There is greater clarity and headroom with the system after the change to active biamping. It is now clear that the little Arcams were being strained at volumes I occasionally listen at. But the resolution improvements are obvious at all SPL levels. I suppose that has to be credited to bypassing the passive crossovers.

Still haven’t gotten through all the variations available on the Bryston 10B crossover but I have measured and listened to several settings. In a horizontal biamp configuration several slope and frequency combinations measured the same. I ended up liking 6db slopes on the high pass and low pass better than mimicking the Magnepan factory asymmetric settings in the passive xo’s.

We were rained in one day and I changed the configuration to a vertical biamp. I wasn’t really expecting any significant change except a little more headroom at high SPL’s. The presentation was different though. I couldn’t put my finger on it, but the soundstage shifted slightly to the left and the vocals on at least one recording started to “bleed” out on the fringes of the soundstage. This recording has always been well centered and precise in the vocals. There is a TV between the 1.6’s and the left of center image on some recordings can be attributed to it. It is also just the nature of Magnepan’s to get little soundstage anomalies. But I have never heard the “bleed” in both speakers before.

I tried changing the right to left balance on the pre to center the image and what do you know. The vocals are now centered and precise without the “bleeding” on the fringe. Tonal balance also improved. The 2 “identical” amps evidentially aren’t biased exactly the same and the little left soundstage shift was a symptom of greater anomalies caused by the mismatch. At least, that’s the story I sticking to today.

Jim S.

stilljd March 29, 2008 18:33