Synergy horn build

[Bergarth]

Love to have something like this for theater application! OMG great work

[Patrick Bateman]

One of the reasons you might opt for a compression driver is because the polars may be more consistent. This is because waveguides need a very specific wavefront to produce consistent polars, and ideally the waveguide and the compression driver should be designed as a single unit.

This isn't to discourage you from using domes; they have advantages too. But if you want insanely consistent polars, take a look at what JBL achieves with the 2408H-1 combined with the PT waveguides. Here's what I measured:



Note how consistent it is.

[jhollander]

Patrick/ John I enjoy your post and projects over at diyaudio. I like that plot. I've got a project for a budget pro 2 way and need to look at how JBL is getting that response. So where did the PT clone come from?

Do you think the polar is more the waveguide than the CD?

[shrub0]

Should I use silicone caulk or epoxy to glue the pvc to wood and pvc to the midrange? Also how was the woofer enclosure volume calculated? I am planning on adding an inch or so of depth and height for an easier fit of the port. 

[jhollander]

I used Loctite power grab tube adhesive.  Silicone is to flexible and the epoxy is to runny.  I calculated the volume in AutoCAD.  I fit the port before adding the top panel.

[jhollander]

This is the updated x-o after Fort Wayne

[shrub0]

Nice John the new frequency response looks smooth! I'm just about to start my clone of your synergy horn. I am using the same tweeter and mid, but decided to try the exodus 6.5" woofer.

Here are the specs:
Qms: 6.7
Qes: .55
Fs: 53 Hz
Vas: 7.23 L
Xmax: 12 mm
Sd: 127 cm^2
Re: 3.81 Ohm
Le: .42 mH

Would you suggest any modifications to the woofer crossover?

[jhollander]

Mark, the Anarchy pair gains about 1 dB of sensitivity over the Dayton DCS165, but the F3 goes from 35 to 44. My thought is to leave the x-o alone and see if the extra sensitivity helps with the bass response.

I'd consider shortening the port to get the bump in the bass response, but in this build the port is picking up some length gain from how close it is to the back of the box. If you intend to change the box depth the port may already be short enough.

[shrub0]

John,
Some questions for you.
What is the part used to mount the woofer ports? What size hangar bolts do you recommend? What is the size of the crossover board?
Sorry to bombard you with details, but I'm building this with my son and want to appear like I know what i'm doing.

[shrub0]

Is this the pvc mounting flange?
https://www.menards.com/main/plumbin...4449120294.htm

[jhollander]

Mark, the pvc port mounting blocks are 1/2 inch MDF with a hole drilled to fit the outside of the PVC pipe. I cut 1 1/2 inch lengths of 2 inch pipe and glued the pipe to the MDF with yellow glue. If the holes in the MDF are two big you might have to use epoxy to get it to dry/ clue in a reasonable time.

The hanger bolts are from bolt depot #8-32 x 1" their part number 13584

I don't recall the board size for the x-o it's close to 9 by 5.5 inches but I can check my other computer Tuesday.

Good luck

[jhollander]

X-o board is 9.25" x 5.5"

[shrub0]

Thanks for the info John. Since I plan to use 1/2" baltic birch plywood are the hanger bolts necessary? Maybe some nice wood screws would be ok.

[jhollander]

Mark, the space is so tight it's hard to get anything in there to attach the drivers. It might be possible for the mid but there's no way for the woofers.

[shrub0]

John, a depth of 2.5" for the midrange enclosure doesn't leave much breathing room for the pole vent. Would 3" be better or would this adversely effect the crossover and frequency response?