[Danny Richie]

As mentioned earlier I am working on a new planar magnetic tweeter that uses the same frame as the previous BG Neo 3.

I am also working on a new wave guide to go with it.

So here are a few pics of the prototype that was 3D printed. This one was printed at a low resolution. I also did a little sanding on it.



The depth puts the center of the tweeter diaphragm back 1.5" from the front baffle.



And as you can see it is only open for the two center rows of magnets.

Here is the back side.



And with a rear cup on it.



Here it is with the tweeter removed. Note the two spaces to each side are a cupped out area filled with cotton. This is to absorb any reflection and add damping.



And with the cotton removed to expose the open area.



And how does it measure?    This is with the wave guide mounted in a small baffle the size of a mini-monitor and with an open back.



That is the smoothest response I have ever measured from a BG tweeter. I am using a BG tweeter for testing.

And here it is with the back cup on it.



Here is an overlay of the two.   



Guys, this is a 5db scale! These babies are smooth as glass. 

[DeeJayBump]

Danny-

Why is the tweeter restricted to only two rows firing through the waveguide?

Are you designing a tweet half the width of the current Neo3, and the wave-guide is forward-looking with that in mind, or is there some other sonic reason for restricting the radiation pattern?

Just curious.

[Jonathon Janusz]

DJB, if I remember what I read on the datasheet for the neo-3 PDR version correctly, the outer two rows are already damped in output to some amount inside the driver enclosure as manufactured.  I'm guessing this is just being more aggressive with the same working theory of the design?

Danny, any off axis (vertical and horizontal) graphs yet?  For an open baffle implementation, it might be neat to have a similar cup made to the front that would incorporate whatever waveguide would be needed for the back, designing the spacing left between them to flush mount the back cup to the back of a standard thickness (0.75"?  1.5"?) baffle, thus avoiding the need for the custom CNC machining on the baffles needed on some of the prior OB designs?

You do know that with measurements like these, the neo-3 as-is is going to be a tough act to follow with a new driver.    Without asking too much on the technical details, what general points are you looking to address or improve upon on the neo3 with your new design?  I'm just curious to know what the theoretical driver properties would be for a driver that does exactly what you like, without compromises?

[Danny Richie]

Danny-

Why is the tweeter restricted to only two rows firing through the waveguide?

Are you designing a tweet half the width of the current Neo3, and the wave-guide is forward-looking with that in mind, or is there some other sonic reason for restricting the radiation pattern?

Just curious.

The pdr version of the Neo 3 that we have all been using has already been restricted this way. The outer rows are blocked off with a very dense felt.

And reducing the width of the playing surface was done (in the pdr version) to improve horizontal dispersion. So it doesn't restrict the radiation pattern. It opens it up.

[mlundy57]

What do they look like above 10k?

[DaveC113]

Looks good, but I'd look into an OS transition at the throat.  Maybe just use these if the dimensions work out: 

http://www.diysoundgroup.com/plastic-seos-12/seosraal.html

Manufacturing something like this in small quantities is an issue wrt cost...

[Danny Richie]

What do they look like above 10k?

They look good up there. Dang I cropped it too far and didn't notice when I saved them. I'll go back and pull those up again and get a response to 20kHz.

Looks like I did not save them as a file. I'll have to re-shoot them. 

[Captainhemo]

The response looks great Danny
What did the diameter of the  faceplate come out  to ?

jay

[studley]

"That is the smoothest response I have ever measured from a BG tweeter. I am using a BG tweeter for testing."

Danny, is it  also better than the performance of the tweeter when installed in a milled out waveguide as in the NX-otica?

[bdp24]

Parts Express is showing at T.H.E. Show in Irvine this weekend, and announced they are the sole U.S. distributor for BG products. Also that a few more models will be added to the three currently available NEO drivers (models 3, 8, and 10), perhaps 8S and 8PDR.

[Jonathon Janusz]

Thanks for that update from T.H.E. Show.  Regardless of performance, that neatly answers well enough the last part of my earlier question.  Great to see the BG products back; too bad about the exclusivity contract. 

It would still be cool to see some more graphs if you've got time, Danny.

[studley]

Well that might mean that Danny can't buy direct from the new owner of BG but perhaps he will be able to negotiate a wholesale deal with PE?

[Danny Richie]

"That is the smoothest response I have ever measured from a BG tweeter. I am using a BG tweeter for testing."

Danny, is it  also better than the performance of the tweeter when installed in a milled out waveguide as in the NX-otica?

I wouldn't say the performance is better or it will sound better, but the new one is a little smoother.

[Danny Richie]

Well that might mean that Danny can't buy direct from the new owner of BG but perhaps he will be able to negotiate a wholesale deal with PE?

The only driver I was using in our products was the tweeter and I am working on an improved replacement for it already. So no worries there. And right now I don't think they have any face plates in for the tweeters, but maybe they will be able to get some pretty soon. So anyone wanting to build out any of our older designs that used the Neo 3 pdr with face plates may be able to do so.

The Neo 8's are really only usable for line source applications and even then I had a custom version made for those applications. So I am not really interested in them right now.

The Neo 10's are great drivers but really difficult to work with and don't come with any face plates. So I never implemented them into a kit. I stocked them for years, but hardly sold many of them. Most of my sales of them were to other dealers. So I am not too concerned about them either.

[Captainhemo]

I wouldn't say the performance is better or it will sound better, but the new one is a little smoother.

I'm assuming the  smoother measuring response is due to the narrower opening covering the outer rows and the  addition of the extra damping ?  It'd be interesting to see a measurement  without the cotton

jay

[Danny Richie]

I'm assuming the  smoother measuring response is due to the narrower opening covering the outer rows and the  addition of the extra damping ?  It'd be interesting to see a measurement  without the cotton

jay

Right now all my test tweeters are pdr versions or custom versions. So they all have the two outer rows damped out already. So the cotton is having no effect on them.

[Danny Richie]

New measurements with the graph set to full range.

The open backed version.



Sealed back version.



And here is a horizontal off axis measurement.



The dropping out area in the 5 to 6kHz range was actually a result of the small mini-monitor sized baffle I was measuring them on. So it was open baffle with not much baffle. Otherwise that area would likely remain flat. I tested it some with cardboard taped to the side and it confirmed it.

[Danny Richie]

I also sanded the edges out a little more and it improved the off axis response. Looks good too.

[Folsom]

Danny, I think this is a really neat direction to head. New products keep things fresh. It's simply different from everything else.

There's not a ton of planar type tweeters uses them yet, either.

[Jonathon Janusz]

Danny, that horizontal off axis looks like it stays pretty consistent to 40 degrees (the blue line, right?), making the overall radiation pattern target about 90 degrees, am I right?  Is it this good in the vertical as well?

Am I reading things incorrectly, or will this allow you to cross the tweeters over at around 1K whether OB or enclosed?  I see you have a good amount of flat output in OB down to 700Hz before it drops off, but enclosed it drops hard right at 1K.

I just got to thinking about production on these parts.  Considering the cost challenges brought up earlier of doing molds for a production run of plastic parts, would there be any sonic detriment to having them CNC machined from aluminum?  If you are rapid prototyping with 3D printing, the jump to machine coding for a CNC mill isn't a big stretch relatively speaking, might eliminate some of the challenges in higher startup cost offshore production, and speed up time to market to get your customers into the new kits sooner.