CMS Author Craig Vecchione Posted February 16, 2007 CMS Author Share Posted February 16, 2007 whoa craig. i have several amps that are + + in bridged mode. i have NONE that are + - I'm referring to the internal connections, which must have the channel signals 180 degrees out of phase in order for the amp to be bridgeable. The two channels' reference points are tied, and the two remaining normal signal points become the + and - of the bridged output. Part of bridging is inverting the input polarities so the + of one channel carries the - return signal. If both channels have the same phase at their respective +'s, and the - references are tied, there's no increase in voltage potential and the amps can't be bridged. Here's a so-so reference that shows the channel relationships a little better than I can explain in words: http://www.bcae1.com/bridging.htm Link to comment Share on other sites More sharing options...
Members agedhorse Posted February 16, 2007 Members Share Posted February 16, 2007 No, it's not possible to parallel 2 seperate amplifiers. Don't even try unless you feel the need to snuggle up to your repair man. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted February 16, 2007 CMS Author Share Posted February 16, 2007 Be VERY careful with Crown and parallel mono mode. This mode is different and uses different output connections than stereo OR bridge mono mode. ALWAYS, read the manufal and be sure you understand exactly what it means before using in these modes. Crown is the exception to the rule concerning parallel mono on many (but not all) models. That's why I wanted to know specifically which '1200' amp he had...I realized Crown's got three amps with that number...but actually the Macro-Tech model is 1202, not 1200. The Micro-Tech, CTs and Xs series all have a '1200' model. The Xs doesn't have the weird output connections...no, they managed to make the input the weird part, as there's no switch...you have to either use a Y-cable, use the Phoenix connector and then patch the 2 channels with a short 1/4"-1/4" cable, or rig some jumpers with the 2 Phoenix connectors:rolleyes: . For the MA-1202, you use the channel-1 input, switch (on the rear panel) the mode to parallel, install a 14ga or larger jumper across the red binding posts, and use the channel-1 output binding posts for the single speaker output. This differs from dual-mono modes (which are also called parallel mode) and is more similar to bridged-mono but doubles the available current rather than doubling output voltage. Link to comment Share on other sites More sharing options...
CMS Author Craig Vecchione Posted February 16, 2007 CMS Author Share Posted February 16, 2007 Getting to particulars, I'd simply use the two Crown's to run the present FOH. Perhaps place one behind each stack, one channel per speaker, in stereo mode. I doubt there would be a noticeable difference in volume. You can then use a USA900 to power a center cluster of subs if you buy new 18" subs as you mentioned and another USA 900 could power the Ross' as a front or side fill if needed, or use the extra amp for additional 2 monitor mixes. It's not ideal, but it's safe and should still sound fine. Link to comment Share on other sites More sharing options...
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