Active vrs passive

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ehh, those are PA amps ? built for active drive ? maybe they dont like passive speakers very much ?
hey, just joking :D

btw, load impedances might have changed with the active xo....and actually, phase could have changed too...and a phase error can be a real bass killer
 
DynaudioAcoustic used to and Quested Audio still use them as studio amps.
Funktion One and Turbosound use and Tannoy used them as PA amps.

Dynaudio and Tannoy were forced to stop using them since they were bought by TC Group who also own LabGruppen.

Since then I added a third (MC750) which before it was mine served in the Abbey Road Mastering suite. Abbey Road are now being paid to use B&W and some lesser amps.
When they had to pay for their monitoring they used Quested Audio.
The engineer I bought it from didn't like the B&Ws very much.

The guy who designed the original DynaudioAcoustic monitors used to believe that there would no difference between active and passive speakers until he built some active ones due to popular demand which did change his mind.

Either way they will drive anything down to a 2Ohm load all day at full power.
 
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As I said box, room, placement and xover point remained identical.

dont forget one important feature, active makes it more easy to adjust levels on each driver
small changes around xo points might occur as a result
and I suppose active also means another amp
and again, the previously mentioned, possible changes in impedance load between preamp and power amp, due to active xo buffers
it really isnt simple at all
 
The thing that isn't always mentioned is the effect of active designs on the power amp'. I have an early edition of Martin Colloms book on ("High Performance Loudspeakers") and even then, in 1978, he lists about 9 advantages for active designs and I think the very first one he mentions is a reduction in IMD in the power amps. IM can be a real pain and it is interesting to do the maths. If a wide range amp feeds a conventional passive xover speaker the frequencies it handles may well be something like 40 to 16,000. This is pretty conservative. But this is still a ratio 400 to 1. With each additional active section the ratios come down quite quickly. E.g. a three way system with 400 and 3,000 Hz xover points will leave the bass, mid and treble amps only having to handle ratios of 10 to 1, 7.5 to 1 and 5.3 to 1. These are significant reductions and if IM is reducing clarity then active xcross overs should make an audible improvement.
 
dont forget one important feature, active makes it more easy to adjust levels on each driver
small changes around xo points might occur as a result
and I suppose active also means another amp
and again, the previously mentioned, possible changes in impedance load between preamp and power amp, due to active xo buffers
it really isnt simple at all

Fair enough but the most audible improvement was in the bass region say up to about 300Hz. The crossover point was 1.2kHz.
 
I like actives because they allow you measure and adjust several variables in real time, with profound speed( Impossible with passives). Linkwitz, who is famous due to the popularity of LR passives in commercial designs, has abandoned passives for actives because "This arrangement allows the amplifier to take direct control of the driver." Less expensive amps can then be used in the design because they don't have any electrical "hoops" to jump through.
Think, for example, what a single amplifier "sees" when it is driving a passive, three way, fourth order design(eek!). If it were the other way around, and actives were here first and good passives were just entering the scene, could you imagine what the establishment would be saying about the use of passives?
Anyway, I think that many passive snobs probably own and use DEQX's as their dirty little secret..
 
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ra7

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There are benefits to both approaches, and done correctly, they should yield identical results. If you're hearing a difference, try to identify what's causing it.

Active is great for prototyping and running through a number of variations. But once the design is finalized, I'd like to go passive - a simpler, more elegant solution. Of course, crossing below 100 Hz is expensive with passive, and active may be easier.
 
I made these posts to a different thread but the same issues keep coming up. There are things that can be done with active analog and active digital that can not be done with passive, but for conventional crossovers thee is no reason a passive system can not perform as well or better than an active. He are my previous posts:


Some simple truths can sum it up. Taken as system the combination of active crossover/amp/driver and amp/passive crossover/driver represent predominately linear systems. Since linear systems with the same frequency response have the same transient response it follows that if the active and passive crossovers systems are designed to have identical frequency response then they must have the same transient response. Any difference is damping due to series impedance in the passive crossover simply means that the transfer function of the passive crossover will have to be somewhat different that that of the active system to account for the difference in damping.

The real difference between passive and active systems is insertion loss and the way the response to changes in VC temperature.

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I read all the time that active filter are better because the transfer function doesn't change with changes in the driver's Z due to a variety of dynamic effects. Again, that is not an accurate statement. The thing that is overlooked is that this is limited to the voltage transfer function of the filter. But in reality, what determines the acoustic output of a driver is the current flow through the VC. Even in that case where the amplifiers output Z is zero applying a fixed voltage transfer function across the driver terminals does not mean the acoustic output remains constant under dynamic conditions. The driver VC Z changes with time (heating) and excursion and these factors will affect the current and therefore the radiated SPL. Active can make a lot of things easier, and I and am fan of actives. But many proponents of active make arguments for them which are overly simplistic and ignore many of the real issues resulting form the dynamically changing VC Z.
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So when you start talking about comparing active and passive, start at the beginning. That is not the amplifier output terminals in an active case. Remember that a simple, text book active HP filter has a impulse that decays exponentially or with oscillations, depending on Q of the filter. The impulse tail will past through and be amplified by the power amplifier and feed to the driver. So it isn't just the amp that is controlling the driver, it's the output of the active crossover and it's particular damping characteristics.
 
no reason a passive system can not perform as well or better than an active.

With a damping factor (at the driver terminals) that varies according to frequency, insertion loss, and all the additional nasties inductors bring along, how could a passive ever be better than an active?

I can see that they can be good enough in many cases, but better than active?

I'm still unconvinced.
 
I made these posts to a different thread but the same issues keep coming up. There are things that can be done with active analog and active digital that can not be done with passive, but for conventional crossovers thee is no reason a passive system can not perform as well or better than an active. He are my previous posts:


Some simple truths can sum it up. Taken as system the combination of active crossover/amp/driver and amp/passive crossover/driver represent predominately linear systems. Since linear systems with the same frequency response have the same transient response it follows that if the active and passive crossovers systems are designed to have identical frequency response then they must have the same transient response. Any difference is damping due to series impedance in the passive crossover simply means that the transfer function of the passive crossover will have to be somewhat different that that of the active system to account for the difference in damping.

The real difference between passive and active systems is insertion loss and the way the response to changes in VC temperature.

------

I read all the time that active filter are better because the transfer function doesn't change with changes in the driver's Z due to a variety of dynamic effects. Again, that is not an accurate statement. The thing that is overlooked is that this is limited to the voltage transfer function of the filter. But in reality, what determines the acoustic output of a driver is the current flow through the VC. Even in that case where the amplifiers output Z is zero applying a fixed voltage transfer function across the driver terminals does not mean the acoustic output remains constant under dynamic conditions. The driver VC Z changes with time (heating) and excursion and these factors will affect the current and therefore the radiated SPL. Active can make a lot of things easier, and I and am fan of actives. But many proponents of active make arguments for them which are overly simplistic and ignore many of the real issues resulting form the dynamically changing VC Z.
----

So when you start talking about comparing active and passive, start at the beginning. That is not the amplifier output terminals in an active case. Remember that a simple, text book active HP filter has a impulse that decays exponentially or with oscillations, depending on Q of the filter. The impulse tail will past through and be amplified by the power amplifier and feed to the driver. So it isn't just the amp that is controlling the driver, it's the output of the active crossover and it's particular damping characteristics.
Understood about active"ringing"(An active implementation is not putting real stress on an amplifier though, while a relatively similar passive implementation does). But being able to test an an almost limitless amount of variables in real time is not just a small advantage over passive implementations.
 
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I can see that they can be good enough in many cases, but better than active?

I think this phrase sums it up fairly well and is how I think of it.

We can debate the pros and cons of each all day, but if we look at it from the perspective of the best passive implementations vs the best active solutions then the active version will win every time. Yes you can argue that going active in certain situations is overkill, will end up costing more and probably wont sound better, so it obviously makes far less sense then a well implemented passive design, but that's not really the point imo. Given that situation the active version wont sound worse then the passive design, it's just that going active wont give you any worthwhile gains.
 
Has anyone here converted existing passive speakers to active?

A while ago I was given some old Mission 702es, and I wasn't keen on them, but they did have good, if 'warm', bass. I ripped out the passive crossovers and connected the drivers directly to a pair of £30 ebay amps driven from a PC with surround sound card and digital crossover software. I didn't do anything except set the amp volume controls to match the tweeter and woofer levels at the crossover. The phases of the woofer and tweeter seem pretty well aligned at crossover, and I've done no measurements.

I am still thrilled every time I listen to them, and I've hardly changed anything about the setup in months. I don't think I'm exaggerating when I say my setup is the best I've heard anywhere. And it looks pretty good too, with the multiple amps and speaker cables; you might almost mistake it for 'high end', except it that sounds so much better.

If the DIY enthusiast can't indulge in a bit of 'overkill' then who can? All those passive speaker designers with their first or second order filters, impedance matching, and power-sapping 'pads' seem like masochists to me.
 
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Active is easier to get right, so for many it's "better", and that's really important. Active can also be hyper-detailed, if you like that sort of thing (it's seductive).

But they best systems I've ever heard have all been with passive filters. All world class, all passive. Really, once you get a really great crossover you shouldn't be hearing it anyway, so what does it matter?
 
I think getting it 'right' has a lot of definitions to different people. If by arriving at something that pleases you in a DIY effort is 'right' for you doesn't mean it's right for someone else.

In my opinion getting a design right is just as hard, or easy, whether you go active or passive, that is if 'right' for you is a perfectly implemented crossover for a certain set of drivers where everything has been put together with a lot of measurements and a large chunk of CAD work.

Coppertop's idea of right in this situation is a fine example. If you're going to put together a system with minimal or next to no measurements then you are far more likely to arrive at something good then if the design were passive. This is one of the reasons why active xovers are very popular. But in that situation neither the active or the passive designs would be my definition of what could be considered 'right'. And in that situation if a proper passive xover were to be designed using measurements etc, then it almost certainly would out perform the active version put together without.

Now if you are putting together a system using measurements and CAD software, then going active is a little easier because it gives you access to building blocks that you just don't have when going passive. But if you were to limit the selection of active to filters to only the ones that can be replicated passively, then neither active nor passive is any easier to design for then the other, they are just different.
 
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