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Multi-Way Conventional loudspeakers with crossovers

Designing a Crossover for a Mini Two Way, How Important is Driver Phase Response?
Designing a Crossover for a Mini Two Way, How Important is Driver Phase Response?
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Old 23rd September 2016, 03:11 AM   #11
MickyG is offline MickyG  Australia
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Join Date: May 2016
Location: Melbourne
While this isn't an update to the original design of the Peerless/Northcreek system I'd specifically mentioned in the opening post, it is somewhat related.

I built 4 cabinets with the intention of doing 2 as described above, and the other two as rear surround duty, with two very cheap drivers: the Dayton shielded paper cone 5.25" woofers and the old shielded "Silky" tweeter. Both were purchased when shielding was a good idea. So they're VERY old but hadn't been touched so are "new" to me.

A few months in and the Dayton Budget drivers are now happily in my system as rear channels, just like I'd planned.

Funny thing about how I progressed with my questions about modelling vs real measurements and phase relationships. Here's what I settled on for the crossovers for the DBP.

First, the as designed one from Wayne Jaeschke (with some nice attention to the peaking on the driver):
dbpxo.jpg

My modified version:
DBP Crossover layout.jpg

Simulated response using PCD 7.
Normal:
DBP Modified.gif

Reversed Tweeter:
Dayton DBP Smaller Sealed (reversed tweet).gif

Measured response using REW.
Normal:
Measured Response.jpg

Reversed Tweeter:
Measured Response Tweeter Reversed.jpg

Bear in mind, the imported response curve was using the measured response with a (probably very poorly done) simulated low end response below about 400hz.

The crossover:
IMG_20160913_220220.jpg

And the two speakers, completed(ish):
IMG_20160917_075347.jpg

Point? The reverse null is pretty extreme and the overall response, while a bit lumpy and certainly not the best shape, is actually not too bad.

Click the image to open in full size.
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Old 14th November 2017, 02:34 AM   #12
MickyG is offline MickyG  Australia
diyAudio Member
 
Join Date: May 2016
Location: Melbourne
I never did update this little project of mine. Might even want to change the title (if that's possible).

I officially finished up the rear surrounds last night with the completion of the last bit: grills. I'd been using them without any protection for over a year now but having children around and the proximity of the speakers to the corners of my couch, meant I needed to address this last little detail.

Some of the missing pictures from the last post till now, starting with the "completed" mini speakers in the state they'e been in for about a year:

IMG_20170226_175607.jpg

IMG_20161203_212859.jpg

I worked quite a lot on the finish, starting with an overall sanding sealer coating, followed by water based white primer, then some outdoor black fence paint in a nice satin sheen. A word of advice on the sanding sealer, it's really only a good idea on the cut surfaces of the MDF. Anywhere else and it was just too waxy, greasy, and meant the paint was peeling off constantly. The white was also something I think I'll skip next time. I just don't know how necessary it was.

The side "cheeks" are Ikea Birch chopping boards that I attempted to cut down to a workable size. I was limited to what I could use, based on the direction I wanted the grain to run (front to back) and the width of the boards. It's certainly different.

And here's a few in progress shots of the grills:
IMG_20171105_184259.jpg

That ridiculous shape is to allow for the offset of the woofer and tweeter and the middle bit to provide some strength. The frame is 6mm MDF and there's a 45 degree chamfer around the edges of every surface, about half way down the edge. Still, I'm guessing there's a fair bit of reflection that will be happening with these openings. Might experiment with some felt later on. The pic shows two grills, as I cut one and then used a heavy top bearing straight cutter in the router to make a duplicate.

Test fitting:
IMG_20171105_205020.jpg

Painted, and ready for fabric. I marked out an edge with masking tape, applied some hot melt glue in a somewhat even pattern, removed the tape and then went on to applying the fabric with the help of an iron.
IMG_20171113_203842.jpg

IMG_20171113_211920.jpg

All finished:

IMG_20171113_212658.jpg

IMG_20171113_212652.jpg

Last edited by MickyG; 14th November 2017 at 02:54 AM. Reason: Images didn't load.
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