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Bi-amping is the practice of splitting the frequencies after the preamp and before the amplifiers. Two amps are then fed the crossed over signals---no amplifier is fed a fullrange signal.


If the crossover is 500 hz one amp gets only 500hz on down signal and is then connected directly to the woofer. The other amp gets fed only 500hz on up and is connected directly to the treble driver. Passive crossovers at the speaker level are thus avoided.


This practice is often called "active bi-amping" if done with an active crossover and called "passive bi-amping" if passive filters are used between preamp and amps.


Bi-amping is popular with DIYers and hornys (many hornys bi-amp with transistor amps on woofers and tube amps on the compression drivers) but is unsuited to many turnkey speakers because they have voicing circuits built into their passive crossovers. If you bypass the speaker's passive and connect an amp direct you'll change the intended voicing of such speakers.


Proponents of bi-amping (I've often bi-amped ) often feel there's an improvement in the sound from eliminating passive elements at the speaker level and that these improvements manifest themselves as improved dynamics, lower distortion and an improved sense of immediacy.


The practice also lets you mix amplifiers to specific jobs, for instance many hornys like the sound of transitor amps on woofers and basshorns but prefer the sound of tube amps for compression drivers, bi-amping lets them make the mix.

 

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The benefit is that you don't get coupling between the electrical circuits of the different speaker elements. (There are tri-amped speakers, too, etc) This means that induction from your mid-range elements won't get into the tweeters and muddy it up.


Another benefit is that you don't have to design a cross-over filter that can take the wattage you throw at your speakers. This means you can have a fancier cross-over filter design over on the low-power side.


If you take it all the way, you design the entire speaker as a system with a line-level splitter, N amplifiers, and N elements. Then you can tune the characteristics of each amplifier to the characteristics of the elements, and get a really clean sound! These kinds of systems are known as "powered monitors" and are usually used in recording studios for near- and mid-field monitoring (and some room monitoring systems, as well).


Again, the audible difference, if done right, is that the mid/high cross-over will be better defined, and you won't have mid-range induction muddying your tweeters' output.
 

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Quote:
Originally Posted by rosh /forum/post/0


Does biwiring really help (indpendent of biamping) ? My understanding of biwiring is simply running two wires instead of one between the audio source and the speaker.

IMHO.... Bi-wiring is a waste of time. The electrical circuit is EXACTLY the same if you run a single full range wire off of the amp and split it into four speaker terminals as running that same full range signal into two speaker terminals and then connecting the four terminals with the same gage wire jumpers. If the circuit is identical, then the sound has to be indentical.


If you run two full range wires off the amp, all you are doing is lowering the gage of the wire in the circuit. This COULD be helpfull I suppose if you are running amps with tons of power (200 or more amps per channel), but even that is debatable.


You WILL get an improvement IMHO if you remove the shiny brass plated nickel factory supplied jumpers and replace them with the same gage and type of wire that you are running from your amp into one set of the speaker terminals.


But like anything else involving speakers.... you may "hear" it differently. Speaker wire is cheap. So it's easy enough to experiment and see if you experience a difference.
 

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Originally Posted by quadriverfalls /forum/post/0


You WILL get an improvement IMHO if you remove the shiny brass plated nickel factory supplied jumpers and replace them with the same gage and type of wire that you are running from your amp into one set of the speaker terminals.

Why?
 

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I like to biwire my speakers if only to get as much power as possible to the speakers. Using 2 sets of 13-ga wires combined at source. What I would really like would be for all amps to have 2 sets of outputs for each channel with a low pass filter for the mid/highs. Some amps actually have this for a sub filter - usually like 20 or 40hz so they don't send any signal below 40hz to the speaker outputs.
 

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Quote:
I like to biwire my speakers if only to get as much power as possible to the speakers.

If you use the proper gauge wire, this isn't a problem.

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What I would really like would be for all amps to have 2 sets of outputs for each channel with a low pass filter for the mid/highs.

That's called a crossover, and they usually build them into the speakers.

Quote:
Some amps actually have this for a sub filter - usually like 20 or 40hz so they don't send any signal below 40hz to the speaker outputs.

This is usually done prior to the power amp stage.
 

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Quote:
Originally Posted by quadriverfalls /forum/post/0


You WILL get an improvement IMHO if you remove the shiny brass plated nickel factory supplied jumpers and replace them with the same gage and type of wire that you are running from your amp into one set of the speaker terminals.

Over that short a distance the jumpers will conduct the signal as good as wire of that same length.
 

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Quote:
Originally Posted by Tom Brennan /forum/post/0


Bi-amping is the practice of splitting the frequencies after the preamp and before the amplifiers. Two amps are then fed the crossed over signals---no amplifier is fed a fullrange signal.


If the crossover is 500 hz one amp gets only 500hz on down signal and is then connected directly to the woofer. The other amp gets fed only 500hz on up and is connected directly to the treble driver. Passive crossovers at the speaker level are thus avoided.


This practice is often called "active bi-amping" if done with an active crossover and called "passive bi-amping" if passive filters are used between preamp and amps.


Bi-amping is popular with DIYers and hornys (many hornys bi-amp with transistor amps on woofers and tube amps on the compression drivers) but is unsuited to many turnkey speakers because they have voicing circuits built into their passive crossovers. If you bypass the speaker's passive and connect an amp direct you'll change the intended voicing of such speakers.


Proponents of bi-amping (I've often bi-amped ) often feel there's an improvement in the sound from eliminating passive elements at the speaker level and that these improvements manifest themselves as improved dynamics, lower distortion and an improved sense of immediacy.


The practice also lets you mix amplifiers to specific jobs, for instance many hornys like the sound of transitor amps on woofers and basshorns but prefer the sound of tube amps for compression drivers, bi-amping lets them make the mix.

Just out of curiosity what would you call it if the speakers were biamped with no filters other than whats internal to the speakers? In other words if both amps were putting out a full range signal. Isn't this setup actually "passive biamping"? It would essentialy be like biwiring but with 2 amplifiers.
 

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Nuthead----That practice is often called "fool's bi-amping" by bi-amping afficiandos.


Passive bi-amping is using passive rather than active filters at the line level between preamp and amp and not the practice you've decribed.


Many technically naive audiophiles use the term "passive bi-amping" when talking of "fool's bi-amping" probably because they then get to throw the term "bi-amping" around..


True passive bi-amping goes back to at least the 1950s, I've used the practice myself and have several DIY filters for use between preamps and amps.


Regards
 

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Never having heard or even seen in print the term "fool's bi-amping", I'll assume its some tube amp lovers brain child. That being said, using a outboard electronic crossover has very desirable advantages, notably not eating up amplifier power with a passive circuit. However the passive design you sketched brings a valid question to mind. What would the benefit be? I would hope as any other skilled audio enthusiast is that the crossover built into my otherwise competent loudspeakers is adequate. If I for some reason thought I needed to bypass the internal crossover and take it upon myself to undo many hours of R&D to possibly achieve some higher performance threshold from my loudspeakers I would probably build said speakers from scratch in the first place. In my setup I have two identical amplifiers driving a set of speakers using the internal crossovers. The main benefit is getting more power to the speakers. Is there a benefit doing it this way as opposed to one large stereo amplifier? I don't know. I had one Rotel and wanted more power. It was cheaper and easier to buy another identical unit on EBay than to sell the existing unit and purchase a more powerful unit.
 

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Quote:
what would you call it if the speakers were biamped with no filters other than whats internal to the speakers?

Maybe you could call that "crap"?


The whole point of bi-amping is to do cross-over with low-wattage parts, where you can do a better job, and to electrically isolate tweeters from woofers.


If you have a bi-amp circuit in the amplifier, but that doesn't do filtering, and then hooked that up to the speaker, you'd either have to do filtering using passive parts at full power, which doesn't really help compared to a full-power cross-over, or you'd have no filtering other than the speaker cones -- you'd get your bass output through your tweeters. Eww!


If you have a bi-wired speaker, then that's not exactly the same thing as a single wire, because of the additional capacitance/impedance of the cables, but it's pretty darn close. Using a thicker-gauge cable would be a better alternative.


And don't attempt to run speakers intended for bi-amping without an actual filter somewhere on the way. Sticking your transients to your woofers, or your bass to your tweeters, will not do anybody any good, and potentially a lot of damage.



Btw: this is one reason I like powered monitors -- they take care of all that within a single enclosure, with minimal distance from amp to each element, and the splitter is where it should be: before the two amplifiers. Go listen to a pair of Genelecs if you don't believe this can help a lot :)
 

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While I have never heard it called fools biamping, that is a good term for it. I used to think that I ws biamping my speakers when I was just wasting amplifier power. I spent three months buiding crossovers for my speakers and now after listening to the results for two months, I can tell absolutely no difference between true biamping and standard amping.
 

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I bi-amped my speakers this christmas and noticed a huge difference in sound quality.



In area's I wasn't expecting really, more midrange claity and highs and a more forward soundstage. The bass was deeper too.



I wasn't expecting any great change in sound at all, just wanted to buy myself a power amp for christmas. So I hooked it up to my woofers and had the other power amp just drive the mid range and tweeters.


I noticed a big difference as did my wife and others who had heard the system on a reasonably regualr basis.
 

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"However the passive design you sketched brings a valid question to mind. What would the benefit be?"


Some feel that putting reactive passive elements at the line level gives better sound than having them at the speaker level. There's also the advantage for the speaker DIYer and experimenter that the crossover frequency is stable and not effected by the impedence of the driver. Many also feel that the amplifiers will perform better if not fed a full-range signal, especially the treble amplifier which may not work as hard as it would if also fed bass signals.


"In my setup I have two identical amplifiers driving a set of speakers using the internal crossovers. The main benefit is getting more power to the speakers. Is there a benefit doing it this way as opposed to one large stereo amplifier?"


No, because you're not really putting more power to the speakers. Think about it; a single full-range amp channel of 100 watts applied to a speaker with a passive crossover is supplying 100 watts to the high pass section and 100 watts to the low pass section.


Using two 100 watt full-range channels, each applied to one leg of that same passive crossover does the exact same thing----100 watts to the high pass and 100 watts to the low pass. All this second scenario does compared to the first is make more heat. See what I mean?
 

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Tom you said "No, because you're not really putting more power to the speakers. Think about it; a single full-range amp channel of 100 watts applied to a speaker with a passive crossover is supplying 100 watts to the high pass section and 100 watts to the low pass section."


The disagreement with the above statement is that 100 watts is all that is available to either the high pass section or the low pass section at any given time. What really happens is the amplifier divides up the 100 watts between the two sections amplifying the full range.


You went on to say "Using two 100 watt full-range channels, each applied to one leg of that same passive crossover does the exact same thing----100 watts to the high pass and 100 watts to the low pass. All this second scenario does compared to the first is make more heat."


I agree, except for the exact same thing part. It seems to me, and I could be completely wrong, that biamping by removing the jumper bars and using separate amps would still be beneficial. I think we can agree that bass frequencies use the most power, especially on peaks, right? Well if I have a dedicated bass amplifier I still have a another amp to handle only highs. Since driving an amp into clipping is much less noticeable and harmful on woofers than on tweeters, dedicated amps makes a lot of sense. Let me further explain: the load an amplifier "sees" is determined by the speaker it is driving, by this I mean or I believe I should say, it doesn't matter where the crossover is located. Even speaker level crossovers lighten the given load on an amplifier. Tom, if I understood your response correctly you are inferring that the amplifier is amplifying the entire frequency range just because it is fed the entire range. Thats what I have an issue with. Since the crossover is in fact filtering the unwanted frequencies I don't believe the amplifier "sees" this added load. What I mean by "seeing" the load is that since the speaker isn't asking for these frequencies to be amplified they are in fact not amplified because the amplifier doesn't see them as a load.


That being said I do agree that outboard electronic crossovers offer the utmost in performance, and passive biamping or fools biamping as you call it doesn't offer a truly significant real world boost in power. Since low frequencies are using the lion's share of power, going with a separate amp for the low section is probably only gaining 20 watts over one single amp and an amp for the high section is being relatively unused.
 

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"Even speaker level crossovers lighten the given load on an amplifier."


It's possible but not a given, nor even likely. If say the tweeter was signifigantly more sensitive than the woofer and one bypassed the passive attenuation circuit I can see it. That's a big maybe. But I concede the possibility.


"Tom, if I understood your response correctly you are inferring that the amplifier is amplifying the entire frequency range just because it is fed the entire range."


That's correct. That is what amplifiers do when fed a fullrange signal, it matters not what the destination of the signal is.


"What I mean by "seeing" the load is that since the speaker isn't asking for these frequencies to be amplified they are in fact not amplified because the amplifier doesn't see them as a load."


Sorry, that's not how it works. And the amp still sees a load at all frequencies, it's just that at some frequncies the load is the resistance caused by the passive crosssover. This energy is turned into heat. that's why crossover parts are rated for power handling, I've seen crossovers that caught fire and others with exploded caps.


"passive biamping or fools biamping "


Note the difference I between passive bi-amping and fool's bi-amping. Passive bi-amping splits the signa at the line level between preamp and amps, it's just like active bi-amping in effect and plan except that it uses passive filters rather than active.


Kind regards
 
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