604e time aligned crossover design(s) ?

[gearfreak]

So I have these 604e's with the aftermarket UREI 800H horn grafted onto them.

I have the mastering labs xovers which AFAIK are not time-aligned, and considering recapping, am instead considering building some time-aligned networks.

I see that the UREI offering for the 604e was their '824' network
http://studioelectronics.biz/ureipdf/824.pdf

*(though I cannot find an 824 schematic)

...and of course I've had a look at Jeff's page RE: the 604e,
The 604E "Super Duplex"

...wherein Jeff does not suggest a TA option for the e.

quoting from his id22.html:
Bottom Line
The N-1500A filter is hard to equal, much less beat, when using competing parallel type designs with the 604E. An N-1500A filter with upgraded components and an MF EQ circuit added is probably the most cost effective crossover improvement one can make for this classic duplex.



So if anyone has experience (or thoughts on) comparing the N-1500A type, to ML Xovers, (or recapped ML xovers), to UREI 824's, I'd be interested to hear it.

thanks!

[donaldpatten]

gearfreak
check my web site

X-Over

the 604E was made in many versions , so a single design is not possible
the 605 is close to the 604E.
if you are interested , the measurements needed are :
woofer impedance and a Zobel to flatten it
woofer horn time offset to design a Bessel low pass time delay filter.
the 605 design may be OK as is for your 604Es

Don

[Altec19]

You can download the 811A manual (which includes a schematic for the T/A crossover) here:

Vintage JBL-UREI Electronics

[gearfreak]

You can download the 811A manual (which includes a schematic for the T/A crossover) here:

Vintage JBL-UREI Electronics

Thanks! The schematic there is for the 829 Network, is it suitable for the e?

[gearfreak]

gearfreak
check my web site

X-Over

Don

Thanks Don! Looks like I have some reading to do.

[Panomaniac]

Don. Most execellent work! Thanks for posting it.

A few years ago I did something similar. Made my own waveform for time alignment. Mine was a little different, but the technique was the same. I did not do your clever all pass filter, tho. That's quite nice.

Again, thanks for posting.

[donaldpatten]

A simple test to see if your system has the low and high acoustic waves timed together, was a by chance observation when I was working with Seadweller. We were looking at a scope trace of the acoustic wave my test pulse developed . We noted that with the woofer playing, and switching the horn signal on/off the pulse jumped up and down. The pulse was taller and narrower with the horn on and the time position (time delay) did not move. Hind sight says of course as you add high frequencies, yes the pulse will get sharper and higher.


Panomaniac
Thank you for your comments
Don

[Panomaniac]

Ah yes, makes good sense. The impulse gets sharper when the horn is in the right place.
Good thinkin'. I see this on the measurement software I now use, HOLMImpulse. Nice software and it's free.