Dayton Audio ND65-8 Actual vs Advertised

[joshk03]

Well I won't be digging a hole in my yard, but I did take a second measurement with the mic turned around and the speaker on the other side. I call them Play East and Play West. My tripod was 58" high.

 

[Winkleswizard]

Yes, it does look as though your lower frequency notches are due to environment rather than design. The ones around 8K and 10k bear some further investigation as they did not shift.

Btw, when you put a driver in enclosure that is not a larger flat baffle, you cannot expect as low an f3 as one that is.

Ww

 

[Winkleswizard]

Lol, knew the higher frequency bumps looked familiar. They are the breakup charecteristic of the ND-65. You could add a passive filter to dampen...

Ww

 

[joshk03]

Here is the REW/UMIK data from both outside and in the attic. I only understand SPL, but phase has me a bit concerned too. Any conclusions the forum members can spot would be appreciated.
CS65 and Bose data via UMIK.zip

Now that the version2 enclosure is dry enough for assembly I have a complete pair of speakers. I am listening to them now. Aside from needing a sub, they sound good.

 

[Winkleswizard]

Will take a look when I get in front of a real computer later. What is your concern about phase? Not much you can do with a full range speaker...

Ww

 

[joshk03]

I just didn't like to see phase shift, but it could be measurement errors since there is no reference.

I realized you guys might be curious to see what I have been messing with. I'm a bit shy to show my unfinished speakers, but I will share the CAD renderings. Hopefully most people that participated are still following this thread. Enjoy!

 

[KEW]

It'll be interesting to see if the new enclosure will change the 8k-10k swing.

That is pretty cool looking!
Is the hole in top for a mount? Wondering how you are going to hold it!

 

[joshk03]

Oh, the mount is the coolest. I use a round in-wall rated cable that feeds tightly through that hole. Then it just hangs from the ceiling. All I need to do is drill a small 1/4" hole into my ceiling and run the cable to the attic and go tie a knot in it. Then I can come down and stand on a ladder and rotate the cable to aim the speaker. When I move out of this house I just have a tiny hole to patch for each speaker. And hanging it like this gives me full control of locating them anywhere I want. Horizontally or vertically.
The air-leak that I spoke of for equalizing atmospheric pressure changes is actually inside the cord. If I blow into the end of the cable, it almost feels blocked but does pass air slowly. it's like a tiny long snorkel.
If all goes well I will make a set to use on my new Denon AVR.

 

[Winkleswizard]

Cool enclosure design!

Cannot open your files, but need to update my REW.

Will try again after Cavs game...

Ww

 

[joshk03]

And it gets better. Since I know the exact center-of-gravity, I can hang it at any angle! In the pictures I posted above, the speaker hangs at an exact 10 degree angle. I can change it to anything I want and instantly re-calculate the entire model. Here is a 45 degree angle for example. Sorry, the model doesn't actually tilt itself on screen, but you can see the hole has moved and still aims at the center-of-gravity.

 

[KEW]

How did you determine the CG for the speaker or is it negligible (as long as you get close)?

 

[joshk03]

It's pretty easy.
Step 1) Be so obsessed with designing things you buy really expensive software.
Step 2) Click the Mass Properties button.

That pink point in the center is the magic spot.

 

[KEW]

It's pretty easy.
Step 1) Be so obsessed with designing things you buy really expensive software.
Step 2) Click the Mass Properties button.

That pink point in the center is the magic spot.

Unless there is a place where you specify the density of the various materials of the speaker as well as the enclosure, the software will assume everything has the same density and calculate the CG based on that assumption! I doubt that would throw things by much unless the speaker frame is made of plastic, and even then it may not be an issue.
What software are you using?
I admire your skill in generating an object such as this. Nicely done!
What are you using for the form for the concrete? Are you milling it with CNC or using a 3D digital printer or other?

 

[joshk03]

Yea, I defined densities, so it's quite accurate. I use Solidworks 2016. It could be perfectly accurate if cement wasn't so darn variable depending on the type and mix. But I took measurements along the way on version2 and now can work backwards to perfect my cement density in the Solidworks material library.
I use a 3D printer to make a hollow shell, then I just pour in the cement mix. Then I pull a vacuum in my vacuum chamber to remove air bubbles and ensure maximum density.

 

[joshk03]

I guess I can post some unfinished pics. If these were the final ones they would get a sanding and painting.

 

[KEW]

Wow! You have a pretty advanced setup for custom fabrications (and the know-how to use it)!
How did the FR graph turn out for Rev 2?

 

[joshk03]

I haven't done the FR measurements on version2 yet. I thought I would play them for a day or two so they burn-in a bit. I'm not sure how much difference that makes, but I am enjoying the tunes. Maybe tonight I will take it outside for a FR measurement.

 

[joshk03]

And yea, I have a pretty advanced setup I am always designing and building something, and I am good at it.
I've wanted a waterjet CNC since before Wazer was ever conceived on Kickstarter. When I saw their design on their launch video, I figured I could build one bigger and better than they could, so I did. They haven't even shipped their kickstarter promises as of today. I was up and running before Christmas last year! haha. And am using a computer-controlled sand system. The gravity-feed idea they use always plugged when the cutting head shut off to move across the work piece. I think they will be limited to slower cutting speeds than mine to prevent their plugging issue.

 

[Winkleswizard]

I updated REW and only get to see part of your data. Not sure what is up, but prob not worth chasing just yet.

Suggest posting a jpeg when you get a chance...

Ww

 

[joshk03]

If you run the REW update check from within the software it will update to my version, "REW V5.19 Beta 9". That should open them fine.