I asked some questions earlier this year about how the UREI 813 elements and their time aligned crossovers would fit in the Imperials and I got an answer from the master himself that it would fit. I have now tonight connected the first speaker of the pair to my HIFI and it is amazing... I built a pair of speakers two years ago based on a Swedish bass reflex patent that was adjusted to match the Altec Lansing 604 8K. They sound very good but now with the Imperial standing beside them they are not only midgets in size but also in sound reproduction. However there is some flaws in the design that I bought and downloaded. The braces A should be at least 130 cm to be flush to the bottom reflecting plate and you should also be careful with the gap from the compression chamber. Minor issues but anyway the sound is amazing. Through my years I have owned a variety of speakers ranging from Magneplanar Tympani and downwards but the old Altec Lansing 604 8G koaxial with the Eminence 15" bass speaker from the old UREI 813 takes the price.    

I have now the second Imperial up and running. Unfortunately was one of the 604 8G and one of the Eminence 15" bass speaker damaged at Johannesburg intl ground handling. I managed to repair the 604 8G but not the bass speaker. Instead I bought a pair of P-Audio C15 500LF 500 Watt bass speakers. They have a FS of 39Hz, VAS 155 liters, QTS 0.29.
The other Eminence is ok but they are not designed for this speaker. I have tested the speakers both with Altec Lansing 604 8K and the UREI modified 604 8G and they work perfect. Together with the new bass speakers they are amazing. I have had several friends visiting wishing that they were not married due to the size of the speakers.

Here is a new picture of the pair. The will be coated with Epoxi and then sprayed with black Gel Coat.

I am presently living in South Africa and visited Sweden last week and found a set of Altec Lansing 811B horns and 908 8B drivers. They sound much better than the JBL 2412H drivers. I have finally sent the Imperials to the paint shop and will publish a picture when they are done. I also found a pair of Mantaray MR94 horns with Altec 288 8G drivers in mint condition. They are huge and they have to wait in Sweden until I move back. It now seems that journey of building and equipping the Imperials pretty much has come to an end.

I just got the Imperials back from the paintshop. The work is not 100% but this is Africa. However they sound very good now with the Altec 908 8B drivers connected to the 811B horns on top.

Yes, that`s the present configuration. All 6 speakers driven through a dbx Driverack 260. The MR94 horns will be a part of the setup when the Imperials have sailed back to Sweden.

Hi Everyone!
I'm impressed by these imperials and am thinking of making one myself. How does one compare to a ported design or a bass-reflex?
Regards,

I have been building my new house for 6 month now. It is nearly finished.
I decided in april that if I have built a pair of modified Imperials, why not continue with a pair of bigger horns? The picture shows the final stages before they were covered. There is now a 6.1 meter long and 0.6 meter horn mouth in the living room floor. I am using 4 pcs  Eighteensound 15" 15W200 woofers. They will give 124db at 20hz. I will cut them at approx 40hz. The imperials will do the rest. I will come back with a report when everything is up and running. I have been involved in modifications of a new 8 channel DSP cross over. The end result turned out to be very good. I will now start distributing them.