Bi-amping?

[JoelS]

newbie question?

what exactly is bi-amping and what are the benefits?

 

[j_garcia]

There are no benefits

 

[fmw]

For home audio there are no benefits because you are referring to passive biamplification. Pro audio uses a type of biamplification called active biamplification. It involves using an electronic crossover component between the mixer and amplifier and removing the passive networks from your speaker systems. I don't recommend you get involved in that either. It has some benefits in pro audio but is probably more of a negative in home audio.

 

[highfigh]

There are no benefits

Yeah, that's why it has been done for almost 100 years.

 

[KEW]

Re: active networks

It has some benefits in pro audio but is probably more of a negative in home audio.

Why do you think the benefits are restricted to Pro Audio?
I like knowing I won't start clipping or blow my speakers if I crank them.
I like not having to second guess whether my amp is adequate for my specific speaker's efficiency/impedance profile!
I like the idea of using Class D amplification for woofers and Class A/B for tweeter.
I like not having to slam watts of power into resistors to match sensitivity between drivers. Doing it with individual amp gains seems much more eloquent (in the simple sense).

...and I'm ignorant of the more technical benefits someone like TLSGuy would address.

What are the negatives?

 

[3db]

I'm reading fmw's post to mean that one has to have more than a layman's worth of knowledge on how the speakers behave and interact in a room to get a good sound which is beyond the majority of users. It would take me considerable time to set something like this up correctly even though I posses a degree in EE and understand the principles behind it.

 

[KenM10759]

If you are bi-amping from a multichannel receiver, the main benefit is that the speaker wire company sells more wire. I learned the hard way. Well, it does give a teeny tiny bit more something because my receiver no longer goes into protection mode with it set at -0dB. I have to go up to 2dB for that but it really doesn't sound a lot louder when it shuts down.

If you are bi-amping by using two power amplifiers, completely different.

 

[fmw]

Re: active networks

Why do you think the benefits are restricted to Pro Audio?

Because there are no benefits in home audio. In pro audio the technique is used mostly to make use of available amplification in complex speaker installations. Tweeters only need milliwats. No point in using a 1500 watt amp for tweeters when a tiny amp will do and is available.

I like knowing I won't start clipping or blow my speakers if I crank them.

So does everyone but biamplification won't help prevent clipping.

I like not having to second guess whether my amp is adequate for my specific speaker's efficiency/impedance profile!

So does everyone but biamplification won't fix a planning error in this area.

I like the idea of using Class D amplification for woofers and Class A/B for tweeter.

OK if you like that then do it. It still won't make any difference.

I like not having to slams watts of power into resistors to match sensitivity between drivers. Doing it with individual amp gains seems much more eloquent (in the simple sense).

Never done such a thing in my life. Why do you do it?

...and I'm ignorant of the more technical benefits someone like TLSGuy would address.

What are the negatives?

The major one is adding complexity to the system for no benefit. Complexity means there is more to break. The other one is adding cost to the system for no benefit.

 

[fmw]

I'm reading fmw's post to mean that one has to have more than a layman's worth of knowledge on how the speakers behave and interact in a room to get a good sound which is beyond the majority of users. It would take me considerable time to set something like this up correctly even though I posses a degree in EE and understand the principles behind it.

No. The problem with passive biamplification is that the second amp doesn't really do anything important since tweeters only dissipate milliwatts. Nevertheless passive biamplification puts full power at both ends of the network. So 99% of the amp driving the tweeters is wasted and not relieving the other amp of anything meaningful or audible.

I don't recommend active biamplification for home use because generally the speaker designer does a better job of tuning the system than the home audio enthusiast will with full control over crossover and driver levels. I think equalization is a better approach for home audio. It is easier to control. Most of the time pro audio biamplification is used to make effective use of available amplification, not to improve the sound quality. Yes it can improve sound quality and is used for that purpose in permanent installations. But most of the time it is an inexpensive work around.

 

[j_garcia]

Yeah, that's why it has been done for almost 100 years.

Not in the home For home use, it is little more than a marketing term. There are many flavors of biamping and how far one wants to go in order to try to try to reap benefits. Those benefits are not going to be realized in the typical home setup.

 

[KEW]

Because there are no benefits in home audio.

I guess I misinterpreted your post.
It sounded to me like you were describing an active crossover system (you were) and I inferred that to mean you believed actively crossed speakers (typical pro audio monitors) were problematic for home audio. Obviously, based on your response, that was not what you were saying. You are saying it would generally be problematic for the average consumer to consider converting a system to an active one, which I agree with and what I see 3db was explaining to me in his post.

 

[TLS Guy]

I guess I misinterpreted your post.
It sounded to me like you were describing an active crossover system (you were) and I inferred that to mean you believed actively crossed speakers (typical pro audio monitors) were problematic for home audio. Obviously, based on your response, that was not what you were saying. You are saying it would generally be problematic for the average consumer to consider converting a system to an active one, which I agree with and what I see 3db was explaining to me in his post.

That is the point. It is hard to do just about any speaker conversion. It is best to start from scratch. However the home DIY enthusiast can bi-amp and tri- amp and should.

In addition bi-amping should make further progress into higher end home audio and migrate towards the lower end.

The lower the crossover the greater the advantages of bi-amping. The least advantage is for the tweeter crossover. Tweeters are almost always more sensitive than the other drivers, the component values are low, and the power is small.

However for a three way it is entirely a different matter and to some extent 2.5 ways.

I don't think a passive three way speaker can be considered state of the art any longer. The improvement in making the lower crossover active are enormous and audible. If you compare the same ATC monitors in active and passive versions, I think anyone would find the active version far superior.

The advantages are better control of the driver. A passive network totally undoes amplifier damping.

Driver and speaker can be designed as a unit.

It allows are much wider choice of drivers. A passive network can only cut and never boost. You can not pad a woofer passively, only with an active network. This widens the choice of drivers enormously.

Eq of drivers, and especially BSC can be much more precise and accurate. This gives active 2.5 ways a significant leg up.

The whole system, especially true full range speakers can be precisely integrated and the LFE signal captured seamlessly.

I have found in general active speakers have a better impulse response than passive ones.

As technology progresses feeding a digital signal to the speaker and the use of fully digital crossovers will allow for perfect time and phase correction. My hunch is that if we could get to that point the improvement would be transformative.

The greatest advantage to my mind though, is eliminating the serious problems of passive crossovers as the frequency is lowered.

In my system here a totally passive solution for what I want and have would be totally impossible. It would be absolutely impossible to deliver the quality I enjoy with entirely passive crossover. Yes, totally impossible.

 

[mtrycrafts]

newbie question?

what exactly is bi-amping and what are the benefits?

Welcome

I think you have your answer on its benefits.

No one, I don't think, explained what it is.
Speakers that have 4 or more terminals on each speaker and uses a jumper strap can be bi-amped when that strap is removed. Some receivers have this capability spelled out in their manual by connecting one pair of speaker terminals to the designated channel and another channel to the other pair on the same speaker.
There are better explanations at the home page and tech section.

 

[fmw]

That is the point. It is hard to do just about any speaker conversion. It is best to start from scratch. However the home DIY enthusiast can bi-amp and tri- amp and should.

I agree if the DIY is an original design. Trial and error with an active network is a bunch easier than finalizing a passive network design. For the quasi-DIY using a proven existing design, I would still recommend the passive network that proved the design.

 

[PENG]

I agree if the DIY is an original design. Trial and error with an active network is a bunch easier than finalizing a passive network design. For the quasi-DIY using a proven existing design, I would still recommend the passive network that proved the design.

I always wonder how good all those enthusiast are relative to big name speaker designers, I would think there are always some top notch ones (TLS could be one, and has the test gear) but not sure about the majority of them. One advantage they have though is, they control how much they want to spend on components, whereas the design team of speaker manufacturers have to take order from their production and sales bosses.

 

[herbu]

what exactly is bi-amping and what are the benefits?

I look at it this way:
Say you have a speaker with 3 drivers, a tweeter, a midrange and a woofer. Each of those drivers has a frequency range, and each range is a curve, not like a square wave.

The goal is to end up with a flat overall frequency response, including when the frequency falls in the transition, (curve), between two drivers. In these transition frequencies, 2 drivers are contributing to the sound. The goal of a crossover is to blend those two contributions such that the result is a seamless, continuous, flat overall response. This crossover design is part voodoo, part science and all critical.

When you hook up a speaker normally, with two wires, the amount of power sent to each driver, at each frequency, is managed by the crossovers... transparent to you.

Active bi or tri amping means you have an external amp for each driver, and run a pair of speaker wires from each driver to an amp. Now there is no crossover in the speaker. YOU control how much power goes to each driver by controlling its amp.

You could do kind of a hybrid setup w/ one amp for the woofer, and the mid and tweeter sharing a separate amp managed with an internal crossover.

Passive bi or tri amping means you simply send the same signal, from the same amp, separately to each driver. I think almost everyone agrees there is little benefit here.

My thoughts: Even if I had the money and enthusiasm to build a home theater with active bi or tri amping, I do not believe my ability to manage the crossovers between drivers is as good as the best professionals. Industry leading crossover designers are highly regarded, and their products are considered best of breed.

If I had the interest, it might be an interesting hobby to explore. But barring some years of education and experience, I'll stick w/ the industry icons and simply plug-n-play.

If I over-simplified, or misstated something here, I'll ask one of the more technical experts to correct me. Thanks.

 

[fmw]

I always wonder how good all those enthusiast are relative to big name speaker designers, I would think there are always some top notch ones (TLS could be one, and has the test gear) but not sure about the majority of them. One advantage they have though is, they control how much they want to spend on components, whereas the design team of speaker manufacturers have to take order from their production and sales bosses.

I think it is fair to say most don't hold a candle to an experienced speaker designer. But if you expect to choose some random drivers and calculate a box for them, the active network is easier than designing a passive network, testing, tweaking retesting and on and on like the pros have to do. That was the point TLS made but I don't consider true DIYers as typical home audio enthusiasts. For almost all home theater enthusiasts biamplification of any stripe should never enter the discussion.

I've only done it once. I bought some fairly high end Vifa drivers to make a pair of d'Appolito speakers as recording monitors. Each had a 1" dome tweeter and a pair of 8" woofers. I picked an off the shelf crossover and had to redo it 3 times before I was satisfied with the result. It took a while with ordering inductors and capacitors, trying them, going again and again. In my case I would agree with TLS's point.

 

[Seth=L]

If you are bi-amping by using two power amplifiers, completely different.

But almost always completely unnecessary.

 

[3db]

No. The problem with passive biamplification is that the second amp doesn't really do anything important since tweeters only dissipate milliwatts. Nevertheless passive biamplification puts full power at both ends of the network. So 99% of the amp driving the tweeters is wasted and not relieving the other amp of anything meaningful or audible.

I don't recommend active biamplification for home use because generally the speaker designer does a better job of tuning the system than the home audio enthusiast will with full control over crossover and driver levels. I think equalization is a better approach for home audio. It is easier to control. Most of the time pro audio biamplification is used to make effective use of available amplification, not to improve the sound quality. Yes it can improve sound quality and is used for that purpose in permanent installations. But most of the time it is an inexpensive work around.

What I meant by my response was the active biamping and the expertise required to to set something like that up.

 

[Swerd]

It seems we lost the OP. I'm guessing that he saw 'bi-amping' mentioned in the owner's manual of his AVR and was curious what it was about. All the subsequent discussion chased him away.

As an interesting aside, Salk has introduced a new small 2-way speaker that is fully active with digital crossover and 2 built-in amps: http://www.salksound.com/powerplaymonitor-home.htm.

At $2195 per pair they aren't cheap. But they can accept digital (S/PDIF or USB) or analog inputs, and have sub woofer outputs. They don't require separate amps, preamp or DAC.

Here's a better web page describing these speakers: http://landing.salksound.com/powerplay.html

It looks to me like Salk is testing the waters with this model. If it is successful, I would expect more to follow.