Waveguide with Exit Angle and Transition Radius Validation - Any Takers?

[GROKAUDIO]

Hi all,

Fairly new here - so sorry if one of my first posts is asking for too much.

Ive been reviewing some of the posts regarding waveguides....

My Goal: I'm trying to build an Oblate Spheroid waveguide to primarily handle physical offset between a tweeter and woofer, yet incorporates both the exit angle and transition radius when designing.

Current Progress: I actually have a spreadsheet which I think allows for entering:

1. the exit angle,
2. throat radius,
3. 1/2 coverage angle,
4. transition radius,
5. and waveguide depth

Also currently charts and summarizes relevant data accordingly in mm and inches according to the waveguide depth.

Most of this was done by downloading a few spreadsheets, merging and modifying accordingly - so they may actually look familiar (so not all my work)

My Need for help: I currently realize that most of the math is somewhat beyond me - which means I 'm asking if anyone can validate the calculations - especially around the use of both the transition radius and exit angle, as well as the KR and frequency calculations.

I would be willing to post as resource to group after we can validate it. As a bonus - I was also hoping to try and add calculations relating to the differences in Radial/Conical pressure to assure the waveguide will work fairly well.

Any Takers?

 

[454Casull]

There's a spreadsheet around that already does that stuff. I think it gets passed around by a guy named John something or other.

 

[GROKAUDIO]

Can anyone point to the file ? Regardless still would like to validate what I have

Thanks

 

[Patrick Bateman]

Hi all,

Fairly new here - so sorry if one of my first posts is asking for too much.

Ive been reviewing some of the posts regarding waveguides....

My Goal: I'm trying to build an Oblate Spheroid waveguide to primarily handle physical offset between a tweeter and woofer, yet incorporates both the exit angle and transition radius when designing.

Current Progress: I actually have a spreadsheet which I think allows for entering:

1. the exit angle,
2. throat radius,
3. 1/2 coverage angle,
4. transition radius,
5. and waveguide depth

Also currently charts and summarizes relevant data accordingly in mm and inches according to the waveguide depth.

Most of this was done by downloading a few spreadsheets, merging and modifying accordingly - so they may actually look familiar (so not all my work)

My Need for help: I currently realize that most of the math is somewhat beyond me - which means I 'm asking if anyone can validate the calculations - especially around the use of both the transition radius and exit angle, as well as the KR and frequency calculations.

I would be willing to post as resource to group after we can validate it. As a bonus - I was also hoping to try and add calculations relating to the differences in Radial/Conical pressure to assure the waveguide will work fairly well.

Any Takers?

Why not just buy this?

QSC PL-000446GP Replacement Waveguide Horn for HPR152i 245-625

Great polars, inexpensive, what's not to like?

 

[GROKAUDIO]

Patrick,

Thanks for reply - but my primary goal is to offset tweter to woofer physical dfferences.

As much analysis as I've done I'm looking to build not buy

M

 

[Richidoo]

You might have more response if you post your generated profile and ask for confirmation. It is not a terribly complicated profile. JoshK created a speadsheet for SEOS project on AVS forum, I think. I think that it could be used for round horn also. It allowed variables like throat angle, mouth radius, etc. You might have to approach the offset you want experimentally.

How much offset are you looking to buy with the horn? Have you ever heard OS horn?

 

[GROKAUDIO]

Profile attached

All,

thanks for input - profile attached

 

[Wayne Parham]

Don't get too hung up on physical offset. In truth, the acoustic center of the midwoofer may be behind the tweeter anyway. It's not always (actually almost never) where the voice coil is.

• The Acoustic Center: How it applies to Loudspeaker Measurements

 

[GROKAUDIO]

Wayne - Thanks!

I have this link - http://www.sbacoustics.com/index.php/download_file/-/view/457/ - which indicates the combinations of Time delay and Physical offset as 48μs and 16mm.

After a brief look at you link - It seems as if the physical offset is only a part of the whole picture when considering a true acoustical offset..

That said - how would you approach this?

 

[Wayne Parham]

You gotta measure it.

Put the system together physically, then measure what you have. Do what you need to do with the crossover for proper summing.

Of course, that approach won't work if you're way off, but it will work great for the kind of speaker you're talking about here. By "way off" I'm talking about trying to mate a 10 foot basshorn with a direct radiator - That's too much difference to "mate" with a passive crossover. But a few inches of offset in a DI-matched two-way speaker is easy to dial in.

 

[GROKAUDIO]

Wayne,

I'm a bit slow today (son just started school...)

I'm with you on measuring...

are you saying:
1. Build with the Waveguide as oblate sphereoid
2. scrap the idea - due to ease of accommodating 16mm physical offset (and unknown acoustic center anyways)
3. Build with a 90X40 or 90x50 waveguide for the Vertical and horizontal alignments regardless of offset...

Maybe I've just asked a silly question...

🙂

 

[Wayne Parham]

I prefer asymmetrical waveguides for a variety of reasons.

To learn more, see the following:

• High-Fidelity Uniform-Directivity Loudspeakers

 

[Wayne Parham]

I prefer asymmetrical waveguides for a variety of reasons.

To learn more, see the following:

• High-Fidelity Uniform-Directivity Loudspeakers