Altec 1234C Crossover Specs Needed

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I bought a used pair of 1234C Altec crossovers, which should be 2-way 12db/octave at 1200 Hz. Although the components all looked stock, I believe they have been re-wired. Does anyone have the original wiring for the crossovers and the values for the inductors?

I reverse engineered the layout: the HF goes through 2 caps in series (6uF & 10uF), with one of the inductors paralelled across one of the 2 caps (nothing to ground). The LF signal goes through the other inductor and out to the speaker. Caps are stock Bennec, 6uF/100V, 10uF/100V, 28uF/125V. The 28uF/125V cap isn't connected. One inductor reads 23405, the other 24042.

Thanks!

[bfish]

The 1231 has the same setup, only the values are different. Mine came dissassembled in a coffee can, and I've had no luck deciding the OEM layout either. I recently noticed one of the OEM 604 XOs (on Jeff Markwartz site) has the same component count, but haven't had time to insert my values to check it.

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Forgot to mention, there are no resistors.

[bowtie427ss]

Here is a pic of an XO pulled from 1234 that i've known since new, i guarantee this is as wired from the factory with no changes or repairs from day one.

Note that at the input connectors the white wire/s are input + and black is input -, the entire aluminum plate the XO is constructed on is also input -

Two of the posts on the terminal strips are connected to the aluminum plate, including the red wire which goes to the red terminal of 808-8B, i believe this was done for phase correction.

The white wire out goes to 808-8B black terminal, the greenish/pale green wire out goes to 421 red, and the black wire goes to 421 black.

Let me know if you have any questions that i might be able to answer, and/or if you want the measured inductor values.

[bfish]

Works for me! YOU DA MAN BOWTIE!!

Really appreciate you going to the trouble.

[bowtie427ss]

No trouble at all................ glad i could help.

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Bowtie - Echoing Bfish here.... Thanks a TON for the clear photo! That's all that I really need to take these back to stock - move two wires and connect one end of the unused cap to ground & they're good to go...

If you know the inductor values, that would be nice to know, but not neccessary. I can draw up & post a schematic, so the values would help.

Thx again! jpg

[bowtie427ss]

The 23405's used as shunt across HF measure .495, and .492 milihenries respectively, not willing to guess if they'd have been spec'd at .49 or .5.

The 24042's used as low pass filter on woofer circuit measure 1.244, and 1.236 respectively, my guess is they were originally spec'd at 1.24mH

FWIW, both 10uF caps are junk well beyond 10% tolerance, the 28's were very close within a couple percent, and i could only check one of the 6uF as the other has a lead broken at the case, the one tested measured 6.5. YMMV, but i'd replace all caps.

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http://<img src=http://myweb.cableon...234Xover5.jpg>

[bfish]

Cool!

You do good jpg, jpg!

It could take a while to get to it, but would you mind if I copied that and pasted the values from my 1231s, so I could post it here as well?

I think a lot of these monitors saw installed use in HOW apps on 70V setups, hence the modded/disassembled examples. Also in my coffecan were a pair of pads and autoformers. A couple extra holes here and there too.

Come to think of it, I made a jpg myself of the plate label screenprint, so I could print and laminate some "unholy" new labels. Just have to paste in your numbers if you need it.