RADIO SHACK 40-1310 SUPER TWEETER
The Radio Shack 40-1310 is a high quality spun aluminum horn super tweeter that has become fairly well regarded in the DIY community. The tweeter comes in it's own pod and with a built-in, low quality 2nd order crossover at 5kHz. The tweeter can be easily removed from the pod to allow for direct mounting into an enclosure and the internal crossover can also be easily removed. While I have not come across any conclusive evidence, several feel that this tweeter was made for Radio Shack by Fostex and that it is very similar to the Fostex FT17H Horn Tweeter.
This tweeter has very good high frequency response and is well suited to add a little bit of top end air and sparkle. The tweeter is very efficient and can easy keep up with high efficiency full-range drivers. The frequency response curve as measured by Radio Shack is shown below. The response is very flat between about 10kHz and 20kHz with good efficiency (about 96 to 98dB).
Resources
- Radio Shack 40-1310 Owner's Manual - (PDF 45KB)
Driver Tweaks
The picture below shows the horn lens removed from the tweeter pod. As you can see, the lens and throat of the horn is aluminum and well built. Aside, given the thickness of the front flange, it would be a good idea to countersink the horn into a baffle if you did not use the pod.
Once the cross over point is set near 10kHz, the tweeter sounds pretty good. However, I felt it would not hurt to add some duct seal to the throat of the horn to deaden any potential vibration. I also added duct seal between the magnet and aluminum lens. The application of the duct seal seems to have made some very subtle improvements.
I like using the tweeter in the pod. In the pod, you can move the tweeter around to adjust the sound. However, I found the screw terminals to be annoying. I removed the screw terminals and replaced them with generic binding posts.
The cross over (shown above) is a simple first order cross over with 1 + 0.22 uF of capacitance. I use these tweeters to add some air and sparkle to the BD-Pipes. The tweeters are very efficent and driven using a low power SE 50EH5 Tube Amplifier.
