Hello all,
Whilst being stuck in lockdown, it’s somewhat comforting to have a hobby that keeps me off the streets at night.
Here’s a passive crossover I developed. My first crossover design.
Attached are on-axis and ~45 degrees off axis response, measured at 50cm; 1/24 octave smoothed, also showing distortion components.
One may notice the dip and peak at 2.5Khz & 4Khz due to tweeter diffraction (position on the baffle, and sharp cabinet edges, but they largely disappear off axis) (See tweeter only measurements)
I’ll be fine tuning this in weeks to come, by experimenting with a lower crossover point to take advantage of the Millennium tweeter- it’s got an underhung voice cool and generous Xmas- I can see why the late Siegfried Linkwitz (RIP) took it all the way down to 1.5Khz (see attached). At the moment it’s about 2.2KHz (+/- 100Hz).
Newer modern tweeters are much more affordable (like SB SDAC29, which I also have on hand) but this one fit my cabinet (110m faceplate)
This cabinet is 21L tuned to 40Hz
Any glaring faults?
Is there too much baffle step compensation?
Are they other measurements I can/should take to optimise the crossover?
Listening tests?
Test tones?
Take it outside and measure at 2-3m?
Ground plane?
Whilst being stuck in lockdown, it’s somewhat comforting to have a hobby that keeps me off the streets at night.
Here’s a passive crossover I developed. My first crossover design.
Attached are on-axis and ~45 degrees off axis response, measured at 50cm; 1/24 octave smoothed, also showing distortion components.
One may notice the dip and peak at 2.5Khz & 4Khz due to tweeter diffraction (position on the baffle, and sharp cabinet edges, but they largely disappear off axis) (See tweeter only measurements)
I’ll be fine tuning this in weeks to come, by experimenting with a lower crossover point to take advantage of the Millennium tweeter- it’s got an underhung voice cool and generous Xmas- I can see why the late Siegfried Linkwitz (RIP) took it all the way down to 1.5Khz (see attached). At the moment it’s about 2.2KHz (+/- 100Hz).
Newer modern tweeters are much more affordable (like SB SDAC29, which I also have on hand) but this one fit my cabinet (110m faceplate)
This cabinet is 21L tuned to 40Hz
Any glaring faults?
Is there too much baffle step compensation?
Are they other measurements I can/should take to optimise the crossover?
Listening tests?
Test tones?
Take it outside and measure at 2-3m?
Ground plane?
Attachments
Looks good. I would just listen to them at this point. See if anything sticks out. Maybe a bit of foam or felt around the tweeter.
You should at least take a gated measurement, for the drivers alone and the complete speaker (*). 50 cm is on the low side for your box, I would try to do it at 70-80 cm. The aim is to have the longest gate depending on the first reflection from your environment. Ungated measurements are pretty useless.
To evaluate the baffle step compensation you have to take also a near field measure of the woofer (0.5 cm from the dustcap).
Have a look here: http://audio.claub.net/software/FRD_Blender/White%20Paper%20-%20Accurate%20In-Room%20Frequency%20Response%20to%2010Hz.pdf
(*) A measurement of both drivers connected together is useful for calculating the time offset between them.
Ralf