Duplex **** (or heaven?)

[chuckkey]

Actually meant an 813A schematic...
Chuck

[joyspring]

Chuck,

Yes, UREI/JBL markedly improved the horn/throat of the Time-Align(tm) monitors reducing the distortion significantly with each revision/series. The B- and C- series both utilised the JBL 2425H compression driver.

The 813A schematic is available at:

http://www.jblproservice.com/navigat...ectronics.html

If you're planning to convert your 813As to 813Cs, there are two issues that you ought to be aware of:

1. There will be few, if any, matching parts in the crossover networks.

The amount of time delay in the LF section, impedance compensation and equalisation differs between the two series as well.

2. The LLF (additional 15" low frequency driver) is different between the A- and C-series UREI Time Align(tm) monitors.

The A- uses the UREI/Eminence 800W driver whereas the C- uses the JBL 2215H.

Hope this helps and good luck,
BobR

[chuckkey]

Thanks, I figured that would be a problem. Ill search for an 813B schematic, I could see whats required to change the HF circuit. The 2425H sure sounds a lot better with that larger throat.
Thanks
Chuck

[chuckkey]

Thanks for all of that. One can get really confused about these model number changes. I finally got it somewhat figured out. The speakers I have are 813A's with the 801aa coaxial driver. The one I picked up is a 801B coaxial driver with the 2425H, from what I believe is an 813B. The networks are 839 and 840 respectively. I now have the schematics for both (thanks for the link) and I see many changes, although not as much of a nightmare as going to an 813C, which is a completely different animal. So I guess what I am looking for is an 801B and two 840 networks. Lot of changes between the two models of networks, different inductances and caps, and pots. The Ebay search is on. Thanks for your help.

[David Yost]

Hello, All

I have a pair of NOS UREI 841 crossovers marked 813BX. I have never heard of this system-- maybe it was a transition model-- and it does not use the lamps of the earlier 813s.

I don't need them anymore since I found 3 813Cs for my LCR HT rig, so if you are interested in them, I will entertain an offer.

Best wishes,
David

[chuckkey]

Ive been searching around for information on the 813 BX and have not come up with much. That system used a 2234H low freuency driver and an 801B Coax. The network is an 841 (L/R) whatever the (L/R) means. Can anyone out there help with this?
Thanks
Chuck

[joyspring]

David and chuckkey:

"Ive been searching around for information on the 813 BX and have not come up with much. That system used a 2234H low freuency driver and an 801B Coax. The network is an 841 (L/R) whatever the (L/R) means. Can anyone out there help with this?"

Search me; I haven't got the faintest on this one :-/

UREI was somewhat of a glorified cottage operation prior to their acquisition by JBL, and I know that UREI was also offering Time-Align(tm) retrofits for 604E and other Altec Duplex(tm) based systems.

So far as I know, the UREI 813B used a Model 840 crossover network, and their naming convention prior to the JBL C-series follows:

system crossover
813 838
813A 839
813B 840

Up to and including the B-series, the 813s utilised a stamped-frame Eminence 800W LF driver, so I find that the 813BX system using a JBL 2234H driver quite curious as well.

It does appear that your supposition that the 813BX may be a transition to the 813C is correct as the JBL acquisition did occur while UREI was producing the B-series.

This is a question for Don McR as he does have personal connections within the bowels of JBL/UREI.

BobR

[Mirrophonic Sound System]

Guess who else made a coaxial ? GAUSS !

I even have their brochure somewhere in my musty files !

[chuckkey]

Guess Ill check it out, they are out here near me, 20 miles or so. THANKS