In Reply to: altec gear in a pi box?? posted by EZ_Angus on July 25, 2002 at 20:08:38:
Yes, the VOT using the 511B Altec horn was used with oem xovers at 500Hz. That does not mean that the HF drivers have not started rolling off at the low end before then(-6 or -10dB by 500Hz. relative to 1kHz.?IIRC), as well as having the distortion start to rise. Better to cross where the drivers are still flat, like 800Hz. If you don't already have the 802's...look for 900 series Altecs, a pair of new 'phrams will set you back another $150, BUDGET that into your purchase from the start, you will be rewarded with near "mirror image" freq. response graphs fron the left and right, and no Al-Weako magnet worries.
T/S data for Altec woofers is readily available, punch them into boxplot or Pi-align and see what they say regarding enclosure size and tuning for BR. Don't know how altec woofs sound crossed at 800, JBL's are awesome, and ruler flat run even higher.
Try for a 24 inch enclosure width to match the top mounted 511B, mount the woof as close to the top as you can, to reduce vertical distance between the drivers, and you are "done". Look at the pics of the Kilomax 4 Pi's with wood horn on top, that's what you want, with a 511B on top, crossed at 800Hz. Sambtw, a set of 4 Pi Pro's would definitly rock your living room as well as 511B's over a 15 inch BR, and they are much more compact and wife friendly.
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