dipole configuration

[hobby1]

gentlemen,

i have a question about the best way to go........
the drawning below illustrate my question, it's 2 dipole panel configurations and ,say the speakers are some 5" or 6.5" use in the mid from 80 to 2000hz for exemple.
according to you,which is better,if there's one?
in advance thank you for reply
greetings
fred

[Rudolf]

According to Linkwitz the alternating mounting should result in less distortion. If your upper limit were 1000 Hz, I would wholeheartedly suggest the right version.
Between 1-2 kHz drivers of the proposed size tend to develop a big difference between front and rear radiation. Have a look at a post (#10) I did recently at the audiocircle OB forum:
http://www.audiocircle.com/circles/i...topic=36331.10

So with the left version you probably would get some linear radiation to the front and a messed up radiation in the back, while the right version would result in some mix, but a better symmetry between front and rear.

Conclusion: If your dipole will be in a “live” room, where much of the radiation to the rear is reflected back into the room, choose the right version. If it is a “dead” room or if you are going to attenuate the back radiation, then the left version might be more appropriate.

[hobby1]

thanks for your reply rudolf !
do you think translate your website in english? it seems it can be very interesting !!!
To return to the subject in the "B" config ,is there any risk with drivers spacing?

[Rudolf]

Driver spacing! I completely forgot to look at that.
You will get into trouble with it.

For 2 kHz wavelenght is < 17 cm. Shortest driver spacing will be the same magnitude. So you will suffer strong interference and SPL lobing.

Is there any reason why you need so many midrange drivers?
If you need those drivers for bass, you should limit them to max. 500 Hz and go with one driver up from there.

[hobby1]

the only reason is that i have these speaker and can have a lot of,first it was for studying,experiment, and now i know that they are best in open or dipole config but these are carspeaker with limited perf(low Xmax,high fr and qt about 0.5),so i got to find the best compromise to use them.....
thank for your help!

[Javachip]

In the "B" (right) configuration, am I correct in assuming that you would need to wire the front-firing drivers out-of-phase with the rear-firing drivers (reverse polarity) in order to avoid cancellation?

[hobby1]

hi
javachip,yes the rear speaker are out of phase in the B config
and since i post i have made this prototype make some measurements,but in room , and it's seems that lobing are not really formed to about 1.2khz on a 80X28 cm panel but difficult to interpret.
distortion are clearly lowered but FR need to be strongly equalised ......normal!!
in term of polar response with this panel can i consider to have a dipolar response from low to mid or a "something like" ?
greets
fred

[johninCR]

For the B config, I think it might be better to put the front firing drivers in the center next to each other. That will put the highest frequencies with their centers closest together, and likely better HF performance than with those centers further apart.

[hobby1]

hi,
johnincr, i have try the config that you propose but it don't seems to give a better result with my measurement setup (in room)
finally i conclude that i can use this speaker in dipole to has about 1khz.
what do you think about use 2 aura NSW2 (1 front 1rear) to complete my config ?