passive or active?

[.::DuD3::. 10+ year member]

what are most of you all running? what are the disadvantages/advantages of both? i'm still a little confused on how i'm supposed to wire them up, but i've been researching for the past couple days and just wanted some input.

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[JimJ 5,000+ posts]

If you have four channels of amplification available and a head unit capable of active operation, no real reason to go passive //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

 

[squeak9798 5,000+ posts]

Presently running passives....ran active many times in the past though.

 

[dkguitarist 5,000+ posts]

passive is already pre-set so all you do is pretty much plug and play.

active you have to manually tune each individual crossover, etc, but the end reward is worth it so it seems.

passive uses 2 channels of amplification; 1 for each side.

active uses 4 channels of amplification; 2 for each side (if 2-way. a 3-way frontstage would require 6 channels of amplification)

passive would use less wiring/time involved and wouldn't have to worry about having alot of amps in your trunk (or wherever) as opposed to active.

those are the only ones i can think of off the top of my head.

oh and i'm going to soon be running active (HOPEFULLY).

 

[squeak9798 5,000+ posts]

what are the disadvantages/advantages of both?

Advantages of a passives; crossover points/slopes are optimized for the speakers in a well designed passive crossover. Additional doo-dads (yes, that's the technical term) can be easily incorporated into them such as zobel networks, tweeter protection, etc etc. Also, less amplifier channels and less processing (and hence less space and money) are needed.

Disadvantages of passives: Crossover points and slopes are static and (usually) can not be changed to fit certain situations better (many times different slopes and crossover points are necessary to work better with certain speaker positioning or vehicle acoustics). Passive crossovers can be "power hungry" and waste some of the input power you are inputting to them. For the people who like to switch drivers frequently (the DIY'ers out there), using a passive crossover makes it very difficult and inconvient to try to switch drivers and still use the same passive crossover. Also, can't use time alignment on individual speakers.

Using some logic, you can probably deduce that the disadvantages of passives are advantages towards active, and advantages of passive are disadvantages of active.

 

[helotaxi 5,000+ posts]

You also need 2x as much power (roughly) to get the same output out of an active setup. 4x75 active isn't the same as 2x150 passive even though both ore nominally 300w.

I'm in the process of building a 3-way active front stage right now.

 

[OlogyAudio 10+ year member]

You also need 2x as much power (roughly) to get the same output out of an active setup. 4x75 active isn't the same as 2x150 passive even though both ore nominally 300w.
I'm in the process of building a 3-way active front stage right now.

But your tweeter sure will be happy without all that low level clipping... 2x30+2x120 or 2x40+2x110 wouldn't be far off 2x150...

Also I don't know of any variable cauer-elliptical active filters on the market //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif so there is a reason to go passive... //content.invisioncic.com/y282845/emoticons/rolleyes.gif.c1fef805e9d1464d377451cd5bc18bfb.gif

Someone needs to make an active C-E filter... Variable caps... fun...

Or just switches to switch between a few freqs...

There are plenty of great reasons to go active...

Have a good read:

http://sound.westhost.com/biamp-vs-passive.htm

 

[.::DuD3::. 10+ year member]

i think i'm leaning towards passive only because i don't want to shell out for another amp. but where would be the best place to look for some passive and active crossovers?

 

[squeak9798 5,000+ posts]

but where would be the best place to look for some passive and active crossovers?

The passive crossover will come with the component set when you purchase it. Passive crossovers are not something you can just "go out and buy" and expect to obtain full performance from the speakers. The passive crossovers need to be built for the specific speakers being used, which is why it's always the best idea to stick with using the passives that came with the speakers (and not to use any other speakers on those passives)

If you are planning to DIY your frontstage, then you could build your own passives. But building a passive network that truly optimizes your speakers performance would require equipment most don't have access to and knowledge that it doesn't sound like you currently possess (no offense). In most DIY situations it's really better to go active. Places like partsexpress do sell passive crossovers....but again, those are just textbook, off the shelf passives that are not going to extract full performance from your speakers.

For active crossovers....there's so many places to find them that it's hard to list even close to all of them. Anymore a lot of headunits have active crossovers built in (Alpine 9815/9835/9855, Eclipse 8443/8053/8454, Pioneer 860/880, Clarion DRZ9255), then there's also the external process/headunit combos like the Alpine H701, Pioneer P9 combo, Sony C90/4000x combo, etc. Then companies like Tru Technology, Coustic, Kicker, Audiocontrol, etc all make external active crossovers that can be used in any system.

 

[.::DuD3::. 10+ year member]

The passive crossover will come with the component set when you purchase it. Passive crossovers are not something you can just "go out and buy" and expect to obtain full performance from the speakers. The passive crossovers need to be built for the specific speakers being used, which is why it's always the best idea to stick with using the passives that came with the speakers (and not to use any other speakers on those passives)
If you are planning to DIY your frontstage, then you could build your own passives. But building a passive network that truly optimizes your speakers performance would require equipment most don't have access to and knowledge that it doesn't sound like you currently possess (no offense). In most DIY situations it's really better to go active. Places like partsexpress do sell passive crossovers....but again, those are just textbook, off the shelf passives that are not going to extract full performance from your speakers.

For active crossovers....there's so many places to find them that it's hard to list even close to all of them. Anymore a lot of headunits have active crossovers built in (Alpine 9815/9835/9855, Eclipse 8443/8053/8454, Pioneer 860/880, Clarion DRZ9255), then there's also the external process/headunit combos like the Alpine H701, Pioneer P9 combo, Sony C90/4000x combo, etc. Then companies like Tru Technology, Coustic, Kicker, Audiocontrol, etc all make external active crossovers that can be used in any system.

cool, i think i have a much better grasp on it now. i've only used coaxials in my past systems, so this is all still kind of new to me. but thanks for all the help!

 

[dogears 10+ year member]

Squeak-great posts !

Helotaxi

You will not need double the power to make an active setup as loud as a passive. Active setups are more efficient than passives and will get just as loud if not louder with the same power as a passive setup. No matter how you look at it the crossover splits the frequencies but SHARES the power of the amplifier in a passive setup. 4 x 75 active vs. 2 x 150w passive, I'll put my money on the active setup being louder and cleaner.

 

[helotaxi 5,000+ posts]

If you understand the electrical theory behind a passive dividing network you would understand how the power is divided within the crossover and that the losses are greatest around the crossover freq but are still fairly small. Away from the crossover point the losses are basically negligible. At lower frequencies, where you need the power for the best midbass response, pretty much all the power is going to the midbass with negligible loss. At higher freqs where the tweeter alone are playing, the losses are usually higher because of a resistor in line with the tweet as an attenuator. As such you wouldn't need double the power on an active setup, but you will need more. Active setups are not twice as efficient across the board, not nearly. The power is most important in the midbass freqs so a passive setup running 150x2 would have a definite advantage in the midbass range over an active one running off 75x4. 3dB of headroom is a big difference.

 

[dogears 10+ year member]

Well if you take in consideration the power loss of the passive crossover and just estimate that the mid is receiving 65% (average since it will vary) of the power of that channel is producing you are only getting 83 watts to the mid. Now you are getting 75w to the active that you can cross lower with a steeper slopes. Still think you will see a 3db difference? Think you will get that much more midbass with 8 watts more? you would see a 3db difference if the mid was seeing the full 150w.

 

[bri487 5,000+ posts]

You also need 2x as much power (roughly) to get the same output out of an active setup. 4x75 active isn't the same as 2x150 passive even though both ore nominally 300w.
I'm in the process of building a 3-way active front stage right now.

You dont need twice the power to run active as you do passive. My fronts are active off of a Zapco Reference 650.6 DC. it sounds a ton better, but there is no give with disortion. it is like an on/off switch.

 

[helotaxi 5,000+ posts]

Well if you take in consideration the power loss of the passive crossover and just estimate that the mid is receiving 65% (average since it will vary) of the power of that channel is producing you are only getting 83 watts to the mid. Now you are getting 75w to the active that you can cross lower with a steeper slopes. Still think you will see a 3db difference? Think you will get that much more midbass with 8 watts more? you would see a 3db difference if the mid was seeing the full 150w.

Do you have any idea how a passive crossover works? Do you know what causes the rolloff of a high or low pass crossover? Where did you get the 65% figure? If you were to take a 2kHz crossover and figure its efficiency at various frequencies I think you would find that figure a good bit off. Right at the crossover freq, it is 50% efficient. Go 1 octave from there to 1kHz and you are already over 80% efficiency. Go another octave to 500Hz and you are over 99%. Like I said, in the midbass region, a 75x4 active is going to lose out to a 150x2 passive. I could go over the math if you really want.