Center speaker from Focal 5V2 - crossover wiring help

Csh1474

Member
2010-10-12 9:59 pm
I have an old focal 5V2 polyglass 2 way component set from my car that is short one tweeter due to damage by a friend with his lacross stick. The speakers and single tweeter have been gathering dust in my closet for a while, so I decided to use them for a center speaker in my home theater setup. I built a vented enclosure for them using an online calculator for the dimensions. It's divided into two cavities so that each woofer has its own sealed cavity of the proper dimensions and port size.

The component set has a 5.25" polyglass woofer, passive crossover and TN45 tweeter. I can't find a datasheet on the tweeter but from online research it appears to be a 4ohm (nominal) tweeter and not 8ohm like some of the newer Focal tweeters. I bought this set back in 2001 and Focal doesn't appear to have many archived datasheets.

The issue I have is how to hook it up. My receiver is an Onky HTRC-260 requiring a minimum 6ohm impedance. Currently i have it hooked up so that one woofer and the tweeter go into a passive crossover and the crossover input is hooked up in series with the second woofer. So the second woofer is receiving the full range of frequencies.

This setup produces decent sound, but the tweeter barely has any sound coming from it. I assume that is because at the high frequencies, the woofer has about 25 ohms impedance and the tweeter is only 4 ohms, so only 1/6 of the power is going to the tweeter and the other 5/6 to the woofer.

Would it be possible to use the second crossover and hook the 2nd woofer up to the low-pass and a 4 ohm resistor up to the high pass and then hook the two crossovers in series. Or is my only option to build a custom crossover for the set? I would like to run what i got if possible to keep the costs low. I'm not clear on how the 4ohm resistor would affect the function of the crossover, especially since i can't find a TN45 impedance vs frequency graph.

(I looked into buying a replacement tweeter, but a pair of focal tweeters is almost as much as i payed for the set in 2001. I also can't find TN45 and a different tweeter would affect the crossover frequency)

I'm looking for any help i can get, cause i haven't found information on a setup like this online. I'll post pics of the speaker box soon. Thanks in advance.
 

kbgl

Member
2010-04-03 1:25 pm
You need to verify what you have, and then figure out what you can use. The connection of the second woofer you mentioned is wrong, or I misunderstand what you are saying.

Do you have an ohm meter available? Measure the woofer. If they are 8 ohms, then don't try to use the second woofer. How did you determine the box size and porting? Did you consider sealed as an option? Do you have a sub? Describe the location of the center. A picture would be even better.
 

Csh1474

Member
2010-10-12 9:59 pm
I have a TN45 tweeter rated no nominal 4 ohm impedance and 130mm Polyglass 130V1 woofer rated nominal 4 ohm. I have the passive crossover designed to hook up these two speakers to one amplifier output. Attached to the crossover the impedance of the component set is nominal 4 ohm. I'll have the electrical diagrams up in an hour of how i hooked it up and i will open up the crossover to determine the components used.

I used this calculator for vented box dimensions. I used the datasheet on the 130V1 from focals website Speaker Box Enclosure Designer / Calculator
 

Csh1474

Member
2010-10-12 9:59 pm
I tested the tweeter with a multimeter and it comes out to around 3.2 ohms, but DC resistance isn't exactly what the system sees as the impedance changes with frequency.

Here is how i have it hooked up now.
current%20setup.JPG


Here is how i was hoping i could hook it up to improve the tweeter performance.
Possible%20Future%20setup.JPG


This is the way i believe it should be ideally setup, but this would require me buying components to build a crossover. I would also need to know the T/S parameters for the tweeter to properly design the crossover, but Focal doesn't have the data sheet on their website anymore.

optimal.JPG


Here is a photo of the finished speaker box. It is made of 3/4" MDF with 1/4" of Pine laminated to the exterior. Its finished with a black water based stain and urethane. The photo is with my cell phone, so it is not that great.
speaker%20photo.JPG


The focal crossover is an FAV1. I believe it is designed for a 3.5kHz crossover frequency. The components appear to be three 7W 2.4 ohm resistors, a 10.0J 100V capacitor, a 3.9J 100V capacitor, a hollow core inductor simply labeled L2 and a ferrite core inductor unlabeled. The boards is glued down to the case, so i cannot see how it is wired. I'll do some more research online to see if i can figure out the specific design of this crossover.

So far it has only cost me $20 in wood and some wire to set this up, so it's been low budget.
 

kbgl

Member
2010-04-03 1:25 pm
Your last sketch is the only way that I would expect to work. Ideally, the woofers and tweeters need to be as close together as possible to reduce lobing problems. If you don't want to measure, you can make a x-over by trial and error, and adjust by ear. This will not be ideal, but it may be good enough to use till you get the bug to make a better one.
 
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