Who Here is Vertical Bi-Amping?

Oldhvymec:
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.

Regards,
-- 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.