S17 - Constant Directivity Dipoles

While the S16 provides smooth directivity, they are lacking rear radiation. In this iteration I want real dipole radiation front and back, and uniform to very high frequencies. This can only be done with extemely short front-to-back distance.


The "tweeters" used areTandBand 3" full-range. They allow three things to happen:

- Dipole peak to occur very high in the frequency range, allowing constant directivity
- Very open rear chamber for good rear frequency response
- Low crossover frequency.


The directivity plot was measured indoor so there is room for improvement when I take it for outside measurement later.

Follow the discussion at DIYAudio.

These are respectable uniform dipolar radiation, impossible to achieve with traditional methods like back to back dome tweeters.

The tradeoff is high frequency resolution of the 3" fullrange drivers.


Paul Spencer said...

Looks like a very good plot! It would be interesting to try a super tweeter, perhaps even with a first order passive. The plot suggests this speaker could use a little room treatment that absorbs more below 2k, could be a nice little project to try.

ttan98 said...


Gainphile can please direct me to the webisite where I can get a copy of the Sonogram software that measures drivers directivity, the software that you use. Send me the info to yttean98@hotmail.com. Thanks

Anonymous said...

Gainphile what was your crossover rate from 8in to 3in? assume somewhere around 600Hz?
Did you not think to try say MTM 3in with supertweeter.
Aesthetics can be taken care of by visually extending baffle width of the top section to your desired 30cm with a frame with acoustically transparent fabrics, whilst underneath it would look similar to latest NaO (i.e. gradually narrowing baffle).
What do you think?