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Impedence through Passive xovers?

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=62339
Printed Date: June 16, 2024 at 11:37 AM


Topic: Impedence through Passive xovers?

Posted By: sedate
Subject: Impedence through Passive xovers?
Date Posted: September 07, 2005 at 1:40 PM

So changing speaker impedence when hooked up to passive xovers also changes the xover point.

Now well the xover point changes, what happens to the impedence the xover shows to the amp? What happens if you disconnect the tweeter or the midbass from the xover and try to run them by themselves, still filtered through the xover? For that matter, do the xover points remain the same when you disconnect one or the other speakers?

Here's my situation, in case anyone's wondering: I have a 4-ohm componet set. Except my xover broke so I got better ones that are optional on this particular componet set. Then, I decided they'd work better as rear-fill so you remove the tweeter and drop 'em, filtered through the xover, in the rear deck. Now, for whatever reason, the amp I'm using suddenly doesn't like the rear-speakers. It jumps in and out of protection when they're playing at any significant volume. I can get the protection circuitry to stop by either dropping the gain to nothing the the channel, or disconnect the xovers. What's the deal?

Yes, I know I need a DMM.

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"I'm finished!" - Daniel Plainview



Replies:

Posted By: haemphyst
Date Posted: September 07, 2005 at 3:38 PM

sedate wrote:

So changing speaker impedence when hooked up to passive xovers also changes the xover point.

Yes, this is correct

sedate wrote:

Now well the xover point changes, what happens to the impedence the xover shows to the amp? What happens if you disconnect the tweeter or the midbass from the xover and try to run them by themselves, still filtered through the xover? For that matter, do the xover points remain the same when you disconnect one or the other speakers?

It SHOULD be (if you are using 4 ohm speakers) 4 ohms below the crossover point and "infinite" above, if the woofer reamins hooked up, or 4 ohms above the crossover point and "infinite" below, if the tweeter remains hooked up. Infinite is not the absolute correct term to use - The amp still sees reactive components, but it's pretty close.

sedate wrote:

Here's my situation, in case anyone's wondering: I have a 4-ohm componet set. Except my xover broke so I got better ones that are optional on this particular componet set. Then, I decided they'd work better as rear-fill so you remove the tweeter and drop 'em, filtered through the xover, in the rear deck. Now, for whatever reason, the amp I'm using suddenly doesn't like the rear-speakers. It jumps in and out of protection when they're playing at any significant volume. I can get the protection circuitry to stop by either dropping the gain to nothing the the channel, or disconnect the xovers. What's the deal?

If I understand what you are saying, when you connect the woofers, THROUGH the crossover, to the amp, but have them in the rear deck, your amp does not seem happy... If you connect BOTH drivers, does the amp behave differently? If you disconnect BOTH drivers, does the amp behave differently? If you hook just the woofers directly to the amp, is the amp happier? Were you at one time running this same set in front, but with a different amp? If so, did it work then, or was the performance spotty as it is with them installed in the rear...

If these are the correct assumptions, I'd say there is something wrong with the crossover modules. Disconnect all the drivers, and if the amp STILL goes into protect mode, then there is DEFINITELY something wrong with one or the other of them. Try connecting them one at a time to see which one it is that is giving you the issue...

sedate wrote:

Yes, I know I need a DMM.

You don't have a DMM? Wanna buy one? LOL

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It all reminds me of something that Molière once said to Guy de Maupassant at a café in Vienna: "That's nice. You should write it down."





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