CAN Bi-Amping been done Correctly?

The more I've tried such experiments the more I realize that the best way is to have 2 amps or 2 pairs of monos of one kind. It's not going to go as with built-in servo-controlled bass drivers that are on some of Genesis, Wisdom and other speakers for sure.

I use a pair of McCormack .5 amps in a biamped configeration with Vandersteen speakers. One of the most substantial improvements I ever made to a system in 30+ years of playing with this stuff. I was amazed!
You have to make sure the amps are identical. I don't believe what you want to do is a good idea. Read Richard Vandersteen's article on vertical biamping. For sonic integration, the amps must be sonically alike. I think this would be even more important with ribbons and dynamic woofers. Also, you have the level matching and sensitivity problems with mis-matched amps. Identical amps will overcome this limitation.
To specifically explain what I did, each stereo amp drives one speaker (one left, one right) One channel in each amp drives the mid and highs, the other the bottom. I have the benefits of mono blocks and different loads on each channel. This gets the most out of each amps power supply. It also bi-wires the system. IT DOES WORK UNBELIEVABLY SO! Hope this provides a little insight.

Mark:
The answer is yes, it can be done. You will need an active crossover and need to bi-pass the internal cross-over of your MLs when using two different types of amps. Undoubtedly the gain will be different. I have a pair of ML monolith IIs which I bi-amp--to great success. I'm using solid state on both top and bottom--but your idea is a good one. I have tried using a tube amp on top and it didn't work, but that was because of the great mis-match (in power) in the amps I was using. Your tube amp needs to have close to the same output and needs high current delivery to handle the panels (this is generally not a problem for most good quality tube amps). I would recommend no less than 100 watts per channel (per driver as well). In terms of cross-overs, Bryston 10B and the Marchand are both excellent. The Marchand is a bit more economical.

Lastly, if you are using a class A SS amp and the tubes--better have a good air conditioner or live in Canada--you are going to generate some heat.

Bi-amping is great for sound. The problem is that it is more expensive. Don't confuse it with bi-wiring which is mostly not worth the effort. It is far to complicated to deal with well in this forum. One of the best discussions on bi-amping that I know of on the web is Rod Elliot's website, www.sound.au.com. The article is caled "Bi-amplification-Not Quite Magic, But Close." The article is located exactly at www.sound.au.com/index.html. If you browse around the website you will find it. The entire site is fairly good and there are some other good articles on amplification too. He is mostly solid state. Give me an e-mail if you have any questions after reading the article. Biamplification is great and it is easy to do. Easier (and better) than passive crossovers if you are into that.
Good Luck,
Craig Klomparens

email address: wryder@chartermi.net

I have a pair of B&W 802 series 3's that are bi-amped with a pair of Parasound amps. The difference was nothing short of amazing.

I don't know if it can be done "correctly", as I don't know what "correctly" is. But if you are asking, if you can have glorious sonics, by bi-amping Martin Logans, yes.
I use Curcio modified MKlll's, on the panel, and solid state, on the bass. With 60 watts, on the stats, and 200 watts, on the bottom, I think it sounds grand. The Martin Logans are Sequel ll. I did a lot of interconnect cable, and speaker cable swapping, before arriving at what I liked.

I work with pro sound reinforcement a lot and multi amping is a way of life. Use a big solid amp for the bottom and you can get away with a smaller amp for the highs and mids because the big power suck is the bass. I don't know why you would need the same amp for highs and lows, especially if you are mixing two different speakers, though you may need to experiment to find an amp combination that suits you. The difference i see in the pro side verses what i see here is that we use a cross over to split the signal out of the board (i.e. the pre-amplifier) where as it seems that in hi-fi applications the full range signal goes to both the mains and the subs with a cross over in the sub controlling what the sub reproduces. The mains are also trying to reproduce that low signal and that may be where the clash comes from...just a guess. In pro set ups you also need to tune the cross overs and eq for the room, it's not a simple plug and play operation. The cable swapping noted above seems to be a dialless method of EQing the system.

Yes!

I have used a tube amp for mid/trebble (passively crossed over), mosfet monoblocks for bass and a bridged mosfet stereo amp for sub, the 3 lots of amps being crossed over electronicaly.
I have used a professional x-over with the resistors and caps swapped for better ones and better op amps also installed.
It sounded pretty good standard and exceptional modified.

Realise that pro electronics are usually better designed and built than hi-fi, unless you are looking in the Krell/Levinson bracket.
It has to be. It gets a hell of a life, both thrashed and shaken. Needs to be able to survive torture tests hi-fi never sees.
Also needs to sound pretty good, mid and high frequencies are usually taken care of by horn drivers - and say what you like, but they are revealing enough to make shoddy electronics horrifically noticable.

Pro x-overs can often be found quite cheap second hand and the only big hassle is using xlr connectors (ballanced) in a single ended system (assuming yours is).
Most can be switched so the output is unballanced with pin 2 hot, pins 1, 3 and the shell cold. Just means a bit of soldering to swap connectors on your interconnects - not very difficult.

I chose a x-over that was internally unballanced and then stripped out the op amps and circuitry that did the ballanced to unballanced conversion. Sounded a wee bit better. I could of changed the xlr connectors to rca's as well - but I've yet to be told something good about rca's! Wrong connector for hi-fi, that is for sure.

The other good thing about pro gear is that they don't make a secret of the circuit diagrams - helps doing mods no end. In fact, the user manual for my one had the circuit diagram in it.

Perhaps the only downfall with some pro x-overs is that they are designed for lower end systems and they invariably use a wall wart power supply.
Best to avoid these, look for one with a fully internal power supply, it will most likely be quite nicely regulated and that helps.

Don't be put off by the fact that you have to set the level for each frequency band with a knob (usualy seperately for each channel).
Your ears will soon tell you when you have it right. Most people start off with too much bass. Take your favourite recording to other places to listen and compare. Accoustic and vocal music is good for set up. Get everyone from the barratone to the soprano sounding good and you'll be real close as we all know what a voice should sound like!

Best of luck, NOTHING beats a good multi amped system in my oppinion!