First VituixCAD Design - Please check

[DeZZar]

Apologies I just noticed I had 'open baffle' ticked at some point running the diffraction model. I re-ran the models to be sure with the following updated result.





Drivers have good phase alignment - this is the 'reverse null' when inverting the tweeter



And just so we are all on the same page, this is the diffraction model I used for the drivers:

[rpb]

This looks like a good x-over. It's not much more expensive than a simple filter that would not work as well.

[DeZZar]

I have to say I'm pretty surprised. I wouldn't have even considered a 10" two way (and probably still wont) but if everything here translates from the theoretical to reality its a bit of a shock. These things could be +- 1.6db f3 to 20K! That's only one dimension of the sound of course, but still not something I would have expected.

[DeZZar]

Here is an update showing "purchasable" values.

You will want to keep the DCR (resistance) on the inductors to a minimum. This is modelled with:
L1: 0.47mH 15AWG 0.19 Ω
L2: 2.2mH 15AWG 0.473 Ω
L3: 0.75mH 15AWG 0.26 Ω
(all available in Jantzen Air-Core)

I recommend the Mills or Superes for the resistors. In terms of caps - spend as much as you like on the tweeter - I recommend just the Jantzen Standard Z-Cap here - you can go more if you like. On the woofer network any of the MPC caps are fine. I tend towards the Cross Caps myself.

[zinger084]

So.....What is your intended use for these speakers? What are your primary performance concerns?

Well I’ll start by saying the two sets I’ve made in the past (18 and 10 years ago) just used prebuilt 2k 2-way crossovers and I used speakers that I liked (one set was Dayton classics with silk domes and others were 8” dynavoxes with mid range morels. I had no idea that there was such great software out there to simulate so many things. I did know that you don’t want square boxes, you don’t want uniform speaker placements on baffles, etc, but this software is amazing.

That said, these two are going to be the rears in my basement home theater buildout. My fronts and center are going to be 7” DA references with morel 378’s. I haven’t started simulating those yet and I’m looking into MTM or MMT layouts.

[zinger084]

Apologies I just noticed I had 'open baffle' ticked at some point running the diffraction model. I re-ran the models to be sure with the following updated result....

Should the microphone in the woofer model actually still be placed where the tweeter is going to be located since that's my 36" seated height listening plane?

EDIT: another item i noticed is that your tweeter diffraction doesn't list the 11.95 properly for the Sd:
https://www.parts-express.com/Peerle...ableshopping=F

[DeZZar]

No the mic should be in front of the woofer - the driver offset is taken care of in the crossover model. 11.95sd noted - it doesn't make any real difference though.

[zinger084]

also, not sure what's up, but i re-ran the diffractions to match Dezzar and here is my mirrored crossover components... with a nasty dip in the middle...???

[DeZZar]

hmmm hard to understand what the difference is but it seems the impedance and phase might be the issue. I'll attach my trace files for the tweeter.

[rpb]

What's that smooth purple arc centered near 1k? Should that be there?

[DeZZar]

That's a "target" you can setup. You can tilt it down/up, set a level etc which acts as a bit of a guide and the system uses it in some of the automated optimisations. You might notice in mine it's just a flat line at 85db. Not sure what Zinger has setup here.

[zinger084]

i fiddled with the components and I think this looks right, but i'm posting my diffraction models and other info here...

[DeZZar]

These are the FRD and ZMA trace files I made for the tweeter. Along with the 0,15,30 diffraction modelled FRD's.

Also on the driver tab of Vituix - I have 'Minimum Phase' selected.

[zinger084]

I'm still not getting the same result.

The steps I'm following are:

1. Open Vituix.
2. Create woofer and tweeter drivers on drivers tab.
3. Load in woofer frd and zma.
4. Trace tweeter spl and impedance to generate frd and zma.
5. Load in tweeter frd (under frequency response) and zma (under impedance response).
6. Make sure minimum phase is checked at bottom of drivers tab alongside smooth 1/12oct.
7. Open diffraction model and model the woofer and tweeter separately with mic in center of each driver.
8. Export the generated .txt full space files in 10 degree increments.
9. Reload these exported files back in as the sole source of frequency responses in the drivers tab to compensate for baffle step (for each the woofer and the tweeter.
10. Look at SPL chart and design crossover.

I apparently am missing something though... and not sure what it is.

Here are mine.
Peerless DA32TX00-08 Response_ZR.zma
[email protected]
Baffle Step Diffraction Tweeter_Full-space hor 0.txt
Baffle Step Diffraction Tweeter_Full-space hor 30.txt
Baffle Step Diffraction Tweeter_Full-space hor 60.txt

[DeZZar]

Steps 3 and 5 are redundant. Not sure that's the difference though if your deleting the loaded files and importing the diffraction ones at step 9.

[zinger084]

additional screenshots

[DeZZar]

Check the files loaded for your woofer. Perhaps just work with the horizontal diffraction files for now, remove the rest.

[rpb]

I know that you are mostly concerned with the software at the moment. I've no experience with it. But, while you are playing with things, note that changing the coil to 2mH will affect the notch that it, and the 1uf cap create. Try a smaller 2 ohm resistor to make it easier to see the notch location. Then alter the 1uf cap higher or lower value, and watch the result. At the same time, I'd try different values for L2., and take a look at R5. Sometimes the interaction between these parts can be sensitive.

It's odd that your result don't match. I'd double check the woofer zma file. I currently don't have a pc to play with the sim, so I'm just making educated guesses.

[zinger084]

will do, thanks for making the suggestion. if i wasn't so far off from DeZZar, i would just plow forward, but there's just such a disparity on the middle i want to make sure i get it right.

[rpb]

Sims are nice for getting close (If your good at it.), but for me, the fun begins when measuring the driver responses, and actually measuring how they respond to a filter..I'm likely one of the few here that does x-overs by trial and error, making many sweeps while changing the x-over.

[dcibel]

zinger084 Have a close look at the frequency response files loaded to the tweeter driver, I would suggest you have the wrong files loaded here.

[zinger084]

i just tried Dezzars frd's and zma on both the tweeter and the woofer and i'm getting the same mismatched results. i'm working through it and will report back findings. i don't know how they can be different if i'm literally using his frd's and zma's but i'll get to the bottom of it.

[zinger084]

well here is the fix... it ended up being a non-connected wire that wasn't showing red, as if it was open either, over the notch near the 2.2. note to self... draw each wire node to node and when adding components, erase that area and completely redraw.



however, another item Dezzar mentioned... listening distance. how does everyone design/take into account their components on speakers that may be flexible in a space?

[DeZZar]

however, another item Dezzar mentioned... listening distance. how does everyone design/take into account their components on speakers that may be flexible in a space?

I had mine set to 1m...which I could be wrong about...my theory is that I want to model against how I will eventually measure for as close as possible results. I've never really paid too much attention to this aspect as I always measure, tweak, measure tweak (repeat) until I'm satisfied with the result and the simulation becomes less important at that point.

If you increase the listening distance in the simulation to say 2.5m you start to get a dip at the crossover point. Not a significant one, and you can tweak the values to flatten it out, the big question being which values would you run with when relying solely on a simulation?

Interested in what others views on this are.

zinger084 either way it's going to be a lot better than a pre made two way crossover ;)

[rpb]

About the only thing you can change is the on, and somewhat, the off-axis response. Speaker position in the room can cause reflections to be of short delay, or long. Your brain perceives each slightly differently. Once you have selected drivers, a lot of the off axis response has been determined.. As to distance to the speaker, there may be small changes in diffraction that are probably meaningless..

AS DeZZar stated, the driver summation can change with distance. It's a geometry thing. For the sim, I'd probably optimize for 2m.

[dcibel]

Listening distance should be set to the distance you typically listen, generally 2-3m for most rooms. Simulating at 1m distance can create problems at actual listening distance as Dezzar has found.

speakers should be designed for flexibility of placement, so design data should be reflection free. Room placement can be addressed by EQ if needed.