Will this damage a passive cross-over
02-06-2004, 07:54 AM
#1
4000 Watt CAFz'r
Thread Starter
Join Date: Nov 2000
Posts: 5,498
If I just run my mids off my passive cross-over
(I have a franken component set..Fusion 5.25 mids, CV passove x-over, and cv tweeters). If I just run the mids off the passive and ditch the tweeters, will this damage the x-over?
(I have a franken component set..Fusion 5.25 mids, CV passove x-over, and cv tweeters). If I just run the mids off the passive and ditch the tweeters, will this damage the x-over?
02-06-2004, 08:17 AM
#2
50 Watt CAFz'r
Join Date: Jan 2004
Posts: 206
Yes it will
The crossover was designed to have two loads on it your mid and tweeter. When you remove one you'll find the impedance of the newtork drops, and power power from your amp may burn out components on the crossover, or your will start kicking into protection from thw low impedance
The crossover was designed to have two loads on it your mid and tweeter. When you remove one you'll find the impedance of the newtork drops, and power power from your amp may burn out components on the crossover, or your will start kicking into protection from thw low impedance
02-06-2004, 01:59 PM
#8
Yankee
Join Date: Oct 2003
Posts: 3,599
The crossover can indeed be damaged by not driving all the intended drivers. This will depend on Xover design and whether or not there is a Zobal network. The consequences would be minor (a burnt resister or two) but it is your call if you want to put it at risk or not.
I went through the same issue when actively driving my Dynaudio 3 way system with 2 amps. 1 amp to drive the woofer and 1 amp to drive the tweeter/mid (there was an active crossover before the amps so the woofers crossover point was met. I am too cheep to spend the 200-300 US dollars for a Dynaudio X-360A, so I just used my 3 way crossover as a 2 way with a power resister in the woofers place (power to the HF unit was actively crossed above the woofers crossover point so there was minimum current to the resister).
BTW I do not think this would give your amp a problem either way, and if it did damage the crossover you wouldn’t know till you tried to use it as it was intended.
I went through the same issue when actively driving my Dynaudio 3 way system with 2 amps. 1 amp to drive the woofer and 1 amp to drive the tweeter/mid (there was an active crossover before the amps so the woofers crossover point was met. I am too cheep to spend the 200-300 US dollars for a Dynaudio X-360A, so I just used my 3 way crossover as a 2 way with a power resister in the woofers place (power to the HF unit was actively crossed above the woofers crossover point so there was minimum current to the resister).
BTW I do not think this would give your amp a problem either way, and if it did damage the crossover you wouldn’t know till you tried to use it as it was intended.
02-06-2004, 02:40 PM
#9
Guest
Posts: n/a
Depends on the passive xover. IF the passive crossover has either a Zobel for the tweeter or some form of tweeter protection such as a lightbulb then the passive and amp may fare alright.
Have a look at a 12db or higher high pass passive. They contain a cap in series, an inductor IN PARALLEL and then whatever else. It is that parallel inductor that becomes your only resistance if the tweety is disconnected and they generally are very very low in resistance.
This means that the amp will see an impedance that gets lower as the frequency goes up which is bad.
Lightbulbs and other protection schemes go before the passive bits so really they just start to activate all the time. This can burn out bulbs but then the circuit is open and not a problem either.
Zobels, by their nature, introduce a resistor in parallel as the frequency goes up so they can stabilize the passive too.
To make a long story long - yes it is a problem but your particular passive may cover it up so you don't see it. [img]graemlins/thumb.gif[/img]
Have a look at a 12db or higher high pass passive. They contain a cap in series, an inductor IN PARALLEL and then whatever else. It is that parallel inductor that becomes your only resistance if the tweety is disconnected and they generally are very very low in resistance.
This means that the amp will see an impedance that gets lower as the frequency goes up which is bad.
Lightbulbs and other protection schemes go before the passive bits so really they just start to activate all the time. This can burn out bulbs but then the circuit is open and not a problem either.
Zobels, by their nature, introduce a resistor in parallel as the frequency goes up so they can stabilize the passive too.
To make a long story long - yes it is a problem but your particular passive may cover it up so you don't see it. [img]graemlins/thumb.gif[/img]
02-06-2004, 04:31 PM
#10
50 Watt CAFz'r
Join Date: Mar 2003
Posts: 359
Inductors have a low dc resistance, but in AC their impedance increases with frequency.
On a 12db crossover without the tweeter connected you have essentially a capacitor in series with the inductor.
The capacitor becomes close to a short and the inductor impedance becomes large.
The inductor willdrop almost all the voltage at high frequencies and will be resposible for the amount of current in the high pass section.
Adding a tweeter in parallel with the inductor increases the current in the high pass section overall ,but lowers the current in the inductor because the impedance of the inductor in parallel with the tweeter is lower and drops less voltage in series with the capacitor.
So with the tweeter hooked up the inductor passes less current.
On a 12db crossover without the tweeter connected you have essentially a capacitor in series with the inductor.
The capacitor becomes close to a short and the inductor impedance becomes large.
The inductor willdrop almost all the voltage at high frequencies and will be resposible for the amount of current in the high pass section.
Adding a tweeter in parallel with the inductor increases the current in the high pass section overall ,but lowers the current in the inductor because the impedance of the inductor in parallel with the tweeter is lower and drops less voltage in series with the capacitor.
So with the tweeter hooked up the inductor passes less current.
