Am I wasting money on the theory of Bi-amping?

@phusis that's just one person's opinion.

The math never worked for me. If I can afford, say a $5K amp… I cannot afford two. I would always match amps… coherence. There is nothing worse than mixing sound qualities (a planar guy for a few decades). So, if I could afford another $5K for amplification… I would choose a $10K amp… it is going to have better dynamics, a much lower noise floor and more natural sound. So… biamping completely loses every time for me. 
 

Well put @ghdprentice 

In the owners manual for my Magneplanar Tympani T-IVa loudspeakers, the company recommends bi-amping for maximum sound quality. From the manual: "By adding an additional amplifier and a crossover you can enjoy the benefits of increased dynamic range and lower distortion." Since the T-IVa features separate binding posts on the midrange/tweeter panel and dual bass panels, it’s simple.

Used stock (mono-amped), the signal from the pre-amp is sent into your power amp, which is then connected via a pair of speaker cables to the Magnepan outboard crossover. The crossover has two pair of output binding posts, one for the m/t panel, the other for the bass panels. So you need two pair of speaker cables to connect the crossover to the three panels of the T-IVa. In this scenario, the power amp sees a full-range signal.

When bi-amping, the pre-amp sends it’s signal to the after-market electronic crossover, which divides the signal into two frequency ranges, one for the m/t panel, the other the bass panels. The x/o of course has two sets of output jacks, one for each amplifier. This scenario keeps the bass frequencies out of the amplifier reproducing the mids and highs, a real benefit.

If you ever see a First Watt B4 crossover for sale used, buy it! No longer sold assembled, only as a kit. 1st/2nd/3rd/ and 4th-order filters (6/12/18/24dB per octave), adjustable in 25Hz increments from 25 to 6375Hz. All discrete components, no OpAmps or IC’s. It sold for $1500 new, a bargain.

True bi-amping bypasses the internal crossovers so you must modify the speaker internally. You must use an external electronic crossover of which there are few analog ones ( I have used the X-Kits for main/sub)  or go digital like the MiniDSP. PA crossovers like DBX and Berhringer are not HI-FI devices.

Running two amps to the two sets of binding posts on a commercial speaker is doing nothing. Nothing as it does not bypass the crossovers.  Just as bogus as bi-wire.  Any rumor's that dedicating amplifier frequencies have any difference is just more snake oil. If you can afford two amps, just buy a better amp and it will make an audible difference. 

Sub to mains, yea electronic as the physical size and cost of a 80 Hz or so passive crossover is insane. Never mind a 20 Hz high pass to the sub.  HP to the mains can make quite a difference in moderate and above distortion but is best done low level. 

Mid to tweeter is where it matters. DSP allows very accurate time, phase, and eq. for any response in your room you want.  Folks like Linkwitz much favored it especially with dealing with open baffles.  Then again, folks like Dick Small say a competent engineer can do just fine with a passive.  As I build my own speakers, I can tinker with the crossover to get it pretty good in my room. It may not be in your room so the DSP side may win there. A MiniDSP can do a lot of things that PC based software does not. 

But, there are always buts, If feeding analog into a MiniDSP, you have additional A2D converters and  DACs that are not exactly state of the art etc. You really need to understand measurement and psychoacoustics to know what the target needs ot be for you. Understanding DIRAC or even REW takes quite a bit of work. I think you can bet a MiniDSP USB in and PCM to external DACs out but that can raise all the same "which clock" issues as any PCM output does. 

Active analog, like the X-Kits, don't have any eq.  More efficient and the crossover is not impacted by the dynamics of the speaker loads and impedance. Very clean if you pick the right op-amp, but can cause turn on and off thumps if you don't handle that elsewhere.  I do not know of another true high end active crossover. Bryson?

Passive is reliable, but hard to mass produce for everyone so eq needed externally. (I use JRiver)   Problem is, even speakers costing several thousand dollars frequently have terrible crossovers a second grader could do better.  There is zero excuse for a commercial speaker not to have a Kipple measured response within 2 dB across the BW and phase alignment within 20 or so degrees at crossover.   If I can do it on a ladder in my back yard, so can big companies.  Focal, Revel, Sonas Faber, Elac, and Dynaudio,  are a few who do pretty well.  How companies like B&W or Klipsch can be so horrible I do not know. 

An odd one left is passive line level.  I do this to my mains on my desktop using an appropriate size cap depending on amplifier input impedance, ( .22u in this case) to give a first order HP. Going above first order is impractical and risks distortion of the inductors. First order is almost always not steep enough for mid to woofer.  I use it to take the load off my 4 inch desktops driven by a 2W amp.  If trying for a second order, you can get into serious preamp impedance load issues.  As I have built amplifiers and studied Self, Cordell, Leach etc, I know how to modify an amp input stage for a second order and can even modify the feedback compensation for further specific eq. Not easy unless you are an engineer. ( LtSPICE is wonderful)

I see suggestions on matching amps for range.  Well, in the days of crappy amps, maybe but we can buy very very good amps now pretty cheap. Do consider how you may effect the sound by amps of different gain. 

One more thing. I am not aware of any PC based software that can do all the DSP work on the host and feed multiple DACs in WASAPI or ASIO without an external master clock.  On the pro studio side, yea, not consumer level. 

@invalid wrote: 

what about passive line level crossovers?

I have no experience with them, but it seems the article provided by @ditusa has some bearing on their usefulness. 

that's just one person's opinion.

What specifically are you referring to here?

YES....Good Integrateds have come a long way in the last 10 years.....Also a real good  tube pre amp with an upscale class D amp is a beautiful combo.....not cheap though...but great for MUSIC enjoyment.

Big difference in a bridge tied load used in mono versus bi-amping. True bi-amping is worth the effort if you equipment has hi-lo and A-B outputs. 

I’ve done a lot of bi-amping, tri-amping, all the way up to 5 way active speakers. It’s all a pain in the ass. If you’re not building your own speakers, it does seem fair enough to call it a waste of time, energy, and effort to bi-amp a speaker that already has a well designed passive crossover built in. However, you might actually like the results, so if you don’t mind the effort and expense of exploring and experimenting, then I would recommend giving it a try. My own experiences with passive bi-amping showed no obvious benefit. I was using solid state amps with plenty of current capacity, and the speakers were fairly sensitive and efficient, so that may have a lot to do with it. If you’re building your own speakers, making a passive crossover network can be a total pain, add up to a lot of expense. You can get active crossovers that include all kinds of shelving, notch filters, parametric EQ, time alignment, etc., assuming you’re willing to go digital. You can also hand pick your drivers so they don’t have any issues in the passband, and get what I think are some pretty stunning results. The active crossover lets you experiment quickly. I have read that a passive crossover never sounds highly transparent, although I think good ones are transparent enough in typical listening rooms. This is one case where people were easily able to tell the insertion of a passive network vs a pure feed in a double blind test. The testers were unable to make a passive network pure enough sounding to fool anybody. A digital active crossover could fool people. Whatever that’s worth, it does seem that for the ultimate in sound fidelity, a digital active crossover has more upside potential. Doesn’t mean you’ll like it better. Just means you’ll have a harder time telling it apart from a pure feed.

In case you’re wondering how these tests were done, they used headphones, split a signal into a low pass and a high pass, and the recombined them to a full bandwidth signal that went to the headphones. The listeners could compare direct feed to the split and re-combined feed. This allowed the passive networks to be at their best, feeding in to very stable, pure resistive loads. (I actually can’t remember if these were entirely passive or included some op-amps to make them work better. If they included op-amps some might be tempted to say that people were hearing the op-amps, but I doubt that. In any case, they were analog, line level networks.) People could easily hear the difference, even though considerable effort was made to optimize the analog networks. A passive network in a speaker is more of a mess, feeding into multiple speaker drivers with all their impedance complexities. It was interesting to me that even though the digital crossover had to do A/D D/A conversion steps, people still noticed no obvious degradation in signal. It may have to do with the people chosen for the test. Over and over I get the impression that audiophiles are particularly sensitive to things that most people don’t notice, but also peculiarly unsensitive, or at least unconcerned with things that most people can easily hear as problems. Audiophiles have learned not just to listen, but to curate particular tastes. It's not just about what is identifiably accurate or inaccurate, but what comes across as most natural and pleasing.

@asctim wrote:

... It was interesting to me that even though the digital crossover had to do A/D D/A conversion steps, people still noticed no obvious degradation in signal. It may have to do with the people chosen for the test. Over and over I get the impression that audiophiles are particularly sensitive to things that most people don’t notice, but also peculiarly unsensitive, or at least unconcerned with things that most people can easily hear as problems. Audiophiles have learned not just to listen, but to curate particular tastes.

This. 

NO! Because it is NEVER the THEORY that is the waste of money. It is always the application / implementation of the flawed theory that is a waste of money. Notice that all these other posters with multi-paragraph theories aren't wasting one dime of their money with their theories.

I have actively bi-amplified my Magnepan 3-series using an external active crossover (Marchand). You have to have a decent crossover or it’s a waste.

My take was that the active bi-amping was a complete sea change in sound. As it should be since you are using an entirely different crossover network and the crossover is before and not after the amplifier, so the amplifier is freed to fully power the drivers it’s connected to. Worked very well.

But that’s because Maggies have that biamp capability without surgery. You have to take out the internal crossover network in speakers to do this right. With most speakers I’d say it probably isn’t worth the risk or effort. The speaker designer had the crossover network in mind. Magnepan clearly had active biamping in mind.

So, in limited circumstances it can be a huge improvement. But, limited circumstances. Biamping without taking out the passive crossovers is just a bit more oomph in power but at the cost of a lack of consistency. I wouldn’t do that.

I biamp in one of my systems.  I use a pair of mono amps to handle the bass and a different pair of mono amps to handle the mids and highs. The mid/high have the bass rolled off using high quality caps at the amp inputs and there is an adjustable unit to balance the bass (which goes through untouched) with the mids/highs.

This is the system that Richard Vandersteen uses and it works very well with my big Vandersteens, although many would prefer to avoid the complexity of four mono amps with an external adjustable crossover for the bass.

Does it sound better done this way?  I was pleased to find that it does and the improvement warranted the extra system complexity.

Whether you would get the same gains depends entirely on your particular system.

Seems biamping in an ideal way would be using a tube amplifier for upper drivers, and solid state for bass. I believe it's widely accepted that tube amps for bass drivers presents lots of less than ideal issues.

To me using solid state across all drivers when biamping will have benefits but if you go to this trouble you might as well go all the way with tubes.

Panzrwagn

"2) "Passive Bi-amping" is BS. You’re still delivering a full range signal to both the LF and MF/HF passive crossovers, the unused half of the signal is just turned to heat."

This is not true. There is no signal flowing through a circuit at frequencies that are filtered out by a crossover network, subject to the slope of the filter. The crossover network doesn't create an offramp for the filtered frequencies to be converted to heat.

OK folks. Listen up. Here's WHY active crossovers are so very much better than passive. A single loudspeaker driver is an inductor, and provides a frequency dependent, reactive load to an amplifier. Looking at the image here, the blue line on the bottom is the frequency dependent impedance curve for an SB Acoustics SB29RDAC Ring Dome Tweeter, and it typical of any dynamic tweeter. As you can see, it is anything but flat, yet it is listed as having a 4 ohm impedance. It's 4 ohms at about 1200 hz, but at 600 hz, has an impedance of nearly 10 ohms.

Now if you put a passive crossover circuit in front of it, you add capacitors, resistors and inductors, which then give you a frequency dependent impedance curve which looks like a Coney Island roller coaster. And that's just for a tweeter high-pass circuit.

Now when you add in mid and bass drivers, with high and low pass filters there... It's a real mess. But we're not done there yet. Nope. Many of your extreme hi-end loudspeakers add in equalization to their crossover designs, which makes that impedance curve even worse. This is very hard for an amp to properly manage. That's why people drop many, many thousands of dollars on things like Krell, Threshhold, Bryston, or Rowland Research solid state power amps.

Now when you use an active crossover, an amp channel only has to manage a single driver. There's no passive, reactive component in between the amp and the loudspeaker driver. Then you don't need a megabuck amp to deal with it.

All of the Linkwitz loudspeaker designs use active crossovers. Earlier designs used analog crossovers, but his last designs were all digital crossovers. There are some digital crossovers that offer DSP EQ, which allows you to tailor the total system response for the room you are in. Then you're not just limited to whatever sound your speakers give you in the room you're stuck with.

The lowest cost active crossovers are typically pro grade, from manufacturers like Behringer, dbx, Rane or even Nady. There are many manufacturers. Some of the best known home audio digital crossovers are from miniDSP.

Another major benefit is that you can use much, much lower powered amps when you use active crossovers. A lot of power is wasted having to push through a passive crossover. You really don't need to push many watts into a tweeter or mid-range driver to get a lot of level out. You could even run a single ended tube amp on your tweeter, and a mid-level tube power amp on your mid-range driver, and a solid state amp for the bass driver. You have a lot of options.

So instead of dropping $7,000 on that Threshold Stasis 8.0 power amp. You could spend much less on an active crossover and the various much more modestly priced amps of your choice.
 

@russbutton  *S*  Someone who can R(ant) & R(ave)s' better than me.... ;)

...and does a fine cover of the sense of the process...

1st serious speakers were a pair of 901s2s' with it's active eq.... Yes, not a 'xover' in fact, but they'd sound all sort of strange without....

Next iteration was a pair of Infinitys' with an equalizer in the tape loop, which began to allow for a crude DSPish approach; xover still onboard the speakers, but edging closer....

Following that, the Kenwood L series with the outboard mono amps....an AudioControl C-101 eq with a calibrated mic that allowed to employ a more serious

launch into DSP.  Sure, the AMT 1Bs' still had their onboard  xover, but it was just a 2 way that handed most off to the large Heils'....and the xover just tweaked the point between....  I still have a pair of the xovers for references' sake, but on the shelf....

These days.....one could say 'in excess', but...*G* I prefer 'flexibility'....

Xovers': a Behringer, a dbx, a Parasound C2, and an ESS Eclipse 2241AM;  the latter an unusual item I've devious designs upon....

Eq available: The 'puter can supply whatever wherever, pre or post....as can a pair of Behringers' and the C2.  All of which can host a mic....

14 channels of amplification, 12 of which can be mono'd to 6.

And a self amp'd sub.

"Bi-amp....how...quaint...." ;)

Anyone recognize the car?

I have days like this....

...too old and tired to chase back anymore...😒

I'm in the camp of using an active x-over and horizontal bi-amping w/different amps, using tubes to power the top and SS on the bottom.  The woofers have been removed from the x-over and wired directly to the binding posts.  (Speakers were built bi-wireable so two sets of binding posts are present.)  I use an original Wavelet active x-over and just picked up a MiniDSP DDRC 88A/BM that I plan to substitute for the Wavelet as I want to see if DIRAC w/BM is an improvement over the Bohmer room correction. 

Never heard of horizontal and vertical bi-amping. 

My assumption for passive bi amping with speakers built for it always was that by removing the 'bridge', I get a low pass for the woofer and a seperate high pass for the mid/high. The use 2 amps to feed those. 

I now assume that horizontal/vertical deals with the option of using 2 stereo amp for the 2x2 'feeds'. Either one stereo amp for each SPEAKER or one stereo amp for the woofers and one stereo amp for the mid/high. If that is the case, what is considered 'vertical'?

I read a few posts claiming BENEFITS of passive crossovers (vs active), but none mentions issues like phase shift from those passive components. 

And can't those mentioned 'beneftis' of passive crossovers not 'simulated' or realized in active crossovers as well? 

@kraftwerkturbo wrote:

I now assume that horizontal/vertical deals with the option of using 2 stereo amp for the 2x2 'feeds'. Either one stereo amp for each SPEAKER or one stereo amp for the woofers and one stereo amp for the mid/high. If that is the case, what is considered 'vertical'?

'Vertical' bi-amping is one stereo amp driving one speaker, its two channels divided over the two pairs of terminals on that speaker. 

I read a few posts claiming BENEFITS of passive crossovers (vs active), but none mentions issues like phase shift from those passive components. 

And can't those mentioned 'beneftis' of passive crossovers not 'simulated' or realized in active crossovers as well? 

Active can do what passive does, and more - while not least getting out of the way between the amp and speakers. 

I knew 2-3 people would show up here to drop their snark-bombs on the topic of biamping, and I wasn’t disappointed.

It has been many years since I biamped, but when I did, it was a noteworthy success. It probably would have sounded even better if I’d had access to one of the excellent, transparent external crossovers that are currently available, but were not back then.

Obviously biamping isn’t possible or recommended for certain setups; but in the right setup, and with the right amps, it can take the sound way higher...

Benefits of Active Bi-Amping (Not Quite Magic, But Close) - Part 1

Phase Response. See article below:

Mike

https://sound-au.com/bi-amp.htm#phase_resp

Through my modified Signet floor standers, it is easily heard, the advantages of bi wiring and, passive bi amping. What a different set of characteristics, between running the system, horizontal vs. vertical. Using many different pairs of the same exact model amplifiers, I came down to really appreciating vertical. When going back to a single amp, things started to shrink, and collapse ( through the speakers, lol ). Over the many years of owning these, these Signets have bettered, ime, so many others. At this time, they are not in use...but they are one of my few audio products, I could never let go of. 🙂☹ My best ! MrD.

• How come they don't design biamping amps that are both tubes for top drivers and solid state for bass drivers?

Maybe I begin to do this and make a lot of money

@emergingsoul I believe McIntosh makes an amplifier like the one you described.

Phase: with ads 1230, only the ads 2000 biamp crossover  will work.

. This is because the internal and ads 2000 crossovers do something to the phase of the woofer . I used an external analog crossover and had some big holes in the freq response as evidenced by using an audessey rc equpped reciever .

I think the culprit was a woofer that was out of phase by 90 degrees.

I thought about triamping my Valkeryie speakers which scream to be triamped but to do it actively would require some serious surgery so I’ll likely “ dumb” Triamp thrm ( passive) and use an old av receiver .

@emergingsoul ....likely 'cause it's only a 'fringe' sort of thing that audioholics end up doing? ;)

It's the sort of thing that appeals to those that don't mind having the backsides of their rigs look like a incident in a pasta factory...😏

A amps and D amps together?!   Dogs 'n cats cohabitating?! OHmG....*LOL*

Likely the sort of thing I'll end up doing anyway....*S*

(...I'd keep the day job...mho, fwiw....amazing what flies these dayz....)

man you guys are still at it.

It works, so depends on your situation, if you can get a hold of it, try it. If you don’t hear the diff, sell it.

I have 4 AHB2 bi-amp on mono-mode to JBL 4367, which the crossover network is well built even its passive. Been building system for 20+ years, and first time ever, I do not foresee even the desire to make a change.

@russbutton 

Now when you use an active crossover, an amp channel only has to manage a single driver. There's no passive, reactive component in between the amp and the loudspeaker driver. Then you don't need a megabuck amp to deal with it.

Indeed! It's amazing what you can get out of cheap amps when hooked up to speakers with an active crossover. With horn loading the problem is amp hiss gets highly amplified. For this reason I add a capacitor to my horn tweeters. It knocks the amp hiss down to below noticeable, helps with the EQ needed for constant directivity waveguides, and provides some protection for the tweeters. I'm not a purist.

@btbluesky 

I have 4 AHB2 bi-amp on mono-mode to JBL 4367

I have no doubt that sounds great. What differences do you notice if you just use a single AHb2 in stereo mode compared to all four in mono?

@asctim , I did just that. Starting with 1 AHB2 with a different speaker, notice the bass is tighter and it was not sterile/cold sounding. Smooth, highend, you are hearing really the upstream/preamp.

Then got another one, mono mode to each 4367, sounding great, everything falls into place. so I ordered another pair for my secondary system, but tested it biamp mono in JBL first, the realism, the "air" is just unbelievable. Diff between ya I can see the imaging, to "where did that sound come from!". Needless to say I left the pair there and got another pair for second system.

Amp hiss, is not a normal thing. It's a product of "too much gain in chain" + "not so good amp". I can crank up to over-concert level, and theres no distortion.

@asctim wrote:

With horn loading the problem is amp hiss gets highly amplified.

Indeed, but using a 16 ohm driver - if available - will help knock down hiss noticeably as well.

@btbluesky wrote:

Amp hiss, is not a normal thing. It’s a product of "too much gain in chain" + "not so good amp". I can crank up to over-concert level, and theres no distortion.

It doesn’t fall back on a "not normal thing" or a "not so good amp." High sensitivity, as has been stated just above, simply amplifies noise. If you removed the passive crossover from your JBL 4367’s and connected your amps directly to the compression drivers, I can assure you hiss would be audible to some degree - and yet your amps are the same; they didn’t suddenly get bad in the absence of passive crossovers (in fact they’d get better).

It’s great though you’ve found a good pairing amp-wise with the JBL’s.

@russbutton --

+1

Another major benefit is that you can use much, much lower powered amps when you use active crossovers. A lot of power is wasted having to push through a passive crossover. You really don’t need to push many watts into a tweeter or mid-range driver to get a lot of level out. You could even run a single ended tube amp on your tweeter, and a mid-level tube power amp on your mid-range driver, and a solid state amp for the bass driver. You have a lot of options.

Options are plentiful, yes. To me though the lesser power needed over the entire frequency range actively would be better served by spreading it out evenly, so to ideally use the same amps top to bottom, or certainly the same amp series/topology with a differentiated power approach for better coherency. To me coherency always comes first, and using similar amps is vital for this to come true in the best way.

If you removed the passive crossover from your JBL 4367’s and connected your amps directly to the compression drivers, I can assure you hiss would be audible to some degree

Nope. You are describing the scenario of what a normal system with an acceptable noise already present in the chain, but not when you are using absolute silent components. Lookup the AHB2 review from stereophile, the amp not only can adjust the sensitivity (9.8V RMS/22dBu, 4V RMS/14.2dBu, 2V RMS/8.2dBu), it has such a low distortion number, akin to the testing equipment that bench test the amp itself. If your upstream is absolutely silent, if theres noise/distortion in your horn, it's something else. Uber horn lovers pay big bucks for expensive tube amps, not just for it's tone/sound, more often it's for the silent. And they do directly connect to the compression driver with active setup.

I had my system horizontal biamped with mac275s on top and mc601s for bass. Tekton set me up with 4ohm biamp xovers. The whole house rumbles 

I would generally agree with a good number of the responses that indicate a "great deal of added expense to do it right" but yet the benefits are there if there is cost no object.

But here in "beerville", after experimenting with multiple different jumper wires between my mids and highs of Aerial 10 Mk II, I did find one that I liked substantially (Signature series, AntiCable).

Then at the suggestion of long time friend/audiophile Duane, I tried some Mosaic advanced tech speaker cables (now defunct) in a bi.wire mode .. UnBeLieVabLe the difference!

If you want similar tech .. Bionic Cables are similar yet better. I am using their entry level RCA, it is also amazing (coming from much a-b'ing on my system)

@barts - Please tell me that you also bi-wire in your tri-amp system.  I’ve often pondered what the limit might be for a complex audio system.  I would expect that the audiophiles with the most complex would also have the perspective that everything matters (why have a complex system otherwise?), so I can only imagine the challenge of optimizing cables and such, particularly every individual cable can be approached uniquely. 

@mceljo 

No I don't bi-wire, there is nothing to bi-wire.  All speakers cables are the same 10ga.  All the interconnects are the same Audience OHNO single crystal developed by Dr. Ohno.

My rig is somewhat easy to understand...just think of it as regular old rig until you get to the x-over, then its like three stereos all playing the same music (in different frequency ranges). Simple.

Regards,

barts 

Multi-amping could have advantages even if done before the cross-overs, and even more so if each channel has its own power supply.

If a speaker has a challenging impedance / phase angle above or below the frequency range of the cross-over the amplifier will often run with more strain and corresponding deviation from ideal performance at these points. A single amplifier channels performance can be dragged down across the entire frequency range by these demands, where as multi - amplified frequency ranges will only be compromised at the particular point of the challenging load, freeing up the other ranges to be powered more optimally. This might be especially true in cases of so called Class A/AB amps where more of the more optimum purported Class A bias will be allowed to run longer before resorting to the less optimum purported Class AB or Class B (these classifications are somewhat nebulous, but the results are somewhat the same).

That these challenging impedance / phase angle loads are more typically found in the bass region where the power needs are greater but where our hearing is usually less sensitive, so meeting the power demands might be more important than ultimate fidelity. On the other hand the power demands of higher frequencies ranges are typically less, but our hearing is usually more critical, and the greater purity of amplification is appreciated more.

Bi-amping is not a "theory" neither are bi-(or tri)wiring. You just need to know what you are doing. Results will depend on the quality of the involved components and als the chief`s skill-level.

Some speakers has terrible passive filters, like the famous old Infinity Kappa 9. Bi-amping won`t solve this, but bypassing the passive filters and instead using an active filter would do. 

If one were to bi-amp with a tube amp for the tweeters and mids, and a SS amp for the woofers, how does one volume match the signals since these are different amps with different gain?  Even if the same wattage the two amps might not be matched?  Thanks. 

I had A pair of speakers that responded well to a krell kav300il on top but needed more juice for the bass. In that case horizontal biamp made sense. Starting from scratch I think I’m getting great sound with a pair of matching monoblocks 1 per channel and if you get powerful enough amps you should hear what the speaker designer intended. My current system Kef Blades has a fairly bumpy resistance so the Mac Mc611’s really get it done. The speaker amp combo can make or break your system.

The very basics: a [speaker] passive crossover comes AFTER the amps, operating at speaker level.  The drivers are connected to the crossover not the amplifiers; active crossover /electronic crossovers come BEFORE the amps, operating typically at [balanced] line level; the drivers are individually and directly connected to a specific amp channel that is for that driver and that driver alone.  

It is hard to understand how anyone could think shoving a bunch of passive electronics with lots and lots of wire into an audio chain between the amplifiers and drivers could be a step up in quality and create a better, more pristine audio chain.  I wonder if passive fans realize how much wire is in an air core inductor used in a high quality passive crossover (300-500 feet or more?).  We don't do any other processing after amplifiers, why is the passive crossover somehow an exception?       

There is so much science here that is quite established and well accepted, since the 60s-70s at least.  ATC and Genelec were offering full [analog] active crossover loudspeakers to the market in the early 80s, some with internal amps, some with external amps.  Both companies sold into home and pro simultaneously.  Now there are many more companies offering active crossover speakers and some use DSP, some still analog.  

There are plenty of options and choices as to how one can approach this active issue and adapt it to your liking, make it sound one way or another.  It does require some work to understand what is happening, but its certainly not complicated.  It is not more expensive or more difficult to operate.     

I cannot help but observe the entire "passive crossover is better" argument appears to be a clear example of marketing not science.   

Brad

^While active crossovers could certainly have advantages. Where as passive crossovers often have implementations to compensate for specific driver anomalies, impedance smoothing, phase and time considerations. Off the shelf active crossovers are typically rather clumsy in those regard, as well as potentially adding noise. Again, active crossovers can certainly have advantages. As was posted DSP could make active more finessed and practical.

@lonemountain

There are pros and cons with active, and with passive crossovers. In a perfect world, active crossovers have some distinct benefits....especially if starting up from scratch, but many of us get to the bi-amp situation once we’re already well invested in our current systems. Sometimes it just not feasible to backtrack to square one.

@unsound reiterated some of the benefits and situation need for passive crossovers. There are certainly active crossovers that can perform some, if not all, of the compensation requirements of some drivers, but what if you already own a really nice pair of speakers that you love and that have excellent, well designed passive crossovers with top shelf parts, and you want to dip your toe into bi-amping? I’d think even a serious audio buff would hesitate before proceeding to gut the crossovers from a pair of Magico, Wilson, or Sonus Faber speakers so they can experiment with active crossovers. Not everyone has the knowledge, expertise, or the will power to actually make such a bold move.....in many cases it’s simply not wise to risk the destruction of a wonderful pair of speakers to pursue an active crossover. If a great pair of speakers sounds good with passive crossovers in a single amp situation, they’re very likely to sound even better with a good bi-amp setup, even with the passive crossovers.

Passive or active bi-amping should not be undertaken without first asking the manufacturer’s advice.

See article below:

Mike

Making the Case for Active Crossovers vs. Passive

@knotscott - yours is probably the only legit answer for not investigating active more thoroughly.  I get that once invested downa path, its difficult to change.

@unsound - comment about passive crossovers having "implmentations to compensate" for driver anomalies sounds like you think active crossovers cannot offer the same or better "compensations".  Actually this is one of the primary arguments FOR active, its much beeter to solve all these issues before the amplifier, not after.  

Why no comment about all the wire and passive components between the amplifier and driver ?   This seems to be the elephant in the room doesnt it? .  

@lonemountain

Why no comment about all the wire and passive components between the amplifier and driver ? ...

I’ll take a stab, but can only speak for myself and guess on behalf of others. If you own a pair of speakers that you love, or simply won’t part with, that have passive crossovers, removing the passive crossovers is likely not an option, so contemplating the amount of wire in the crossovers is likely just a moot point.