Fullrange + waveguide experiment, and introducing the ugliest driver in the world

[chazdrumzalot]

So my GRS FR-8 drivers and waveguides arrived yesterday. After removing the dustcaps and a quick trip the the hardware store, I've come up with what you see below. Yeah...not pretty. I'm going to burn them in a bit and try them on an OB just for the experience, but without testing equipment I'm pretty much just driving in the dark with no lights on. The inspiration for this frankenstein of a driver was this.

[mashaffer]

Isn't all that added mass going to have a wee bit of effect on the TS params?

[chazdrumzalot]

No added mass, it's acting as a phase plug. The reduction of Mms by removing the dustcap will undoubtedly have an effect though. How much I can't say; like I said, I'm in the dark here!

[vacuphile]

Hi Chazdrumzalot,

I hope you are in a position to do some acoustic measurements on this setup, which would interest me a lot.

It could lead to a lot of diffraction ripple on axis, but then again, it might not and it might be great,

vac

[ra7]

Do you have a driver at the throat of the waveguide? Or is the waveguide just a phase plug?

Me and my friend were talking about such an experiment with a front loaded horn for a big woofer and a smaller horn for a compression driver mounted coaxially. Hard to pull off though.

[auplater]

Why mess with some disaster like this?


when it's easy to get this,open baffle, w/o all the fuss?


grn 0
red 15
purple 30
blue 45
orng 60

[vacuphile]

Why would you build an OB if you can fold that baffle into an enclosure and get something like this:

zelfb2.jpg

Measured at 0-45-90 degrees

Seems flatter on a 5 dB scale than the OB at a 15 dB scale.

[MisterTwister]

I had similar project, except a tweeter was attached to a horn.
Imageshack - img0462pz4.jpg
Imageshack - cimg1240qs0.jpg
Imageshack - h511omnisb5.gif

[auplater]

Well... those traces were in room 15 feet distance... here's near field set up "flat"
sounds WAY TOO BRITE!!




and 15 feet away, setup "FLAT"



funny how smoothing and setup can influence a plot, eh? Not to mention test conditions??

[chazdrumzalot]

Originally Posted by auplater

Why mess with some disaster like this?

when it's easy to get this,open baffle, w/o all the fuss?

Well, I don't know what project that is, but I would assume it's more expensive and involved. I'm also hoping to learn something from messing around with this! But I don't want to waste too much money learning and experimenting, hence the cheap driver. I wouldn't be doing this if I were after a super-flat response.

Mistertwister, your project looks interesting. The next logical step with this is to install a helper tweeter inside the waveguide. Do you document your project anywhere?