Are there guidelines to follow?
First post in a while since I've been so busy with work, but I finally got around to building my next project, and it brought up an issue again that ive been having with two different tweeters now. That issue is the size of the inductor in the second order high pass filter, during my last build i had some advice that the inductor shouldn't be lower than .22mh but the thing is, these two tweeters both need one quite a bit smaller than that to get the crossover point high enough. Adjusting the inductor is the only thing that moves the point to the right place. On my current design its down to .15 or there about to give me a 4500hz xover. (I realize the first cap should be the part that decides the freq of the crossover point but as i adjust that, it just changes the spl of the whole tweeter either up or down)
So my question is, is there a minimum and maximum value I should be staying within, not just with inductors but with all the parts?
Where did you hear this from? I use lower inductor all the time without issue. You just need to remember that it will pull down your impedance, so you really need to be cognizant of that. But if your impedance is fine, there should be no reason that you can't. If you want to input your design on here, we can take a closer look at it for you.
Ahh, thank you for clearing that up for me, after reading your comment I decided to re-read the message I had recieved regarding the inductor, it turns out I had mis understood what he was telling me as i shouldn't ever put a lower inductor into that part of the circuit, but it makes more sense now that he was talking about the effect it was having on my impedance as apposed to a 2.2mh inductor. All this time I have been avoiding using smaller inductors there, and really struggling to get a good response graph, I have even changed tweeters due to it 😂
I'll upload my latest attempt at a crossover shortly so that you can take a gander and give me your proffesional opinion on it, i think its ok, seems to be in phase, and I've tried to use the least amount of parts possible. Hopefully you give me the thumbs up with it but im man enough to take some constructive critisism.
Thanks again for what you do with this site 👍
The drivers I'm using for this build are the ND65-8 (2 wired in parallel) and the ND20FA-6 to create another MTM. I chose to do another MTM as I want to be competent at designing those before moving on to more complicated builds. I have a 3 way speaker planned for the near future which I could use some advice on but that will be a few months down the line and only if this one works out to be ok.
Also I think the little hump at 6500hz is due to diffraction, I did my best to filter that out but its being very stubborn, overall I think the response is +/-2db. I tried to bring out as much bass as possible from the speakers as they are quite small, they are front ported too using a slot port.