So I have built the Pass AB amp and am pleased with it. The problem is that I'm running maggies and can tell I need a little more power. Can I run a balanced signal +/- into the right and left of the amp input and pull my speaker output from the two positive outputs of the amp? Bridge them in this manner? If so I have other boards that I could build another unit and bridge it also. I understand the load issues that the amp will see and have to take that into consideration. Just thinking out loud.
Maggies are Magnepan magnestatic speakers, not electrostatic.
And yes, they are very power hungry. My monoblocks provide 600 watt into a 4 ohm load, and my Maggies 3.6R do not complain, when I drive them close to the clipping limit. It´s loud, but not near "call the police"-loud. I often heard people say, that Maggies are not dynamic and don´t play bass very well. I can only say one thing to that: They play with too small amps. A good 300 watt+ with a well dimensioned power supply will make them really sing.
@Freecrowder..... You don´t mention which Pass amp. If the output is below 100watt, just forget it. It´s far from enough to really make them sing
Also, when driving them the way, you describe, the amps sees a load of 2 ohm. Make very sure, that it´s stable when doing so
And yes, they are very power hungry. My monoblocks provide 600 watt into a 4 ohm load, and my Maggies 3.6R do not complain, when I drive them close to the clipping limit. It´s loud, but not near "call the police"-loud. I often heard people say, that Maggies are not dynamic and don´t play bass very well. I can only say one thing to that: They play with too small amps. A good 300 watt+ with a well dimensioned power supply will make them really sing.
@Freecrowder..... You don´t mention which Pass amp. If the output is below 100watt, just forget it. It´s far from enough to really make them sing
Also, when driving them the way, you describe, the amps sees a load of 2 ohm. Make very sure, that it´s stable when doing so
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This is not too bad. Remember, most Maggies are an almost flat 4 ohm load over the whole frequency spectrum.
You could send Nelson an e-mail and ask him, what he thinks of the bridged mode. If he says "go", then just do it and build one more
So want tom show some interesting results from my balanced attempt with the Pass AB. Ran into some issues with the Doug Self preamp as source. Feeding SE input and using balanced output. You can see from attached pics that the gain between the two phases is not identical. One is 1.25vac and the other is 1.09vac at 1000hz. So looking at the output across 5.5 power resistor on scope I see two signals. I have not completely thought thru that buts seems like I should have seen one signal that is sum of two outputs. HMMM. someone set me straight. You can actually see that as it clips the higher gain signal clips first. I'm assuming this is all related to the fact that the two phases aren't matched in gain. I'll need to troubleshoot gain stages. But interesting that the AB puts out ~430W into 5.5ohm at clipping. Plenty for the Maggies.
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Two channel scope if you can get one would be super handy... I’ve played with bridge and floating outputs on amps and they’re sometimes seem just idiotic how they behave when being measured.
The most reliable solutions for me were to keep the grounds intact, and use the scope A-B function to display the composite waveform. If your waveform doesn’t clean up, it looks like you have some oscillation going on...
The most reliable solutions for me were to keep the grounds intact, and use the scope A-B function to display the composite waveform. If your waveform doesn’t clean up, it looks like you have some oscillation going on...
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So what is attached is short video of scope screen. This phenomena only shows up at lower frequencies~100hz and lower. This shot is 20hz. It looks like crossover type distortion. Do not understand why it travels around the sine. Tried cranking up the bias just to try and it makes no difference. Just plan on injecting signal and tracing circuit to find issue. Anyone seen anything like this.
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