# bi amping question?



## nineballg (Jan 19, 2008)

does anyone know if it is a waste of time and money to bi amp without external crossovers. for example: use one amp for lows and one amp for highs, and a processor, thats all.


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## Kal Rubinson (Aug 3, 2006)

nineballg said:


> does anyone know if it is a waste of time and money to bi amp without external crossovers. for example: use one amp for lows and one amp for highs, and a processor, thats all.


You will get many opinions. Mine is that it is not worth the bother if your single amp is adequate.

Kal


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## nineballg (Jan 19, 2008)

thanks, my amp is very good. but im looking to get the most out of my speakers. i only use my system for movies. if done correctly with crossovers, does anybody bi amp there entire home theater surround system, or is it primarily for 2 channel audio.


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## thxgoon (Feb 23, 2007)

Most people who bi amp fall into the two channel category IMO. I've heard of very few who actually bi amp the entire system. Using the internal crossovers of your speakers you don't gain much from bi-amping other than extra power from the additional amp.


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## jerome (Apr 24, 2007)

What kind of amp(s) do you have? Many use the same physical amp (but different connectors on the back of the amp) to bi-amp the speakers. The amplifier produces (more or less) the same amount of power to the speakers. In this case, there's no real benefit.

In my opinion, it's as useful as bi-wiring in this case: the same amplifier is connected to the same speakers via two pairs of cables instead of one pair in the single-wiring case.

Bi-amp becomes useful if you have two phisically different amplifiers. For instance, Arcam P1000 includes 7 different amplifiers. You get more power to the speakers if you bi-amp.

At the end you will have to try it to hear if that's really worth it for you. Speaker cables are usually not cheap and, if the benefit is minimal, so you could probably use this kind of money on another piece of hardware :spend:


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## thxgoon (Feb 23, 2007)

jerome said:


> Bi-amp becomes useful if you have two phisically different amplifiers. For instance, Arcam P1000 includes 7 different amplifiers. You get more power to the speakers if you bi-amp.
> 
> At the end you will have to try it to hear if that's really worth it for you. Speaker cables are usually not cheap and, if the benefit is minimal, so you could probably use this kind of money on another piece of hardware :spend:


Even in this case the only real benefit is that of the extra headroom offered by the extra power. And even then there is not much benefit because the majority of the power is used in the bass/midbass section of the speakers... where the power runs out first. You're absolutely right though about saving money on cables as it doesn't take a really expensive cable to deliver the entire signal, money is much better spent elsewhere.


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## lcaillo (May 2, 2006)

The real advantage of biamping is being able to move the crossover from passive in speaker to active before amplification. That is, if the speakers really allow biamping and not just biwiring, and if you get the slopes and levels right on the electronic crossover, and if you have a good electronic crossover. Lots of ifs...


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## Kal Rubinson (Aug 3, 2006)

lcaillo said:


> The real advantage of biamping is being able to move the crossover from passive in speaker to active before amplification. That is, if the speakers really allow biamping and not just biwiring, and if you get the slopes and levels right on the electronic crossover, and if you have a good electronic crossover. Lots of ifs...


This generally demands a custom made crossover since simply manipulation of slope/level/frequency is, more often than not, only part of the functions required.

Kal


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## lcaillo (May 2, 2006)

What other functions?


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## Kal Rubinson (Aug 3, 2006)

lcaillo said:


> What other functions?


In band frequency/phase correction. Multislope roll-offs. Just off the top of my head. 

Kal


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## lcaillo (May 2, 2006)

The whole point is that these are easier to manage in low level signals with active devices compared to passive crossvers at high power levels. Today, with digital filters as easy to design and apply as they are, the advantages of biamping (actively) are greater than ever.


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## Kal Rubinson (Aug 3, 2006)

lcaillo said:


> The whole point is that these are easier to manage in low level signals with active devices compared to passive crossvers at high power levels. Today, with digital filters as easy to design and apply as they are, the advantages of biamping (actively) are greater than ever.


That is certainly one valid point. However, *my *point was that this requires knowledge and skill since there is no off-the-shelf crossover that will do these things out of the box. Either one must design it or program it. This, alone, makes active biamping, though desirable and advantageous, out of the reach of the vast majority of audiophiles.

Kal


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## nineballg (Jan 19, 2008)

thanks for the reply. im currently using jbl synthesis amps. one 5 channel and one 2 channel for my 7.1 system. i could get my hands on a carver av-705 5 channel amp, therefore bi amping 5 speakers of the 7 speakers. but since im using the internal crossovers on the speakers, im not sure if i'll benefit enough so its worth the money.


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## lcaillo (May 2, 2006)

Kal Rubinson said:


> That is certainly one valid point. However, *my *point was that this requires knowledge and skill since there is no off-the-shelf crossover that will do these things out of the box. Either one must design it or program it. This, alone, makes active biamping, though desirable and advantageous, out of the reach of the vast majority of audiophiles.
> 
> Kal


These additional factors are far from well handled by passive crossovers. The fact is that many here are biamping their systems in precisely this manner when they use the BFQ and REW for their subs. The additional factors that you described are far from well defined and addressed in most available speaker designs, and by choosing filter type, frequency, slope, and levels carefully in commercially available active crossovers, one can achieve significant gains with biamping. Audiophiles have done so for many years. The better speakers these days certainly have improved crossover designs, but there are still gains to be made with active biamping. Certainly, many do not understand the difference between active and passive biamping, nor even the difference between biamping and biwiring, but the fact that a majority of audiophiles might not be capable of doing something does not change the fact that the concept has merit. Geez, the majority of audiophiles probably think that they have to spend thousands on interconnects.


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## Kal Rubinson (Aug 3, 2006)

lcaillo said:


> These additional factors are far from well handled by passive crossovers. The fact is that many here are biamping their systems in precisely this manner when they use the BFQ and REW for their subs. The additional factors that you described are far from well defined and addressed in most available speaker designs, and by choosing filter type, frequency, slope, and levels carefully in commercially available active crossovers, one can achieve significant gains with biamping. Audiophiles have done so for many years. The better speakers these days certainly have improved crossover designs, but there are still gains to be made with active biamping. Certainly, many do not understand the difference between active and passive biamping, nor even the difference between biamping and biwiring, but the fact that a majority of audiophiles might not be capable of doing something does not change the fact that the concept has merit. Geez, the majority of audiophiles probably think that they have to spend thousands on interconnects.


Ok Ok! This seems to come down to the ability of the user and that is wildly variable. That it can be done successfully is acknowledged. Whether it can be done by the majority of people who ask if biamping is advantageous and who cannot distinguish most of what you are discussing is highly unlikely. 

Also, I think you underestimate the sophistication of the passive crossovers in quality loudspeakers and overestimate the abilities of many users of commercially available crossovers. Of course, anyone is free to try.

Kal


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## lcaillo (May 2, 2006)

I think you underestimate the limits of passive crossover design. Ask any speaker designer if it would be easier to deal with the multitude of variables in passive high level crossovers or in active line level crossovers. The answer would be virtually unanimous, other than their preference to do things the way they have become accustomed to doing. Passive crossover systems are easy to market and cheap. Active systems are expensive due to the additional amplification needed. The fact is that the additional factors that you suggested are NOT primary concerns with passive crossover designs.

Most users can't calibrate their displays properly either. That does not keep us from discussing the matter openly and does not lead us to make a case against calibration nor against DIY attempts at doing so. On the contrary, interest in the matter has spawned a market in low end equipment and software to do calibration. To argue that biamping is not a significant option because most people can't understand it would be like saying it is pointless to attempt to calibrate your display yourself.


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## Kal Rubinson (Aug 3, 2006)

lcaillo said:


> I think you underestimate the limits of passive crossover design. Ask any speaker designer if it would be easier to deal with the multitude of variables in passive high level crossovers or in active line level crossovers. The answer would be virtually unanimous, other than their preference to do things the way they have become accustomed to doing. Passive crossover systems are easy to market and cheap. Active systems are expensive due to the additional amplification needed. The fact is that the additional factors that you suggested are NOT primary concerns with passive crossover designs.


I can agree with all that (and I think I did already) except for the last sentence. If you want to include the cheap-and-cheerful designs that seem to dominate mass market HT speakers, you would be right. However, the passive networks in high quality speakers owe their complexity to a specific concern for those "additional factors" and others. That those same engineers might have had an easier task with an active line-level design (analog or digital) is a given.



> Most users can't calibrate their displays properly either. That does not keep us from discussing the matter openly and does not lead us to make a case against calibration nor against DIY attempts at doing so. On the contrary, interest in the matter has spawned a market in low end equipment and software to do calibration. To argue that biamping is not a significant option because most people can't understand it would be like saying it is pointless to attempt to calibrate your display yourself.


It ain't that they can't understand it but that they do not and, more than likely, will not devote the time and effort to do so. I have never said that it cannot be done and done well (in the past, inspired by Linkwitz' older publication, I devoted a lot of effort to such), merely that it is far from a trivial undertaking. Hey, the majority of inquiries about this come from AVR users who simply want to make use of currently unused amp channels. 

Kal


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## lcaillo (May 2, 2006)

I made a simple point regarding the advantage of biamping. That point is valid, and it is a worthwhile endeavor for a real enthusiast who is willing to learn about the principles of crossover design and operation. I would not recommend it for someone with unused channels on an AVR. We don't really disagree very much here, Kal. I just find your initial comment and the generally negative view to be counter to the general theme of HTS. Many of the members and readers here are very much the sort that will experiment and learn. To argue that most users are not capable of understanding nor learning how to manage their crossovers in a forum where there is great interest in DIY speakers, subs, screens, and calibration is just a bit out of sync. If you were writing an article for a mainstream publication, you would be more on target.


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## Kal Rubinson (Aug 3, 2006)

It seems that we do not disagree on much except, perhaps, our view of others. Your original post implied that the process is easier than, imho, you should have. My response was to point out that it was more complex than you suggested.

As for the people around here being up to such challenges, I will defer to you. My comments were made about the general population, some of whom do pass through here. :bigsmile:

Kal


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## lcaillo (May 2, 2006)

Just trying to remind you how special the folks here at the Shack are, Kal.

I get what you are saying, and I do agree, for the general population. Just remember that the whole industry has been dumbing itself down for years, and as a result we have great misconceptions in the public about many audio and video matters. My point is that we do not need to participate in that dumbing down here.

As always, intelligent give and take on an issue leads both sides to find where they agree and both to find what matters in their opinions and perspectives.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Kal Rubinson said:


> This generally demands a custom made crossover since simply manipulation of slope/level/frequency is, more often than not, only part of the functions required.
> 
> Kal


What else would a crossover have to do besides those three things?



Kal Rubinson said:


> That is certainly one valid point. However, *my *point was that this requires knowledge and skill since there is no off-the-shelf crossover that will do these things out of the box. Either one must design it or program it. This, alone, makes active biamping, though desirable and advantageous, out of the reach of the vast majority of audiophiles.
> 
> Kal


 This is a fairly common refrain when this topic comes up, but I often wonder just how much of it is verifiable - and indeed, actually verified - and how much is merely repeating what someone who was supposedly knowledgeable on the subject had to say? Someone who probably was a passive crossover designer to begin with? And probably did not even peruse active options for whatever speaker he was designing? 

Regards,
Wayne


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## Kal Rubinson (Aug 3, 2006)

Wayne A. Pflughaupt said:


> What else would a crossover have to do besides those three things?


Asked and answered. Many crossovers attempt to correct amplitude and impedance anomalies within (and/or outside) the passband. The complexity of the crossovers in better speakers is a reflection of these efforts.



> This is a fairly common refrain when this topic comes up, but I often wonder just how much of it is verifiable - and indeed, actually verified - and how much is merely repeating what someone who was supposedly knowledgeable on the subject had to say? Someone who probably was a passive crossover designer to begin with? And probably did not even peruse active options for whatever speaker he was designing?


Three issues here. First, I have done passive crossover design for many speakers in the past (more than 20 years ago) and can say that more than a simple single-frequency filter was required to get them to measure and sound best. I have spoken to some, more current and commercial designers who have found the same. 

Second, active options are great but not for commercial designs where the major part of the market has rejected active speakers, admittedly, out of general ignorance. This means that the designers for this market do not bother to develop active options. 

Third, the rise of computer modeling and DSP filters has made the job of making a custom crossover much better and easier. Still, this means that the user/designer has to customize the filters to the particular speaker/box configuration in use. This demands the knowledge and ability to measure and model. 

I never rejected active crossovers for speakers. I am, in fact, in favor of them. Perhaps the folks in this forum are more capable of this than are most of those who ask about biamping. If so, have at it.


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## Wayne A. Pflughaupt (Apr 13, 2006)

Kal Rubinson said:


> Asked and answered. Many crossovers attempt to correct amplitude and impedance anomalies within (and/or outside) the passband. The complexity of the crossovers in better speakers is a reflection of these efforts.


”Amplitude anomalies” being inherent SPL differences between the drivers – i.e., level-matching? “Impedance anomalies” being, ensuring the system’s impedance is a nominal 4 or 8 (or whatever) ohms?

Regards,
Wayne


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## Kal Rubinson (Aug 3, 2006)

Wayne A. Pflughaupt said:


> ”Amplitude anomalies” being inherent SPL differences between the drivers – i.e., level-matching? “Impedance anomalies” being, ensuring the system’s impedance is a nominal 4 or 8 (or whatever) ohms?


Nope. In both cases, I am referring to the variations of the individual mounted driver, not the differences between drivers.

Kal


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