9861 Crossover

[hmole]

I have a pair of 9861 HF crossovers as seen here: Altec 9861

It appears to be the HF crossover between the 2 HF units, but they are missing the C1 capacitor, apparantly scavenged by someone somewhere along the line.
oes anyone have an idea of what that capacitor might be? Or what the crossover points would be.
This is apparently the ELTORI Japanese line of Studio Monitors by Altec.
The stying of the crossover exactly matches a n n1285 crossover I have but it is vertically oriented intead of horizontally and is marked as made in Mexico.
This is a 2 way crossover, but lacks the large coil I would expect for LF, instead there are 2 modest coils.
This crossover was front mounted with HF and MF knobs, so I am thinking there was a secondary crossover internally or in the rear for the LF driver and that split off to this Driver.
I will attempt to post some photos later.

I am unsure what to do with these, I purchased them off Ebay in a box with some other random stuff.

The Component list for the 9861 may have been:
416
802
902-16hf or a 902-8a(The little one with the tiny Manta Ray as seen on some of the later 604s

Thanks
Harry

[hmole]

I posted photos over on Lansing Heritage as it is easier to post photos there.
Thanks
Harryphotos

[Art J.]

Hello Harry, I traced the circuit out and the missing capacitor is part
of the midrange bandpass. If it crosses at 1.2k as stated here

http://www.audio-heritage.jp/ALTEC/s...model9861.html

the missing capacitor would be 16uf, if into 8 ohms.

The crossover is complete,
E1, + input
E2,- input
E3, woofer +
E4, woofer -

mid and hi horns come off the center terminal of respective L-pad and black terminal.
Hope this helps. Art

[hmole]

Quite remarkable, Thank you, I didn't quite get to that page, And I couldn't have made that jump to the capacitor value from there anyway.
Thanks, now I have to complete the crossover and see what it sounds like, I am not sure I see the reasoning behind what Altec has done with this, it is 2 902 drivers, one 811, one little MR, does this make that much difference at the top end?
Bill @ GPA said that he had some of those little MRs, but I would be on my on attaching it to the driver.
Again thanks
Harry

[Art J.]

Yes, I don't understand the reasoning on the whole setup.
Horn loading a 411 to run it up to 1.2k has me scratching my head.
That capacitor value could be a few UF more to allow for some
overlap, depending on how they figured it. It would be interesting
to grab a complete set for study. Good luck with it.

[altec-man]

Hello Harry, I traced the circuit out and the missing capacitor is part
of the midrange bandpass. If it crosses at 1.2k as stated here

ALTEC LANSING ?X?s?[?J?[?V?X?e??Model9861?̎d?l ?A???e?b?N

the missing capacitor would be 16uf, if into 8 ohms.

The crossover is complete,
E1, + input
E2,- input
E3, woofer +
E4, woofer -

mid and hi horns come off the center terminal of respective L-pad and black terminal.

Art

Art J.

Did you happen to have a copy of the traced-out circuit.

Hope this helps.

[Art J.]

Art J.
Did you happen to have a copy of the traced-out circuit.

Hi Altec Man, that post was from 2 years ago but I remember it.
I just worked it out on a piece of scrap paper and that's as far as it got.
Hopefully Harry is still around and can tell us what become of it.

[altec-man]

Art J.

It would be good to know the component values and schematic layout so that I can add it to my A7-XS clones using the N1201-8A xover (Model 19).