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Multi-Way Conventional loudspeakers with crossovers

Which configuration?
Which configuration?
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Old 9th November 2019, 03:46 AM   #1
jcl1 is offline jcl1
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Join Date: Nov 2019
Default Which configuration?

New here, first post. This is pretty much my first enclosure + DIY crossover attempt as well. Wondering if you guys to take a look at this project and let me know what you think. I would love to get some guidance/expertise on anything I can improve upon.

I looked into many options for HT surrounds. Originally, it was going to be in-walls, but I don't really want to cut holes in my walls, so then looked into on-walls. There are some nice ones (Definitive Tech, Martin Logans), but starting thinking what would be involved in going the DIY route?

Two main goals:
  1. Shallow depth, tall and thin as possible
  2. As much low-end performance as possible
  3. Decent components but lower cost if possible

Chosen components:
Playing with WinISD, I came up with three configurations, each having 2X 5" mid/bass drivers, 1X 1-1/8" tweeter, and passive radiator(s) in different configurations. I call these:
  1. 5 x (6x3)
    Click the image to open in full size.
  2. 5 x (8x2)
    Click the image to open in full size.
  3. 5 x (10x1)
    Click the image to open in full size.

A spreadsheet for calculating volumes of these configs:
Click the image to open in full size.

From WinISD below. To keep excursion of the passive radiator(s) within xmax, a high-pass filter at 60Hz is applied for 6" and 8" passive radiator configs, except for the 10" config which is filtered at 50Hz:
Click the image to open in full size.

The high-pass filter also keeps the cone excursions all below xmax.
Click the image to open in full size.

The 6" config gives the highest SPL:
Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

With VituixCAD, I came up with this 2-way 3rd-order crossover design, crossed at 1750Hz, and with a parallel notch filter to flatten out the tweeter a bit:
Click the image to open in full size.

QUESTIONS:
  1. In WinISD, for "System input power", I put 100W for two 50W RMS drivers in parallel. Is this correct?
  2. I did not find a way to include passive radiators in VituixCAD? Is it possible?
  3. Which configuration would you go with?

Thanks for taking a look!
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Old 9th November 2019, 08:06 AM   #2
AllenB is offline AllenB  Australia
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Join Date: Oct 2008
Question 1, Yes.
Question 2, Either use WinISD to export the PR responses or screenshot them and use VC to trace them. Then use VC to combine them.
Question 3, Distribution of bass sources can improve room modal behaviour. Don't know how yours will fare without for example testing, but the one with the more PRs may have a benefit. On the other hand, being against a wall will negate this to some extent, but offer other benefits, and it can all be fixed in other ways. Maybe I don't have a preference?

A note about your crossover. Your woofer shows narrowing in the top octave. This is a common issue with 180 degree baffled two ways. A suggestion: your response is a little hot in this octave, you could reduce the woofer here, and otherwise try to make the tweeter dominant in this octave.
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Old 9th November 2019, 09:25 AM   #3
Zuhl is offline Zuhl  England
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You need to tame that 1-2kHz response. That kind of lift will make the speaker sound 'shouty'.

What responses have you used for this? There doesn't seem to be much in the way of BSC.
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Old 9th November 2019, 09:59 AM   #4
AllenB is offline AllenB  Australia
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Yes 1-2kHz (thank you), I was looking at the red trace in the 2nd plot from the top in the middle column of the crossover screenshot when I wrote my last sentence.. but I should have mentioned the frequencies.
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Old 9th November 2019, 05:47 PM   #5
jcl1 is offline jcl1
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Thanks for this feedback!

I traced the transfer function magnitude of the PR from WinISD into a frd file:

Click the image to open in full size.

I added a pr driver to VC, provided the FRD file, but how do you incorporate the PR in VituixCAD?

Along the way, I brought the crossover down a bit to 1600Hz which smoothed out 1-2kHz range. I also brought down the tweeter a bit to hopefully address BSC. Speaking of BSC, I was not aware of this and did some research. Does this basically mean I need to bring down the tweeter a bit in order to compensate the speaker being up against the wall? (which squashes the lower end) Or do I need to add some circuitry to the tweeter to address BSC?

Here is my updated VC grab:

Click the image to open in full size.

Thanks!
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Old 9th November 2019, 07:43 PM   #6
jcl1 is offline jcl1
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Btw, (not able to edit my previous post for some reason, sry)...

Zuhl, to your question about which responses I'm using... I'm using FRD and ZMA files for the woofer and tweeter downloaded from parts-express. Is that what you're refering to?

Click the image to open in full size.
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Old 10th November 2019, 04:48 AM   #7
AllenB is offline AllenB  Australia
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Quote:
Originally Posted by jcl1 View Post
I added a pr driver to VC, provided the FRD file, but how do you incorporate the PR in VituixCAD?
I've not done a PR with VC, but I wouldn't create a driver to do it. VC has a tool (Tools menu) called (I think) merge. This is normally used when measurements only work down to the upper bass (which is typical in a room), and you measure the bass separately and combine them. It joins two frds using one below and one above some frequency.

You'll need a shot of the PR+driver low end. (You may use VC to scale it as well)
Quote:
I also brought down the tweeter a bit
Flat isn't necessarily a perfect choice anyway.
Quote:
Speaking of BSC, I was not aware of this and did some research. Does this basically mean I need to bring down the tweeter a bit in order to compensate the speaker being up against the wall? (which squashes the lower end) Or do I need to add some circuitry to the tweeter to address BSC?
The ideal on-wall speaker needs no compensation. What you are building isn't ideal, but it is not typical BSC either. Exactly what is hard to say, but I'd be happy to make a few guesses to set you in the right direction, just say so..

Oh, and what do you mean by squashes the low end?

Last edited by AllenB; 10th November 2019 at 04:51 AM.
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Old 10th November 2019, 05:03 PM   #8
jcl1 is offline jcl1
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Join Date: Nov 2019
AllenB, you're definitely helping point me in the right direction. Now I see I need a better understanding of half-space, diffraction, BSC, merging in order to incorporate the PRs into the simulation with any kind of accuracy. Looking into how to do that now using VC.

Last edited by jcl1; 10th November 2019 at 05:16 PM.
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Old 12th November 2019, 06:41 AM   #9
jcl1 is offline jcl1
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I decided to investigate a 3-way design since I was having a tough time working out the crossover region of the 2-way design.

New 3-way layout:

Click the image to open in full size.

I followed this VituixCAD video which I think shows how to incorporate the baffle into the simulation:

YouTube

From what I gathered, the Enclosure is used to combine the woofer and passive radiator responses into one, and Diffraction tool does the baffle compensation and exports off-axis responses of all the components (woofer+pr, midrange, tweeter). Then with all this data, the crossover can be designed in VC.

First, the Enclosure tool gave the total SPL and impedance data for the woofer+passive radiators:

Click the image to open in full size.

Then, I used the Diffraction tool to get off-axis data for each woofer+PR, midrange, and tweeter:

Woofer+PR:
(note, I don't know if there's a way to layout the PRs here, but I believe they're still represented in the data that came over from the Enclosure tool)

Click the image to open in full size.

Midrange:

Click the image to open in full size.

Tweeter:

Click the image to open in full size.

When exporting each of these from the Diffraction tool, if the corresponding driver is selected in VC, then the off-axis frequence response data is automatically loaded onto that driver. Nice!

After a lot of tweaking, here is the crossover I came up with so far:

Click the image to open in full size.

Comments? Feedback? I would love to understand what can be improved since I'm still very new to this.
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Old 12th November 2019, 09:31 AM   #10
AllenB is offline AllenB  Australia
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3-way, ok. I didn't think the 2-way was going so badly. I wouldn't put too much stock in a simulation close to the breakup region of a driver.

Is that two tweeters side by side? Something I probably wouldn't do.

Not a bad attempt with the crossover but a few issues, one is the impedance falling near 2 ohms.
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