart by hand.
The two inductors side by side surprised me, I thought that was a no-no. The box above them houses the capacitors encased in wax.
The black stuff, below, peeled away in chunks and was playable enough about about an our to pull wires away from it.
There's a crossover in there somewhere:
Interesting to me that the caps have color-coded wire. Red for one, black for the other.
It ain't the prettiest thing, but I am so glad to say that it works, and does just what my ears were hoping for. Outside of the blue box in the image below is the rebuild of the N-800F crossover. In the blue box is the 30923 attenuator with the output for the crossover to the tweeter running through the attenuator, the red and black wires coming in at the bottom. Those wires could be connected directly to the tweeter to remove the attenuator from the circuit. But I am leaving it connected for a while as I like what it does. Previously the horn just seemed a little harsh (and I am on old 1970's Sansui solid state and (ahem) listen to CDs. I didn't spend more than an hour or two listening to these speakers previously, trying to get a sense of them. With the attenuator I find the bass more present and voices more ... listenable?
The speakers are all buttoned up for the time being. I want to spend some time with them They currently replace a pair of Bose 901s that I've had for a few months, and those are parked on top of a pair of Fisher XP-10s I still like, too. Of the three, these Altecs have better defined bass, and more of it at low volume which I really like. I haven't really cranked them yet, that will require moving some furniture to expand the space,
OH!!!!! The capacitors ALL had failed. Two were outside limits, and the other two could not hold a steady reading. The resistors were, as expected, in fine shape. I chose not to reuse the inductors but could have.
This is what Google had to say about the attenuator:
The Altec 30923 is a specialized network used to attenuate mid-frequencies
in Altec horn/driver combinations, specifically designed to smooth the "shout" or harshness from high-efficiency drivers. Often found in early-1970s Seeburg jukeboxes and used in vintage Altec systems, it bridges efficiency gaps between horns and woofers.
Key Uses and Functions:
- Shout Reduction: It reduces excessive forward midrange energy in drivers (e.g., 802D) connected to horns (e.g., 511B), resulting in a smoother, flatter response.
- Jukebox Application: It was frequently utilized in Altec speakers installed in Seeburg jukeboxes.
- Constant Directivity (CD) Correction: It can provide necessary equalization for horn drivers to balance the frequency response.
- Efficiency Balancing: The network helps attenuate the "ultra-efficient" horn drivers to better match the output level of the woofer.
The network provides a more balanced sound by attenuating the 1-6kHz range while leaving higher frequencies relatively intact.
their cnc. They are extremely heavy, solid as a rock. They sound incredible on my old Accuphase seperates.
