On 11/09/2010 10:15 PM, [email protected] wrote: >> i've seen p.a. power amps die after starting to oscillate in the >> ultrasonic range. only a month ago, a qsc amp died on me this way. it >> had 3 12" monitors connected to it (and yes, it's being marketed as >> 2ohm-safe), and all of a sudden, its clipping leds went full on. > > How was the wiring ? > > 1) Separate (long) cables to each speaker. > 2) Daisy-chained, one long cable and few short ones. > 3) Daisy-chained, all long cables.
daisy-chain, 10m to first, 5m to second, another 10 or so m to third. >> funnily >> enough, it even *created* a signal at its inputs - when connected to a >> cheap small yamaha mixer, the mixer's master meter would max out (and >> fall back to zero when the amp was disconnected, so i can be sure it >> wasn't the mixer that generated the problem signal). > > That's really scary. Not only did the amp generate this signal, but > it managed to create a level at its input that even when driving the > low output impedance of the mixer was enough to max out the meters... yup. believe me i was impressed. imagine my utter joy when right in the middle of the show, a security guard radioed me with the delightful news that a sizeable black cloud had just emanated from the amp rack at position 20 (where the audience was due to arrive in 5, no 4, minutes...) the stink was noticeable 30m down the road. -- Jörn Nettingsmeier Lortzingstr. 11, 45128 Essen, Tel. +49 177 7937487 Meister für Veranstaltungstechnik (Bühne/Studio), Elektrofachkraft Audio and event engineer - Ambisonic surround recordings http://stackingdwarves.net _______________________________________________ Sursound mailing list [email protected] https://mail.music.vt.edu/mailman/listinfo/sursound
