Ripped from http://melhuish.org/audio/diy21.htm

by Giuseppe Pipitone

First of all a few words about the reasons of this realization: I have read a lot concerning the pros and cons about full range speakers, since I was not able to listen to any of them, I decided to build a low cost pair. The drivers I choose, Monacor sp-200x, feature a very wide region of linear response. I was aware that a 20 cm driver had to somewhat lack in the very high range, since I had no prejudice, after a few email exchanges with Thorsten Loesch, I thought that the work of adding some energy in the very high range of the audio spectrum could have been done by a piezoelectric tweeter. I know that may folks think that they sound awful, but the work it was supposed to do was really easy: emitting something above 13KHz with a good dispersion. Well, they proved to be perfect (and really cheap) for this aim.

All lengths are in centimetres.

• Inner sizes 22.2 x 109.2 x 30.

• Outer sizes 26 x 113 x 33.8 (I have used 19 mm MDF).

• Inner volume of the box 70.8 l (it has been computed by subtracting: 0.5 litres for the speaker and 1.5 litres for the 7 inner reinforcements of 1.9x22.2x5).

• Tuning frequency=41 Hz.

• Inner diameter of the vent 9.4.

• Outer diameter of the vent 10.

• Length of the vent 9.3.

The Box

Notes:

1. The seven reinforcements have been placed in a way similar to the Cheap Trick.
2. I have fixed the front baffle with some screws in order to allow an easy remotion. In this way it is possible to change the speaker mounted with (at most) the substitution of the baffle itself.

First order high-pass filter for the Motorola KSN 1005:

Please take care of the phase-inverted connection. In this way, according to my ears, it sounds better, but feel free (and please let me know) if you find out a more satisfactory arrangement. I also suggest listening to the loudspeakers (after some hours of working) without the tweeters and only after this test deciding about the need of the tweeter.

How do they sound?

What can I say? I am not as experienced as to be able to give you the exact value (but WHO can?) of these two cheap and large objects. I like them very much. They are fast, detailed, able to give a good 3-d image, with very deep bass, and a lovely "voice". But the most important thing is that they let you experiment the magic of full range drivers without spending huge amounts of time and money.

For any questions and or suggestions please write to Giuseppe Pipitone

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