12trxb question

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diyAudio Member
Joined 2004
There were several versions of these made, some for other manufacturers like Knight.

The early ones had a metallic pinkish color frame and basket and had a couple different versions of the tweeter (very early ones were narrower).

Later versions had a white frame and were seriously heavy. Both came in eight and sixteen ohm versions.
kvk said:
Saw these on ebay--


I looked around the web at 12trxb pictures and the ones I saw look different, like a big cast frame with ridges. Was there more than one construction for these? This pair looks to have a stamped steel frame.

Having used EV speakers for some 30 years I would suggest these....



PS or if you can find them MC8A(s) - much like the Fostex FE207E.


diyAudio Member
Joined 2004
Those are the later cast frame ones. The frame is so heavy that they'd probably survive re-entry from space...

The 12TRXB's model like a poor man's PHY-HP KM30. They look like they'd be great in an open baffle with a SET amp. The 12TRXB had a little less bass when modeled in the PHY-HP baffle compared to the KM30 due to it's slightly higher Fs.

If I had the room for big open baffles, I'd definitely give 'em a go.
Great Fun

I have a pair of EV 12" SP12B and T35 tweeters that I bought in 1975. I haven't used them for the past several years because of the size of the cabinets. I got rid of the cabinets after we moved because I had know where to put them. They were huge.

I pulled the drivers out today and mounted them on simple OB. I used what I had on hand so it's nothing special. They sound wonderful javascript:smilie(':D') and are easily a match for my Fostex FE166-ESR BLHs. This is the first time I have listened to an OB. They are truly special.

The SP12B is running full range. The T35 is crossed using a 1.5 uf cap and L-PAD.

Using Martins MathCad worksheets the bottom end is somewhere between 60 and 70 hz, which seems to be pretty close to what I am hearing. I filling the bottom end with a sub.

I will have to see if I can convince my wife that a nice looking OB in the living room would be a great thing javascript:smilie(':D'). I don't think she is going to go for it; anyhow a couple of pics.


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