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.?
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I recently tried vertical bi-amping and I am very impressed with the results.

You’ll get better sounding mids and highs with "horizontal bi-amping", as the amp that serves the mids and highs is often staying in Class-A bias, and because of that is never sounding stressed out going into Class-B trying to do the bass as well.
This leaves the bass to be handled by amps that do bass well, and if the speaker is not too low in impedance (>3ohms) this can be done with Class-D as it’s what they do very well.

And "vertical Bi-amping" it’s also advantageous, as the whole power supply of one amp can concentrate itself on driving one bass speaker instead of two, therefore not taxing the power supply so much helping the mids and highs also

Cheers George
For me, ime, vertical bi-amping is the way to go. Horizontal bi-amping, with 2 different amps ( such as tube on top and ss on bottom, or 2 different brands for top and bottom ), usually for me, exposes a disconnect, a lack of coherence, if you will, between top and bottom. I unfortunately, hear the differences, between the 2 different amplifiers ( tone, attack, harmonics, speed, dynamics, etc.). Vertical bi-amping, again ime, keeps things consistent and coherent, in every case. I will say, two lesser amplifiers, being used in a vertically bi-amped situation, often, does not sound as good, as one really awesome amplifier, feeding the speakers, full range. Solo piano, cello, or vocal, makes this easy to hear. Use your ears, try, and determine what works best for you. Enjoy !, and be safe out there. Always, MrD.
Why stop with bi-amping? The advantages are so great I'm buying 34 amps, one for each of the drivers in my Moabs. I do worry about trying to use one Dayton sub amp to power two subs. Also should the amps be stacked vertically, or horizontally?
Talk about a spaghetti factory... LOL  MC I got to see the cable job on that one... 

Horizontal bi-amping works great equil loads per rail.
Vertical doesn't. 1 channel uses 200 watts one uses 30. Seems wrong?
When you can match a 200 watt amp for the bass, and a 50 watt (of higher quality) for the mids and highs.

Before the wonderful refinement of class D amps, the room could get cooking. I used 4 565 Adcoms and 2 MC240, with a C20....warmed the whole house, for 10 years in the winter 80-90, now half as hot, and 10 times the bass power, 1/4 the wattage....

WHY VERTICAL.  I see no reason.

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Seems like there are pros and cons to each.

Vertical: Each amp is only asked to drive one bass driver (the majority of the load), very high channel separation similar to monoblocks, easier to integrate than horizontal bi-amping, unbalanced rails an issue?, etc.

Horizontal: Can use 2 separate amps that are optimized for low and high frequencies, lower channel separation than vertical biamping or monoblocks, challenging to integrate?, etc.

Bi amping is similar to bi wiring. You are simply running the power of the amps through the exact same internal crossover network of the speaker. This serves little to no benefit.

The benefit I see with vertical is that the mids and tweeters have their own channels of amplification and in a well-built amp, one shouldn’t effect the other. Asking a single channel in an amplifier to deliver massive wattage for the mids while still being delicate enough to reproduce good highs seems like a tall order. With vertical, even if they share the same power supply/transformer, there should be some benefit as the channels are isolated from each other. That’s my thoughts on the subject and my listening impressions line up with that.
Matrix: Can use zillion amps one per driver per frequency in a 4D matrix.

Unless you take the red pill in which case you wake up and say, "Tube integrated!"
Horizontal: how easy is it to truly gain-match two different amps?  How much does it limit your choice of components?
Generally, with gain matching two amplifiers, which would be important for any success, the more sensitive amplifier ( louder ) would need to be attenuated, which can be done if the amp has input level controls ( as most pro amps do ), or, you can connect a passive volume control, such as a Schiit SYS ( often mentioned, by my good friend, georgehifi, here on these pages ), connected to the inputs of the more sensitive amp ( xtra set of ICs required ). The Schiit is single ended only, but other passives are available ( ex. Douk audio ), available in balanced configuration. Easy peezy, lol....
Horizontal: how easy is it to truly gain-match two different amps? How much does it limit your choice of components?
If you really want to have success biamplifying, it's best to use an active crossover. That solves level and amplifier matching problems, and allows fairly easy horizontal biamplification.
When you can match a 200 watt amp for the bass, and a 50 watt (of higher quality) for the mids and highs.
A point to keep in mind when horizontally biamping using two amps having much different maximum power capabilities, without using an electronic crossover "ahead" of the amps (i.e., using the amps in a passive horizontal biamp configuration), is that chances are you won’t be able to utilize a lot of the power capability of the higher powered amp.

While a passive horizontal biamp configuration reduces the amount of current and power the high frequency amp must supply at low frequencies, it and the low frequency amp must (to a close approximation) both put out equal voltages, corresponding to the full frequency range of the signal. If they are not set up to do that the amps are not properly gain matched.

And if there is a large disparity between the power capabilities of the two amps chances are very good that the lower powered amp will not be able to supply as much voltage as the higher powered amp, without clipping. Therefore the user will probably not be able to turn the volume control up high enough to utilize all or even most of the power capability of the higher powered amp without driving the lower powered amp into clipping.

An electronic crossover "ahead" of the amps would eliminate that concern, as well as providing the benefits @cleeds referred to above.

@d2girls, that issue is likely to be particularly pertinent with the combination of an MC462 (450 watts) and an MC275 (75 watts) that you referred to. In terms of listening it might not be a problem, of course, depending on speaker sensitivity, listening volume, etc. But at the very least you would be paying for a lot of watts with the MC462 which couldn’t be utilized in that situation.

-- Al
After rebuilding my two Dynaco ST-70s with the VTA mods, I stumbled into Bob Latino’s suggestion to do vertical bi-amping. It obviously requires two identical amps. After having them hooked up that way for a few months now, I can definitely say that it makes an easily audible improvement in separation, imaging, clarity through the mids and highs, and dynamics vs using just one of the single stereo amps, and even vs using one channel of each amp as monoblocks.

Like any system upgrades or changes, how audible an improvement is depends a lot on the other variables in the system. Some components are simply more revealing of changes than others....for better or worse.

My speakers have passive crossovers, so that’s the route I pursued as a path of least resistance. I’m getting excellent results with them in the vertical bi-amp configuration, so am reluctant to head down the rabbit hole of active crossovers, but maybe someday for curiosity sake. I’d assume there are good and bad examples of both, so likely pros and cons with each.

I don’t know if this subject has been mentioned, but one of the benefits of vertical bi-amping with tubes amps is the ability to tailor the tubes with one matched set that has deeper tighter bass on the channels that go to the woofers, and a different set that has more open and clear mids and highs on the other channels. "Mismatched matched" sets on each side, with both amps setup identically of course.
Knotscott, that’s an interesting concept with the “mismatched” tubes. It makes a lot of sense.

I started with a stereo amplifier and then went to two stereo amplifiers in monoblock configuration (only using one channel on each amp). I really appreciated the step up from one stereo amp to “monoblocks.” It was a big improvement. I wasn’t there long before I tried vertical bi-amping and finding that I really like the results.

I use left and right channel tube preamplifiers. I could definitely try something somewhat similar to what you described with your stereo amp “mismatched” tubes concept. Thanks for the suggestion.
My main system is a two way vertically bi-amped. There are no passive crossovers and I use a Xilica 3060 and two Crown XLI800 amps. The Xilica does time alignment, gain, crossover points, crossover types, and slopes and EQ. It will store up to 30 presets so if you want to tailor your system to specific genres you can do so. Critical setup is done with a calibrated UMike and REW, a free audio analyzing program.

I was forced into doing this because my single fold horn has a 108" throat depth and I wanted clarity. I fought the idea of going active for years and instead tried things like Audyssey room correction and recapping crossovers. I could no longer do this, and succeed with this 108" throat system, and what I discovered is there are so many tools in there to correct things with that I will never go back no matter what I own in the future.
A bit complicated to get going on but once you do you can work on any speaker known to man and never buy another crossover and have tuning capabilities others can only dream of.
My current system is 8 individual amps, one for each speaker group.  That is line of six tweeters (one line for each side), a second line of 4  mids (again a line for each side),  a single fill-in for low mid, and 4 woofers in a bin (again 2 bins).

My point of interest in the design concept was that the audio band is 11 octaves wide,  3-octaves on the tweet (2.5k TO 20k), 3 octaves on the mids (312 TO 2.5k), 1-octave low-mid (160 to 312) and 3-octaves of low-end (20 to 160) so that each individual combination of amplifier and speaker is operated in a relatively limited bandwidth domain, and thus dynamic stress level by asking not a lot from each.

As I have a 50-year history of high-end audio design and fabrication this was just an advanced hobby project, an easy and not expensive  build 10 years ago when I moved into a this new house, and I was able to optimize each amp/speaker combination.

It works quite well.  As I now have a new no-feedback current mode gain cell topology that I am integrating into my new products designs, I guess I will have to rip this all out and update/grade it over the next couple months.

Good to throw it all out and start over again, it has demonstrated that the 4 way system idea yields good results. Such is the fun of audio.
I have been bi-amping for 5 years now and can't see going back. I agree using an active crossover is the way to go. I started with a 2-way active crossover and now have a 3-way. I removed the passive crossovers from my current speakers and instead rely on the filters in the active crossover. I use an Acoustat TNT-200 for everything below 100 Hz and they power up to 8 woofers in a distributed array. A pair of Music Reference RM-200s are horizontally bi-amped on the mains and each drives a mid-range ribbon (100 Hz to 650 Hz) and treble ribbon (650 Hz and up).
Check out http://www.linkwitzlab.com/
I have all three of his last systems. Bought the Orion, built the LXmini and the LX521.4. One feature they share is the following equipment architecture: source>pre-amp>(crossover/equalizer)>amplifier channel>driver. The Orion has two tweeters (one forward and one backward facing), one mid-range, and two woofers (one forward and one backward facing) per side. A minimum of 6 channels of amplification are required, 8 channels makes more sense so the woofers can be fed by pairs of bridged channels. To allow flexibility, a 12-channel amplifier (ATI AT6012) is recommended. The LXmini has fewer drivers than the Orion, the LX521.4 has more.

The benefit of the approach is that each driver has the optimal crossover points, roll off and amplitude relative to the other drivers. Analog solutions for the crossover exist as do digital solutions to allow you to dial in the set of curves that works best in your room. I never thought to refer to it as ‘vertical’ or ‘horizontal’; it’s just every driver getting exactly the set of frequencies where it performs optimally.

IF (and this is a big IF) you have the time and inclination to fuss around with your system to make it sound just right in your room and some budget to try a few different solutions, you might find the Linkwitz path fruitful. This is not plug-and-play gear; it takes time and a lot of listening, moving things, and swapping gear to get it right – and every little component and every wire matters. After living with 'oct-amped' (is that even a word?) dipoles I’ll never buy a 2-way speaker in a box again.

my jbl 4435 studio monitor sound better bi-amped bi-amping  and bi-wiring is not the same horizontal bi-amping is better bass less I M D better  woofer damping less T H D and it is not hard to do
I don't mean to give the impression this isn't a serious subject worthy of discussion. I tried very hard to get my speakers to go bi. But it just wouldn't work. Turns out they are trans.
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.
Don't get too hung up on all this. Any given method (stereo amp, bi-amp, passive x-over, active x-over) in one system can better any given method in another. 

Which is better? 
Stereo amp
Passive bi-amp (vertical or horizontal)
Monos with bi-wiring
Active x-over

Answer: Yes, or Depends on the variables 

What's really fun is when you think the one system sounds soooooo good, then change it up and find that a different amp sounds better in a different configuration! Lot's of fun realizing that there is no consistency to the superiority of particular methods. 

Even better, the fun that results when you change something like a DAC, and then the amp that was worse sounds better than the one that sounded better with the previous DAC! It's exciting when you can't easily peg an amp as "better" simply by building one or two systems.  

Change speakers; start over again.   :) 

mkgus OP
... for those who use electronic crossovers, is it a requirement to convert the signal to digital to do the processing?
... vertical bi-amping with active crossovers is not for the faint of heart and requires lots of knowledge and experience ...
Not necessarily.
If you're using an active crossover, I can't imagine why you'd want to do vertical biamping, other than perhaps for convenience in physically locating the amplifiers.

I have to agree with cleeds "not necessarily" for active crossovers. I was able to accomplish it with a little research, and if I can do it, anyone can do it (I'm electricity challenged).
To your original post - I tried bi-wiring and bi-amping with some little Castle towers in our apartment. I couldn't detect a discernible difference from the two setups. When I purchased Magnepan 1.6's for my "man cave" in our new house I had the two matching two channel amplifiers. I tried horizontal and vertical bi-amping through the passive crossovers. Each sounded a fraction different, but I didn't have a favorite. Then I read a white paper on active crossovers over at the Planar Asylum and decided to give it a try. I was able to get a used Bryston 10B analogue active crossover for a decent price and set about gutting the 1.6's passive crossovers. The only "hard" part was figuring out the polarity of the panel drivers for the rewiring and someone on the Asylum had already posted it so that was that.
Now that made a huge difference from the passive setup. Everything, and I do mean everything, was better. Again, I tried horizontal and vertical bi-amping setups and while the sound was different I didn't have a favorite so I stayed with vertical with it's less messy cabling. I haven't delved into vertical with two different amplifiers and there may be some further gains to be had there, but I was happy with what I have.
An interesting side note - As I was playing with frequency and slope settings on the crossover I was measuring the room responses with REW to get a baseline for what I liked (and no it wasn't the flattest curve). I noticed that two slope settings measured the same but distinctly sounded different. I don't have "golden ears" so it was pretty plain. I queried the Planar Asylum and the moderator cited "group delay" for the audible difference. Basically, if I understand correctly, it's the differences in the length of the wiring path in the crossover between the two settings. Who'd a thought.
Anyway, good luck on your journey.

Jim S.
I’m using a Rane 23B 3-way stereo Active Crossover with balanced inputs and outputs. Each speakers crossover frequency and volume control are adjustable with rotary dials. For example, I bought SEAS Millennium tweeters with a max low XO point on the spec sheets at 2000Hz. I simply adjust the rotary dials to the same frequency, then, used a sound level meter and test disk to set the volume levels of each driver. The same set-up method followed with matching Seas 7” woven midranges and a pair of handy 15” Yamaha bass drivers, all 8 ohm.

The Rane 23B recieves balanced L/R analog output signals from my preamp. The analog outputs from the Rane 23B connects to a Proceed AMP5 at 125WPC that handles the mids and tweeters, and a Lexicon LX-7 at 250WPC that handles the bass drivers. Looking at the SEAS midrange natural roll-off pattern and SLM testing, I chose 100 Hz as the XO between the 15” bass and 7” midrange drivers.  

If I change drivers, I can easily readjust the Rane to match the spec sheets. I’ve been very happy with the sound quality and especially, the quick adjustability of XO points and driver volume levels.

For a SVS PB13 subwoofer, I disabled all SVS preamp adjustments, or, play it "wide open” at a Very Low Volume.The sub is connected directly to my preamp’s L/R coaxial outputs to match the Balanced outputs connected to the Rane. My concern of playing higher frequencies wide open was quickly proven wrong. It’s clear and smooth from top to bottom and gained an appreciable “depth”.