Who Here is Vertical Bi-Amping?


I recently tried vertical bi-amping and I am very impressed with the results. For the record, I am using “vertical” to refer to using two stereo amplifiers (one amp per speaker) where each amp uses one channel for the midrange/bass driver(s) and the other channel for the tweeter. I am using passive crossovers between the amps and speakers.

My first impression is that there is a noticeable increase in detail and a large reduction in treble harshness at higher listening levels. This makes sense to me because now the tweeter is independent of what the midrange/bass driver is doing. (Technically its “independence” is equal to the channel separation spec of the amplifier.) When the mids call for lots of power which can stress the performance of that channel, the tweeter performance isn’t affected. 

After reading what I could online, I was hesitant to even try vertical bi-amping since I saw lots of mixed reviews on bi-amping in general. I decided I had to try it after reading this post on another forum by Mark Donahue of Sound/mirror Inc. (no affiliation):

“...We have been vertically biamping the speakers here in our mastering studios for 25 years and have yet to find a monoblock that delivers better performance than a pair of stereo amps.
Going back almost 20 years we were looking for a big solid state amp to drive the brand new at the time B&W 801 II. What we found at the time was that the larger monoblock amps from B&W (MPA-810) and Threshold (SA-1000) did not sound nearly as good as the similar stereo amps in a vertical biamp configuration. Every couple of years we would try out the new big monoblock de jour (Krell, Spectral, Cello.....) and every time we found that the stereo sibling of the big monoblock yielded better imaging and lower overall distortion.
Recently we went through the entire routine again. I finally had to retire my five trusty old Threshold S-500 series II due to the need for true balanced inputs. I tried the Classe CAM400 and was underwhelmed with the imaging and clarity. I then replaced them with the (Less Expensive!!) CA-2200 stereo amp and the difference was shocking. Better imaging, better impact and smoother frequency response from my Dunlavy SCV’s.”

I’m very glad I tried it as my system is sounding much better! Does anyone here vertically bi-amp their speakers? If so, what has been your experience and do you find it better/the same/worse than monoblocks, stereo amps, horizontal bi-amping, etc.?
128x128mkgus
Hi mkgus. You asked for responses from people who have done vertical bi-amping. I have, and I liked it. I tried passive hi and low pass filters for the inputs of the amps (easy and cheap: $5-$10). That was better. Keep the lows off the tweeter wires, etc. Then I thought about the passive crossovers between the amps and the speakers. That prevents the amp from exerting control over the speaker's movements made possible by negative feedback and good speaker wires. Why not eliminate the passive parts? They can be quite expensive and an electronic crossover (miniDSP) can be had for under $100 (but you need a computer to set it up). I first tried it with the Linkwitz LXmini speakers (Madisound has a "package" kit) and the result was wonderful. [Tweeters should be protected by a capacitor double the size you'd use in a simple crossover just in case the amp bows up or a cable ground goes bad at high volume levels.] If you use a stereo amp for the woofers and a different one for the mid/tweeters (horizontally?), clipping in the lows will not be very audible as the distortions will not be going to the mid/tweeters. This lets you use a great, but low powered, tube amp for the tweeters and a perhaps powerful but cheap solid state amp for the woofers. The value of the direct connection between the amps and the drivers cannot be overestimated. I've since built the Linkwitz 521-4 system with a four way electronic crossover for each stereo side. Eight channels of amps for stereo, what fun! The results are worth it. If you're in the Southern California area, come by and hear the systems. I can loan you an electronic crossover to experiment with. I'm working on a three way setup for my home studio. You can use DBX 223 type units and have manual control over crossover frequencies and levels, extremely useful! Keep smiling.
mkgus - I should have mentioned in my earlier post that in addition to doing vertical bi-amping with a pair of Dyna/VTA ST-70s, I also use an amplified 12" subwoofer, meaning that the ST-70s don't have to power a large woofer in my system, which most smallish tube amps don't do particularly well.  My main woofers are 8" kevlar Focal woofers that are pretty light and in a transmission line, and the amps seem to have no trouble with those.  
mkgus - I have been horizontal tri-amping for years using 4 ARC amps.
Two stereo amps running in mono, one for each woofer, a stereo amp for the mids and stereo amp for the highs.  I took out the cross-overs from the speakers and use an active cross-over after the pre-amp and before the amps.   https://www.marchandelec.com/xm44-electronic-crossover.html

It is quite eye-opening when you see the power disparity (meters on amps) between the lows,mids,highs.  

Seems like you're happy with your new configuration, but as almarg said
you would see a big leap in performance if you bypass/remove the internal speaker x-over and went direct to the drivers. Given this may take some thought on crossing over the mids to the highs. But then you can run in a horizontal bi-amp configuration which as you mention takes the load off the power supply of the mid/high amp. 
Thank you everyone for sharing your systems and experiences with bi-amping. Some of these systems that use active crossovers seem high tech. Very impressive. Thank you boomer for offering to let me hear your system!

One question I have for those who use electronic crossovers, is it a requirement to convert the signal to digital to do the processing? If yes, does that affect sound quality at all? I’m thinking that doing an extra conversion step to digital and back to analog could be detrimental, but maybe that’s not how you do it or maybe it’s not that detrimental. The DSP I use for my subwoofers, for example, allows for it to be hooked up to a computer for streaming so it could be the source with no extra analog/digital conversion step. 
Also, I’m beginning to see why my previous internet searches didn’t bring up as much information as I was looking for. Doing vertical bi-amping with active crossovers is not for the faint of heart and requires lots of knowledge and experience. As such, there probably aren’t that many people doing it, relatively speaking.