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Waveguide/horn & Compression Driver Suggestions Wanted


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10 hours ago, Masis Ingilizian said:

Regarding protection of the tweeters, so obviously the lower its cut off the more likely it is to be damaged. I am using a 20UF cap what else do I have to do? Just not play it to loud. I will be using a active crossover 24db so wouldn't that protect it somewhat as well?

Yes.    As long as you don't put significant energy into the tweeter below the resonance frequency of the horn+tweeter (so, about 1000hz), then it will be fine.

 

Both the capacitor (assuming it it the right size) and the active crossover, will stop that from happening.

Edited by davewantsmoore
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10 hours ago, Masis Ingilizian said:

I am aware of measuring off axis gives you the frequency curve compared to on axis to see at what degrees you've lost a decent response(although still in the learning stage) so thanks for explanation.

To be honest all I'm doing here is following in the footsteps (parroting) the greats in this field.

 

If you'd like to truly understand the significance of the polar plot then you'll find the attached white paper by Dr Geddes foundational. 

 

I think of a single, on-axis measurement (plot) a little like trying to drive your car with the windscreen painted out entirely in black. The only part you can see through being a small pin prick hole,  directly ahead. Looking through a windscreen like that doesn't tell you much about what is happening around you.

 

A polar plot gives you a 180 degree view from your windscreen, preferably in both the horizontal and vertical - once you understand how to interpret the polar (google spin-o-rama for the JBL reference measurement approach for this)  ?....

Geddes directivity whitepaper.pdf

 

 

JBL spin-o-rama specification...

 

 

JBL Spinorama reference.png

Edited by Maz4bz
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10 hours ago, Masis Ingilizian said:

But we are just using REW right? And the spectograms on it?

I use Omnimic and REW. You can download both for free.

 

Omnimic is designed to be used with its companion Omnimic microphone. However this doesn't stop you from using the Omnimic software to load your curves measured using REW (for example) and generating the charts it produces. 

 

As far as I'm aware, REW doesn't have the capability to assemble a polar plot which is a minimum necessary requirement to understand the true success of any build you've completed.

 

If you have a look at my Klipsch KG 5.5 update and 2.5 way conversion thread you can see there how I used the polar measurements of my modifications to validate my work and incrementally refine the result. ?

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  • 9 months later...
On 16/09/2020 at 5:39 AM, Maz4bz said:

 

Here's the Dayton/JBL PT/Econowave clone horn measured with the Alternative Imports 44mm VC CD. You can see the horn looses control just below 1khz (tho a normalised plot which I don't have to hand would help clarify if it were a little higher) but I am using a crossover to a 12" around 1.5khz to match directivity, protect the CD and keep the CD sounding clean at higher power levels.

 

 

1022114322_AED2SmoothedPolar.jpg.17ed0efd6a5a17b703c2272befe4c9a6.jpg

 

These AE CD's are quite nice for the price. I've also used the 34mm voice coil version and they have all been very pleasing for a budget build.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 image.thumb.png.503c43cf52844fee2e3e49220ed6d3e4.png

 

This is my horn with the DE250 40 degrees of axis, is this enough to figure out when the horn loading ends? And if so what am I looking at...?

 

I didnt take these measurements, I found the measurements in the DIY forum a great find to be honest. 

 

40degreesoffaxishorn.jpg

Edited by Masis Ingilizian
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On 17/09/2020 at 1:22 PM, Maz4bz said:

To be honest all I'm doing here is following in the footsteps (parroting) the greats in this field.

 

If you'd like to truly understand the significance of the polar plot then you'll find the attached white paper by Dr Geddes foundational. 

 

I think of a single, on-axis measurement (plot) a little like trying to drive your car with the windscreen painted out entirely in black. The only part you can see through being a small pin prick hole,  directly ahead. Looking through a windscreen like that doesn't tell you much about what is happening around you.

 

A polar plot gives you a 180 degree view from your windscreen, preferably in both the horizontal and vertical - once you understand how to interpret the polar (google spin-o-rama for the JBL reference measurement approach for this)  ?....

Geddes directivity whitepaper.pdf 3.71 MB · 1 download

 

 

JBL spin-o-rama specification...

 

 

JBL Spinorama reference.png

 

This Is one of the best most concise explanations I have coem across, well done. 

 

I have been doing a lot of reading in the last 10-12 months planning on building a cd system for the shed (think jbl 4345 clone with modern components) 

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