Why are these speakers so bright but others not?

You are correct about different amps for different speakers - the match is critical, but even more critical is the speaker set up in the room. And, even if properly set up I would not expect them to sound the same, no matter how highly regarded. Except for a slightly low ceiling you have a reasonably sized room for all of these speakers. Different designs require different speaker and listening position placement and acoustical treatment to get the best sound. You are presently considering 3 different designs all of which need different placement considerations. You have a lot of work to do on each speaker before you can fairly judge its value to you in your room.

the psb's are by far the best match with your system. the ocm is avery neutral ss amp and the arcam is likewise. the psb's easily are the best overall performers in this group.

I did play with speaker and seating placement somewhat, but I was just surprised how not good I found the Revel and 3.6R's in my room. Not that they aren't excellent speakers - the clarity and lack of distortian in Revel's midrange came through unhampered as did the sense of space with the Maggies (although obviously constrained in my room and placement).

The PSBs and the Martin Logan's ended up being located very close to the same location which was interesting because they are so different a design. My PSBs (original golds) are front ported and the MLs have the panel and on of it's woofs rear firing. I think the MLs also did well in my room because of the narrow dispersion (i.e. mitigating brightness of untreated room). I thought I could place the Revel's in a fairly similar location to the PSBs, but I could't get enough bass without putting them pretty close to the front wall. I do have lumpy response in my room below 60Hz.

I originally built my system around the PSBs way back when, hence the amp, but I fell in love with vocals and instruments on the MLs despite some of the other tradeoffs (bass in my room, some dynamics). Midrange is so much cleaner and so much more detailed.

It could be a number of things, but since I have had a similiar situation recently, I wanted to let you know that uncovered windows (at least in my room) were a disaster.

My system was sounding bright, and I recently bought auralex room treatment. I put it on all of the critical spots; my system was still harsh sounding. Then I saw a picture of someone's room on this forum who had a similiar room setup and size (smaller than your) and bingo! I had blinds over my windows and assumed that they would defuse the sound WRONG! Just like this gentleman, I put a folded blanket over the blinds and added some other treatment to just the window. I got the soft warm fuzzy sound back instead of the "I paid all this money for this kind of sound what the?"

Can't promise you it will work and I feel your pain, but it just takes a minute to listen to it before and after you throw a comforter over the window to see if it helps.

Hello,

It looks like your system is a bit bottom heavy....in this I mean that you have focused much attention on the speakers and yet a major upgrade to your phono or CD setups and perhaps even more so, the preamp, would bring far more refinements than trying $4k+ speakers in your system.

I heard the AI Mod 3 years ago and it was not bright at all. In fact, it was a bit too laid back for me compared to the ARC LS5, CJ Premier10, Sonic Frontier SFL2 and CAT preamps I auditioned at the time. I would think the AI is a good fit if your system is typically on the bright side. But the AI is also a subtractive product when it comes to resolution.

Another link in your system that is key is the preamp to amp cable. Something like a Cardas Golden Cross could do wonders for you to bring on more warmth and remove some of the edgy brightness and fatigue.

I understand how Magnepans would be considered bright in many systems. I have always needed to use at least a 1 ohm resistor in the tweeter attentuator for the 3.3s and/or 3.5s and my system was not bright at all. My guess is that Magnepan designed this to have their speakers work in a wide variety of systems. If you still have the 3.6s, you should try 1, 2 and 3 ohm resistors at the attenuator terminals. I use BAT 31SE, AesthetixIo, Manley DAC and Wolcott electronics....none of which are bright at all and yet I use 3 ohm attenuators.

My room is nearly identical to yours so I have the same placement limitations. The 3.5s work incredibly well now that I have focused much attention to upstream components.

From what you have written here, you should check out a great deal on a pair of Vendersteen 2 sigs or the 3A. Each of these are much less than the other speakers you have tried and the extra money spent in other areas would be of far greater benefit. But I think speakers like the Maggies will reveal much of the other "problems" upstream.

Hope I have given you some ideas to consider.

John