Help with MTM 2 way crossover!!!

Donny14

Member
2016-02-16 2:53 pm
Hi,

Heres my designe.. I have 2 RS180-8... A 1 RS28F-4. I want to build a pair of speakers with these! Each speaker will contain those 3 speakers obviously.. Since ive only really ever explored the world of full ranges and have attempted one multiway system, im still a bit new to crossovers but still understand them fairly well!! I was wondering de f anyone had any suggestions on the volume of the cabinet, and the spacing between the centers of woofers and tweeter? And then what would the optimal crossover be?

My real problem is that i dont have the simulators or required programs to calculate this!! I really need help for mainly the cross overs!

Please let me know what you think and ask any questions!!
 

wintermute

Administrator
Paid Member
2003-08-03 11:43 am
Sydney
Just mount the drivers as close together as possible.

Your tweeter can be crossed low by the looks of the specs.

Download xdir Tolvan Data It will give you an idea what the lobing will look like at various crossover frequencies.

Note that 1/4 wavelength (CTC distance is no more that 1/4 wavelength of the crossover frequency) is the holy grail, but that is generally quite difficult to achive. even 1/2 wavelength is quite good, but still difficult to achieve with all but the smallest M's and a very small faceplate tweeter).

I have a crossover frequency much higher than 1/2 wavelength on my own MTM, That is not at all noticable when seated, but you do notice quite a roll off in the treble when standing (due to there being a null at that height).

having a play with this calculator (to see what the wavelength is at various frequencies) will show you why it is VERY hard to get to 1/4 Wavelength! The CTC distance is between the centres of the M's!!

Tony.
 
Aye I remember someone recommending the Parts Express RS180 design when I first found this DIY website.
Probably should have listened back then, but then again -- wouldn't have found these (image below) Dayton 28F tweeter with Anarchy woofers: They measure beautifully and have unbelievable bass extension.
Would like to hear a side by side comparison someday RS180 vs. the Anarchy.

MTMs.png
 

eriksquires

Member
2013-05-10 4:11 pm
Hi,

Heres my designe.. I have 2 RS180-8... A 1 RS28F-4. I want to build a pair of speakers with these! Each speaker will contain those 3 speakers obviously.. Since ive only really ever explored the world of full ranges and have attempted one multiway system, im still a bit new to crossovers but still understand them fairly well!! I was wondering de f anyone had any suggestions on the volume of the cabinet, and the spacing between the centers of woofers and tweeter? And then what would the optimal crossover be?

My real problem is that i dont have the simulators or required programs to calculate this!! I really need help for mainly the cross overs!

Please let me know what you think and ask any questions!!

Hi Donny!

I just posted a process in another thread, here. It does assume you know your cabinet dimensions though. For that, I suggest WinISD (not the pro version!). Start there, then follow the instructions in the thread above.

You will need something if not OmniMic. Lots of people use Room EQ Wizard. There's also a really cheap calibrated mic you can use with it, here. It's for smart phones with apps. I'm not sure how easily you can export from your phone to XSim, but you should be able to get the mic working with a PC or laptop just as easily.

Once you have at least FRD and impedance plots you should be able to get lots of help here. :)

I just realized you are specing Dayton drivers so the impedance charts would be a breeze. Also, cabinet information is included in the Parts Express page. Just double up the cabinet volume for 2. Use WinISD to see how well it may fit into smaller or larger cabinets as well as for picking the exact port diameter and length. A lot of times the difference between optimal volume and 30% less makes very little difference so you can fit a lot of things into the standard Dayton cabinets.

Best,


Erik
 
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