Urei 811 A (604 8G)

[wpod]

Greetings- I recently picked up a pair of UREI 811A speakers locally for a decent price. Couple of questions, is the 800H-A H.F. horn (blue colored plastic w/blue foam) still available anywhere and is the blue foam part available seperately?Also, in the three page "manual" that I downloaded, it lists these speakers as being 87 dB SPL/volt /meter sensitive (misprint?). Unless I'm missing something in the crossover schematic , did UREI pad these drivers down 10 dB or more to possibly facilitate the time-align thing? I thought that the Altec 604 8G driver was closer to 99 dB @1 w/1m. As an experiment, I was considering removing the upper woofer (2226J) in my JBL 4648A cabinets ( currently not in use) and with a raised baffle, mount the 604 8G in it's place. I'd then have to play with the crossover point to the other 2226J. Has anyone done this yet with their Tent Sale specials or am I off my rocker? Thanks very much, wpod

[doodlebug]

Just curious, I have a set of the first version 813s with the blue horn on the Altec 604 but this version came without the foam around the rims. I believe the foam showed up on the 2nd version.

In either case, I duly sent mine off to Bill at GPA for a recone and magnet recharge. This really brought the sensitivity back up.

The other thing I did was to swap out the crossover caps given that mine were getting over 30 years old.

Hope you like 'em as much as I do, too. The 813s are _huge_.

Cheers,

David

[wpod]

David- What are the sensitivity of your speakers, do you happen to know? Does Great Plains stock any parts for these speakers, in particular, the foam horns? My 811A have the Altec 604 8G drivers (ferrite), so I won't need to remagnetize them fortunately. I took a look at the crossovers and it looks like they used all polypro caps, which should hold their values much better than electrolytics. Did yours have electrolytics? Is there a UREI forum by any chance? Thanks very much for your help. regards,wpod

[speakerdave]

604-8G are Alnico.

[doodlebug]

David- What are the sensitivity of your speakers, do you happen to know? Does Great Plains stock any parts for these speakers, in particular, the foam horns? My 811A have the Altec 604 8G drivers (ferrite), so I won't need to remagnetize them fortunately. I took a look at the crossovers and it looks like they used all polypro caps, which should hold their values much better than electrolytics. Did yours have electrolytics? Is there a UREI forum by any chance? Thanks very much for your help. regards,wpod

Whew....lots of questions...and SpeakerDave is correct on this vintage of Altec motor.

On the sensitivity question, I'd expect some tradeoff of sensitivity with linearity given the complexity of the crossover. I don't have the means to measure my speaker sensitivity - too much hardware involved to be cost-effective. I can tell you that they will produce quite the wall of sound and authority when driven with quality electronics.

I doubt GPA would have stock of blue UREI horns or the foam versions for that matter. The good news is that they've just revamped their own 604s with the UREI-shaped horn. Earlier versions used the MantaRay-styled horn. I'd suggest you chat with Bill at GPA....and don't bother emailing him...call instead during biz hours. Note, though, that GPA's version does not use the foam - as in the attached pic.

Yes, the crossovers have non-polarized caps that might have been made by Bennic. Mine did but I swapped them out with Solens as in the attached pic. An easy thing to do and it did make some sonic improvement. My own personal policy is to swap out crossover caps if they're 20+ years or older. There have been discussions back and forth here and elsewhere in audio circles on what caps and whether there's benefit. You'll find its much like everyone's opinion on wine: everybody has a different one.

As far as forums go, the LH site, here, and GPA's own forum are about as knowledgable groups as you'll find out there. There's a bit more daily activity here, too.

Hope that helps.

Cheers,

David

[wpod]

Speakerdave- Thank you for setting me straight on the ferrite/AlNiCo thing. I had it set in my feeble mind that when Altec switched to the newer style frame , that they also changed the magnets to ferrite. In a way, I'm pleased that they are AlNiCo.
DBug- Thanks very much for your info on the GPA horns, I will try to give Bill a call today to see if his new blue horns are for sale seperately.I remember reading an article once on why UREI used the foam as well as the "felt" dots and the slits to control the "problems" that were generated by the multicell. It would be interesting to hear from Bill how he acheived a favorable (I assume) result with just the plastic. Thanks again guys, regards, wpod

[doodlebug]

One minor correction, the GPA horns are not blue from the pictures I've seen. The plastic horn didn't correct multicell problems but replaced the original Altec multicell diffuser.

As for the foam and slits, there are some articles floating around on the 'net where this was discussed and I believe you've got the gist of it.

Enjoy those 811s. In a way, I'd like to have a smaller cabinet instead of the 813s - they're huge!

Cheers,

David