Why are these speakers so bright but others not?


I'm in the process of upgrading my 10 year old system. It currently consists of:

Arcam FMJ CD23
VPI HW 19jr./Audioquest PT6/Sumiko BPS
Audible Illusions Mod 3 pre
OCM 500
Monster Sigma Retro Gold interconnects and speaker cable
Monster AVS 2000/HTPS 7000 power conditioners
Martin Logan Odyssey speakers

I previously had PSB Stratus Gold's and had finally tuned and tweaked my system so that it was reasonably balanced in my room (approx 20 X 13.5 X 7.5, glass on one side with only partial treatment). I had the opportunity to borrow and purchase equipment from work with mixed results.

ML Odyssey - these worked great so I bought these and am sticking with them. Bass is still uneven and not as extended as the PSB's though.

Revel Ultima Studio - very bass lean and tinny

Magnepan 3.6R - edgy and bright. way too big for my room anyway so I'm selling these.

What gives? Why are two speakers so well suited to the room and too very highly regarded speakers not?

I'm going to borrow an amp from work to see if that changes the situation since I know some of these speaks are tough to drive. Any more ideas?
donato
John, thanks for the helpful info. I picked up some Xterminators at work and biwired using the Sigma Retro Gold. I TAKE BACK WHAT I SAID ABOUT THE BRIGHTNESS! Even without playing around with placement, they sound good. I think it was due to my not making sure all the bananas were screwed in tight with those little hex screws where the bananas go in (Doh! Maggie rookie move on my part. Never had to futz with bananas much before). Mid bass seems much more prominent than with the Odysseys. A bit of sibilance still, but the Xterminator connectors are undoubtedly a compromised connection in comparison to hardwired and my room is not treated. I can see that these would likely be more finicky about room the placement than the MLs appear to be (although I haven't found optimal positions for either) and in their current placement, they sound constrained, like they're begging for more room to breath.

Now for another question: I get plenty of volume out of my CD player connected through AUX port on the AI Mod 3 (AUX port avoids the resistor in the signal path on the CD port), but definitely seemed to hit the ceiling with my DVD player connected to the DAT port. I'm not sure if this is a I-don't-have-enough-power-for-the-Maggies issue (my OCM supposedly is 225W at 8 and almost double that I believe at 4 ohms) or it's some funky gain issue with the DVD player and the preamp. My Arcam puts out a higher than average 2.3V or so.
i would experiment with the following:

the tubes in the audible illusions
change the ic and speaker cable ( i would suggest cardas neutral speaker cable, they will let you know exactly what is happening upstream)
change out the amp ( can sound bright and a little edgy).

your speakers are very revealing and when you have the right combo, you will know it.

good luck,

mike
John, thanks for the helpful info. I picked up some Xterminators at work and biwired using the Sigma Retro Gold. I TAKE BACK WHAT I SAID ABOUT THE BRIGHTNESS! Even without playing around with placement, they sound good. I think it was due to my not making sure all the bananas were screwed in tight with those little hex screws where the bananas go in (Doh! Maggie rookie move on my part. Never had to futz with bananas much before). Mid bass seems much more prominent than with the Odysseys. A bit of sibilance still, but the Xterminator connectors are undoubtedly a compromised connection in comparison to hardwired and my room is not treated. I can see that these would likely be more finicky about room the placement than the MLs appear to be (although I haven't found optimal positions for either) and in their current placement, they sound constrained, like they're begging for more room to breath.

Now for another question: I get plenty of volume out of my CD player connected through AUX port on the AI Mod 3 (AUX port avoids the resistor in the signal path on the CD port), but definitely seemed to hit the ceiling with my DVD player connected to the DAT port. I'm not sure if this is a I-don't-have-enough-power-for-the-Maggies issue (my OCM supposedly is 225W at 8 and almost double that I believe at 4 ohms) or it's some funky gain issue with the DVD player and the preamp. My Arcam puts out a higher than average 2.3V or so.