Crossover Input

[adam215]

Hey guys, I have a couple of Vifa NE180W-04 and Dayton RS28A-04 laying around and I've been trying to layout a design for a set of bookshelves using them. I've done my best to try to learn VituixCAD and I have come up with a Box/Baffle/Crossover design I think I'm satisfied with. I just wanted to throw it out there in case anyone has useful input or in the event that I'm missing some critical step or information.

[adam215]

The box will be 20 L rear ported. The baffle will be 9 X 14. Here are the FRD and ZMA files if anyone wants to take a crack at something different:

[DeZZar]

Where did the measurements come from - are they parts express or your own?

Is this the woofer?

https://www.parts-express.com/Peerless-NE180W-04-6-1-2-Full-Range-Woofer-264-1096

If it is, how did you come up with 20L? It doesn't look very happy with 20L from what I can tell....?

[adam215]

Where did the measurements come from - are they parts express or your own?

Is this the woofer?

https://www.parts-express.com/Peerless-NE180W-04-6-1-2-Full-Range-Woofer-264-1096

If it is, how did you come up with 20L? It doesn't look very happy with 20L from what I can tell....?

The Tweeter measurements were from PE. The Woofer is from the enclosure tool in VituixCAD and then the diffraction tool.

Ya I see now that the box recommendation for a vented design is .25 cubic ft. 20 L was just an arbitrary volume from the size of the cabinet I was going to build.

[DeZZar]

yeah this isn't really a woofer that's going to play deep bass. I would tend to target better dynamics and align it more towards say a QB3 alignment. If you want to try and squeeze as much bass as you can, based on the params published I would try 10L net volume tuned to 55hz. It'll be a lot happier in that space.

Crossover wise - few things you could tweak. Impedance could be smoother, phase could be a little better - but really its just academic at this point until you actually measure the drivers in the box.

[adam215]

yeah this isn't really a woofer that's going to play deep bass. I would tend to target better dynamics and align it more towards say a QB3 alignment. If you want to try and squeeze as much bass as you can, based on the params published I would try 10L net volume tuned to 55hz. It'll be a lot happier in that space.

Crossover wise - few things you could tweak. Impedance could be smoother, phase could be a little better - but really its just academic at this point until you actually measure the drivers in the box.

OK, I'll adjust the box. How can I smooth the impedance or clean up the phase? I guess I just need a reasonable jumping off point for the xo so that I can make adjustments from there.

[DeZZar]

You need your real world measurements in your boxes before you can really start tweaking the crossover.

I'd get your boxes put together then take some measurements. Once you have those then you can start to model up the crossover. Any suggested changes to value etc at this point is somewhat meaningless - it could end up completely different when you create the real thing.

[Chris Roemer]

These are measured T/S parms from about 4 yrs ago: Qes 0.40, Qms 6.8 (Qts 0.378), Fs 44, Vas 0.67cf, Re 3.4, Le 0.64
In 0.7cf (20L) tuned to the low 40s (2"id x 5" OR 2-1/2" x 8") it should do nearly 40Hz - which is all you really need for music. 32wRMS yields about 102dB @ Xmax.

You should be able to go 2nd order (elec.) on the filters. Drivers aren't too hard. You don't seem to have hardly any baffle-step.
Paul Carmody (in the "Stickies") has a great write-up on using (mfr.) measurements w/J Bagby's tools to get pretty dang good sims.
That's how many (if not most) of his designs have been done (OS, Amigas, Carerra, Swope, Classix(2), and oodles more).

I think I ended up w/6 elements - total (as opposed to 9). Most tweeters need some attenuation (if you've got BSC simmed in).

[chrisn]

Nice drivers, they should sound good together. On the crossover, why is there a 2.2 ohm resistor in series with the woofer? It's weird the tweeter has no padding to match the woofers level. Is the notch in the tweeters response around 2.5k-ish inherent to the tweeter on the baffle?

As others have mentioned it's better to use in box measurements, but nothing wrong with practicing with simulations I think Zaph has measurements for both the drivers, which should get you within tweaking distance if the drivers haven't changed much over time. With those drivers you could experiment with different filters, like LR2 vs LR4 or something in between

[adam215]

For some reason when I put the woofer in the box the response jumped way above the tweeter in the SIM. I think I maybe have the box way too big.

The notch on the tweeter was just trying to deal with a spike I saw on the response in the SIM. The spike was after it was placed on the baffle.

Again all of this was just in the simulations I haven't actually measured anything in box before

[Wolf]

I have a pair of the NE180-4 as well, and measured the T/S myself.
This should help you out...







I'm pairing mine with the Morel CAT378.
Wolf

[chrisn]

That impedance curve looks smooooth! No surround resonance?! Models nice too

[chrisn]

This is your crossover simulated in PCD using Zaphs measurements for the woofer and either PE or Zaph for the RS28a, on an 8.5x13.5" baffle:





The 4.7uf cap on the tweeter is so small it's rolling the tweeter off around 10k-ish. I'll try simulating it and post the result if it's any good. What size baffle are you thinking of using?

[adam215]

Thx for all that data Woof, appreciate you taking the time.

The baffle is 9 x 14 but I was thinking of using facets for appearance sake.

[adam215]

This is your crossover simulated in PCD using Zaphs measurements for the woofer and either PE or Zaph for the RS28a, on an 8.5x13.5" baffle:





The 4.7uf cap on the tweeter is so small it's rolling the tweeter off around 10k-ish. I'll try simulating it and post the result if it's any good. What size baffle are you thinking of using?

Wow, that SPL looks like garbage

[Wolf]

My simulation with the CAT378:


And box:


The reasons I used the CAT378, is the cone on the NE is pretty deep, and I figured it would help with acoustic offset alignment. The RS28 is also a good choice as far as where your bar is set.

Good luck!
Wolf