Jims 3 way speaker build

[a4eaudio]

jimbones I'm not sure what the Omnimic options are but see if you can display down to 10hz or when 5hz. It won't matter for crossover work but will show more of the woofer and port roll off.

[DeZZar]

zma and jpg woofer no xo

There we go. You can't really bypass the crossover parts - if they are still connected to the woofer in any way - they'll have an affect.

So we can see now that the port length with all final stuffing in place is tuning the box to what looks like 38-39hz - a little too high.

You should run the woofer and port frequency response again with the crossover parts completely disconnected. We're looking for a response pattern that shows a deep null in the woofer response around 38hz. With this tuning in a 70L net volume box we should see an f3 around the mid to high 30's with a fairly humped up response around 50hz.

If we see an f3 much much higher than this then it might be reasonable to conclude that either the woofer needs A LOT of break in to reduce compliance and fs OR for whatever reason its seeing a smaller volume, in effect, than intended. Maybe the size of the holes in the brace although I'm not so sure about that - you could try increasing the number of holes or the size of the existing ones.

[jimbones]

zma and jpg woofer no xo

[jimbones]

Dezzar I reconnected the XO, I will do it again woofer alone

[DeZZar]

No, not at all Jim - the overall shape of the impedance curve will be the same - the differences will be fairly minor - a shift in the tuning point, change in peaks etc - not what we're seeing here. You could 100% stuff the box and still not see this sort of change. There's no chance stuffing alone is going to suddenly introduce a 1.5ohm minimum dip in the woofers response where it was perfectly smooth and showing 9ohms without the stuffing.

You said 'bypass' the crossover parts - are they still connected to the driver?

[jimbones]

The stuffing did that

[rpb]

Is there a high-pass setting? Sweeping a ported speaker might require one to protect the woofer.

[rpb]

Are there multiple tracks of the same type to choose from?

[DeZZar]

Somethings off....This post here: https://techtalk.parts-express.com/f...01#post1492201 has a normal looking impedance for a ported woofer. Its absolutely uncorrelatable with the above result and it should be very similar - just with a change in where the deep null is positioned and perhaps some small changes to that resonance spike.

[jimbones]

auto is unchecked but I dont think I can change the sweep, its a prerecorded cd

[rpb]

I thought the holes in your brace looked small, but someone said they were fine.

[DeZZar]

Mate I have to be honest and say I have never seen a raw driver in cabinet impedance sweep look like that! Something's not right. This is without crossover parts in place?

It should essentially look just like the example.one I posted earlier.

[jimbones]

DeZZar this is a 4 inch flare one side only. attached are the exported zma for the system. the screenshot of it with phase (scary low impedance) and exported frd for woofer and port as requested.
I have a suspicion that the braces are interfering with internals of the cabinet. Maybe I am way off here.....

[rpb]

I don't have an omnimic but I was looking at the owners manual, and speculating that a setting could alter the measurements. There's many adjustments. Maybe a high-pass? Didn't see one. What I saw on page 69 mentioned an auto gain function that should be unchecked.

With HOLM.... You can start a sweep at a higher frequency so that the woofer doesn't unload below tuning. Perhaps Omnimic has that feature, and a factory default setting.

If that mic works with any computer, I'd download HOLM, and see what differences, if any, show up.

[DeZZar]

Can we get the latest frd for woofer and port and can I confirm the inner diameter of the port? Run your impedance sweep again to see where the port has landed the tuning.