Urei 801 System/813 Network

[mick c]

Hi guys, just won this gear on ebay. Its a urei 801 system (drivers only) with the 813 network. (uses second LF driver).
I need some advice on what size enclosure I need to make all this work. I have a couple of spare E-145's I can use for the VLF section. Looking at some urei 813 boxes, it apears the coax box is sealed. Some ideas would be great. I have 2 2245's for subs.
Mike.

[dancing-dave]

Get crazy and see if there's a rear-loaded horn design you can use for them. I've read of different people using 1 coax + 1 woofer in the Decware Imperial horn with favorable results (www.decware.com). But, if you want to keep your cool, then you should contact JBL Pro, or a UREI 811/813/815 owner for box/port dimensions. Either case; those are some fine speakers with wonderful imaging.

[subwoof]

Hey mike - I should have the shipping total for you later today...:o)

The 15 that JBL used is the 2234 ( 2235 w/o mass ring ) - and the previous models ( altec and EV framed coaxes ) used an emminence 15 with foam surrounds.

The 813 used a single 8 ohm, the 815 used double 16 ohm.

If you want the deep bass, use the foam. The 2245H's would also work - look at the box size for the 4345 to get an idea. The coax should be in a sealed chamber in that case.

There is an excellent thread on homebrewing 4345 done by another aussie - do a search on this site.

All the uries were ported - they installed a foam block into the rectangular port to keep the console operators aim off.

sub

[Don McRitchie]

According to JBL literature, the helper woofer in the 813C (which is the system that Mick C's drivers came from) was the 2215H.

http://www.jblproservice.com/navigation/UREI%20Time%20Align%20Series.html

The system that used the 2234 was the 813BX that I believe was primarily intended for the Japanese market. That system used the older PAS/JBL hybrid coax.

If the intent is to reuse the cross-overs for the VLF transition, then there is little choice but to seek out 2215's (older Alnico 2215B's or LE15A's should work). Otherwise, biamping would be the easiest way to integrate 2245's.

[aust-ted]

Mick

I have a pair of UREI 811B which are the earlier single ones with the PAS driver. They certainly are ported. They have what looks like a rectangular resistive port on the front baffle. I assume yours would be similar.

I am curious why UREI built used 15" drivers to use in a speaker which are only rated at 80Hz, -1dB.

I was planning to build a pair subwoofer boxes to complement them using 2231s. Believe active biamping would be the way to go. The UREIs are 99dB efficient. Perhaps you might get away with a pair of 2245s or dual 2235s or 2231s with a passive xover.

Regards
Ted

[Mr. Widget]

I am curious why UREI built used 15" drivers to use in a speaker which are only rated at 80Hz, -1dB.



Here is your answer. :D




The UREIs are 99dB efficient.


Widget

[aust-ted]

Mr Widget

Yeah that makes sense. Had not looked at it like that before.

Ted

[mick c]

I noticed that in the 813's the box is sealed for coax, could someone give me an idea on what size sealed box to use?. For the vlf section I figure if I made it 4.5 to 5.0 cuft tuned to 40 hz (vented) I could try a number of drivers. I have one 2245 I plan on puting into a 9 cuft enclosure and tuning it to 30hz for a sub. Having said that, I guess I'd like to tune the LF and VLF enclosures for maximum mid bass slam. If I used the e-145's I have could I use them in the same enclosure as the coax (e-145 based)?.
Thanks for your interest!!!!

[Robh3606]

Hello Mike

Nice score:thmbsup: I have a Urei 811C clone as my center. I also use E145's in my mains as the mid bass driver. They are in 5 cu ft and need a sub below 40Hz. You won't get enough out of the 145's as helper woofers. You would be better off with 2235's or Le15H's. You could just run them as 811C and build seprerate sub boxes under each.

Rob:)

[mick c]

Hi Rob, can u tell me the size of the enclosure for your 811 clone, and is it sealed or ported?. I'm going to use the e-145's for my mid bass as I have 1 2245 I'll utilise for the mono sub. I wasn't sure on the enclosure sizes, I figured if I made the helper box 5cuft tuned to 40hz it allows me to experiment with other drivers down the track.

[Robh3606]

The 811 is in 4 cubic ft vented box. The design was for a center channel so the F3 is up there in the 70's. 5 cubic ft is real nice volume for 2235's. The 2245 should work great with them.

Rob:)

[mick c]

Hey Rob, cheers for that. I wasn't sure to seal or vent the coax enclosure. I don't know the crossover frequency of the so called helper woofer, so when i work that out I guess that will make the call.
thanks again.
Mike