Waveguide profile ideas for group experiment

[Pete Schumacher]

Re: Waveguide profile ideas for group experiment

I thought you may have had something specific in mind. Keeping it proportional brings it up to about 6" in the small dimension and 8" in the large. That will be a nice size and hopefully maintains most of the performance of the round ones you tested. I'm curious if it is the mouth size/shape that has the most influence on the transfer function or the depth.

I'm glad the profile you described is showing the most promise, because as of right now, that is the only profile I can generate with the elliptical mouth. I'm on vacation for a bit here, so I won't be able to get these going for a while. In the meantime, I hope your wrists start feeling better.

Dan

Feels like one of D,Rose's cabinet clamps is trying to show me how flat it can make my left wrist at the moment. One hand typing sucks.

[Pete Schumacher]

Re: Waveguide profile ideas for group experiment

Here's the shallower of the two newest Dan sent. Conical with a medium roundover??? 0 20 45

Not bad at all

[DanP]

Re: Waveguide profile ideas for group experiment

Those most recent ones are still elliptical, they just begin flaring right at the throat opening instead of coming straight out like the first ones I sent. This shape was a recommendation by Phil Bamberg after seeing the first 6 at InDIYana. To me, this one looks like the best one so far. Am I reading the graph right that there is still 10dB of boost at 1kHz? Tweeter still RS28F?

Dan

[critofur]

Re: Waveguide profile ideas for group experiment

Could we have a larger picture of the measurement, and, is there a CAD file available for that profile? I'd like to cut some baffles with it soon and try 'em out with some other tweeters too. :D (I'd like to see how it works on the XT25SC90-04, among others...)

[Pete Schumacher]

Re: Waveguide profile ideas for group experiment

Could we have a larger picture of the measurement, and, is there a CAD file available for that profile? I'd like to cut some baffles with it soon and try 'em out with some other tweeters too. :D (I'd like to see how it works on the XT25SC90-04, among others...)

I wish they'd allow for larger resolution PNG files. Check the post above for the larger copy.

[Pete Schumacher]

Re: Waveguide profile ideas for group experiment

Those most recent ones are still elliptical, they just begin flaring right at the throat opening instead of coming straight out like the first ones I sent. This shape was a recommendation by Phil Bamberg after seeing the first 6 at InDIYana. To me, this one looks like the best one so far. Am I reading the graph right that there is still 10dB of boost at 1kHz? Tweeter still RS28F?

Dan

I'll re-run the RS28F from the same distance to verify the total boost.

I do like the way this one looks.

[greywarden]

Re: Waveguide profile ideas for group experiment

Wow! Am I correct in seeing that close of a reponse from 0* to 45* off axis????

Is that horizontal or vertical, and with the waveguide does it make a difference?

[Pete Schumacher]

Re: Waveguide profile ideas for group experiment

Wow! Am I correct in seeing that close of a reponse from 0* to 45* off axis????

Is that horizontal or vertical, and with the waveguide does it make a difference?

Circular waveguide . . . so it makes no difference.

All from 1m away, plus or minus an inch or so.

[carlspeak]

Re: Waveguide profile ideas for group experiment

Here's the shallower of the two newest Dan sent. Conical with a medium roundover??? 0 20 45

Not bad at all

Pete: If I may troll a bit here with a couple questions.
1) The notes in the lower right of the HI graphic regarding HD "OK, OK, OK, etc." Did you add those? or, did HI include them automatically?
2) The off axis measurements relative to on axis are impressive. However, the significant fall off in overall response beyond 2 kHz doesn't seem impressive. Am I missing something?

[Pete Schumacher]

Re: Waveguide profile ideas for group experiment

Pete: If I may troll a bit here with a couple questions.
1) The notes in the lower right of the HI graphic regarding HD "OK, OK, OK, etc." Did you add those? or, did HI include them automatically?
2) The off axis measurements relative to on axis are impressive. However, the significant fall off in overall response beyond 2 kHz doesn't seem impressive. Am I missing something?

Holm added those. I'll have to look into what that refers to, but I think it just means I've included HD plots for each measurement.

That's not really a fall off above 2KHz, thats a gain relative to 20KHz as you go down in frequency.

When that curve is EQ'd back to flat with the HP function, the distortion levels down to 1KHz will be dramatically reduced compared to the naked RS28F. And you'll also notice that the response will remain the same as you move off axis, unlike the non-waveguide version.

[greywarden]

Re: Waveguide profile ideas for group experiment

Plus you'll only need 1 maybe 2 components to flatten that out.

It looks like a keeper, man!

[critofur]

That one's looking good!

Have you compared impedance between flat baffle & waveguide? I'm wondering if there's enough difference that you need to use the specific waveguide's measured impedance, or, just any old measurement will do...

That last waveguide, is it 2" deep? Could somebody post a side view profile and some type of CAD files for that design?

[Pete Schumacher]

Re: That one's looking good!

Have you compared impedance between flat baffle & waveguide? I'm wondering if there's enough difference that you need to use the specific waveguide's measured impedance, or, just any old measurement will do...

That last waveguide, is it 2" deep? Could somebody post a side view profile and some type of CAD files for that design?

2" deep, yes. Can't imagine it would change impedance much, if at all. But I can take a sweep tonight and see what it looks like.

[DanP]

Re: That one's looking good!

Have you compared impedance between flat baffle & waveguide? I'm wondering if there's enough difference that you need to use the specific waveguide's measured impedance, or, just any old measurement will do...

That last waveguide, is it 2" deep? Could somebody post a side view profile and some type of CAD files for that design?

Here's a cutaway of the CAD model. PM me your e-mail address and I'll send the actual model to you, or anyone else for that matter. The model is in STL format, however, which is going to be a little bit difficult to interrogate.

Dan

[Pete Schumacher]

Re: That one's looking good!

Here's a cutaway of the CAD model. PM me your e-mail address and I'll send the actual model to you, or anyone else for that matter. The model is in STL format, however, which is going to be a little bit difficult to interrogate.

Dan

That one sure seems like a winner at first pass, at least for the RS28F. On axis, there's a little bump around 8KHz, but it's not horrible, and as you notice, off axis it smooths out beautifully.

I wouldn't mind having the STL file for it. How simple would that be for a CNC guy to translate into cutting instructions on a 2" thick hunk of MDF? Obviously, only need the WG profile . . .