Need some help please

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Hi All,

I just found this page and it looks like there are alot of knowledgeable people in here.

I am hoping someone can help me out. I am planning to build a subwoofer for my car with 2 12" woofers that I have. My problem is that I do not know what the T/S parameters are for these speakers.

The are made by Electrovoice and the model number is 12TRX. They are quite old, so they are not on their web site. I tried emailing them (Electrovoice) but got no response back.

Anyone in here ever used this woofer before?

I was planning to use them in a bandpass enclosure, can I use a close enough guide to build the enclosure?

Sorry for all the questions and thanks to anyone that can assist.
Unless you can measure the parameters of the driver, I would suggest going with a sealed enclosure. This is a broad generalization, but you can yield acceptable results using between a 2 and 3 cubic foot sealed enclosure per driver. The best thing to do would be to build some temp enclosures and experiment.
diyAudio Moderator Emeritus
Joined 2001
Old is right. From what I can see from a search, that model had alnico magnets!

Actually, from what I can gather, alnico has some superior properties to ferrite, not sure why the switchover.

Anyway, here is a message board where some people were talking about using the EV 12 TRX. Check the Email addresses-they might be able to help.

I read in one message that the EV 12 TRX was different from the EV 12 TRX-B. Wouldn't know for sure.

There are ways of measuring for speaker parameters for the do-it-yourselfer if it comes to that.

Good Luck!!
diyAudio Moderator Emeritus
Joined 2001
Here is one link:

This one has a link to a nice spreadsheet to simplify matters:

A lot of people recommend this freeware. I can't get the thing to work, but it is recommended by many:

This is an extremely nifty tone generator. I save mine to Program Files, so I can have it any time I want. You can either go up or down in preselected amounts, OR you can highlight the frequency display box and write in any frequency you want. Normally, you want to put it in sine wave mode for testing speakers, of course. You can go from 100 Hz to 99 Hz to 98 Hz, etc., if you want to. Just hook your sound card up to your stereo amp, and you are all set.
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