2-way crossover with 15WU8741T00 advice needed

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achoh

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Joined 2021
#1
Hi to all. I am very new in DIY, but decided to make Scanspeak Lumine, as heard it at Youtube and was impressed by their clear sound. But as i already have 8-ohm tweeters (the ones from Sony ss-g55, 8 ohm, biocellulose), and decided to use 8-ohm version of SS 15WU8741T00, instead of 4-ohm 15WU4741T00 (mainly to avoid different impedance of tweeter and woofer). It seems that it will be something very different from the Lumine, but I hope that the woofer will give a good quality sound. Followed instructions in "Introduction to designing crossovers without measurement " thread, and made calculations, so I ended with the crossover shown. Can someone explain what is the role of R3 and L2 in the original Lumine crossover, and give advice on this crossover in general? Thanks in advance.
 

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#2
R3 and L2, along with the drivers form the second branch of the respective filters, increasing order to three. What you've drawn do not use further branching and are therefore just second order filters. You have also forgotten to invert one of the drivers to compensate for the 180* phase shift between them.
 
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#3
I would advise rather to modify the original loudspeaker that you are using as parts donor. Its woofer seems worth exchanging for the one with better bass capabilities. A three way like that is superior to a lumine kit. There is a SS-G55 service manual available, and it appears to be an intelligent design.
 
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#4
Thank you both for advices! Unfortunatelly i already sold ss-g55, than bought just tweeters, as they are the best tweeters i ever heard - amazingly natural and fast. I also have a problem with a space, so going with something small 2-way bookshelf, in the size of Lumine, is the only option. That's why need to create some "Lumine-style" project, already purchased boxes and damping, but stucked at crossovers for now.
 
#5
To make any kind of a simulation to help you with this project, first we need a manufacturer datasheet containing FR, Impedance and T/S parameters of the unknown tweeter, measures of an enclosure (and baffle). I don't know if you can find anywhere Sony specs, but these would either have to be measured or made up by guessing a lot. So in short, tell us exactly what parts (their specs) do you have right now.
 
#9
Btw, there is a difference in impedance between tweeters of ss-a5 and ss-g55, last ones i measured today - 8 Ohm. SS-a5 tweeters are 6 Ohm. So at least no need for impedance equalization in the crossover probably? Eh, wish to have some electrical background, to fully understand the roles of each passive element in the speaker crossovers.
 
#11
Well, try changing 22(R4) in the original circuit to a higher value around 40. It's more or less the same curve, only with 6 ohms (vs 8).
Untitled-1.jpg

.. wish to have some electrical background, to fully understand the roles of each passive element in the speaker crossovers.
Click to expand...

For scaling LC filters according to changing impedance (8 ohms to 4ohms etc.), use R1/R2 = L1/L2 = C2/C1. New filter works for new load impedance, with the same cutoff frequency, Q factor and response.

All the best.
 
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#15
I use regular SPICE to verify filters and networks but you may want something else that simulates loudspeakers properly. Try VituixCAD maybe.

Here is an online filter simulator for getting to know the basics of how values scale with frequency, load impedance etc.
 
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