Am I on the right track? Bookshelf speaker Fountek FW146 / Dayton DC28F

[WernerM]

I took a few guesses here at woofer diameter and at the depth of the woofer voice coil (-Z offset). Here is a quick sim I did...

[WernerM]

If you want detail of the woofer and tweeter sections let me know I'll post them. This is just a reference of what things to look at. The driver phases track on top of each other in this sim well beyond 1 octave above and below the crossover point. Power response isn't bad through the crossover point and the reverse null (gray sharp V dip) at the crossover point is about -35dB. also I did add a parallel RLC network to help smash the woofer breakup. Oh and the phase angle stays between 30 and -30 in the system impedance window (Wolf suggests to keep that between the 40's).

[crossbound]

Great. that gives me something to shoot for. I guess at this point my biggest challenge is to get Phase lined up..

[WernerM]

I can't tell you how many hours I sat smashing my head against a wall trying to get good sims when I first started. Then I figured out that I was trying too hard and that I was trying to FORCE the crossover point. IF you are taking forever to try and get a good sim then take a break. This took about 20min. Sometimes we try too hard to force drivers to work instead of finding their natural crossover point. I chose a crossover point near 1 octave above the tweeters Fs but low enough that I could deal with the woofers breakup easily. This one was 11 components. Second Order on the woofer and Third Order on the tweeter.

[crossbound]

Oh I know.. I'll give it one more try before calling it "quits".

[WernerM]

Don't call it quits lol. You can get it. When you are playing around, look at a value of one component and double it or halve it. Then watch the sim and see how it affects the driver fr, phase and impedance. Then put the value back to original. Doing this will help you to understand how each component affects the fr, phase and impedance of each driver.

Now the other thing that will affect it is where the resistors are placed in the crossover. So if you are close, but it still isn't quite right, try moving a resistor before the crossover if it is after, or move it after if it is before, and see how that changes it. You can even split the difference between the two, so if you need an 8 ohm in series try a 4 ohm before and another 4 ohm after. The last thing about resistors is that you can add a resistor in series with a parallel component, such as with the cap in a LP circuit, or the coil in the HP circuit.

Point is before trying to make it perfect, just do textbook values and then play around so that you can understand what happens. Leave driver phase on, you will notice that as the phase aligns, the reverse null gets better.

The sim I did was a quick one just to give you an idea of what things to look for. I most likely would make minor changes depending on how these will be used, and also to try and make the impedance phase angle better (better impedance phase angle means an easier load for amplifiers IIRC).

[WernerM]

I did play with the sim a little more tonight before getting ready for work. I moved the crossover to 1.3kHz and was able to do more BSC at that point. Was also able to flatten the impedance phase in the tweeter, smash the woofer breakup even lower and produce a better looking result overall. I don't like the fact that 1.3kHz is less than one octave above the tweeters Fs, but it might be fine. I'll have to look back at it to see what level the tweeter response is at Fs. I didn't have a chance to post a pic of the sim. May play around with a 1.7kHz crossover point tomorrow and post both. It has been a couple years since I simmed anything, so it felt good to get back into the saddle. Anyway in your trials I wouldn't go any lower than 1.3kHz just make sure the tweeter response is around 20dB down at its Fs of 900Hz. I think that is a low enough level not to hear any distortion, but I may be off on that. The lower the better though...

[rpb]

I obsessed over this one, cause that's what I like to do! Part count is high, but cost reasonable. Sixth order at 2k.

[Millstonemike]

I obsessed over this one, cause that's what I like to do! Part count is high, but cost reasonable. Sixth order at 2k.

Were there pic.'s with this post? I don't see any.

[isaeagle4031]

Here is what I came up with so far. About 15 minutes playing around. 2nd order with a tank cap on the woofer, 3rd order on the tweeter. 2k cross. The woofer follows a bw3 slope at about 1800 and the tweeter is bw4 at about 2500. 9 components 2 coils, 3 resistors, 4 caps.

[Wolf]

Were there pic.'s with this post? I don't see any.

I see it just fine. Recently, there was an issue talked about when Chris Roemer uses the 'latest activity' setting instead of 'posts', and the LA version shows up without links or attachments.
If this is the case, hit the 'posts' button, and they'll show up for you.

Later,
Wolf

[Millstonemike]

I see it just fine. Recently, there was an issue talked about when Chris Roemer uses the 'latest activity' setting instead of 'posts', and the LA version shows up without links or attachments.
If this is the case, hit the 'posts' button, and they'll show up for you.

Later,
Wolf

"posts" button worked, thanks. But I liked the LA version

[crossbound]

I just realized late last night that I had the driver geometry set up incorrectly and that caused most of my phase issues.. The Z offset I just had to guess at. Can that kind of data be found anywhere. It surely is not on the driver spec sheets.
If I get a chance, I will post what I came up with later tonight.
And now a totally different question. Air core versus iron core inductors. Difference? Usage? Advantages, disadvantages for one over the other?

[PWR RYD]

A good estimation for a 1" dome tweeter and ~6" woofer would be -.020 meters to -0.025 meters. So your -0.032 is a little too much.

[isaeagle4031]

A good estimation for a 1" dome tweeter and ~6" woofer would be -.020 meters to -0.025 meters. So your -0.032 is a little too much.

Agreed. I used .025 for the offset.

As far as air vs laminate core, I simmed for a laminate core with less resistance. On a woofer, about the only times I consider an air core is if I NEED the higher dcr or if I have concerns of power saturation.