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In Reply to: I think I answered my own question... posted by stevenk on November 17, 2006 at 18:49:48:
If you reverse the wiring on the tweeter, you will also want to invert the connections of the speaker wires to the drivers. Simply reversing the tweeter will keep the drivers in proper relation to each other but instead of the bass, mid, tweeter being +,-,+ they will be -,+,-. You then correct this to +,-,+ by reversing + & - from the amplifier.I may be an egoist but at least I don't talk about other people.
Follow Ups:
I'm biamping so do I reverse the + and - from all amplifiers?
steve
If you are actively biamping and simulating the original crossover (3rd order low pass to the bass and 2nd order high pass to the mid-treble) then I suggest keeping the wires to the tweeter as is thus maintaining it's correct (+) polarity and then reverse the wires to the bass and mid. This will then put the bass in (+) phase and the mid in (-)phase. I suggest this because 1) I tend to be compulsive 2) you can then plug the speaker wires in normally and 3) if you sell the speakers then the next owner will not have any problems.
However, if you are like me and use a 24db L-R then it gets a little more complicated -- reverse only the bass so the bass and mid are in identical phase(+)and then reverse the treble putting it in (-)phase.While you are doing all this, if you haven't done so already, take the time to do some other upgrades - namely remove the fuses if you haven't had any problems with clipping or at least replace the fuse holders, replace the Magnepan wires (I suggest magnet wire), and replace the Magnepan steel jacks. And while you are at it think about externalizing and upgrading the internal mid-treble xo.
I may be an egoist but at least I don't talk about other people.
I'm using a Dahlquist LP-1 active crossover which has 18dB low pass and 6dB high pass crossover points. I already rewired the internal wiring with magnet wire, removed the midrange fuse and rebuilt the mid/high crossover outboard and replaced all the binding posts. I already had the midrange wired out of phase with the ribbon and the bass panel per AndyR's suggestions--this was running the panels in their stock configuration.So now that I've reversed the panels, I wired the ribbon opposite of stock as AndyR recommended and I've reversed all the amplifiers + and - connections to the system. It sounds pretty good right now--much more detail but the mids sound a bit recessed. It would seem to me the mid should still be out of phase with the bass and ribbon since the crossover network hasn't changed. I guess I don't understand why the ribbon wires should be reversed.
Thanks,
steve
After more listening, it turns out the bass was what was really light, so I reveresed the bass amps polarity to the panels back to the same (+ to + and - to -) and the bass sounds much better now. This still leaves the mid/hi amp out of phase with the outboard crossover. Is this correct or not?
Thanks,
steve
Your goal is to have the bass and treble in correct (+) polarity and the mid in reverse (-) polarity. IME it is better to have the bass in + polarity which is what you also found. If I understand you correctly at this point the mid and treble are in reverse polarity which is what you want (mid + and treble -). However, you may find it advantageous now to reverse the speaker connection to the mid-treble thus making the mid (-) and the treble (+). The result will be (+),(-),(+) which is where you were before all the swapping.It is important that the mid and treble have reverse polarity because the mid-treble crossover (low and high pass) are 2nd order. The low pass and high pass 2nd order filters are 180 degrees out-of-phase and thus will cancel creating a big sonic hole at crossover point. By wiring them with reverse polarity, you end up with the phase angle being zero - this is called phase aligned or phase corrected.
This polarity stuff gives me a headache.
I may be an egoist but at least I don't talk about other people.
I think that's what I have now. What threw me off was wiring the tweeter in reverse when I switched the panels. I've tried it all three ways now and it definitely sounds best this way. Thanks for you help. This did give me a headache. It was worth it though. Reversing the panels is definitely an upgrade in detail, slam and clarity with the IIIA's. It's a no brainer why Magnepan went this direction with the 3 series.
steve
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