I recently picked up this pair of large stand mount home brewed speakers using Vifa XT25TG30-04 and Dayton RS180-8; thanks pjblakey!. The waveguides are turned from cherry wood and profile is taken from Zaph Audio website. The enclosures are transmission line and scaled similarly to PMC twenty series. They were designed and tested using MiniDSP, but my goal is to finish the speakers and build a passive crossover that makes these sing.
With an initial guess based on the previous electronic crossover, I started with a 2nd order 2-way crossover, the speakers had an impressive start. To no surprise, the bass has great depth and extension for a monitor (bookshelf) speaker for the size due to the TL design, and they will not require a subwoofer for music on first impressions. I have some phase issues to deal with on the tweeter, but as of right now, these would already be good off the shelf speakers without further tweaks. The sound stage is great and the body and sense of space of the music reproduction is just as good.
My next step is to adjust the crossover point up a little from 1800hz, drop the output of the tweeter a little, and see if the frequency response would benefit from a notch filter or two after that.
With an initial guess based on the previous electronic crossover, I started with a 2nd order 2-way crossover, the speakers had an impressive start. To no surprise, the bass has great depth and extension for a monitor (bookshelf) speaker for the size due to the TL design, and they will not require a subwoofer for music on first impressions. I have some phase issues to deal with on the tweeter, but as of right now, these would already be good off the shelf speakers without further tweaks. The sound stage is great and the body and sense of space of the music reproduction is just as good.
My next step is to adjust the crossover point up a little from 1800hz, drop the output of the tweeter a little, and see if the frequency response would benefit from a notch filter or two after that.
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Based on the manufacturer graphs on the woofer, it appears that the frequency response start to waver from 1.5kHz - 2.5kHz, but then really drops off after 3kHz. So possibly a 2kHz 6dB crossover would be an appropriate match for rolling off the top end of the woofer until it gets real ugly at 4kHz, and still be a high enough point with the tweeter waveguide mounted? Due to the nominal 4ohm tweeter and 8ohm woofer, tonight I'm going to try a 20uF cap on the woofer and a .6mH coil on the woofer and see where it gets me. I'm also going to try a 16uF cap and .5mH inductor for what should be a 2.5kHz which should be beneficial to the tweeter, but may be detrimental to the response of the woofer.
I'm also going to try a 6dB L-pad on the tweeter as a start.
I'm also going to try a 6dB L-pad on the tweeter as a start.
Coming.
For the sake of testing, I know putting two inductors in series creates a total inductance of their added values. Can this reasonably be done in crossover testing without negative effects? Maybe addition of the coils resistances? i.e. I'd rather add a 0.1mh to a 0.5mH for testing than purchase a 0.6mH coil for a possibly unsuccessful test.
For the sake of testing, I know putting two inductors in series creates a total inductance of their added values. Can this reasonably be done in crossover testing without negative effects? Maybe addition of the coils resistances? i.e. I'd rather add a 0.1mh to a 0.5mH for testing than purchase a 0.6mH coil for a possibly unsuccessful test.
Most problably that's the break up o the RS180 what you are hearing. First order electric or not, what you need is a notch filter, most simple way just a small cap parallel to the coil.
What do you suggest for software? 
This looks very similat to 2/3rds of mine which are still under construction and will have a mid in a sealed spheroid on top for a MTW transient Peters 3 way.
http://www.diyaudio.com/forums/multi-way/297171-rs28f-rs180p-b80-hole-filler-3-way.html
I am using two passive radiators on the back
The RS180P has a harmonic distortion peak at 2kHz - inherent in the driver be manages to sound fine when XO'd at around 1500Hz.
http://www.diyaudio.com/forums/multi-way/297171-rs28f-rs180p-b80-hole-filler-3-way.html
I am using two passive radiators on the back
The RS180P has a harmonic distortion peak at 2kHz - inherent in the driver be manages to sound fine when XO'd at around 1500Hz.
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Omnimic, DATS, and XSim(or PCD) are the bare minimum for accurate crossover development.
http://audio.claub.net/software/jbabgy/jbagby.html
http://www.diyaudio.com/forums/software-tools/259865-xsim-free-crossover-designer.html
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http://audio.claub.net/software/jbabgy/jbagby.html
http://www.diyaudio.com/forums/software-tools/259865-xsim-free-crossover-designer.html
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