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View Full Version : Running Tweeter on passive crossover without woofer??



badstang123
08-13-2006, 10:40 PM
Can I hurt the tweeter by running it off the passive crossover with the woofer disconnected. I sent my woofer out for warranty and didn't want to hurt the tweeter if it was bad to do this. Thanks.
- Justin

heyman421
08-13-2006, 10:42 PM
two seperate circuits, you'll be fine

although, that may depend on the way your xover's wired....

better wait for a 2nd opinion

FoxPro5
08-14-2006, 12:22 AM
You're cool. But why would you just listen to the tweets without the mids anyway??

ItalynStylion
08-14-2006, 02:59 AM
I think he just has one of the mids that whent bad and sent it out and he just is going to run what he has till he gets it back

DC8 Flyer
08-14-2006, 03:07 AM
EEEK
I could be wrong on this, but if you don't have both speakers hooked up to a passive crossover, doesn't that do funky things to the OHM load the amp sees? I think I read that in one of the tutorials that came with WinISD, but I could be very wrong


this is what I read in the WinISD tutorial, not sure it applies to you though

Notice that in each branch, the inductors and capacitors are in SERIES with each other (L1 is in series with C1, and C2 is in series with L2). In each branch, the inductor and capacitor are each chosen so as to offer 8 ohms of reactance at 1500 Hz. What this means is that at 1500 Hz, the cap is offering 8 ohms of capacitive reactance, and the inductor is offering 8 ohms of inductive reactance. Capacitive reactance and Inductive reactance are exact opposites, and cancel each other out! If you have 23 ohms of capacitive reactance, and 18 ohms of inductive reactance in a circuit, the net reactance is 5 ohms (the difference of the two). If the woofer or tweeter are removed from the circuit (become unplugged, or electrically "open" during play), then what you have is 8 ohms of capacitive reactance, and 8 ohms of inductive reactance in that branch. Since the two reactances cancel each other out, then the amplifier effectively sees a grand total of ZERO ohms at 1500 Hz! This will result in a damaged amp. Keep this in mind when considering implementing a 12 dB/Octave passive crossover into your system. Amps with built in short circuit protection will most likely survive this scenario, however...

ItalynStylion
08-14-2006, 11:38 AM
Oh snap!

In this case though i think the resistance would double would it not? Only one path for the electric current instead of two (tweet and woofer)

I think its a good idea just to wait till you get your mid back

FoxPro5
08-14-2006, 01:47 PM
Christ...just get a DMM and measure the resistance if you're so worried. If you double the resistance (6 ohms to 12 ohms) the power is halved.

badstang123
08-14-2006, 04:51 PM
I have some 6.5" mids in my doors that are only playing from 80hz-250hz. I think I'll just hook the one up to the crossover for the time being until I get the 5.25" MB Quart back. I'm sure I will notice a midbass speaker missing far less then a main one for the components in my kicks. It will be kind of ghetto but probably the best idea for the time being.

wesl56
08-14-2006, 04:54 PM
it will be fine... the crossover has nothing to do with load... look up a diagram if u want to see

GordonW
08-14-2006, 05:55 PM
EEEK
I could be wrong on this, but if you don't have both speakers hooked up to a passive crossover, doesn't that do funky things to the OHM load the amp sees? I think I read that in one of the tutorials that came with WinISD, but I could be very wrong



This can definitely happen.

What happens, to paraphrase the WINISD manual, is that without the woofer inline to "damp" the crossover, the coil and cap in the woofer crossover will resonate at the crossover frequency, and will SHORT the amp at that frequency. Many amps will go into overload from this... spitty, harsh sound, and sometimes, even "whistle tones"... ie, OSCILLATION.

I've HEARD this happen, in a very few cases. In at least one of those, the amp was SMOKING before we could turn it off...

If you're going to do this, get a VERY HIGH POWER resistor (4 to 5 ohms, at least 50 watts... you could parallel 2- 8 ohm 25 watt resistors) and put IN PLACE of the blown woofer. That way, the crossover sees an appropriate load...

Regards,
Gordon.

badstang123
08-14-2006, 07:02 PM
I put my midbass speaker on it and it's much better. The tweeter was making some weird sounds and now it stopped. I guess this will be okay for now. It's just weird having sound coming from a kickpanel on one side and the door on the other.

helotaxi
08-14-2006, 09:59 PM
Christ...just get a DMM and measure the resistance if you're so worried. If you double the resistance (6 ohms to 12 ohms) the power is halved.

We're talking impedance not resistance. Impedance is frequency dependant, resistance isn't. Whatever you measure with the DMM won't matter for squat once you apply an AC voltage to the circuit.

headless
08-15-2006, 10:53 AM
I don't know about other speaker sets, but my Germanium's manual says you will fry your **** if you try to push power through your x-over with only a tweeter or only a woofer connected. It states to "NEVER APPLY POWER TO YOUR GERMANIUM CROSSOVERS WITHOUT CONNECTING BOTH LOUDSPEAKERS FIRST" or something very close. Maybe other company's x-overs/speakers work differently; i'd call them and ask.

squeak9798
08-15-2006, 07:52 PM
IIRC it's only a problem with 2nd order crossovers. I may be wrong, but I have that in my head for some reason and I'm too lazy right now to actually put forth the effort to research it at this moment.

But, the moral of the story is that it is possible to damage your equipment by leaving one of the outputs on the crossover "open"