Active v Passive speakers - discuss

Oh God not the ADM.....

All is part of the discussion IMO and i don't think we can neatly put these things into compartments, but generally speaking:

Leaving aside the inductance of the driver, I would regard the ADM9 as active because it places the crossover (most of it) behind the power amplifiers.

Contrast this with the AVI Neutron with Amp Pack bolted onto the back. Here the power amplifiers are driving the speaker drivers through an entirely passive filter. So I'd call that powered passive. In reality this is little different to standard passive other than using a very short speaker cable and long interconnect.

I would regard a Cube with built in amplifiers as powered passive.
It has no filter network sitting behind the amplifiers.

But those are just my own definitions.

 

Well we have to have a consensus otherwise the discussion wont work so I will follow those guidelines.

 

My definition of active is where the frequency range is split before the power amplification and where more than one power amp is used.

You can have fully active - 1 amp per drive unit. Or actively bi-amped - 2 amps spread amongst 3 or more drive units - which is a sort of halfway house between passive and active.


Benefits of going active are that you are giving the amps an easier time - which can help give a sense of greater dynamic ease. Also, with some gain matching you can mix amplifiers - in my actively bi-amped system I've got an ss amp for the bass and a valve amp for the midrange and treble for a best of both worlds blend.

For some reason a lot of people go active with either an amps in the box approach or by using the same amps for every frequency band. I think that this is a missed opportunity to do some amp blending.

Another fringe benefit is that if you're using an adjustable active crossover, you don't need a pre-amp.


Drawbacks are that active crossovers use transistors or valves - which can introduce some hash and loss of transparency. Valve based active crossovers are expensive. Or you can get digital active crossovers which I've not tried yet - mainly because I'm not too sure about taking my analogue signal converting it to digital and then converting it back to analogue. Another drawback is the cost of buying 2 or more power amps plus the active crossover.


An area of Internet forum knowledge that seems to be lacking is in finding the best active crossovers for general use at various price points. Ashly? Marchand? Behringer? A N Other?


A lot of speakers aren't easily converted to active use because of the difficulty in getting at the passive crossovers. And I wouldn't bother going active with many 2 way speakers because the tweeter amp would be having such an easy time and would hardly be helping the mid-bass amp at all. But then I wouldn't bother with most 2 way speakers full stop - due to the unsatisfying bass from most of this breed.

 

As far as possible benefits go I think the only real benefit to active operation is that filtering through gain is less likely to be detrimental than passive/subtractive filtration. It may make choosing drivers easier for the designers as well.

Maybe there are some secondary benefits in terms of ease of use, cabling, siting etc, but all that really matters is the sound- surely?

I'd concur with Rob in that ADM's are 'active' while the others with amp packs are just passive powered.

My only experience of truly active digitally EQ'd speakers has been with meridians and i've always found them even blander than their passive.

 

To my mind the definition has always been:

Powered monitor: a speaker with one or more amp built-in, i.e. it has a mains / PSU input and a line level input on the rear panel.

Active speaker: a speaker that has a powered electronic crossover / frequency divider that drives a power amp stage per drive unit. These electronics can be internal e.g. ATC, KRK or external e.g. Naim, large PA rig etc - an active speaker can also be a powered monitor.

Things that fall in no-mans land e.g. a bi-amped pair of ES14 should just be described as what they are, in that case I'd say a passive tweeter and a mechanically rolled-off bass mid. It's certainly not active as there is no electronic crossover / electronic frequency shaping.

Tony.

 

I always thought that there are two divisions;

Line-level vs. amplified level crossovers
Passive vs. active components used in the crossover

Of course the directly wired full-range speaker has no crossover and IMO falls outside this discussion.

It could be argued that by definition, a crossover can only be part of a speaker where the frequency range is divided over more than one driver. Simple frequency response filtering is not strictly speaking a crossover as such.

It would be fully possible to build an active crossover operating on the already amplified signal. Not useful perhaps, but possible as a proof of concept.

It might also be that some "active" designs are in fact line-level passive designs, much like the RIAA eq in some phono stages is done passively and for others actively.

If you see the speaker driver as a passive component in its own right, then a passive crossover is one where there are no active components involved.

 

Very armusing.

Full definitions are too complex to be useful, what do you call a system with a passive line level crossover and one power amp per drive unit?

I use active speakers (crossovers and power amps built in) connected to a DAC with an integrated digital volume control by a balanced connection. Three boxes in total. Permanent sources are the TV tuner, DVD player and a Squeezebox receiver.

An active crossover can be more complex with less compromise. So you can tailor the crossover points, perform some time-alignment, whatever the designer feels necessary.

And because you have a separate power amp per drive unit you can tailor them to the purpose. So the bass amp can have a lot of power but it only needs to be able to reach 500Hz. My speakers use a 16 Ohm midrange unit which means the attached power amp can remain in Class A over a wider range for less standing dissipation. Etc etc.

The biggest downside (from a hifi hobbiest pov) is that there is nothing much to play with.

Paul

 

This is a passive system in my opinion.

What do you call a three way system with an active line-level crossover for the bass but the mid/treble is passively crossed line most sub/satellite systems are built?

 

To be honest, people who are trade should just put up with these jabs since its natural behavior for us customers to doubt the honesty of every trade members conviction. I've never seen any trade member diss their own products or philosophy on any forum ever, but I've seen plenty of hyperbole and attacks on other principles and business practices.

When you go into business, you get the forum suspicion as a perk, there is nothing to be done about that.

Time to go back on topic soon maybe?

 

I came here as an individual not as trade, I do not promote any of my work here, but it would be exceedingly daft and marketing man like if I didn't believe in what I do, so those are my points of discussion, not the product. The only reason there is a reference to trade in my header is I was told to do it, so I took the piss out of it by calling my trade Muppet Labs.

I am an individual and I post as an individual, I am not trying to get *any* of you as customers. What you are saying is called prejudice!!

 

I don't deny that it is prejudice, but it is also inevitable.

 

No prejudice is inevitable, it is personal choice, so it is obviously your choice and a very few others, 99.9% of members on this forum either do not practice it or don't voice it.

 

my biggest problem with active speakers (powered active monitor by Tony's terminology) ... is that I rarely believe the integrated amplifier to be of the highest quality.

I normally see (at best) a cheap 'plate' style amp stuffed in a loudspeaker box, or similar of low quality.

This works for a subwoofer perhaps, but I like the best amp I can afford at anything other than sub-bass frequency.

If you dont believe amps make much of a difference, or perhaps feel a class T amp is all the amp you'll ever need - then this type of speaker can be perfect for you.

Loving valve amps, having heard Berning, Audionote, Canary Audio, Border Patrol, Kondo (my favourite valve amps in other words).. it will be a cold day in hell before I chop such an amp in to favour a souped up tin can..

..I also think for domestic use, a really good passive crossover sounds better than an active one. The extra gain stages I put down to what I personally hear as lower fidelity. This is not always true of course - a friend had a (I believe £5,000) Nelson Pass active crossover that was blinding. Few would stretch to that, and compared to the price of a few capacitors and inductors..

 

Back to Robs point. In a simple crossover what is the value of typical inductance in series with the bass-mid unit of a small modern speaker, and what is the inductance of the voice coil of the driver? Can a notional electrical inductance be assigned to the frequency dependent mechanical impedance of the bass driver that causes high frequency roll off?

I am asking what proportion of the high frequency roll off of is effected by the series inductor, and what proportion occurs in the bass driver as its electrical and mechanical impedance rises with frequency..

If the greater effect belongs to the series inductor I wonder what Rob's claim amounts to.

On the other hand I do really accept that we have a very complex set of electrical and mechanical effects to manage with good engineering practice.

And again. What of the claim that a passive crossover after the power amp introduces more distortion to the whole system than would a well designed line level crossover.

Why is that?

And how do the parameters vary between passive and active analogue line level filters? (I guess you could design a simple passive filters with resisters, inductors and capacitors, or you could fold those filters into active stages with feedback.)

How do these two sorts of line level active crossovers compare with a crossover implemented in the digital domain - ie before the DAC?

 

Please read -

We've been over this many time but I will clarify the issues and the forum position with regard to conduct and trade membership one last time.

This is the last time - future mention will be removed.

Those who've not read our AUP should do so but it contains the following:

In relation to comments directed as individuals, this means a poster may expect to have their personal viewpoint or motives on an issue politely investigated or queried and, if they choose to respond, should be expected to do so in a similarly polite manner. It is rudeness, aggression and insult that should be avoided.

Those are the rules.

On the issue of trade members, we will classify these as sole traders, partnerships, company owners, directors, journalists and others that ZG Admin consider to be in the audio trade. All are required to display their trade status and again this is covered in the AUP.

We aren't having further discussion on this.

<< Thread pruned Rob, Dev >>

 

Superposition - or whatever the precise technical term for it is.

Superposition when you have 2 sine waves at different frequencies imposed on top of each other. Best illustrated by a diagram:



A passive amp coping with the signal shown in the diagram would be the bottom trace and would have peaks of +/- 2. In an active system each amp would only have to go to +/- 1. The active amps are having a much easier time.

Music isn't a couple of simple sine waves. Music has transients. The same superpositional principles still apply.

 

It is such a complicated question, and the answer can only really be ''it depends''

Take the JBL Charge-coupled crossover.

http://www.audiokarma.org/forums/showthread.php?t=137190

Not really an active crossover, not really a passive crossover from what I can see.

All I can really say - I'm not clever enough to design it.

Oh to have the resources of Harman International...

 

Isn't that intermodulation?

 

This thread has gone quiet.

I have some questions on the table.

http://www.zerogain.com/forum/showpost.php?p=281641&postcount=34

Rob?

 

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