Urei 811B schematic help needed

[Mr. Widget]

Drool!

YES!

Very pretty, thanks for posting the pic. I rarely click on links.


Widget

[rusty jefferson]

Earl, Sorry for the delay. My friend hadn't apparently downloaded the link ESO posted but had a couple drawn out schematics. One of them matches the schematic in this link I just found and is legible. The schematic Heather posted appears to be the 813A schematic, not the 813B. Check this link and see if it looks right to you, it does appear to be the 830 network for the 811B. It might be worth a PM to ESO to see if he agrees as he's built several of these I believe. If it is right, perhaps Rob could get it into the library with a link in this thread to it?

https://www.google.com/url?sa=t&sour...vFEbrg_NCQ5AkZ

[rusty jefferson]

I just noticed the link I posted a few minutes ago isn't to a JBL Pro or Harman server but a restoration guy in Europe I wasn't aware of.

https://robertmelchers.nl/index.php/nl/

[Earl K]

Hi Rusty,

Thanks Much !! for your efforts.

What you've found here makes more sense for the C3+C4 values in the woofer section ( plus overall, it's a clearer scan of what Heather has posted > which had the added "Helper-Woofer" LP section within it ).

I'm going to model this eventually, once I get given some measurements ( which are in the works but waiting on some HF parts to arrive ).

If it doesn't model well with these updates C3+C4 values ( being 10uF and 14uF respectively ) I'll ask ESO what he in fact used.

Thanks Again!!

[rusty jefferson]

Earl, You are correct, Heather did post the 813B, not 813A schematic. My bad. Too many UREI combinations. :-)

[Earl K]

And now:

Some more pics of eso's spectacular work ( before they get lost in the ether ).

[Mr. Widget]

Absolutely magnificent!

Thanks for sharing!!!!


Widget

[eso]

Here's the parts matrix for the Urei models, and a partially cleaned up schematic for the 840 network for 813B monitors.

There are significant differences in the time correction between each different series from the Altec 604 8G through the full JBL version. There are also other differences in both the LF and HF sections between the 811, 813 and 815 models as the duplex cone does not need to extend as low and the HF section needs less padding with greater woofer output.

I'm also supposed to receive a pair of the earliest 824 networks to upgrade for a customer and reverse engineer while I have them. These were an aftermarket offering for upgrading existing 604E monitors that is a 16Ω version that would time align 604E and earlier goemetries.

BTW, That fiddleback anigre pair of 811A is still available if anyone is interested.

eso

[eso]

Here's a parts list I did years ago for the 840 (813B) network.

In the '00s I did verify this with the former JBL archivist. I think his name was Everett. He was a good guy.


eso

[eso]

Really, I can read... I just now realized that this is asking for the 811B–830 network...

Here's a clearer copy:



eso