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Need waveguide assistance
So I have 4 Buy Other Sound Equipment 2" compression drivers. They had a funky waveguide attachment that combined them into a "line array" horn. I'd like to be able to use them, but it would require some sorta mounting system/face plate. Not sure if they should be used as straight up dome tweeter style or waveguided. Here are some pics of the units. Only did a preliminary measure with the first part of the OE guide as it's what holds the dome assy in place.
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First thought is to modify the first part that holds the dome in place, then somehow adapt that to a waveguide as it has a phase plug deal in it. Then I thought if someone wanted to print something to adapt straight to a waveguide, might be a fun project for them. Then there's just make a faceplate for dome tweeter action. What would you do?
If I'm looking at the photos correctly that is a bit of an unconventional compression driver. Usually the dome is in the other way around, with the compression/phase plug bit on the back side like this:
It looks like the "compression" part is happening in that block that is attached to the dome. How big is the throat openning on it? If it's 1", can you not just screw this into a "bolt on" horn or waveguide with 1" throat?
^^ yup that's what I would do. Mount the compression horn assembly with the phase plug, screen and foam gasket directly to a traditional horn. The throat adapter piece with the waveguide will have some resonance that may limit the usable FR range. What's the diameter at the screen?
It's standard. Looks like a dome tweeter. That front piece has the what I'm calling the phase plug. Has little slits around the edges and the three towards the top of the dome.
The opening is 1", so yeah I looked at horns. Kinda didn't want that, waveguide is more intriguing or just dome. But why neck it down to 1" when it's a 2" dome?
That’s how compression drivers work. A large surface area gets “compressed” down to a smaller exit. Yes, the front neck is part of the driver construction, usually the dome is “inverted” arrangement so there’s less of a protruding neck, see the first diagram above that I posted.
What you have would commonly be referred to as a 1” compression driver, they’re sized based on the throat exit for mating up with horns with the same size opening.
Try it with any horn or waveguide you like with 1” throat and flat bolt-on mounting surface.
The necked down is part of the driver design. IIRC you control the volume of air in front of the diaphragm for frequency control. I did a bunch of this modeling in Horn Response but don't remember the details. So the throat adapter (phase plug piece) is part of the driver design.
Dig, guess I'll play around with it and see where it goes. Guess I kinda want to uncompressionize it. Thanks for all that👍🏻
Hard domes typically need a phase plug, so I'd start there. Would be fun to 3-D print something.
Kinda what I thought and threw it out here. The mids that were with these ended up being 18Sound units. 🤘🏼
Those are sweet.
The other FR on that graph above is those. They're definitely pretty nifty! Wish they were a bit more woofer than midbass.
https://www.eighteensound.it/en/products/lf-driver/8-0/16/8nmb750
Nice!
InDIYana Event Website
Wolfy's Photobucket
To update this, Ken Rhodes hooked me up up with an adapter. I sketched up what I needed and he turned that into a printed part. I cut the part in half and basically clamped the compression driver and horn together, easy peasy. Took a quick on axis HD measurement.
I have four of these drivers, two measure like the first plot, the others are like the second. 🤷🏼♂️ QC issues, probably, I chose the latter two. Just for the fact of a bit lower HD towards cut off, not sure yet where they'll even be crossing at.
Go Ken go!