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Multi-Way Conventional loudspeakers with crossovers

New crossover for my current speakers
New crossover for my current speakers
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Old 22nd November 2017, 08:46 PM   #1
Rullknufs is offline Rullknufs  Sweden
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New crossover for my current speakers
Default New crossover for my current speakers

Hello everybody!

I have a pair of DIY speakers using a pair of Morel CAW638 woofers and a Morel CAT408 tweeter in an MTM design. Baffle is 24cm wide.

The current crossover is a very simple one, 7.27F cap (6.8F + 0.47F) and a 0.27mH inductor coil.

I know absolutely nothing about crossovers and crossover design so maybe you can help me out a bit? I asked in a Facebook group and was recommended this

Click the image to open in full size.

It makes very little sense to me and I have no idea whether or not it's a good starting point for a new crossover.

What would you recommend? And why?
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Old 23rd November 2017, 12:18 AM   #2
asuslover is offline asuslover  Romania
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New crossover for my current speakers
No experience ? No measuring instruments? Then try this:Crossover Design: Madisound Loudspeaker Parts: Raw Speaker Drivers and Passive Crossover Parts
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Old 23rd November 2017, 05:38 AM   #3
system7 is offline system7  United Kingdom
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I think asking Madisound to do it for you is not very diy!

Firstly could you elaborate on what you have right now. I would guess the basses are running direct, and the tweeter has the series capacitor and the shunt coil? A second order tweeter filter?

This shouldn't be too hard. One of our moderators knows a thing or two about Morel drivers, too.

These are excellent and expensive drivers which can work OK on the simple filters, but we like to do a proper job for the top sound.

Click the image to open in full size.

What you have there is a simple coil and cap filter, better than your current effort, because you have impedance correction on the bass units for 6dB slope, and correction of the tweeter resonance for another smooth slope. Again 6dB/octave (electrically), IIRC.

Before I build it, I would want to know the values are correct. I'm busy right now, and would only do this if you are serious about the project, but we need to look at the frequency response and impedance of the drive units to see if it all looks reasonable. The homework to take out the guesswork.

The stuff below won't make a lot of sense initially, except to suggest this has been done before, but us filter people undersand it all instantly.
Attached Images
File Type: jpg Eltim CA620 MkIII Serial Crossover.JPG (38.3 KB, 567 views)
File Type: jpg Eltim_CA620mkIII_schematic_Series_Crossover.JPG (55.4 KB, 558 views)
File Type: jpg Morel CAT 408 Tweeter.JPG (33.7 KB, 560 views)
File Type: jpg Dynaudio Sirius 17W75.JPG (42.8 KB, 185 views)
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Last edited by system7; 23rd November 2017 at 06:01 AM.
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Old 23rd November 2017, 07:44 AM   #4
Lojzek is offline Lojzek  Croatia
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Quote:
Originally Posted by Rullknufs View Post
Hello everybody!
What would you recommend? And why?

I am always interested in poly cone woofers technology so I will make you a filter proposal and a drawing of a baffle. Have you decided how much enclosure volume would be acceptable? Smaller ones lack woofer output. 30-40 liters would be enough to employ all the capabilitities these units have.
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Old 23rd November 2017, 08:41 AM   #5
AllenB is offline AllenB  Australia
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The crossover you post is probably a good start. Some of the values, take for example the RLC across the tweeter need to be selected carefully using measurement of some sort to work properly.
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Old 23rd November 2017, 10:19 AM   #6
Rullknufs is offline Rullknufs  Sweden
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New crossover for my current speakers
Quote:
Originally Posted by asuslover View Post
No experience, but I have a MiniDSP UMIK-1 measuring microphone and a multimeter.

Quote:
Originally Posted by system7 View Post
I think asking Madisound to do it for you is not very diy!

Firstly could you elaborate on what you have right now. I would guess the basses are running direct, and the tweeter has the series capacitor and the shunt coil? A second order tweeter filter?

This shouldn't be too hard. One of our moderators knows a thing or two about Morel drivers, too.

These are excellent and expensive drivers which can work OK on the simple filters, but we like to do a proper job for the top sound.

Click the image to open in full size.

What you have there is a simple coil and cap filter, better than your current effort, because you have impedance correction on the bass units for 6dB slope, and correction of the tweeter resonance for another smooth slope. Again 6dB/octave (electrically), IIRC.

Before I build it, I would want to know the values are correct. I'm busy right now, and would only do this if you are serious about the project, but we need to look at the frequency response and impedance of the drive units to see if it all looks reasonable. The homework to take out the guesswork.

The stuff below won't make a lot of sense initially, except to suggest this has been done before, but us filter people undersand it all instantly.
The tweeter have only the caps and the coil is for the woofers, so first order?
What values are you wondering about if they are correct? I am serious about the project. I built these when I was just a kid in high school with little knowledge and money. Now I have a well paid job that gives me plenty of spare time (working 12hr shifts 3 times a week) so I don't mind spending a little money on improving these speakers. As you say, they are good and expensive drivers and I feel like they aren't being used to their full potential with the current crossover, which is a shame I think.

Quote:
Originally Posted by Lojzek View Post
I am always interested in poly cone woofers technology so I will make you a filter proposal and a drawing of a baffle. Have you decided how much enclosure volume would be acceptable? Smaller ones lack woofer output. 30-40 liters would be enough to employ all the capabilitities these units have.
I have nice cabinets in 18mm top quality birch ply already. Cabinets are ~53.8L not excluding volume of drivers, braces, port, etc. So net volume is probably around 50L. Baffle is 100cm tall and 24cm wide (39.37" x 9.45"). Bass output is plentiful and well enough for my apartment.
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Old 23rd November 2017, 06:58 PM   #7
Lojzek is offline Lojzek  Croatia
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Have you learned how to measure speakers with a microphone?
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Old 23rd November 2017, 07:25 PM   #8
asuslover is offline asuslover  Romania
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New crossover for my current speakers
When I suggested "Crossover Design: Madisound Loudspeaker Parts: Raw Speaker Drivers and Passive Crossover Parts" I meant the design only, not the actual crossover, my advice was only to try to help him save his time and money, capacitors and coils are not cheap, his drivers are not cheap either.
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Old 23rd November 2017, 08:23 PM   #9
Rullknufs is offline Rullknufs  Sweden
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New crossover for my current speakers
Quote:
Originally Posted by Lojzek View Post
Have you learned how to measure speakers with a microphone?
I think I have a basic grasp of how it works, but I'm sure there's more for me to learn.
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Old 24th November 2017, 10:56 AM   #10
system7 is offline system7  United Kingdom
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I had a little go at this one, but if Lojzek is on it, I'll keep largely schtumm here.

Click the image to open in full size.

I don't know what this is at all really. It isn't right for the CAT 408 on the 800Hz Fs correction at all. At the bass end the coil seems excessive, and the impedance correction looks overdone.

The Frequency response of the Morel CAW 638 is quite challenging, but might be OK on a coil and impedance corrrection like 0.6mH and 4.7R plus 27uF. I seemed to get a second order tweeter too, which actually wasn't too bad on existing 6.8uF and 0.27mH with the usual option of a ca. 2.2R resistor at the input for level adjust. People have also used a 4.4kHz trap on that bump but I didn't go into that. I had these files, because I think we did this one a while back.
Attached Images
File Type: jpg Morel_CAW-638.JPG (82.0 KB, 215 views)
File Type: jpg Morel_638_Trap.JPG (49.7 KB, 93 views)
File Type: jpg Morel CAT 408 Tweeter FR.JPG (68.6 KB, 87 views)
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Last edited by system7; 24th November 2017 at 11:14 AM.
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