deciphering a passive crossover

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=105273
Printed Date: April 29, 2024 at 7:40 AM

Topic: deciphering a passive crossover

Posted By: nickdahl
Subject: deciphering a passive crossover
Date Posted: June 05, 2008 at 3:36 PM

My car's previous owner had a nice stereo installed, but when he removed it, he left the speaker wires. Attached to the speaker wires for the rear speakers are a crossover network. So, I'm wondering if I might recycle it, and use it with the Silver Flute 5.5" 4-ohm speakers I'm installing there.

Here are the values for the inductor, resistor, and capacitor:

Inductor = 0.3 inH

Resistor = 5SG 15ohm J MD IWAKI

Capacitor = nichicon 6.8uF 50V BP-S (k)

I believe this is a bandpass network, but I'm unsure what the cutoff frequencies would be. Thanks for any help you might give!

Nick

Replies:

Posted By: nickdahl
Date Posted: June 05, 2008 at 3:51 PM

Here are some pictures, if they help:

posted_image

Thanks,

Nick

Posted By: DYohn
Date Posted: June 05, 2008 at 5:00 PM

Your attempts to hot link the images was unsuccessful. Try uploading to this site. In order to help you with your crossover network I need to know how the three components you mention are wired together.

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Posted By: nickdahl
Date Posted: June 05, 2008 at 5:34 PM

Let's try this again...

posted_image

The network is wired like this: the + speaker wire running between the amp and the speaker is separated by the network. The network is built by taking a capacitor leg,a resistor leg, and one side of the inductor coil, and tying them together. The same thing is done with the other legs. The + speaker wire connects to the network by entering on one side, and exiting on the other.

Thanks again,

Nick

Posted By: haemphyst
Date Posted: June 05, 2008 at 6:31 PM

I'd almost bet that is a Zobel. I don't think it's a crossover. What driver SPECIFICALLY was it connected to, meaning a woofer, a mid, or a tweeter? I think you'll have to know that...

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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."

Posted By: nickdahl
Date Posted: June 05, 2008 at 6:39 PM

haemphyst wrote:

I'd almost bet that is a Zobel. I don't think it's a crossover. What driver SPECIFICALLY was it connected to, meaning a woofer, a mid, or a tweeter? I think you'll have to know that...

Nakamichi SP-55C. 4 ohms. Two-way speaker.

These speakers were left behind...they're fairly well rusted out and look absolutely shot. They were mounted in the rear seat speaker position of a 1983 Porsche 944.

Thanks,

Nick

Posted By: falconyellow
Date Posted: June 05, 2008 at 7:04 PM

That's a 6db bandpass with attenuation, sorta.

Posted By: stevdart
Date Posted: June 05, 2008 at 9:28 PM

Wired as you described, it looks like a parallel notch filter that was used to suppress unwanted exaggeration in the 10 kHz region. See this calculator. I wouldn't use it for any other speaker, and I wouldn't even reuse it for the same speaker it was made for. The cap looks to be the electrolytic type and should be considered no longer useable. And not to be left out, the coil is tiny gauge and thus has a high DCR, and the resistor is low quality and inductive (I'm willing to bet).

(...assuming your post above detailing the values meant to read " .3 mH " for the coil...)

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: nickdahl
Date Posted: June 05, 2008 at 9:53 PM

Thanks for the advice, and for the link to the calculator. Just wanted to be sure it wasn't going to be useful before it hit the bottom of the trash can!

Thanks again,

Nick

Posted By: stevdart
Date Posted: June 05, 2008 at 10:16 PM

Stash the coil in your parts bin. It's copper. Maybe you could use it someday, like in a tweeter crossover network (where DCR is not typically an issue).

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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.

Posted By: falconyellow
Date Posted: June 06, 2008 at 12:52 AM

Nevermind my last post, I'm a dork... posted_image

Posted By: haemphyst
Date Posted: June 06, 2008 at 10:21 AM

nickdahl wrote:

They were mounted in the rear seat speaker position of a 1983 Porsche 944.

Shoulda left 'em in... You halved the value of the car by removing them, no matter WHAT their condition! LOL

Just ribbin', man... Starting a new job on monday, so I am in a good mood today! posted_image

Actually I worked on one of those cars... I put an Alpine DAT deck in one, with a changer, Nak subs literally in the rear seat foot-wells, the big (at that time) Alpine 5 channel, ADS plates in the doors... Sounded REALLY good, as I recall. Less than one week, and the guy had ALL of the stuff ripped off. (We couldn't talk him into an alarm...)

SHARPEST car I have EVER worked on... That one, and the 88 Dodge Daytona. (And by "sharp", I mean EVERYTHING I'd touch wanted to cut the ever-lovin' doodie out of me, not that it was a good looking car...) IIRC, that was the car I was working on when I almost cut the end of my finger off with a Dremel... Anybody remember the little Dremel SAW BLADES??? ('nuff said)

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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."

Posted By: nickdahl
Date Posted: June 06, 2008 at 2:58 PM

haemphyst wrote:

nickdahl wrote:

They were mounted in the rear seat speaker position of a 1983 Porsche 944.

Shoulda left 'em in... You halved the value of the car by removing them, no matter WHAT their condition! LOL

Just ribbin', man... Starting a new job on monday, so I am in a good mood today!

Actually I worked on one of those cars... I put an Alpine DAT deck in one, with a changer, Nak subs literally in the rear seat foot-wells, the big (at that time) Alpine 5 channel, ADS plates in the doors... Sounded REALLY good, as I recall. Less than one week, and the guy had ALL of the stuff ripped off. (We couldn't talk him into an alarm...)

SHARPEST car I have EVER worked on... That one, and the 88 Dodge Daytona. (And by "sharp", I mean EVERYTHING I'd touch wanted to cut the ever-lovin' doodie out of me, not that it was a good looking car...) IIRC, that was the car I was working on when I almost cut the end of my finger off with a Dremel... Anybody remember the little Dremel SAW BLADES??? ('nuff said)

I know what you mean. Everytime I work on the car, I come away bleeding. I have the alarm waiting!