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Multi-Way Conventional loudspeakers with crossovers

Crossover exercise !
Crossover exercise !
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Old 20th July 2018, 06:38 PM   #1
Aatto is offline Aatto  United States
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Default Crossover exercise !


So just for sake of practicing, I decided to design a 4 way crossover from scratch. Drivers are :

Tweeter : Dayton Audio RST28F-4
Mid : ScanSpeak 10F/8414G10
Woofer : SBA SB23NRXS45-8
LF : Dayton Audio RSS265HF-8

the only reason i chose these is because i had the frd/zma for them !
it is a simple 1st order crossover crossed at 100/700/7000Hz.

So tell me how i did, why good, why bad and what would you change ?

Thanks
A.
Attached Images
File Type: jpg 4 Ways - 02 XO.jpg (48.1 KB, 496 views)
File Type: jpg 4 Ways - 02 Graph.jpg (86.1 KB, 491 views)
File Type: jpg 4 Ways - 02 GD.jpg (72.1 KB, 487 views)
File Type: jpg 4 Ways - 02 SR.jpg (25.9 KB, 478 views)
File Type: jpg 4 Ways - 02 Impedance.jpg (61.1 KB, 474 views)
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Old 20th July 2018, 10:11 PM   #2
PeteMcK is offline PeteMcK
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the SB23NRXS45-8 will need at least a 2nd order HP filter, look at the breakup zone on its FR graph;
you haven't said whether you took baffle step into account...
not much point in zobelling the tweeter, if you're using a flat baffle I'd go 2nd order for the tweeter
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Impedance varies with frequency, use impedance plots of your drivers and make crossover calculations using the actual impedance of the driver at the crossover frequency
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Old 21st July 2018, 12:03 AM   #3
system7 is offline system7  United Kingdom
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You are wasting your time with Mickey Mouse circuits.

Try designing something good.

Replicate this Troels Gravesen 3 way with the SB bass, the scan mid and the tweeter. Try to get the same slopes.
SBAcoustics-3WC

If you are struggling for a starting place, try this configuration for some typical component values back from when he gave it away:
SEAS-3-Way-Classic

You might end up with something you fancy building. I enjoy trying Troels circuits with different drivers. It's the idea that matters.
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Old 21st July 2018, 04:31 PM   #4
Aatto is offline Aatto  United States
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Quote:
Originally Posted by PeteMcK View Post
the SB23NRXS45-8 will need at least a 2nd order HP filter, look at the breakup zone on its FR graph;
you haven't said whether you took baffle step into account...
not much point in zobelling the tweeter, if you're using a flat baffle I'd go 2nd order for the tweeter
no baffle step here, i know w 1st order i need a baffle step but it s just training.
I have a working two way with SBA and SS, and as suggested i used a zobel on woofer to help w breakup and still keep it 1st order, i think that would do trick here as well instead of going 2nd order. the reason i skipped that here is that the graph look flat and i thought i can get away w it.

System7 suggested XO from Troels designs have a 2nd order on tweeter as well, will study it more

Quote:
Originally Posted by system7 View Post
You are wasting your time with Mickey Mouse circuits.

Try designing something good.

Replicate this Troels Gravesen 3 way with the SB bass, the scan mid and the tweeter. Try to get the same slopes.
SBAcoustics-3WC

If you are struggling for a starting place, try this configuration for some typical component values back from when he gave it away:
SEAS-3-Way-Classic

You might end up with something you fancy building. I enjoy trying Troels circuits with different drivers. It's the idea that matters.
the reason i start from scratch was to learn, but having an starting point will also help, from my understanding Troels SBA crossover has a 1st order on woofer and 2nd on mid and tweeter, it would help if i had the FRD files for this so i could simulate and see how it works, i may need to start tracing

thanks for the input guys, lemme know if you have any other suggestions, gonna start working on my homework.
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Old 21st July 2018, 06:15 PM   #5
eriksquires is offline eriksquires  United States
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You are also missing driver distances. Once you add that in all your phase matching will go to hell.

Best,

Erik
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Old 22nd July 2018, 01:07 AM   #6
system7 is offline system7  United Kingdom
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I dislike all the CAD sims I have seen. They all seem quite unintuitive to me. They seem to all stem from Linux open source code.

Visaton Boxsim has a much shallower learning curve IMO:
Software | Visaton

Just stick any project bpj file you want from this huge library of designs in the projekte folder and you get the whole thing to play with.
Boxsim Projektdatenbank

I don't think 2 wege is difficult to translate to two way! You can import frd and zma files for non-visaton drivers and guess acoustic centre. But really, seen one woofer, you seen 'em all...

FWIW, acoustic centre is usually near the middle of the driver voicecoil. It's important for phase. Visaton files include the figure, and you soon spot the pattern.
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Old 22nd July 2018, 01:07 AM   #7
wintermute is online now wintermute  Australia
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Crossover exercise !
I'm having a bit of a play just with the SB driver, without having put baffle step in the equation and I must say it will require a really complex filter to try and get it doing a 1st order acoustic at 100 and 700Hz!! I like a challenge but it does not look very feasible.

That is one of the misconceptions that people have. A first order crossover doesn't mean first order electrical. A true first order crossover is far more complex than a cap or an inductor. If I manage to pull something off (for that one driver) I will post it, but I'm not holding my breath

Tony.
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Old 22nd July 2018, 01:11 AM   #8
wintermute is online now wintermute  Australia
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Crossover exercise !
Steve, have you had a look at vituixcad? I've started using it recently and really like it.

Tony.
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Old 22nd July 2018, 01:33 AM   #9
system7 is offline system7  United Kingdom
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I did try Vituix CAD. I hadn't a clue what was going on even with the supplied file from somebody here.

If I want to know what to do with a driver, I usually just go to Mr. Troels Gravesen. DIY-Loudspeakers

A safe pair of hands as us Cricket fans say. Our own Michael Chua is a clever bloke too.

Seas ER18RNX with 27TDFC

Speaker of the Year, IMO. Genius. (OK, the tweeter section could be better... but clever.)
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Old 22nd July 2018, 02:17 AM   #10
wintermute is online now wintermute  Australia
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Crossover exercise !
OK I had a play. Note that this is just the traced manufacturer curves. No baffle effects, no changes to reflect a proper alignment of the driver. I chose 88db as the target. Also this does not take into consideration how it will mate with other drivers!! It was purely an exercise in seeing whether I could massage it to fitting a 1st order slope at 100Hz HP and 700 Hz lp.

I modeled in vituixcad but did the overlays in speaker workshop. Black is with the network shown, blue is the original driver response, and green is the OP's single 1.2mH coil.

Tony.
Attached Images
File Type: png sb23nrxs45_1storder.png (28.8 KB, 103 views)
File Type: png sb23nrxs45_network.png (9.7 KB, 101 views)
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