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comment: 604D was in the 1957 catalog and was not superceded by the 605 until 1959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:

[Alien_Shore]

I'd recommend that you measure them, and build a XO...
Don's site is a wealth of info, and he's very generous with his advice as well. He helped me a ton with my 604E.

[alancohen]

I'd recommend that you measure them, and build a XO...
Don's site is a wealth of info, and he's very generous with his advice as well. He helped me a ton with my 604E.

I measured them...they're both 15"...

...and weigh a ton.


DCR on the LF drivers is exactly 11.0 and the HF drivers are 8.0 and 8.1.

The alchemy of XO design is fascinating to me. If I didn't have so many other things tugging at my coattails, I could see myself getting lost in it learning as much as I could about it.

[cradeldorf]

I'll say this. Once you get those baby's all set your gonna be very happy. Wish I was of more assistance but I've only had the opportunity to play with the half roll surround sound of my C's. I'll say that when I first got my setup and one was a C and one was an E they were worlds apart on their sound. I thought there was something wrong with the E. It was an extremely costly mistake to send them to GPA to have them looked at as they came back sounding the same. I told Bill the E didn't sound as good as the C and thought it needed a phragm. I found the new phragm in the C when I looked. It wasn't the phragm at all because before I sent them I could turn the attenuator in the E's crossover and hear it changing. Between one running a N1500 and the other running an N1600 plus one being an accordion surround and one being a half roll surround there was a definite difference in sound.