Beyond the Ariel

[Sheldon]

Originally Posted by Elias

Hi,

I plotted some wavelets from the RAdian/Azurahorn IR file.

Here's a 'CSD' equivalent wavelet:

Can I see consecutive reflections/diffractions? Either the driver, or the throat-mouth ping-pong?
- Elias

A little open cell foam, ala Geddes, might be worth a try.

Sheldon

[Lynn Olson]

Reflection off the lower bass cabinet is a possibility too.

It doesn't look like the system is going to need much equalization, except for a possible 1.5~1.8 kHz moderate notch filter for the woofer to smooth out the lowpass curve.

[dantheman]

Here's what REW shows:





A horn polar response and we're ready to build a crossover. I don't know that I'd worry too much about that top octave. I'm sure that's just me however. If you want a deeper look into the noise floor, just let me know.

Dan

[g3dahl]

Originally Posted by Lynn Olson

Reflection off the lower bass cabinet is a possibility too.

I expect there would be some. Measurement was done with the horn in position on top of the bass cabinets. I buried the bass cabinets in a mountain of Bonded Logic to attenuate the reflection, but that would have only .

During the test, I set the window at about 4.4 ms, which would shut out reflections from other objects in the room, such as the amp on the floor. But eventually they all get there!

BTW, the picture is a quick re-creation of the arrangement so you can see how things were placed. During the test, the mic was on axis with the driver.

Gary Dahl

[Pano]

Yeah, lot's do a crossover.
How fancy do you want to get?

[soongsc]

Originally Posted by g3dahl

... I have attached the corresponding files in .pir and .wav formats. Vertical scale is arbitrary; the gain of my power amp hasn't been accounted for. The mic preamp doesn't invert phase, so it's probably the power amp, a Parasound HCA-1500A.

...

Gary Dahl

If you are using a wm61 type electret condenser capsule, its normal connection method results in inverted signal.

[g3dahl]

Started on the Zobel network for the TD15M this afternoon.

The calculator at mh-audio.nl - Calculations provided values of 8.25 ohms and 2.94 uF, so I began with 8 ohms and 3 uF:



Next, I tried it with a 2 uF cap. The green trace shows 3 uF; the yellow trace shows 2 uF:



Finally, I tried a 4 uF cap (yellow trace). The green trace is 2 uF.



I wish I could overlay all three traces, but I couldn't get more than one overlay.

Comments? I think 2 uF looks best, but I'm new at this.

Gary Dahl

[Pano]

With an impedance plot like that, why do you need a Zobel?

[soongsc]

I would recommend flatening the system impedance rather than doing it for each driver. The thing is that components will all interact with each other. Of course you can still flatten the final impedance of the system and still have zobels for each driver, but it seems component count would be more, and there may not be audible benefits to be gained.

[Elias]

Hi,

In the wavelet reassignment I draw red arrows to point the consecutive reflections/diffractions, and mapped them back to the wavelet shown in white lines.

These consecutive reflections/diffractions are typical for horns and waveguides and they can be repeatedly seen in the horn honk thread with all the horns and waveguides. Some have more of them than others.




- Elias

Originally Posted by Lynn Olson

Reflection off the lower bass cabinet is a possibility too.

Originally Posted by g3dahl

I expect there would be some. Measurement was done with the horn in position on top of the bass cabinets. I buried the bass cabinets in a mountain of Bonded Logic to attenuate the reflection, but that would have only .