fe107e update

[Dave Jones]

As described in a recent thread, I've recently made some small towers (ML TL) using Fostex fe107e's. The input for Martin's software is below.

The speakers sound amazingly good, considering what they cost to build -- less than 45 bucks a side.

Here are some updates:

1) With the speakers near a back wall, and listening at about 2.5 meters, I've settled on a baffle-step compensation circuit comprising 5 ohms of resistance and a 2.75 mH inductor with a DCR of about 1 ohm.

2) I've applied three very thin coats of dammar varnish to the cones and center caps. I used Winsor and Newton artists' painting varnish, which is very dilute. It's only had a day or so to dry. My initial impression is that the treatment improved the sound. What I'm looking for is less cone resonance, particularly on vocals when the singer attacks a note strongly. In that regard, the speakers still do not seem to be as good as the Lynn Olson Ariels I've been listening to. No surprise there. But I can't do an A/B test easily. I'll give the varnish a few more days to dry.

I also applied epoxy putty to the backs of the posts (for stiffness) and felt to the fronts (to kill reflections back into the cone). I don't know if those tweaks helped, but they didn't hurt.

3) The speakers can't keep up with the subwoofer I built using a Peerless 10" XLS driver and 400 gram passive radiator. No surprise there, either. If I crank it up to moderately high volumes, the sub is just idling, but the mains start to show rather too much excursion, IMO. They could use a high pass filter. But they will play plenty loud enough for the office. I'm going to build yet another, smaller sub. The XLS will go home with the Ariels and basically cover the 20-40 Hz range.

[Dave Jones]

I just noticed that the comment says FE-164. Ignore it.