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Azura Trio 4-way horn project starts - Cessaro look


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Guest atilsley
Posted

@ Mal


 


I like that three-way boxed pic...have thought about this config for quite a while.


 


Could be made up quite easily of:


 


Faital Pro 1500Hz horn with one inch compression driver


Faital Pro 500Hz with two inch compression driver


Dual 12 or single (or dual) 15's, eg Eminence or Faital Pro


 


Heaps of options to play with. Make passive mid/HF's...and active bass...easy.


 


Build nice box using Birch with Palesander veneer....pro spray in two pack poly...like that Sub project on SNA....nice.


Posted
  On 10/10/2014 at 1:05 AM, atilsley said:

SET friendly

 

Perhaps, but you must see the electrical impedance to know this.... Without matching the horns and drivers extremely (impossibly?) carefully, you will have mechanical resonances which reflect back to the amplifier   (can be seen in an impedance measurement).

Guest atilsley
Posted
  On 10/10/2014 at 3:26 AM, davewantsmoore said:

Perhaps, but you must see the electrical impedance to know this.... Without matching the horns and drivers extremely (impossibly?) carefully, you will have mechanical resonances which reflect back to the amplifier   (can be seen in an impedance measurement).

OK, got it...thanks.

 

With the stated drivers I have ordered (Faital Pro HF200 and JBL 2420, plus the B&C 8PE21 woofer), do you anticipate a problem/mismatch? I would have thought these drivers have proven themselves to be well matched in the horns.

Posted

I notice you're sending the full signal to the Cymer. Make sure you load it's output correctly otherwise it could break into oscillation.

Posted
  On 10/10/2014 at 5:06 AM, ehtcom said:

I notice you're sending the full signal to the Cymer. Make sure you load it's output correctly otherwise it could break into oscillation.

Why would that be? I mean what would be the difference as if he's using a normal passive speakers?

Posted
  On 10/10/2014 at 4:06 AM, atilsley said:

OK, got it...thanks.

 

With the stated drivers I have ordered (Faital Pro HF200 and JBL 2420, plus the B&C 8PE21 woofer), do you anticipate a problem/mismatch? I would have thought these drivers have proven themselves to be well matched in the horns.

 

"match" isn't a yes or no thing....   all the horn parameters have an effect on what the match looks like in the frequency response (and hence the time response).... and it's never perfect.

 

The more damping your speaker gets from your amplifier, the more these problems are swamped out..... this is a very deep topic, but debate rages as to whether this is a good thing or not.   (I am mostly on the side of not)

 

The bottom line is that planning to use an amplifier which offers little damping on a very sensitive speaker means that you will see the resonances of the system clearly in the response of the speaker.     The gold standard solution is to reduce the resonance.

 

 

 

There's really only limited ways to investigate.

 

Model or simulate the results

 

Build some horns and measure the drivers in them.    Assuming the the mouth and flare work for your system, then the next critical part will the be the throat and transition to driver (phase plugs, etc.)

 

 

 

I am working through exactly the same issues right now with my own horns.     Changing the damping properties of the system, by adding mechanical damping to the horn and driver, and reducing electrical damping by using different amplifiers (or resistors).

 

... one day I want to build an amp with adjustable output resistance.

Guest atilsley
Posted

Thanks...how do you add mechanical dampening to a horn?

Guest atilsley
Posted

Faxcomp, thanks...I enjoy the interaction and building stuff.

Posted
  On 10/10/2014 at 5:55 AM, davewantsmoore said:

The more damping your speaker gets from your amplifier, the more these problems are swamped out..... this is a very deep topic, but debate rages as to whether this is a good thing or not.   (I am mostly on the side of not)

 

8 is the magic number :-)

Posted (edited)
  On 10/10/2014 at 8:21 AM, atilsley said:

Thanks...how do you add mechanical dampening to a horn?

 

Filling.     Like foam.     Filling more than the throat is patented though.

 

The foam changes the acoustic load on the front of the driver.

Edited by davewantsmoore

Guest atilsley
Posted

Martin has completed the 340 and 550 horns...just waiting on the 160's.

 

I will have the CAD drawings made up this week for the bass unit and stands.

 

Ive bought al the mix of wiring, terminals etc.

 

All drivers ordered and in Sydney.

 

F5 amp confirmed for mid bass.

 

Bass amp the final item outstanding...but have Rotel unit on standby.

 

The American Walnut on Euro Birch ply (25mm for bass, 18mm for stands) will take two weeks to get laid up.

 

Got to put my mind to Sonotube etc.

post-103876-0-72849100-1413168960_thumb.

Posted

Great work by Martin. Are you going to reinforce the rear face of the horns, particularly the 160?

Guest atilsley
Posted

3G

I wasn't sure about that.

If I run horn to 160, would this make the need for more reinforcement....as opposed to, say, 250hz?

What sort of reinforcement....extra fiberglass? Martin did this for my own 340's...

Posted

I did not take any measurement so my comment is based on bias and sticking my finger in the air :) I reinforced my horns with about 30 litres of fibreglass resin, two layers of 6 oz cloth, 40 kilo of sand and about 4 sheets of MDF cut into rings.  They are a lot more inert to the highly scientific knock test, if it was worth the months of work, I don't know, I never tried them before the butchery began.

 

You seem to work at quite a fast pace, maybe try them first, then consider adding fibreglass thickened with an inert material and add layers over time so you don't overheat the horns when the resin goes off.

Guest atilsley
Posted

Thanks. How did you add the sand?

Guest atilsley
Posted

Cool...looks heavy.

Do you add any wool or felt in the back chamber?

What freq range for your 160?

Regards

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