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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
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cleeds
5,674 posts
 
mkgus OP
... for those who use electronic crossovers, is it a requirement to convert the signal to digital to do the processing?
No.
... 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.
stilljim
36 posts
 
mkgus,

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.
soundsbeyondspecs
132 posts
 
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”.        
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