The PA130 MTM - 102dB with 8 watts, under $90/pair

[max_andrews]

Bored at work, fun! Would be great paired with a sonic impact t-amp. I might offer these up as a kit if I have the time...

[Xander]

looks fun, what are the box dimensions?

[cjd]

That minimum phase modeling? Does it include box response or something? Something in the data looks weird.

C

[Gir]

Looks good! Are these simulated or actual measurements? They've got some good low end extension for smaller speakers. Is it ported?

[ThomasW]

looks fun, what are the box dimensions?

They're on the drawing.

Looks good! Are these simulated or actual measurements?

They're sims or as we prefer to call them vaporware...

[max_andrews]

Looks good! Are these simulated or actual measurements? They've got some good low end extension for smaller speakers. Is it ported?

As Tom mentioned, these are simulated from PE's data. I'll be building them soon and I think one guy on the PE board happedne to have the parts already so he was going to give them a shot this weekend. They are indeed ported, 2" diameter by 6.5" long. If you make the box 12" deep you can get a bit more extension with a 2.5"x 6" vent.

The use an EBS style rolloff, so the F3 is high but the extension is decent.

[max_andrews]

That minimum phase modeling? Does it include box response or something? Something in the data looks weird.

It's what FRD extracted after I merged the box response, could that be what you're seeing?

[cjd]

Did you extract miminum phase and properly set z-axis offset? If you didn't do the phase step you're going to get very different results in reality.

C

[Jed]

I agree with CJD, the phase doesn't look right and you are getting a dip at 5kish as the result. Don't let that discourage you though. This is design that looks like it has a lot of budget appeal.

[max_andrews]

Did you extract miminum phase and properly set z-axis offset? If you didn't do the phase step you're going to get very different results in reality.

Minimum phase was extracted after the last step for each driver, after baffle modeling, bass modeling, etc. Acoustic offset is set at 1" for the tweeter. I think the 5khz phase issue is due to the woofer's breakup at that point, but a notch might be rather pointless because the effects are so small and will completely disappear just a few degrees off axis, and given the budget another $7 worth of inductors would drive me nuts I'll do a bit more modeling tomorrow and see if a notch can be done on the cheap. Is that the only place where the phase looks funky?

[max_andrews]

updated crossover

Thanks for the advice everyone! The problem was solved by very slightly lowering the xo point for the tweeter (to about 3050 from 3200), as well as adding a .025mh inductor (tiny!) in series with the shunt capacitor in the woofer's circuit. This significantly attenuates the breakup node and improves phase. +/- 2.5dB from 100hz-20khz, not bad IMO

In terms of added cost, if you use NPE caps for everything (the last one used a dayton 5% poly for the first tweeter cap), it should be exactly the same at about $95/pair including terminal cups, drivers, XO parts, and port tubes.

Image not available

[cjd]

Thanks max. It's hard to tell and it looked like it may have been a standard glitch in SW from files without phase data, or with PE's phase data. So I asked to be sure.

C