One inch waveguide/horn - which one?

[catapult]

I cant really interpret the 60 degree beaming frequenzy from this... Any help?

Why 60 degrees? Are you using a 120 degree horn? If you're using a more typical 90 degree horn, the 40 degree curve would be pretty close. Look for the frequency where the 40 curve is 6dB below the 0 curve.

 

[catapult]

It should be noted that you'll also need to measure the horn/ compression driver combo in order to know precisely how the directivity changes over frequency...

Regards,
John

Right. From the same site as the other measurement, here's a QSC 90x60 waveguide with a B&C driver. The 45 degree curve is light blue. It looks like somewhere in the 1200-1500 range would be a good place to cross to the TD12M.

 

[tinitus]

How do you define the needed beaming angle
How many db below linear

On above it seem like its loosing its directivity below 2khz
And the TD12M at 1khz
Should they be crossed around 1.5khz?

 

[Robh3606]

"How do you define the beaming angle
How many db below linear"

Hello Tinitus

Typically it is the -6db point.

Rob

 

[Defo]

Thought it might be usefull to give some insight of my project idea...

My goal is to build an high efficiency slim good looking (something like Zu Druid) two-way using the AE TD12M and either the B&C DE250 or DE10 (depending on the crossover frequenzy I will settle at).

Because looks are important ill most likely will use the Stereo-Lab 1000hz horn. The dispersion of the Stereo-Lab is around 60 degrees as stated earlier, so therefore I need to know where to cross over to the TD12M to match dispersion as good as possible

 

[ZilchLab]

On above it seem like its loosing its directivity below 2khz

I agree. The lines are convergent rather than parallel.

 

[catapult]

most likely will use the Stereo-Lab 1000hz horn. The dispersion of the Stereo-Lab is around 60 degrees as stated earlier, so therefore I need to know where to cross over to the TD12M to match dispersion as good as possible

I assume that's 60 degrees total so that's 30 degrees each side. On the TD12M curves, 30 would be somewhere in between the 20 and 40 curves (obviously ).

I agree. The lines are convergent rather than parallel.

Some of that is true and some is an optical illusion due to the change in slope. Looking at the light blue 45 degree curve, it's about -7dB at 10K, -5dB from 1.3K to 5K, -3dB at 1K and quickly loses all directivity below there. Any reasonably sized horn is losing directivity down low so there's nothing new there.

 

[Robh3606]

Hello Zilch

That other plot is for a 10" 2123. Attached is a 12" 2206 plot. Looking at the plot and using -6db as the basis for the matching point the 1.28K frequency line would be close to that for a 90/100 degree horn. Think 4425 as an example.

I know these are sims but they seem to be fairly accurate.

Rob

 

[Defo]

I assume that's 60 degrees total so that's 30 degrees each side. On the TD12M curves, 30 would be somewhere in between the 20 and 40 curves (obviously ).

That makes sense.. So 60 degree beaming frequenzy would be around 1,7 khz then. Looks like ill have to use B&C DE250 to get this low, or will DE10 be able to handle this with 24db LR slopes?

 

[longdrive55]

Re: Re: Is there a formula.....

The chart in Dickason Fig. 0.14 suggests a 15" is 60° @ ~2 kHz.

There's a formula, Keele, I believe.

OR, you push a button, apparently. Here's a 12" JBL midbass driver:

Wow Zilch you actually managed to post the polars for the exact driver I'll be crossing over to in my 3 or 4 way (TBD) OB build. That's the EXACT data I needed. Thanks for that.

 

[Ang]

Let me confirm that A.) I doubt you'll ever get a response from assistance audio, and B.) The DDS waveguides sound very nice, but the quality is still terrible. Bolt holes are completely wrong for any major compression driver and drilling and attaching your own is a pain because of the shoddy construction.

JBL waveguide (or now the qsc) are the way to go.

 

[ZilchLab]

Hello Zilch

That other plot is for a 10" 2123. Attached is a 12" 2206 plot. Looking at the plot and using -6db as the basis for the matching point the 1.28K frequency line would be close to that for a 90/100 degree horn. Think 4425 as an example.

I know these are sims but they seem to be fairly accurate.

Rob

Thank you, Rob!

I DID look it up, I promise.

[THEN, I forgot.... ]

 

[longdrive55]

Let me confirm that A.) I doubt you'll ever get a response from assistance audio, and B.) The DDS waveguides sound very nice, but the quality is still terrible. Bolt holes are completely wrong for any major compression driver and drilling and attaching your own is a pain because of the shoddy construction.

JBL waveguide (or now the qsc) are the way to go.

Just an FYI, but the round QSC waveguide that looks like the DDS is going to take some modifications to make it work with a standard 1" exit CD. The rectangular shaped one that Augerpro tested (with great results) IS a direct bolt-on for a standard 1" though.

I'll be getting both next week. Once I figure out how to mod the round one, I'll post my results.

 

[Defo]

The tractrix horn with it's 1000 HZ flare will not load much below around 1800 HZ, it's dispersion is 60 degrees. You will need the 400 flare horn they sell if you want to go down that low
range.

Im confused... as in the description of the horn it says that the cutoff frequenzy is 1000 hz.

"On offer is 1 piece 1" Stereo Lab CF > 400 Hz spheric wave tractrix horn. You can use this horn above 400 Hz." This is for the 400hz horn though...

Does the small Stereo-Lab 1000hz tractrix beam less than the larger ones at higher frequenzies? Considering the larger ones are way longer in depth..

Bumping this question...

 

[Brett]

Im confused... as in the description of the horn it says that the cutoff frequenzy is 1000 hz.

Cutoff freq is the mouth circumference, not where it will load too. I made this mistake when I was testing some trax mockups some years ago, and they dropped off rapidly before Fc. I saw a comment by JLH (?) that 1.414x Fc was where they would begin to load properly and this seemed to be so for the Edgar salad bowls which are 350Hz Fc, but used from 500Hz. My 270Hz Fc trax loaded well from about 400Hz, maybe a bit higher.

"On offer is 1 piece 1" Stereo Lab CF > 400 Hz spheric wave tractrix horn. You can use this horn above 400 Hz." This is for the 400hz horn though...



Bumping this question...

Marketing spiel =/= truth.

 

[Defo]

Cutoff freq is the mouth circumference, not where it will load too. I made this mistake when I was testing some trax mockups some years ago, and they dropped off rapidly before Fc. I saw a comment by JLH (?) that 1.414x Fc was where they would begin to load properly and this seemed to be so for the Edgar salad bowls which are 350Hz Fc, but used from 500Hz. My 270Hz Fc trax loaded well from about 400Hz, maybe a bit higher.

Marketing spiel =/= truth.

I see So the 1000hz tractrix will load properly from about 1400hz then?

Is this the case for all horns, or just spherical / conical ones?

 

[dobias]

5kHz 12 inch waveguide

What are the advantages & disadvantages of using a 12 inch waveguide only for frequencies above 5 kHz?

 

[Brett]

I see So the 1000hz tractrix will load properly from about 1400hz then?

Somewhere around there. Measurements would confirm.

Is this the case for all horns, or just spherical / conical ones?

Conicals will generally load higher, and expo and hypex will be different also. The comment I made was for trax only.

 

[pk]

Hi Defo,

I have attached a measurement I had made with a B&C DE25 (previous model of the DE250) on the StereoLab 1000 Hz horns. As you can see this combo loads down to app. 1500 Hz.

Best regards
Peter

 

[Defo]

Hi Defo,

I have attached a measurement I had made with a B&C DE25 (previous model of the DE250) on the StereoLab 1000 Hz horns. As you can see this combo loads down to app. 1500 Hz.

Best regards
Peter

Thanks for the measurement! Not as smooth as the B&C graph, but acceptable. How does the combo sound?