Passive and active biamp together

Hi guys, I have a question for those of you with experience in both passive and active biamp.

Preamble 1: I was using passive biamp with 4 identical monoblocks, but, especially after a fine tuning in room acoustics, found out I got no significant advantage, so I reverted to single amp, putting the extra pair of monos for sale.

Preamble 2: my loudspeakers have double inputs (binding posts) for lows and mid-highs (xover freq 350hz@24db/oct), but the xover network, for what I can read in the manufacurer user manual, is pretty complex, making its removal unfeasible for going active.

Question: somebody told me that putting an active xover between pre and power amps, would be of great advantage anyway, even though the passive xover is not removed, because the amps would only take care their part, and especially because there would be much less energy dissipated in the passive xover, of course provided the active one is set at the same freq and slope, and its quality matches the rest of the system.

Haven't sold the monos yet, do you guys think there could be a point in this, worth getting a, say, Marchand XM126 tube xover to try?

Thanks to all,
Thanks guys for your informative replies.

Ivan, had a look at your great system, and you happen to use exatly the same Marchand XM126 active X-over I was thinking about, but it's not clear to me if you have removed the passive X-over inside your RBH speakers, have you?

Rodman, the reason why I said that removing the passive X-overs from my speakers is not practical, is that the manufacturer states that it implements a compensation network to correct phase and to linearize impedance, whatever that means, so I figured that wiring the drivers directly would mess up too many parameters, but I may be wrong of course. I'm not sure I understand how the slopes would become 48db/oct though, what I was told is that the passive X-over, presented with a signal already filtered, woudn't have to dissipate the exess energy, hence the advantage.
It's certainly a can of worms, Cptaz. I'm currently actively biamping. Before removing the passives, I implemented both active and passive as you described. It really did not sound right, as Ivan indicated. Removing the passives and going fully active yielded by far the most significant audible change in the system since I began messing with it. So, at the very least, it's interesting. I'm happy with the results but not yet satisfied.

I've been fearless mostly because none of my equipment is all that valuable. Your system? I dunno, man. I'll bet those speakers sound great as is. You might consider shooting an email to Marchand. Other members have reported that he is very helpful and willing to advise. As for myself, I'm currently using a cheapo Behringer CX3400, and I feel pretty good about moving forward eventually, probably Marchand's passive line level (XM-46).

If you end up communicating with Marchand, I do hope you'll share the experience.



No, I did not remove the internal crossover from my speakers. I simply removed the jumper between the binding posts. My situation is very similar to yours. A third set of amps would be required to remove the internal crossover, a separate set for the tweeters. Additionally you would also need to know where the tweeter crosses over with the midrange. Some people do actually tri-amp, but it would have been overly complicated, not to mention expensive, for me to do it. I'm sure, were you to want it, that the fine folk at Marchand would be willing to build you a crossover to manage the task. But, I can't imagine, unless you are feeling wildly experimental, why you would want to try that. I bi-amped out of necessity, not adventure. In my case, bi-amping pushed my speaker's efficiency from 88dB to 92dB, just enough to liberate the potential of my 11 watt amps.

I just recently took the Marchand out of my system. After a couple of years internal debate--uncomfortable with many of the reported problems with high efficiency speakers--I had the good fortune to run into a pair of Zu Audio Essences that I could take home before buying. I ended up liking them enough to keep, so I'm simplifying my system. My decision was both acoustic and economic. The Zu's are only slightly better than the RBH's in my system, a function of synergy rather than quality of design. I decided to keep the Zu's, in the final instance, because i expect a return on my earlier investment. I can now sell my speakers, my autoformers and the crossover. These sales will pay for my new speakers, and leave me with quite a bit of cash left over.

In any case, I stand behind my earlier statement. I know I needed to actively bi-amp, but I believe that your decision should be based on what kind of sound you want. It may be that you would be better off changing speakers. Perhaps a different amp would do the trick. It would help if you told us what you love about your components and what you believe needs improvement. I would consider bi-amping only if I were certain that I did not want to relinquish either amps or speakers.


Michael, thanks for your advice, yes my speakers sound great to my ears, I don't think I will at this point, but if I do contact Marchand and follow that route, I'll definitely share the experience.

Ivan, I'm glad you found an improvement by simplifying things in your system, actually I don't feel wildly experimental, just mildly, and only because selling those monos is taking a lot longer than I'd like, you know these are not easy times for selling or buying where I am.
In fact, I love the way my system sounds as it is, I was just hoping to get more of what I have without messing up too much, but apparently that's not likely to happen.

Thanks to all,
Marco- The 48db/oct slope will result, because what is left, after the 24db/oct attenuation of the freqs(by the active X-over), is indeed, a SLOPE(the freqs are not completely eliminated). The passives continue that attenuation. Just as holding a horizontal straightedge, first at a 45 degree angle, then- holding it at a further 45 degrees, results in a 90 degree angle from it's original position. Enjoy your experiments, and- happy listening.