My New Magnepan 1.7i's sound dull and lifeless on the top end...why?

@kingbarbuda I made the crossover myself, just upgraded the factory crossover, kept the values exactly the same.
You need 115.8uf total for the mid section (3x33uf+10uf+6.8uf), 10uf for the tweeter, and a 1.4mh inductor for the bass panel.
If you follow the existing layout, you can just build a crossover using the same layout. A schematic is also available online.
I had to build a box attached to the speakers in the back of the panel, I put my crossover inside it. You can go about doing it however you see fit.
I went with mundorfs because they are very highly rated boutique parts, build it well and build it once.
Changing the crossover is an absolute must on these speakers.

P.S. Just  watched GR research's video, and his  way of building the crossover is his own, but I can tell you this, the stock configuration after changing all the parts is not lacking in the least. Treble is beautiful, shimmers that are incredibly detailed and never harsh. Everything is in balance. 

I would put pictures up if I could, the crossover box looks very nice on the speakers, I have also done a stand upgrade in the back. Both are bolted into the stock frame.

Just updated my Account picture. You can see the crossover box there. 

I just bought a used pair of 1.7i speakers, in pristine condition and only 7 months old. I own a pair of .7s and wanted to upgrade. The 1.7i speakers sound bad. Dull, bassy, no high-frequency detail. I was hoping to get more low-end response, but I wasn’t expecting the dull, lifeless sound. I am very experienced in setting up Maggies. Magna Risers don’t help. Different amps don’t help. Tweeters in vs. out don’t help. Neither does moving the speakers and my listening chair help. I can get them optimized, but I can’t remove the shelf in the frequency response (about 5 or 6 dB starting in the midrange, so that the lower mids and bass are elevated). Is this how they sound? Is there a large variation from one pair to another? My .7s sound awesome in the same room with the same equipment.

@eatapc Hi. I am a former Maggie 1.7i owner. This is what I recommend:

1. Magnepans NEED subwoofers. They do. They are ribbon speakers with no air movement and no percussion. There is no slam. They need subwoofers. I added a pair of REL T/9i subs to my 1.7i and it revolutionized the sound. 
2. I agree the binding posts, fuse and jumper are steel plate garbage. I replaced the steel plate jumper and cheap fuse with Mike Powell’s silver upgrade. It’s a sliver humper and a silver tube replacing the fuse. Those changes greatly improved the top end. I am sure if you are handy enough and can replace the crossover and binding posts, more benefits will accrue. 
3. These Maggies need powerful solid state amps for regular driving, but also for headroom and dynamics. Schiit Vidars are insufficient. Amps like the Brystons and Pass Labs are good. 
I hope this was helpful.