Introduction to designing crossovers without measurement - Page 10 - diyAudio
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Multi-Way Conventional loudspeakers with crossovers

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Old 26th August 2012, 08:16 PM   #91
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Wow, excellent and detailed work AllenB, this will be of great help for newbies like me who want to take the DIY route. (My goal is to design a stereo system having a common sub-woofer, and a pair of woofer-tweeter network.)
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Old 15th November 2012, 07:54 PM   #92
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WOW ....what a great explanation
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Old 5th December 2012, 08:44 AM   #93
deena is offline deena  India
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Good effort, simplified, practical steps.Thanks Allen for the thought.
BTW, for members interested in similar methods.check this too - Practical tips loudspeaker DIY
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Old 26th December 2012, 04:30 PM   #94
rave959 is offline rave959  United States
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Allen B,

Thank you for taking the time to explain the basics. It helped me understand the fundamentals. My hat's off to you.


Sincerely,
Christian
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Old 18th January 2013, 01:09 PM   #95
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Still working through it all, but I have to say this is one of the most helpful and succinctly written pieces on audio i have ever read.

Bravo!
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Old 12th February 2013, 07:50 AM   #96
Stevenn is offline Stevenn  Australia
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Thanks AllenB for a very helpful tutorial that has certainly helped me understand speaker design basics.
One qsn - which software programme are you using to model response from 2 drivers at once? I have used WinIsd and Unibox but unless I am misusing them (entirely possible!) they only model one driver at once.

Thanks
Stevenn
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Old 12th February 2013, 11:20 AM   #97
AllenB is offline AllenB  Australia
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You're looking for crossover design software rather than box software, and it has always been a little hard to come by. For many years out of necessity I wrote and used my own software to model speakers and design crossovers. Then I got myself onto the net, but there still wasn't much. Professional packages used to be little known and quite expensive.

The program I used for the illustrations in this thread is xoversim, available at the FRD consortium where you'll find a number of good tools. xoversim only does crossovers, but it's effective and doesn't take long to get results once you learn to use it.

The *.frd file seems to be at the centre of most crossover design tools. It's a text based file that lists frequency, level and phase and it's companion file, *.zma is for speaker impedance. You can create them with sims or from real measurements.

Speaker workshop is one that I use more often nowadays. It might seem clunky and a little austere at first, but get past that and it has such a versatile manner that you can experiment freely, as opposed to just filling in all the boxes and pressing the 'give me the answer' button. Good for manipulating FRD files and making crossovers.

These days I prefer to measure as much as I can before designing a crossover, but at one point I would simulate as much as I could instead. Some people simulate their box, baffle, and even the drivers response and impedance in order to create their data files to make crossovers with. If you look through the FRD page you'll find a number of tools and it is often necessary to use several at a time to achieve the end result.

One of these is PCD (passive crossover designer). I don't have much experience with this one but it seems popular. It is based on an excel spreadsheet. It seems reasonably straightforward to use and combines some of the above functions.

For more advanced users, there is Speak available from gedlee.com which is known for being accurate particularly with modelling wave constraining devices. For existing programmers there is Akabak. It is script based, and the hardest to use but the sky's the limit. I've also used a more recent program called (if I remember correctly) 'xo', which can model crossovers taking into account a speaker's directivity and display polar plots.

With that said, I still find it near impossible to design a crossover 'properly' without continuing to write my own utility programs. The most important thing is simply to know just what you are trying to achieve and how you would like to get there.
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Old 12th February 2013, 07:54 PM   #98
Stevenn is offline Stevenn  Australia
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Thanks AllenB yr reply.
I have downloaded Jeff Bagby programme and it is a little daunting... to the novice.
Main issue for me is the FDR and ZMA files, the only way i could create them was to use Unibox first and then export those files to Crossover programme. Is this correct?

Also if i have a sealed 1" Peerless 812978 tweeter, what do i put down for Vas? Programme does not work without some value here.

Thanks
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Old 12th February 2013, 09:08 PM   #99
JackNZ is offline JackNZ  New Zealand
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This is a very good tutorial. Shure took a long time writing it.
Good you pointed out that a speaker with a 12dB lowpass over it is not necessarily dropping of 12dB/okt but more, adding the filters reaction to his natural slope. Very important information for people that are thinking of using standard x-overs which they can buy and then believe they would have a certain filterslope and they're drivers would then work together like in the book.
I still prefere meassuring during designing x-overs but not everybody will get themselves the necessary equipment and then there's still much to go wrong.
By the way hello to everybody here. I came to this forum because there's much real knowledge around here as I can see.
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Old 13th February 2013, 05:34 AM   #100
AllenB is offline AllenB  Australia
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@Stevenn, There are many ways to create the files. A common approach would be to use the SPLTrace utility from the FRD software pages. Find a response plot from your manufacturer and turn it into a data file (this may get around your Vas problem, and in a better way as well).

You can then use another tool to extract phase information from that data file. Don't forget to include the physical separation (ie. the extra delay from the way the drivers are mounted on the baffle) when you go to use FRD data that has had a minimum phase extraction tool used on it.

I like to create new sets of data files after each significant process. This way I have snapshots I can go back to when I make a mistake, or when I change my mind on how I'll process something.

You can also create useful files by exporting a measurement. You can often export as a text file, ascii or in some human readable form. The most you may have to do is open it up in a text editor (notepad) and strip the headers (title lines) and rarely to remove commas, and to check the last line ends with enter being the last thing pressed.

You can even use the text editor to create the files.
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