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Multi-Way Conventional loudspeakers with crossovers

2 way TL using SB23NBACS45 and SB29RDCN
2 way TL using SB23NBACS45 and SB29RDCN
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Old 8th November 2018, 12:03 AM   #91
Zvu is offline Zvu  Serbia
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Quote:
Originally Posted by Dissi View Post
Slowly, slowly.

From the LspCAD 6 manual (http://www.ijdata.com/LspCAD%206%20manual.pdf, page 6):
Back when i used PCD7 (forerunner of WinPCD) there was a catch about Z offset (positive value is closer to the listener).

Since Jason uses WinPCD i have no clue if it should be positive or negative value. That's why i offered both options so he can check in his simulator to see when will he get the same result.

When he does, that's the right offset.

Last edited by Zvu; 8th November 2018 at 12:08 AM.
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Old 8th November 2018, 01:43 AM   #92
eg92b16a is offline eg92b16a  Australia
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Hi,

The Z value in WinPCD is negative for further away from listener. The tweeter is set to zero for x,y, and z, as I'm measuring on axis with the tweeter. Woofer y coordinate is -185mm, and z coordinate is -14mm, so below tweeter and further away.

I tried plugging the crossover into winPCD, but because of the parallel bypass caps on the coils, it's hard to implement. I have to create a 4th order crossover, delete the coil values and then add 2 x series LC circuits. I think it works out, because when I create the crossover in X-Sim, the response looks similar.

The Z offset is quite tricky to get correct and very different to implement depending on the software used. I have WinPCD, Virtuix CAD, and X-Sim, and they can all give different results for the same data input. So which one should I believe?
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Old 8th November 2018, 07:58 AM   #93
Zvu is offline Zvu  Serbia
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Using crossover from post 81. i get the same results with PCD7 and LspCAD6.

Here is comparison:

1.png


As you can see, offsets are good and i attached an explanation for Z offsets in PCD7. In PCD7 i had to enter -14mm because it takes the tweeter as a reference point and woofer's acoustic center is behind the tweeter. In LspCAD i entered +14mm because it takes microphone as a reference point so you have to add the distance in regard to mic. In both tweeter is X,Y,Z - 0 offset.

2.png

4.png

Here's the tweeter.

3.png


I really don't know why are you getting different results but it could have something to do with simulated listening distance or Z offset.

Last edited by Zvu; 8th November 2018 at 08:18 AM.
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Old 18th November 2018, 06:05 AM   #94
eg92b16a is offline eg92b16a  Australia
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Default Finished

Hi all.

Here's my final crossover design for this project. It's a combination of Zvu's crossover and my own, using components I had in my parts bins.
The off axis response is really good and power response is excellent. I've checked and confirmed this in Win PCD. Everything matches in both software packages. It was the determination of Z offset in Virtuix CAD where I came unstuck.
I have been listening to them now for a few days and I like the way they sound. Slightly subdued but detailed at the same time. Female vocals shine. Bass is fantastic (I've turned my 12" subwoofer off).

Thanks to all who have helped and commented. I was close but not quite there until Zvu chimed in.
This is a great forum and look forward to doing more DIY projects in the future.

Cheers. Jason
Attached Images
File Type: gif SB TL 16.gif (209.0 KB, 101 views)

Last edited by eg92b16a; 18th November 2018 at 06:18 AM.
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Old 18th November 2018, 10:40 PM   #95
Dave Bullet is online now Dave Bullet  New Zealand
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You are re-extracting minimum phase after applying all your FRD modifications (baffle step and / or baffle diffraction) aren't you?
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"Usual diyaudio train wreck of dubious drivers and just the crossover to sort out. Well, how are you on crossovers and modelling? Pretty green, I reckon" - system7 (Steve)
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Old 19th November 2018, 03:06 AM   #96
eg92b16a is offline eg92b16a  Australia
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Quote:
Originally Posted by Dave Bullet View Post
You are re-extracting minimum phase after applying all your FRD modifications (baffle step and / or baffle diffraction) aren't you?
I'm using actual data obtained via calibrated ECM8000 mic and associated hardware. Using REW to extract frd files with minimum phase data.
My technique was explained quite a few posts back. Is there a problem with the way I have done things?
Nothing was mentioned previously?????
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