[JohnR]

Maybe I should have asked how can one type of biamping sound better than the other as far as sound quality is concerned.  I would like a detailed reason for this.

I thought this had already been discussed. The passive components between the amplifier and loudspeaker driver are removed in an active system. (OK, maybe not all, but most of them.)

[andyr]

...  What I don't understand is why so many people say it's not worth biamping unless you go active. ...

Hi Warner,

As I understand it, the reason why there is a generally accepted view that passive bi-amping is not worth it, is because unless you have the crossover before the amps, each amp is still being fed a full-range signal from the preamp and not all of its power is being used to deliver the intended frequencies.

When you have a line-level crossover (which is more commonly active but could be passive), the frequency split is made before the amps, so they can concentrate on delivering their total power into their allotted frequency band.

...  Maybe I should have asked how can one type of biamping sound better than the other as far as sound quality is concerned.  I would like a detailed reason for this.   Thanks. ...

In spite of the above, a couple of doctor friends of mine (who have identical systems - monstrous Dalis driven by a humungous Bryston) have told me their sound is greatly improved when they use both of their Brystons to drive one pair of Dalis - ie. they are passively bi-amping!  

Moreover, the sound was different depending on whether they had one Bryston per Dali or used one for the highs and the other (identical Bryston) for the lows.  One way round was definitely superior ... the other not much better than just using one Bryston.  

Regards,

Andy

[andyr]

... there are many of us who try hard to minimize the number of components between the source and speakers as every one, we believe, including interconnects has the potential to further color the sound. ...

Hi Tweaker,

I certainly agree with you that every additional component has the potential to colour the sound.

However, you should not forget that the passive crossover in a speaker is "another component" ... so going active is not simply a matter of just adding something which will degrade the sound.  It is also removing something which, undoubtedly, was damaging the sound (the passive crossover)!  

Unfortunately though, a crossover - active or passive - is a necessary evil unless you are a member of the "single driver" creed.  If you follow a different faith, then some sort of crossover is required and I personally believe active is better.  But that's because I'm a paid-up member of that sect!  

Regards,

Andy

[Dan Banquer]

I have a question or two that maybe someone could help me with. Over the years I have observed that with most speakers; active biamping or triamping appear to make the loudspeaker less reactive to the room. I have noticed this appears to have greater effect when a loudspeaker uses a stiffer slope on the crossover such as an 18db slope or 24 db slope.
I have no idea why this happens so if any of the loudspeaker guys could inform me as to why I would greatly appreciate it.
                d.b.

[JoshK]

I am certainly not an authoritative figure on the subject, however, I have an idea why that might be, or at least a couple of ideas to ponder.  Aside from being able to more accurately dial in the relative balance of the speaker taking into account baffle step and room gain, there are still a couple of plausible explanations.

When active amping with steeper slopes, the less overlap leads to less combing and ultimately this leads to a more even power response all other things held constant.  I believe in many situations an even power response will create a more even reverberant field from the room, so the sonic impact of the room affects the wide spectrum of frequencies with less prejudice.  My hypothesis is that this will lead to less objectionable influence from the room.

I think this is why many prefer wide dispersion speakers, because the lower frequencies will be wide dispersion regardless, so wider dispersion in higher registers evens out the overall balance and power response.

[Dan Banquer]

Josh: I would think there would be less overlap witha 24 db slope than a 6db or 12 db slope. Passive or active. Right?
For some strange reason I think the passive crossover makes many speakers more reactive to the room, but I don't know why.
                   d.b .

[Tweaker]

andyr.
 Perhaps I am in the process of being converted. As Occam pointed out, much to my chagrin , I already do have a Behringer DEQ2496 with all the extra cables required (and all of those bad ICs,etc.) in the system and it did not do any damage. Quite the contrary, it did a lot of good and was very transparent. I probably won't be trying active bi-amping anytime soon, however. Different priorities now. Just ask my wife.

[JoshK]

Dan,

Sorry, I misinterpreted your question, I read it too quickly (that is my common mistake due to having too many things to do).  You are right I believe in your response, that that is an obvious outcome of the higher slope regardless of passive or active, but why active or passive for a given slope would add an additional room benefit isn't clear.  

Maybe this is what I implied in my first paragraph that in level matching the 2 or 3 amp/driver combinations you naturally take more of the room's influence on response into consideration than a fixed passive one-size-fits-all-rooms solution would.  It requires much higher knowledge on the users parts, but when done correctly adds the additional information in your specific application into the equation.

Food for thought anyway....

[warnerwh]

Tweaker, if you're using the DEQ 2496 purely in the digital domain then the ic's and opamps will not be putting any sonic signature on the sound I'm aware of.  If you're using the DAC in the Behringer then of course you are but get this.  A guy wanting some Vmps speakers last week told me he likes the dac in his Behringer better than his Spectron.  I'm not positive it was Spectron but I remember it had been similar, far from an inexpensive piece of pro gear.

I also use the DEQ 2496 in the digital domain.  As far as I'm concerned the gains it has for my system easily outweighs any downside.  It's probably impossible for anybody to tell the difference using it just in the digital domain anyway.  The AKM dac in it is quite good. I've had a couple of EE's in this industry tell me how impressed they were with what was in the inside of one of these for the money.

I still haven't seen anybody show me measurements at the speaker drivers that would account for an improvement in sound with an active crossover over a passive crossover all else being equal.  I don't care if one measurement appears superior than the other but just different would be adequate, but it must be enough of a difference to be audible.  I'll leave the opinion of what sounds better to the person who's listening.

[Tweaker]

warnerwh,
I am using the Behringer dac. It replaced an Art DI/O with a Bolder Cables p.s. it sounded so good. I don't know about how it stacks up to the big boys but to my ears it does a very good job.
 I passive bi-amp, which I know is a misnomer to some, and the results of that have been significant. So much so that when I first tried it my wife was so smitten with the improvement that she insisted that we keep the amp (I had purchased from AVA on a 30-day trial to give passive bi-amping a try) and that she would pay for it!
It is obviously a subject that some feel strongly about and, as I will most likely never try active bi-amping, I will probably always have a feeling that I may very well be missing out by not taking that extra step.

[andyr]

...  still haven't seen anybody show me measurements at the speaker drivers that would account for an improvement in sound with an active crossover over a passive crossover all else being equal. ...

Hi Warner,

While Dan's comments are intriguing (why should an active crossover with the same slopes as the original passive be less reactive to the room?) I suggest you are missing the point with your comment above (about measurements).

Avoiding the argument of whether electronic components in either the active or passive crossover are degrading the sound, and also assuming the drivers are mainly resistive - like my Maggies - so don't need (passive) impedance correction networks, the fundamental difference between active and passive is that:
a) with active, the amps are directly wired to the drivers;
b) with passive, there are series components between the amp and the drivers.

a) means the speaker sounds much more dynamic compared to b) as the amps are able to exert "iron-fisted" control over the drivers ... when series components are "in the way", this reduces the amp's control over the driver.

I don't believe you could easily measure this "dynamicicity" but you can certainly hear it!     I think there are few people around who would say "a more dynamic speaker is a worse speaker"!!  

Regards,

Andy

[warnerwh]

Andy: Just how much dynamics you're losing should be measureable. I'm not saying that if it doesn't measure well it doesn't sound good either.

You say that having "when series components are "in the way", this reduces the amp's control over the driver"  

Now we have these caps and inductors in front of the speaker driver, ok?  
Please forgive my ignorance as I'm just trying to understand here.  Does this mean that there's resistance of some sort in these passive devices not allowing the amplifier to operate at it's capability?  If this is the case I'd think this should be able to be measured at the speaker driver and if not, why?  Thanks

[andyr]

... Does this mean that there's resistance of some sort in these passive devices not allowing the amplifier to operate at it's capability? If this is the case I'd think this should be able to be measured at the speaker driver and if not, why? ...

Hi Warner,

As to the effects of these passive components which are "in the way" of the amp controlling the driver, the way I look at it is as follows (and I'm sure there are lots of EEs out there who will laugh at my primitive thinking!) ... yes, resistance plays a part but there's more at work here!

For instance, if the speaker manufacturere (like Magnepan) has used cheap and nasty, narrow-guage-wire inductors then these have a significant resistance.  Replacing them with, for example, 8g North Creek inductors delivers you much more bass punch, because the internal DC resistance of the inductor is now down around 0.1 ohm instead of 0.3-0.5 ohm.

However, just like the old flyboys used to say there was a big difference between flying a plane when they had their feet on the rudder control directly, compared to later "fly-by-wire" technology, I suspect the inductor by its very nature introduces a "looseness" into the circuit ... the amp is not able to grab the driver by its throat and shake it - which it can do when it's directly connected to the driver!!  

Now, you could certainly destroy the punchiness of an active setup by using excessively long speaker cables which gave you a high resistance between the amp and the driver ... I believe you get the most out of an active setup if you have the amps directly behind each speaker, with very short speaker cables (thus minimising resistance and inductance).

I have no idea whether what you can hear is measurable or not!  

Regards,

Andy

[Occam]

... I already do have a Behringer DEQ2496 with all the extra cables required (and all of those bad ICs,etc.) in the system and it did not do any damage. Quite the contrary, it did a lot of good and was very transparent ...

Tweaker,

Actually, those 'jellybean' IC opamps in your Behringer DEQ2496 are not particularly transparent. Rather, the benefits of ameliorating your room modes and other frequency anomolies result in a net gain in overall resolution. My point wasn't to say that additional electronics, cables, etc... in your signal chain don't add problems, but if you're clever (and lucky), the good provided can outweigh the bad.
As to whether you'd experience a similar net gain by going from your present passive bi-amping to line level active crossover bi-amping of your VMPS RM2 Neo speakers, dunno. I'm unsure, but believe that VMPS speakers typically have reasonably benign and shallow slope crossovers -
http://www.audiocircle.com/index.php?topic=27238&postdays=0&postorder=asc&start=20