Post Directiva r1 Passive Crossovers here

[Rick Sykora]

I have a pair of ptt6.5x8nfa01 . I want to try this xover. What should I change on xover

As the r1 project was done with the 4 ohm version of the Purifi, you need to measure the response and impedance and update the VCAD project. You may be able to re-use parts of an existing project but significant modifications will need to be made.

 

[Trifonov Audio]

Hello everyone
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[XMechanik]

Yet another approach.
spl response is around +-1dB aroud a constant level in the 44Hz-17kHz range. The power response and related characteristics are very smooth.
In the thread I found that there is a problem with the woofer version and measurements so this xover is perhaps just a curiosity.

 

[abdo123]

Yet another approach.
spl response is around +-1dB aroud a constant level in the 44Hz-17kHz range. The power response and related characteristics are very smooth.
In the thread I found that there is a problem with the woofer version and measurements so this xover is perhaps just a curiosity.

View attachment 241488

Can you overlay this crossover over the original?

 

[XMechanik]

Can you overlay this crossover over the original?

Is that it? Not very readable btw, but if you define the aspect to focus on, something can be filtered out.

 

[abdo123]

Is that it? Not very readable btw, but if you define the aspect to focus on, something can be filtered out.
View attachment 241677

This is pretty incredible, you basically recreated the digital crossover with just a sensitivity penalty.

 

[wunderblunder]

So what ended up measuring best here in practice?

 

[Rick Sykora]

So what ended up measuring best here in practice?

Ideally, would need me (or someone) to measure using the same conditions. As this has not happened, the ability to compare the VCAD sims depends on the source measurement data used (typically mine or Amir‘s). Since we do not know for sure, would have to ask each designer...

Unless you find a particular design appealing, would use the latest from @ctrl or @TimVG. Otherwise, suggest you check with the crossover designer.

 

[Alan J]

Sharing what I'm working on. I'm planning a Directiva r1 build with passive crossover and probably the -NAA aluminum cone driver. My box will be a bit different as well, so clearly I'll need to use my own measurements and change the crossover, but it helps to go through the process with existing data.

I took what @ctrl provided here and deleted the unused DXT dsp chain. Per @ctrl's intentions (if I followed correctly) that provides corrections to Amir's NFS data as a baseline for crossover design.

The DXT part is what @617 provided back at post 5. (Note: Others have suggested that the DXT will benefit from a couple of parallel notches but that's another matter.)

The Purifi part uses the topology from the SPK16 app note, with the impedance network for the aluminum cone driver shorted out. I used Purifi's values as a starting point (crossover freq unspecified but similar?). Series resistance values of inductors included in optimization were inserted as separate components so they could be locked to reasonable approximate values. I then used VCAD's optimize function on the woofer network (other than inductor series resistance) and the tweeter series resistor. I re-checked inductor DCRs, adjusted to available values, and checked that there was little or no effect of any adjustment.

The biggest inductor is big but manageable - 28 ml volume without subtracting for the air core. If using the aluminum cone version, notch filters per the Purifi app note would be recommended. Seems promising.

EDIT - VCAD is showing huge power dissipation in R7. The topology is from Purifi (and doesn't seem at all unusual) though the component values are changed.

VCAD project attached.