Hello CWelsh52 and everyone, I'm glad that active crossover works well for you, but it doesn't make things any easier for me. I still don't know which type of amplifier is best for direct connections to a horn speaker with a recommended 800 Hz crossover frequency and a 15 inch woofer? Thanks
Well it kind a depends on what sound you like. At the moment, i am driving a 15" bass woofer with an F6 and a Fulltone driver with the ACA Mini, with a crossover point (-6 dB) at 160-170 Hz. All driven by a ZM iron Pre and a NP FR EQ before the BiAm6-24. The ACA Mini is to be exchanged by a ZM LuDEF amp very soon.
Some of the questions you can consider, for choosing an amp:
What is the sensitivity of the driver?
What is the resistance (8/4/??)?
What kind of sound do you like? Consider harmonics, both the content (neg 2nd dominating, 3rd dominating etc.) and the amount - to my ears, too much harmonics content, can make some simpler music sound out of this world, while take the life out of more complex music
Some might use a class D for bass and choose a glorious sounding, low efficiency class A amplifier for mid and tweeter.
There is no correct answer, the fun is in the journey
By the way for the right music i highly recommend the ACA Mini, it really sounds good - instruments and voices are magical with it.
On one of yours the lead spacing looks to be 15mm. I think you want 5mm for that figure. I can't see that data on your second cap variant. For what it's worth I used these:
https://www.digikey.com/en/products/detail/wima/MKS2D021001A00MSSD/9370565
https://www.digikey.com/en/products/detail/wima/FKP2D014701G00HSSD/9370190
These for my first variant and recall the crossover point is as you calculated. I've since changed those caps to cross ~ 100hZ.
Paid the princely sum of $3 for a wood +mdf chassis. These crossovers are so quiet at least in my experience require no shielding, I had it sitting naked on top of my Iron Pre no problems.
Thanks, @JKiriakis. With help from others, I did get it all figured out.
Pretty cool chassis you've got there!
Pretty cool chassis you've got there!
I was involved in evaluating these crossovers early on in the piece.
Just be aware the slope refers to the acoustic slope. Given no driver is ever ideal you will need to tweak the crossover voltage drive.
I recommendation is to make a voltage drive measurement in REW and Save these curves.
Then use these curves as objecti
Just be aware the slope refers to the acoustic slope. Given no driver is ever ideal you will need to tweak the crossover voltage drive.
I recommendation is to make a voltage drive measurement in REW and Save these curves.
Then use these curves as objecti
The other thing to bear in mind is the LR24 low and high pass filters have non symmetrical group delay. What this means is that you will need to take this into consideration when looking at the driver offset. The effect is that the on axis lobe will be tilted.
You can incorporate analogue 3rd order Bessel all pass filter to compensate for the difference in the group delay.
The alternative is to introduce phase compensation by shifting one of the crossover points slightly. This will move the on axis axial response to produce a flat response in the crossover region. Vance Dickason covers this in the Loudspeaker Cookbook.
It’s more of an issue for tweeter crossover points than say a horn @ 800 hertz.
Above all measure your native driver frequency response on the loudspeaker baffle before commencing the active filter design process.
Also use DATS3 to check the impedance for driver resonances.
Try and also measure the 30 degree off axis response as well. This will help you realise the optimum crossover point in a two way design.
Tip. Do not attempt a nearfield indoor measurement with the mic right on the dust cap. This will cause errors in both the low and high frequency response. Your measurements should be at 3 x the diameter of the driver. Use 1/12 octave smoothing. Better still do it outside a a chair if it’s not raining to avoid loosing resolution lost with Gating.
You can incorporate analogue 3rd order Bessel all pass filter to compensate for the difference in the group delay.
The alternative is to introduce phase compensation by shifting one of the crossover points slightly. This will move the on axis axial response to produce a flat response in the crossover region. Vance Dickason covers this in the Loudspeaker Cookbook.
It’s more of an issue for tweeter crossover points than say a horn @ 800 hertz.
Above all measure your native driver frequency response on the loudspeaker baffle before commencing the active filter design process.
Also use DATS3 to check the impedance for driver resonances.
Try and also measure the 30 degree off axis response as well. This will help you realise the optimum crossover point in a two way design.
Tip. Do not attempt a nearfield indoor measurement with the mic right on the dust cap. This will cause errors in both the low and high frequency response. Your measurements should be at 3 x the diameter of the driver. Use 1/12 octave smoothing. Better still do it outside a a chair if it’s not raining to avoid loosing resolution lost with Gating.