Crossover for RAAL 140-15D x ScanSpeak 12MU-4731T0

KING DRANZER

Member
2020-01-28 10:18 am
Not long ago I was looking for advise on Tweeter and Woofer selection for Two way crossing. I was looking for ribbon speaker which could have decent vertical dispersion. After a great help from forum members and gathering info from other sources, I had to settle for RAAL 140-15D which is considered to have best off-axis coverage for any ribbon tweeter(correct me if I am wrong). As I am going with that high caliber tweeter I guess I must pair it with suitable woofer. My limitation for woofer is that the size should be 3" or 4" max and nothing big and should be recommended for sealed enclosure so I picked up ScanSpeak 12MU-4731T0. I will using two woofers in series and cross them with tweeter in parallel. If there is a better woofer that can be paired in combo of RAAL 140-15D then please, I am open for suggestions.



This being my first crossover I need to be corrected and advised to do it right. This is what I have done so far using software "Passive Crossover Designer". I am posting few pics below.



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I would like to know what am I doing wrong and what to improve and do correct.
 
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You can post the x/o schematic.
By looking at the component values for the HP something is not right, very odd values.
Have you designed crossovers before?

Check RAAL site, there is a recommended x/over as a good starting point.

The impedance with two 12MU's in series and RAAL should be min 9 Ohms rising to above 15 Ohms in the tweeter range, considering the needed padding resistance.

Also TNT is right, the 12MU is not a woofer, even with a sub. You want a proper 3-way, a single traditional (<80/100 Hz) sub will not be optimal.
 
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This is a very rough simulation based on traced FR and Impedance curves for both drivers (12MU 2Xseries) and is only a guideline of what is to be expected in the final system impedance. This is not an actual representation of the baffle/box you will be using, for that you need to measure. I did not use your zip files but my own tracings.

See attached:
 

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This is a very rough simulation based on traced FR and Impedance curves for both drivers (12MU 2Xseries) and is only a guideline of what is to be expected in the final system impedance. This is not an actual representation of the baffle/box you will be using, for that you need to measure. I did not use your zip files but my own tracings.

See attached:
This is what I am getting as a result by inputting your values.



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Tweeter Inverted Polarity.
 
OK so this is different than the initial 1-Ohm diving curve, now the impedance looks as expected. So go on from there and tweak.

What are you using for FR and Imp: traced graphs from manufacturer or other site, or you do have the speakers+box and your own measurements?

The only correct way is to use the measurements from the actual speaker/box. What I showed was only a guideline, which does result in a predictable Impedance, and is a possible starting point for further refining.
 
OK so this is different than the initial 1-Ohm diving curve, now the impedance looks as expected. So go on from there and tweak.

What are you using for FR and Imp: traced graphs from manufacturer or other site, or you do have the speakers+box and your own measurements?

The only correct way is to use the measurements from the actual speaker/box. What I showed was only a guideline, which does result in a predictable Impedance, and is a possible starting point for further refining.


Thank you will tweak it further.



I was taking the info from graphs provided by Manufacturers.


Is the pairing of that RAAL tweeter and ScanSpeak woofer good. Or is there any other recommendation for woofer which is better suited for that tweeter while having same or even compact dimensions than that Scanspeak,


What will be total impedance of the speaker.
 
Correction: the simulation was done with the 8 Ohm version of Scan 12MU and not the 4 Ohm, by mistake. But the principle is the same...Lower L1 inductor for the LP, lower series R for Tweeter padding.

The RAAL is top-notch driver. You want the smallest possible quality-matching mid-bass. Your first idea was 2x12MU, so not so small baffle. For the same baffle surface, or even smaller, there are number of excellent 5" drivers.
If the price reference is the cost of two 12MU's, then you have wide choice starting with SB (NBAC and CAC), then Satori 13's, then Scan 15W Revelators, SEAS Excels, up to Audio Technology. All the usual suspects.
 
Correction: the simulation was done with the 8 Ohm version of Scan 12MU and not the 4 Ohm, by mistake. But the principle is the same...Lower L1 inductor for the LP, lower series R for Tweeter padding.

The RAAL is top-notch driver. You want the smallest possible quality-matching mid-bass. Your first idea was 2x12MU, so not so small baffle. For the same baffle surface, or even smaller, there are number of excellent 5" drivers.
If the price reference is the cost of two 12MU's, then you have wide choice starting with SB (NBAC and CAC), then Satori 13's, then Scan 15W Revelators, SEAS Excels, up to Audio Technology. All the usual suspects.


The baffle is thin and tall with max width 4". So I can add multiple drivers in vertical array. But I plan on building separate partitions for each woofer of volume 2l which will be closed as recommended by manufacturer for that 12MU driver.