Flex Your PCD Mettle:

[dantheman]

Re: Flex Your PCD Mettle:

That's sweet Pete! Thank you for your contributions. Top notch work again.

Dan

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Played with it some more. 12 components. Now, the response stays within +- 1.5dB. And look at the reverse null. 1393Hz ;)

[Pete Schumacher]

Re: Flex Your PCD Mettle:

I will rather go with few dB less than 2 notch filters :D Like Z-man used to say, everyone has their own way of dealing with issues.

Thanks for suggestions. I'll try the 12dB/o and 18 dB/o for midbass and i'll post some listening impressions after.

If anyone has anything to say, feel free to comment. That's why the pictures i posted are here for

Regards, Z ...

Those notch filters are cheap. And they do the job of forcing the correct response from the tweeter to get LR4 acoustic.

With only two components, the woofer is following an almost ideal LR4 slope. The tweeter/waveguide combo has some serious issues with getting that shape down to a lower frequency with a simple XO. That's why I posted the first one crossing at 2KHz.

You also mentioned problems at 2KHz. You cannot fix it in the woofer, because the problem lies in the tweeter. Without some serious EQ, there's real linearity problems with that waveguide. When you compare it to the QSC 152i waveguide, the differences are quite apparent. Without the EQ at 2KHz on the tweeter, you'll either have the peak at 2K, or the broad dip just before it. There's also the problem with the broad bump centered around 8KHz, and EQ is the only solution for that as well.

Personally, that WG would seem to better match a smaller format woofer instead of having to be forced to go lower in frequency to match a 12".

Is 11 components really all that much for a 2-way that keeps response to +-2dB?

[Zvuchniak]

Re: Flex Your PCD Mettle:

I will rather go with few dB less than 2 notch filters :D Like Z-man used to say, everyone has their own way of dealing with issues.

Thanks for suggestions. I'll try the 12dB/o and 18 dB/o for midbass and i'll post some listening impressions after.

If anyone has anything to say, feel free to comment. That's why the pictures i posted are here for

Regards, Z ...

[Pete Schumacher]

Re: Flex Your PCD Mettle:

That is 2KHz xover frequency... I thought that whole point of Econowave is to, in some way, replicate the JBL 4425 but with constant directivity.

Every one of the JBL top line speakers had xover frequency between 700 and 1500 Hz. I think that 2000Hz is way high for 12" midbass and for what Zilch was trying to do...

I do not have measuring equipment yet so i will have to wait to finish the speakers and then invite someone to do the measuring and tweaking of the crossover. I will post my results here...

Regards...

OK, even more EQ.
I like the way this looks!!! :D

1500Hz LR4

Woofer:

2.2mH, 22uF

Tweeter: pos polarity

10uF in series with 4 Ohm, .2mH shunt.

parallel RLC BEFORE the crossover:
.55mH, 12uF, 8 Ohm

parallel RLC AFTER the crossover:
.4mH, 1.5uF, 25 Ohm

[Zvuchniak]

Re: Flex Your PCD Mettle:

OK, I ran a sim with no acoustic offset, with the mic position midway between woofer and tweeter, and a baseline sensitivity of 92dB.

Woofer XO:
2mH, 15uF

Tweeter XO: (pos polarity)
4.7uF, .2mH (.2Ohm 20ga)

L-pad:
3.3 series, 6.8 shunt.

Waveguide EQ:
series connected .05mH, 10uF, 2 Ohm. Placed in parallel with the 6.8 Ohm resistor and tweeter terminals.

That is 2KHz xover frequency... I thought that whole point of Econowave is to, in some way, replicate the JBL 4425 but with constant directivity.

Every one of the JBL top line speakers had xover frequency between 700 and 1500 Hz. I think that 2000Hz is way high for 12" midbass and for what Zilch was trying to do...

I do not have measuring equipment yet so i will have to wait to finish the speakers and then invite someone to do the measuring and tweaking of the crossover. I will post my results here...

Regards...

[Zvuchniak]

Re: Flex Your PCD Mettle:

I will make some pictures of baffle and upload them in few minutes...

EDIT: Here it is



http://img222.imageshack.us/img222/4543/img0103qy.jpg

[Pete Schumacher]

Re: Flex Your PCD Mettle:

FRD and ZMA are from here...

For JBL+D220Ti from post's number 1 and 5

http://techtalk.parts-express.com/sh...95&postcount=1

http://techtalk.parts-express.com/sh...46&postcount=5

For Eminence Deltalite II 2512 from post number 136

http://techtalk.parts-express.com/sh...&postcount=136

OK, I ran a sim with no acoustic offset, with the mic position midway between woofer and tweeter, and a baseline sensitivity of 92dB.

Woofer XO:
2mH, 15uF

Tweeter XO: (pos polarity)
4.7uF, .2mH (.2Ohm 20ga)

L-pad:
3.3 series, 6.8 shunt.

Waveguide EQ:
series connected .05mH, 10uF, 2 Ohm. Placed in parallel with the 6.8 Ohm resistor and tweeter terminals.

[Zvuchniak]

Re: Flex Your PCD Mettle:

FRD and ZMA are from here...

For JBL+D220Ti from post's number 1 and 5

http://techtalk.parts-express.com/sh...95&postcount=1

http://techtalk.parts-express.com/sh...46&postcount=5

For Eminence Deltalite II 2512 from post number 136

http://techtalk.parts-express.com/sh...&postcount=136

[Pete Schumacher]

Re: Flex Your PCD Mettle:

This is what i get with crossover from post number 1192 if i move acoustic center of the Deltalite 2512 1"/25mm closer to the listener...



http://img406.imageshack.us/img406/9654/12dbo.png

And reversed polarity...



http://img89.imageshack.us/img89/2565/12dboreversed.png

Care to share the FRD and ZMA files you're using?

[Stu]

Re: Flex Your PCD Mettle:

Nice to see you guys are keeping this fantastic thread alive. What a great testament to the wonderful Man that Zilch was and still is. It will be nice to see this still moving forward in years to come

[Zvuchniak]

Re: Flex Your PCD Mettle:

This is what i get with crossover from post number 1192 if i move acoustic center of the Deltalite 2512 1"/25mm closer to the listener...



http://img406.imageshack.us/img406/9654/12dbo.png

And reversed polarity...



http://img89.imageshack.us/img89/2565/12dboreversed.png

[Zvuchniak]

Re: Flex Your PCD Mettle:

Here it is with xover for DL2512 you've posted early on http://techtalk.parts-express.com/sh...&postcount=145 (Woofer XO: 3mH, 15uF + 2 Ohm, 1mH). I've kept the 6.8uF+7.8ohm zobel on it.



http://img688.imageshack.us/img688/1363/s18dboxover.png

With reversed polarity...



http://img576.imageshack.us/img576/7...edpolarity.png

I'll try to adress that little peak at 7KHz

[Zvuchniak]

Re: Flex Your PCD Mettle:

I'd relax the woofer transfer function just a bit in the XO region, try to fill in the dip a little more.

I also notice that you aren't including any acoustic offset for the tweeter and woofer.

So you have the minimum phase included with the plots?

There aren't any acoustic offset in my opinion (in mine configuration). I will post pictures with woofer and tweeter on the 1.1" board for you to evaluate, but i think that they are dead on. I was trying to allign the voice coils of both units. I used this cross section of Eminence 12" to se where it is...



http://img407.imageshack.us/img407/3687/eminence.jpg

I have problem with filling that dip. When i let DL2512 do the frequencies that it should i get a nasty peak at 2KHz.

Woofer response was satisfying when i did the 18dB/o xover but than sensitivity is way down for speaker 95dB in bass region and i've been trying to avoid that.

I'm gonna try today to see what can i do about it.

Thanks for your advices Pete...

[Pete Schumacher]

Re: Flex Your PCD Mettle:

I'd relax the woofer transfer function just a bit in the XO region, try to fill in the dip a little more.

I also notice that you aren't including any acoustic offset for the tweeter and woofer.

So you have the minimum phase included with the plots?