[Danny Richie]

Your measurements look a lot like those I have taken of them, except that the actual sensitivity is about 5db higher than your measurements show.

[Russell Dawkins]

I have just measured Neo3pdr with and without back cup from 1 meter on a 5'X7' baffle.  The red is with the cup.

I don't understand why there is such a divergence below 1.3 kHz. There is a difference of 10 dB throughout the region.

 Is the volume contained by the back cup small enough to create a low Q resonance falling between 1.5 and 5 k, thus boosting the output in that zone, or what else explains the increased output there? That's pretty large difference.

[johnk...]

They were purchased from GR Research just a few weeks ago.  Yes there is a price to pay in sensitivity.  I am intrigued by their use as dipoles and hope that they will impart some of this rear tweeter effect.

Maybe I'll pich up a new sample fromt Parts Express and see how they measure.

[pixelpusher]

Your measurements look a lot like those I have taken of them, except that the actual sensitivity is about 5db higher than your measurements show.

My measurements are not calibrated for absolute SPL.  I suspect they are a bit low.

[Danny Richie]

I took some measurements for you guys yesterday (tried to anyway) with and without the back cup. But I really didn't have a baffle to mount them to. So I quickly mounted it on a sheet of cardboard, just surface mounting it, and it effected the response more than I though it would.

I'll give it another shot the next time I get a chance.

[pixelpusher]

Today I measured the Neo3pdr on my 17.5"X48" dipole baffle.  This baffle seems to exaggerate the lower resonance. The blue line is the 5'X7' baffle.  The green is the 17.5"X48" baffle.

At 45 degrees it flattens out.  Interestingly at 60 degrees the Neo3pdr is pretty flat from 1k to 10k. (purple line below)

[konut]

Hi pixelpusher. Are those last measurements with the cup on, or off?

[pixelpusher]

Hi pixelpusher. Are those last measurements with the cup on, or off?

off

[johnk...]

Based on your plots it looks like you are using a 5msec window which make me wonder about the frequency resolution in the area of the resonance. Still, your measurements are starting to look more like mine. Looks like the tweeter is very sensitive to baffle loading in dipole mode. Not a surprise for a low mass film tweeter.

[konut]

If one were to use the NEO3pdr in dipole mode, would I be correct in assuming that, if it was mounted in its own baffle, the size of the baffle would determine the lowest possible useable frequency before cancellation would occur? IOW, for eaxmple, a higher crossover would allow a smaller baffle?

[pixelpusher]

Hi,
  Just thought I'd share this latest measurement of the Neo3pdr in a shallow (1 inch deep) waveguide.  Looks like a bit of an improvement over the flush mount measurement and allows for alignment to the midrange. Red is with waveguide, green is the flush mount plate. The waveguide is a crude attempt made with modeling clay.