TB 3″ copper final build

Well, hasn’t the price on this driver and TB in general gone up…? It’s a nice driver, but I’m not sure if they’re priced to move, so to speak…

Anyway, I had mine on sale from the original price. That was a good deal. Now, well, it’s up to you to decide. The final curves in the box shown in the prior post are shown below.

First, an on axis FR curve, normalized to 2.83v. It’s not super sensitive, but about right for a 3″ driver.

So, 78dB sensitive. I ignored the trap for the 5-20k region given the off axis response-if anything a full range driver has less high frequency energy in it’s power response. Listen 15-30 degrees off axis if you wish. See the power response below.

What kind of low frequency response do you get? Below you’ll see a “flex curve,” which is praxis’ way of adding low frequency info after the reflection free interval into the gated FR above the first reflection. It gives you a rough idea of in room bass response. You have to smooth it, so you should only use it to make general impressions of relative bass, mid and highs.

There is a 6-12 db/oct rolloff starting roughly at 150 hz. That is, it needs a sub for anything serious.

What about distortion?

If you crossed it over at 150 hz, then the most you could get out of these cleanly is in the low 90dB/1m peaks. Pretty good for a bedroom or small apartment speaker. Pushing it 4 dB higher gives the following graph

You can see the higher order distortion start to creep in, just getting to -60dB. That’s about the most you can get.

So, how do they sound? Well, I’ve got them in my daughter’s bedroom as an alternative to the typical pathetic boom box setup. For voice, small acoustic ensembles in a small room, they work very well. They don’t have the “air” that comes with a small tweeter, but the power response is pretty forgiving and they don’t have that forward sounding tendency that the typical 2 way 4LR/1″ dome has.

Let me know if you want the details of the box and the crossover, which is just a 3 component trap. The LCR trap combines with the natural curve and the baffle response of the box to give almost complete baffle step compensation. It’s not too much-mostly because of the significant roll off at 150 hz.

If you’re wondering why a simple trap works, the graph below explains it. The natural response of this driver is not flat. However, placing the driver on the baffle results in the following curve.

The net effect of the natural driver response and the baffle is a low Q peak centered between 1-2k. All that was necessary was a trap to flatten this.