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Multi-Way Conventional loudspeakers with crossovers

Crossover exercise !
Crossover exercise !
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Old 22nd July 2018, 08:02 AM   #11
TBTL is offline TBTL  Germany
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Ouch, that seems complicated for a first order roll off.

Aatto, do you want to build passive crossovers or is DSP also fine? DSP is easier because there is no interaction between different crossover components or between the components and driver impedance. Shaping the transfer functions of the individual drivers and time aligning them (matching phase) also can be done separately. Just add or modify filters until the transfer function of the individual drivers matches some target curve. Then add delay for matching phase. You do need measuring equipment though, for measuring the transfer function after each filter modification, because many crossover design programs do not support simulation of DSP filters.

Last edited by TBTL; 22nd July 2018 at 08:05 AM.
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Old 22nd July 2018, 11:18 AM   #12
wintermute is offline wintermute  Australia
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Crossover exercise !
I read long ago that in order to do a true first order acoustic rolloff it usually requires a quite complex crossover (unless you have drivers that are completely flat for a long way either side of the intended pass band).

I'd never actually tried it, so the above is a first attempt and there may well be a better way, but as can be seen a simple electrical first order circuit doesn't cut it with this driver

Tony.
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Old 22nd July 2018, 12:25 PM   #13
system7 is offline system7  United Kingdom
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I don't have shares in Visaton, but I think Boxsim supports electronic/DSP crossovers, just not something I have used in the toolkit.

I tend to look at designs, maybe sim them, and ask myself what is good about them.

This is something ancient by W. Marshall Leach, one of the great theoreticians.

Click the image to open in full size.

Click the image to open in full size.

For those that are weak on theory, all good three ways look like this on Steen Duelund target curves if you want everything else to line up nicely:

Click the image to open in full size.

Don't argue about it with me. It's function of a complex variable, great mathematics, and it is proved for eternity like the Pythagoras Theorem. So just don't!

Marshall Leach has done a "proper job" on impedance correction on the bass there. It's not just an RC, is it? He has chosen flat and easy drivers. Lot to like. Very educational.

Now revisit Michael Chua's brilliant Starling. Do you get what is great about the bass section? Do the sim!

Seas ER18RNX with 27TDFC
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Old 22nd July 2018, 02:00 PM   #14
wintermute is offline wintermute  Australia
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Crossover exercise !
A question for Aatto. How did you get the dayton to do 90db? Is that with two in parallel? That would make sense since it is an 84db driver...

edit: oh I see, overlap

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Last edited by wintermute; 22nd July 2018 at 02:09 PM. Reason: light bulb...
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Old 23rd July 2018, 04:35 PM   #15
Aatto is offline Aatto  United States
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Quote:
Originally Posted by TBTL View Post
Ouch, that seems complicated for a first order roll off.

Aatto, do you want to build passive crossovers or is DSP also fine? DSP is easier because there is no interaction between different crossover components or between the components and driver impedance. Shaping the transfer functions of the individual drivers and time aligning them (matching phase) also can be done separately. Just add or modify filters until the transfer function of the individual drivers matches some target curve. Then add delay for matching phase. You do need measuring equipment though, for measuring the transfer function after each filter modification, because many crossover design programs do not support simulation of DSP filters.
I already build some w miniDSP, and was able to do a Harsch XO w my FAST system, and if i ever want to build such 4 way monster I would go with DSP for LFs and Passive for HF, mr Troels did same thing in one his speakers if i m not mistaking or was it someone else ?

anyhow this is just a pure training attempt to learn about more complex setup and at the moment i m not planning to build such speaker, i did some simple working passive XOs before and i m just trying to learn something here

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Originally Posted by wintermute View Post
I read long ago that in order to do a true first order acoustic rolloff it usually requires a quite complex crossover (unless you have drivers that are completely flat for a long way either side of the intended pass band).

I'd never actually tried it, so the above is a first attempt and there may well be a better way, but as can be seen a simple electrical first order circuit doesn't cut it with this driver

Tony.
I can see what you r saying, and as you said it depends on driver and how they behave, your attempt on the crossover was very interesting, i m still studying it to learn the effect of each step.
talking about 1st order, i did designed the simplest 1st order for my FAST and it is in my current system and i m really enjoying it, it was running w miniDSP
and mr Harsch XO but i prefer the passive XO, anyhow you can see the attached files. i just added a zobble to woofer and some padding to FR.
But I know this is not the case all the time and i wouldn't get away w it in other case. could it be better ? absolutely. but I ll learn and make it better.
Attached Images
File Type: jpg _DSC6937.jpg (162.5 KB, 211 views)
File Type: jpg unnamed.jpg (340.9 KB, 211 views)
File Type: jpg XO 02 FR2.jpg (103.7 KB, 77 views)
File Type: jpg XO 02.jpg (26.8 KB, 69 views)

Last edited by Aatto; 23rd July 2018 at 04:52 PM.
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Old 23rd July 2018, 11:26 PM   #16
wintermute is offline wintermute  Australia
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Crossover exercise !
I was going to say that active would be the way to go with the lower drivers. I've got effectively a three way (separate cabs for woofers), with an active cross at 270 hz between the woofer cab and the MTM with a passive crossover on the MTM. It works quite well.

Quote:
Originally Posted by Aatto View Post
anyhow this is just a pure training attempt to learn about more complex setup and at the moment i m not planning to build such speaker, i did some simple working passive XOs before and i m just trying to learn something here
Playing with this sort of thing in sims is the best way to get a feel for how you can alter the response of a driver to match your goals, you can learn an awful lot before you even purchase a component, and when you do purchase some components you have a much better chance of it being right, or close to right the first time

Quote:
Originally Posted by Aatto View Post
I can see what you r saying, and as you said it depends on driver and how they behave, your attempt on the crossover was very interesting, i m still studying it to learn the effect of each step.
talking about 1st order, i did designed the simplest 1st order for my FAST and it is in my current system and i m really enjoying it, it was running w miniDSP
and mr Harsch XO but i prefer the passive XO, anyhow you can see the attached files. i just added a zobble to woofer and some padding to FR.
But I know this is not the case all the time and i wouldn't get away w it in other case. could it be better ? absolutely. but I ll learn and make it better.
If you have measurements on that baffle and impedance measurements taken in the box as well, then you have all that you need to start playing and making improvements. You could try designing a 2nd order and a 4th order (acoustic not electrical) as well, make each and listen to them and see how they sound. When you nail it you will be amazed at the difference.

My MTM's started off with just a cap on the tweeter with the M's running full range and they sounded pretty good like that, then they progressed to a 2nd order acoustic crossover, and sounded better, but I was still looking for more. I then went to a 4th order acoustic (both the second and fourth order were bessel) and it was a quantum leap. I've been listening to that version for about 8 years now, but I'm looking at doing a new crossover now I've learned a few more tricks from seeing what others have done, and playing with sims.

Tony.
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Old 13th September 2018, 12:45 AM   #17
Aatto is offline Aatto  United States
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Default any improvements ?

Ok, Here's a 2.5 way XO, I used SBA NRX as a sub, I know it is a woofer with a wide FR but why not it is an exercise, the Mid is Volt 228.8 and Tweeter is 9130 with LR2.
Tried to hit Steen Duelund target curves as system7 suggested, so any improvements since last time or any suggestions ? how the impedance curve look ? I m abit concern about very mild dip between 1k and 2k, I know I can work around it tho.
Attached Images
File Type: jpg FR.jpg (225.5 KB, 61 views)
File Type: jpg Imp.jpg (222.7 KB, 53 views)
File Type: jpg Sim.jpg (61.4 KB, 64 views)
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Last edited by Aatto; 13th September 2018 at 12:52 AM.
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Old 13th September 2018, 08:33 AM   #18
wintermute is offline wintermute  Australia
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Crossover exercise !
I'm a bit concerned about the low freq impedance. I've nevervseen a resistor in parallel with a shunt cap. Not sure how that will affect the two shunt caps in paralell. But I'll assume they are effectively around the 50uf mark.

What's the impedace curve like without them?

Tony.
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Old 13th September 2018, 09:19 AM   #19
DBMandrake is online now DBMandrake  Scotland
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Quote:
Originally Posted by system7 View Post
I did try Vituix CAD. I hadn't a clue what was going on even with the supplied file from somebody here.
If you originally tried Vituixcad 1.x try 2.x. It's a major rewrite that switched from gluing together predefined ladder networks to full free-form spice style circuit design, and in the last few months it has improved a lot further as the author is constantly pumping out minor revisions.

Hands down the best free crossover CAD software I've seen or used, I used it exclusively (together with ARTA for measurements) for my last speaker design, and the results were spot on to its predictions. It can also do a lot more than just the crossover, it also does T/S box simulation, nearfield/farfield splicing including a 3D diffraction model, off axis, power response and polar response patterns etc if you provide more than just on axis measurements to it...

I started on V1.x then switched to V2.x when it came out part way through the design process, I found both very easy to use and rarely refer to the manual.
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Last edited by DBMandrake; 13th September 2018 at 09:28 AM.
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Old 13th September 2018, 10:09 AM   #20
Dave Bullet is offline Dave Bullet  New Zealand
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Originally Posted by eriksquires View Post
You are also missing driver distances. Once you add that in all your phase matching will go to hell.

Best,

Erik
He's right. your inputs are crap = crap result.
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