Magnepan MG 1.5 Qr crossover upgrade
Maggies are great to listen to but can however perform a lot better, and I mean a tremendoes lot, with an upgraded crossover network.
The upgrade that we describe here will cost you some money but it will be really worth it and upgrades your MG 1.5 Qr to a dream speaker which performs at its peak.
On the right you find the original crossover installed by the manufacturer.
As always it is unbelievable that an expensive unit is equipped with a crossover like this. Very inexpensive parts that you would expect in a cheap loudspeaker system but not in a Magnepan, so we need to upgrade this to a level that should have been there in the first place.
In this project we will tell you how to open the speaker to get to the crossover, remove all the parts, rewire the connections to the panel, build the replacing (external) crossover and connect everything again.
Read carefully and make excellent solder joints for good connections.
Before you start prepare your workspace. You need a large flat surface with something on it to protect your expensive loudspeaker.
Put the unit on its front on the table and remove the stands by removing the four screws that hold it in place.
Remove the terminal plate by unscrewing the four screws that hold it in place, pull the plate back and cut the wires. Remove any staples that are under the terminal plate that holds the speaker cloth in place, there probably will be two to four.
After that remove the screws, maybe like ten pieces, that hold the front in place and turn the unit on it’s back.
Pull away the front cover but be careful this is attached with sticky tape to prevent the panel from vibrating. Use a large coin or something like a blunt kitchen knife to pry loose the sticky stuff but leave it in place for later.
Remove al the staples on the bottom side of the panel, there are a lot of them even more than on the photo on the right, by using a small screwdriver and a pointed plier.
The cloth is folded into the gap on the bottom so be careful not to damage the wood of the base. Also there can be staples on vertical sides of the panel.
Only pull it back to have the crossover parts and the terminals connecting the panel exposed.
Next drill out the pop rivet that holds the black coil on the left into place and be careful not to damage the wooden plate holding it.
Carefully disconnect the terminals that connect filter to the panel, cut all the parts and wires and desolder the wires from the soldertags.
When all the old parts are removed you can start rewiring the panel and prepare for connecting to the terminal plate. Colored wires are supplied in the upgrade kit.
Please note that right and left panels are each others opposites so when the right speaker is on its front like in the photo the tweeter connection is on the right and the midwoofer connection on the left. On the left panel this is the other way around.
Also note that the plus and minus terminals of the panels are actually NOT mirrored, see the schematic for the correct connection. When you connect this wrong the panels will be out of phase and it will sound horrible.
Do NOT connect the panels terminals directly to the terminal plate but use the solder tags and make an extension. The photo on the right will give you an impression on how to do this the correct way.
The schematic for the upgrade is simple but effective. We have selected the best parts for this and all parts including colored wiring are included in the upgrade kit.
Because the parts for the new crossover will not fit in the space of the old crossover it will be external. To prepare for this we need to connect the panels to the terminal plate connection for ‘high’ and ‘low’.
Also to prevent damage when the external crossover is connected incorrectly the tweeter fuse must be connected in series with the tweeter connections on the panel.
Connecting the panel to the speaker terminal is now very easy. The tweeter on the panel is connected to the ‘high’ and the midwoofer section on the panel to the ‘low’ terminals.
Make sure you put the fuse in series with the tweeter panel, if you should ever connect the crossover incorrect you will not blow the tweeter on the panel.
If the tweeter fuse ever gets blown replace it with one with silver contacts and a silver fuse wire inside. More expensive but worth it.
Make sure to connect the plus and minus to the correct terminal.
We recommend building an external crossover in a sturdy case with gold plated terminals to connect to the loudspeaker system like in the photo on the right.
This crossover has NO capability for bi-amping because it is not smart to do this with a Magnepan. The midwoofer and tweeter are accoustically coupled and if there is a slight phase difference between the amplifiers outputs this has a huge influence on the sound reproduction of the panel. So this is a no go but it makes the crossover hardware easier to hard wire.
In the photo on the right you can find how to hard wire the crossover.
Terminals are from top to bottom:
Note how the small air coil is directly soldered to the output posts of the tweeter.
The case you will have to build your self and all parts are included in the kit.