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View Full Version : Heathkit as-101 Altec valenica crossovers gone bad?



in_to_the_60`s
02-18-2008, 07:24 AM
I recently picked up a pair of minty heathkit as-101`s i was told there the same as the valenica`s. I did check to look at the drivers and there original Altec`s in mint condition. My question is does the crossovers go bad over time??? Is there any upgrades?? They sound good but i think they could sound alittle better or should? Any help would be great.

Zilch
02-18-2008, 03:15 PM
Yes, replace the 8 uF, 10 uF, and 11 uF capacitors with new metallized polypropylene equivalents. Use either 8.2 uF or the parallel combination of 4.7 uF with 3.3 uF for the 8, and 9.1 uF and 12 uF in place of the 10 and 11, respectively.

Heath AS-101 is a kit version of Altec Valencia. The 806 compression drivers in them have excessively forward midrange and rolled-off highs. The stock passive crossover has some compensation built into the highpass filter which tames the mids somewhat, however there is insufficent headroom between the woofer and compression driver sensitivities to do adequate full-spectrum compensation.

Flattened response and HF extension out to ~14 kHz may be achieved via biamping the stock drivers and engaging the CD horn compensation built into an active crossover such as the Behringer CX3400. Further extending the VHF response to 18 - 20 kHz is apparently not practical with the 806 driver:

http://audiokarma.org/forums/showthread.php?p=1473345&#post1473345

A better result may be accomplished passively if you're willing to swap out the compression drivers for improved Altecs with higher sensitivity and tangerine phase plugs, and upgrade the crossover, for example, to that used in Model 19 or similar. It may also be possible to supplement the stock crossover with an additional compensation network. These approaches are untested and undocumented presently, though similar projects are in progress.

Alternatively, either BMS 4550 or 4552nd may be substituted for the HF drivers, retaining the stock crossover and adding on a supplemental compensation filter, which upgrade has been tested and documented for both the 8- and 16-Ohm versions of Valencia and similar. An AudioKarma member, Steve O, is completing an improved, comprehensive crossover redesign for incorporating BMS drivers in these systems.

There are additional options by others, largely undocumented to date, and some indications that Valencia bass response may also be improved....

in_to_the_60`s
02-18-2008, 05:37 PM
What is biamping?? I am not really into the technical part to much.

Zilch
02-18-2008, 11:48 PM
What is biamping?? I am not really into the technical part to much.Use "Search" to find info about biamping in these forums.

Specifics re: biamping AS-101 are in the manual: