Anarchy and rs28f m/t my first speaker design

[rpb]

I was looking at the speaker photo. It looks like you may be planning to use the speaker close to the wall. My room is small, and my speakers are positioned similar to your photo. Mine have very little BSC. Your sim adjusts very nicely by simply changing the coil on the woofer, and a resistor on the tweeter. I used your sim with a 1.2mH coil, and less tweeter padding. The response remained very flat without changing other components. In fact, I touched the bottom of the chart with a reverse null! A 1.5mH works well too. (I know that's not better, but it looks cool on the graph!)

One other thing was tweaked. On the woofer notch, I reduced one ohm to about .2 ohms which I would ballpark the coils resistance.

[isaeagle4031]

Maybe its just me. I prefer to keep all measurements the same thru my process. Perhaps I am wrong, but I also know I have had excellent results with this method. I don't listen at less than a meter either, closer to about 2.5-3 at least. The better I can get the phase aligned and the larger the area that it is aligned on the shorter distance, the better it does at the actual listening position.

[joe_bernardi43]

At .5m the phase tracking is off but they will never be listened to that close. At 1m and beyond the phase lines up nicely. I hope my measurements were accurate enough that they measure the same as the sim but I won't know for a while, I have to wait until payday on the 16th to order parts.

[isaeagle4031]

I am well aware of that. Part of finding the correct acoustic offset is setting the distance. But it has been my experience, to keep it the same so that you are looking at the same refrence point throughout.

[dcibel]

In PCD the mic distance doesn't affect anything other than the phase relation between the drivers, given the x-y-z coordinates. With that consideration, it's probably best to set it to your intended listening distance.

[isaeagle4031]

Personally, i keep it the same through out the design process, then adjust it to see what if any effect there is.

[dcibel]

Are you measuring at 3m distance now?

You may enter any mic distance you wish for crossover simulation.

[isaeagle4031]

Are you measuring at 3m distance now?

[isaeagle4031]

Even that seems like too much Chuck. When I have used the Eclipse woofer with dome tweeters I am almost always in the 24 mm range for a relative offset. Keep in mind, that if you are working with OmniMic then you can't say what the actual offset is, you can only find the relative offset for this particular set of measurements. Theses are two different things. 2.75" is way out of range though.

Jeff B.

I agree Jeff. And after seeing it, I remeasured, rechecked, and then remeasured again. Maybe it was because I used the raw files from omnimic (and used the same through out) but measurements with the crossover matched the sim dead on.

[joe_bernardi43]

Are you sure this is your first x-over? You seem to be very good at this!

i will take that as a complement.

[joe_bernardi43]

its my first time taking measurements and designing a crossover from them. i have played around with pcd quite a bit with traced frd and zma files.

[rpb]

Are you sure this is your first x-over? You seem to be very good at this!

[joe_bernardi43]

That's what I thought too, that's why i was questioning it. I have been messing around with pcd and this is what it looks like now.

[Jeff B.]

For a little perspective on your offset, i recently finished a crossover using the rs28f and eclipse w6520r. My z offset was .043. I would not expect the anarchy too be much more if ot all than that. Both drivers are flush mounted as well.

Even that seems like too much Chuck. When I have used the Eclipse woofer with dome tweeters I am almost always in the 24 mm range for a relative offset. Keep in mind, that if you are working with OmniMic then you can't say what the actual offset is, you can only find the relative offset for this particular set of measurements. Theses are two different things. 2.75" is way out of range though.

Jeff B.

[rpb]

If you can afford too, buy about $300 worth of x-over parts. You have 45 days to return what you don't need, or want to keep. I use jumper leads to connect everything on the floor behind the speaker, and most of my parts look more or less unused. Some have been soldered, and were used in speakers that were later disassembled. I probably have $500 worth of parts on hand. Making changes to a x-over, and hearing the results within minutes, or hours, is just plain fun.