What does more power do for Magnepans?

El,

Thanks. More coherent than I could of posted to Dan's question.

Dan... I went to active biamping for a couple of reasons. The 1.6's are reputed to benefit greatly from better crossover parts. My little Arcam Alpha 10's are 100w/8ohms 170w/4ohms and theoretically a little short of wattage at SPL levels I occasionally listen at. A Bryston 10B came up used at a good price, so let’s kill 2 birds with 1 stone. Improve the crossover with the Bryston (bypassing the stock) and get the best I can out of the little Arcams with active biamping.

After the change, it became obvious that I had been straining the amps through the stock crossovers. Clarity and control were immediately present and at much higher SPL’s. There is some reading available on the theory. I don’t really have a good enough grasp on the basics to completely understand all of the principals. In case you want to read it.

http://sound.westhost.com/biamp-vs-passive.htm
http://www.passlabs.com/products.htm (XVR1 manual)

Now the bad news... all those new and old pop/rock CD’s that I used to love so loud... well some of them aren’t so great when you can actually hear what is going on in the recording.

BTW – I made the change to a vertical biamp yesterday. It made a tremendous difference in presentation. Don’t know what to make of it yet.

Jim S.

Jim S wrote:
I made the change to a vertical biamp yesterday. It made a tremendous difference in presentation. Don’t know what to make of it yet.

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Your results mirror mine. Vertical bi-amping rules! Or at least it's really different, and maybe better... Jury is still out.

I've been playing around with vertical bi-amping my Maggie 1.6's for the last month as well. Previously, I was horizontally bi-amping with an Innersound ESL-II at 600wpc into 4 ohms powering the bass panels and a McShane-modded 70wpc HK Citation II on the treble panels. I had carefully level-adjusted the two amps, using a RTA analyzer with a calibrated microphone, using a sweep generator to make sure the sound output was even across the frequency spectrum in my listening room, measured from my listening chair.

Even though I use an electronic crossover, I was concerned that I might be hearing phase anomalies with the mix of the two different amps. So I built a new modded Citation to match the first one. These tube amps have HUGE power transformers that will pass a clean 70kHz signal, very high quality! They seem to have enough power to do a credible job with the Maggies, especially since the amp outputs are connected directly to the drivers, with no inductors or capacitors in the signal path to soak up power.

Of course, 70 watts on each bass panel driver isn't all that compelling with Maggies, so I've also recently inserted a high-pass filter on the bass amps to cut off frequencies below 80Hz, which are handled by a pair of subwoofers. The amps seem to be quite happy with this load.

Gains: much more coherent image, but a somewhat thinner sound overall. Acoustic recordings and female vocalists are clearly more accurately reproduced. Piano is especially much more realistic.

Losses: I miss the iron grip that the Innersound had on the bass panels. I never used to feel the need for a subwoofer, but now it's mandatory, and the bass overall is a bit wooly, especially things like timpani.

Overall, I think vertical bi-amping with matched stereo amps has real potential with these speakers. However, if you want to do it with tubes, you face certain compromises in terms of full dynamics, or you need to spend megabucks for high-output tube amps. It seems silly to spend huge amounts for VTL-750's or whatever, but I think the resulting sound would be worth it! I haven't yet found a sand amp I like nearly as well on the mid/highs, but that certainly is next on my list to explore.

I'd be interested to hear your impressions after extended listening with your setup.

Dfhaleycko,

I will post impressions, but I think it would be better if I let Pal have his thread back and post to my system.

I haven't had a chance to sit down and listen for long periods. Too much work!!! I didn't expect a huge difference between horizontal and vertical with "identical" 2 channel amps (maybe not so "identical" after all). Just a little bit of extra headroom. But the presentation is different. Some talk of letting a system settle after changes. I am beginning to wonder if that isn't part of the difference.

I am going to run RTA when I get a chance and see if it measures slightly different. Will post the results.

Jim S.