Members Guitar Guru Posted May 13, 2011 Members Share Posted May 13, 2011 Tried the amp forum, but no success. Hopefully some luck here. So I have a Mesa 4x12 standard slant cab. I also have a Mesa 2x12 slant vertical cab. The 4x12 can run in stereo at 4 ohms per side, or 8 ohms mono. It also has an option for an "out", to hook it up to another cab. The 2x12 is an 8 ohm cab. I have a poweramp that I can run one out of at 8ohms, or stereo outs at 4ohms. So, does that mean I can run it stereo at 4 ohms, and power both cabs? If I link both cabs via that "out" from the 4x12, how would I have to run my poweramp then? Any help would be greatly appreciated.....I just don't want to damage anything. Link to comment Share on other sites More sharing options...
Members Rich4Once Posted May 13, 2011 Members Share Posted May 13, 2011 You don't say what kind of power amp you have, and it does make a difference. I pasted this from here:http://aga.rru.com/ In general, you should match impedances. If you must mismatch, mismatch in the right direction, but stay as close as possible. So what's the right direction? With tube gear it's better to have the speaker impedance lower. Connecting a 4 ohm load to an 8 ohm amp may be OK, but connecting a 16 ohm load to an 8 ohm amp is probably not. Connecting a 16 ohm load to a 4 ohm or 2 ohm amp is begging to destroy the amp. Running too high of a load on tube gear can fry anything (and occasionally everything) in the outputs, including tubes, transformers, resistors and tube sockets. With solid state gear it's better to run a higher impedance. Connecting an 8 ohm load to a 4 ohm amp should be fine. Running too low of a load with solid state will fry your output transistors, and possibly more. Link to comment Share on other sites More sharing options...
Members andreas Posted May 23, 2011 Members Share Posted May 23, 2011 Indeed, knowing what power amp we're talking about would be really good. I'm a bit interested in the outputs being described as a single 8 ohm output and a pair of 4 ohm outputs. That sounds like a mono amp to me. Does the amp have one or two inputs (or one or two volume controls)? As far as the cabs, running the 4x12" in 4 ohms stereo means it works as two separate cabs (with 2x12" a side). Running it 8 ohms mono means using all 4 speakers together. I'd imagine you can only use the "link" or "out" if you run the cab in mono configuration. That would make a total load of 4 ohms (8 ohm 4x12" + 8 ohm 2x12" = 4 ohms) for the amp. But you really need to figure out how the power amp works (if it's mono or stereo, for starters), before you move on. Link to comment Share on other sites More sharing options...
Members jimbles Posted May 23, 2011 Members Share Posted May 23, 2011 With tube gear it's better to have the speaker impedance lower. Connecting a 4 ohm load to an 8 ohm amp may be OK, but connecting a 16 ohm load to an 8 ohm amp is probably not. Connecting a 16 ohm load to a 4 ohm or 2 ohm amp is begging to destroy the amp. Running too high of a load on tube gear can fry anything (and occasionally everything) in the outputs, including tubes, transformers, resistors and tube sockets.With solid state gear it's better to run a higher impedance. Connecting an 8 ohm load to a 4 ohm amp should be fine. Running too low of a load with solid state will fry your output transistors, and possibly more. This don't sound right to me. Granted I've no experience designing circuits with thermionic valves, but if the load is reduced, the current draw will go up, and this is what can overheat and damage components. Link to comment Share on other sites More sharing options...
Members Rich4Once Posted May 26, 2011 Members Share Posted May 26, 2011 Well, I got that information from posted answers by amp techs, so follow it or don't. Link to comment Share on other sites More sharing options...
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