N1600 crossovers for my 604Ds

[alancohen]

I'm sure this has been discussed ad infinitum. I did a search and tried weeding through all the posts, but couldn't really distille the info down to the lastest and greatest.

I'm planning on dissecting the N1600s that came with the 604Ds. Apparently they are the same model number, but the chassis are a different size. I will likely want to replace the 16uF caps and pots if they look original. I don't think there is much else in there that might need attention.

I found this:



Is this the schematic I should be working from, or is there a better option?

[cradeldorf]

I don't have a clue. I wish you the best with whatever you do though. The last D's I saw had accordion surrounds, I would think they would be closer to an "E" than a "C" in character but I have no knowledge to back that up.

[donaldpatten]

Alan

This was drawn from the original N 1600 C that came with my 605A's . I am not really positive of the iron core 1 mH coil value.
The air core 1.4 mH with a parallel 15 Ohm resistor produce the same freq resp curves.
I think you will be OK with this Clone , or if you have the original XOs replace the 16 uF caps.
If you need +2 dB at 10kHz add a parallel 2 uF cap in parallel with the 5 ohm resistor to lift the highs.

Don

www.donpatten.com

[alancohen]

Thanks CD and Don. As far as I can glean, the 604D is identical to the 604C. I found this page:

Altec 604's - the various models

Where it says:

Altec 604D (looked just like 604C)
HF horn: 90h40v
X-over: 1600 Hz
Power: 35 watts, 50 peak
Impedance: 16 ohms
Weight: 40 lb.
Magnet: Alnico
Response: 30Hz - 22kHz
Free Air Resonance:
Frame: green hammer-tone
Cone: all paper cone
comment: 604D was in the 1957 catalog and was not superceded by the 605 until 1959
after that 604Ds were built one-off for special customers i.e. recording studios

I have read this same info elsewhere.

I have seen Jeffs XOs for 604Bs w/E cones as well as 8Gs, but nothing for the 604C. I like the idea of a little time delay.

To add to the confusion, mine were reconed by GPA. I guess I should call Bill and see what he might have put in there and what he would suggest. He's got XOs but they're $178/ea. I think I could come in at half that if I build my own.

Here's a pic of the cones on mine:

[cradeldorf]

It may look the same but that surround is gonna be way different. I just pushed on my E cone the other day and it moved very easily, barely any pressure made it move. Then I did the same thing to one of my C's it wouldn't barely budge. Personally If it was me I'd shoot for an E crossover alignment ala N1500. But that's just how I roll.

[alancohen]

Maybe I'll use Jeff's 604B w/E cone time delay w/EQ comp one:



And here some better pics of the babies...

[alancohen]

These are the XOs that came with the drivers. They're N1600Bs. I opened one up. It's a little nasty in there. A big hunk of tar takes up 1/4 of the chassis. I screwed the back back on and will have these on eBay ASAP. I can't imagine they're any good.



And here is the GPA cone # if that means anything to anyone: