This is interesting -- from:
http://www.classicspeakerpages.net/IP.Board/index.php?act=idx
Guest_whboyd_*
Group:Guests
Posted 18 December 2003 - 12:02 AM
Hello - I've recently tested the amp sections of the Powered Advent from the 70's. The results may be of interest to some here:
The woofer section is flat up to the 12db/oct rolloff at about 4500hz. The lower end can be boosted up to 6db at 30hz if desired. You can also throw in a 6db/oct rumble filter below 20hz if desired.
The tweeter section rolls off below about 4500 too, first at 6db/oct, then going to 12 db/oct. below about 1500. I've not yet tested the Drivers to see what they are doing acoustically, but clearly the electrical crossover is much higher than the original Advent passive crossovers.
If the woofers have a gradually falling high end (not hard to imagine with that heavy cone & a ten inch diameter!), and if the tweeter response actually rises below 5000 down to it's resonance, then the actual "acoustic" crossover could be lower than 4500, maybe even match that of the original design - or the 1500hz published. If this proves the case it could explain why this design had apparently better "highs" than the passive models with the same drivers. The tweeters would have been basically flattened electronically and boosted in amplitude....and the bass improved in depth by the added boost on the low end.
I'll test the drivers soon with the original passive xover as well, and make the curves available on this site if anyone is interested.
I had double Advents in the 70s - I loved the smooth extended bass, wide soundstage and realistic string tone. I then used the woofers as subs for years after and am going to go back now & rebuild them as triple or quad-advent systems. The powered advents were amazing with their dynamics - the crossovers could be helpful to those of us wanting to duplicate or experiment with the designs nowadays.
Happy Holidays to all!
Bill
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