[dayneger]

I was wondering whether there's more data available for the "GR Neo 3 with Waveguide & Back Cup" DIY kit?

Specifically interested in the horizontal and vertical off-axis charts, sensitivity, power handling, etc.

Also, since the DIY perspective isn't necessarily depth-limited for the cone time alignment, was there a deeper wave with even better performance?  Possibly available for DIY printing, if it didn't make sense to offer it yourself?

Apologies if the above was posted elsewhere already and I missed it.  Thanks!

[Hobbsmeerkat]

To get an idea of it's overall performance you can also check out the NX-Bravo measurements.

Here are some raw responses when in a 8" wide baffle:

On Axis (Red is with the cup installed)


Horizontal axis up to 40 degrees


I currently have plans for a 1" deep version (vs 0.8725" deep) but I haven't had an opportunity to print it out yet or do any testing to see how much different the response might be.
I don't know if I would go much deeper than 1.25" as it might cause cancellation issues. At which point the waveguide would really need to get larger than the current faceplate size would allow.

Sensitivity is right around 92 on the low end (900-1000Hz), but if you cross around 1500-1800Hz, you can get it flat to ~95dB without too much trouble.
Power handling will really depend on how/where you cross it over, and your crossover slope, but its low-end response can also be influenced by waveguide wall thickness, baffle width etc which will really determine the crossover you need.

With the NX-Bravo, we've got it crossed at ~1000Hz with a 3rd-order slope so it has roughly the same ~700Hz -15dB point as the NX-studio, so it can handle quite a lot of power without any issues. (We have yet to burn one up) the woofer will likely run out of x-max before you fry the tweeter.
The rest of the NX-kits have use a 2nd-order slope, crossing around the 1500-1600Hz range

Danny decided against allowing customers to print off their own waveguides.

[dayneger]

Thanks so much for posting the additional information, Hobbs!

I'm not particularly experienced at looking at these responses, but it's interesting to see the off-axis diverge a little, reconverge around 1700 Hz or so, then diverge more rapidly. 

Is it typical for a planar magnetic tweeter to fall off more rapidly off axis than, say, a regular dome tweeter?  Is that driven by the size of the diaphragm?

However, being able to cross so low is quite intriguing.  Could this actually pair well with a high-efficiency 12" mid/woofer (possibly Dayton PA310 or SB 12OB350), assuming an active crossover and subs below?

[Hobbsmeerkat]

The bunching up at 2700Hz is due to the 8" wide baffle.
The 7.5" of the final cabinet pushed the bunching up around 3000Hz the size of the round over you use also has an effect, the larger the round over the less pronounced it is.
The 8" baffle I tests either had 3/8" or 1/2" and the first pair we built out used 3/4" 2nd pair was 1/2" so it stands out a little more.
The only means to avoid it would be to have a baffle that continuously curves away from the driver.

Yes, a typical dome tweeter is a 1" circle which will have a consistent radiation while while ribbons and planars will depend on the shape and area of the playing surface.
the thick yarn added to the outside rows improves the horizontal axis with minimal change to the overall frequency response. but being taller than wider means the vertical response will suffer by comparison, and the taller the driver is the worse the vertical response becomes.

As for pairing this driver to a 12", it would work better than most drivers tend to be limited to 1500-2000Hz. They begin to beam starting around 600-700Hz, so for a smooth horizontal response you will need a much larger horn/waveguide, much like this:



Which when made from MDF, would measure like this:

This would allow you to cross to a 12" woofer at the frequency ranges where it begins to beam, while still using a small enough cap in a 2nd order network that will easily protect the tweeter even at such low frequencies.

[dayneger]

My bad, you're absolutely right--the bunching is around 2700 Hz.  Misread the graph. 

I'm not familiar with the yarns you mentioned, but presumably they essentially reduce the open width of the diaphragm, making wider directivity easier to achieve in a given amount of space?

It's great to see the return of the giant donut!  I thought it looked pretty cool... reminded me of some of Joseph Crowe's beautifully machined horns.  Not that I pretend to understand when and why a waveguide is considered a horn, but from what I gather the combination of directivity and coupling efficiency can be very interesting.

I realize that suggesting a transition to a 12" driver was a stretch; yet have also read about OB implementations of a dome tweeter in a waveguide being paired with decent if imperfect success even to a 15" driver (aided by DSP IIR and FIR filters). 

A 12" driver has the Sd of about 3.7x GR165s.  A 10" driver has 2.5x 165s, and for the bold and brave, a 15" has 6x 165s.  If they're light, high-efficiency cones that could be fun to experiment with.