Flex Your PCD Mettle:

[Pete Schumacher]

Re: Flex Your PCD Mettle:

I haven't read this whole thread or the AK one either. I did see Fastbike's standard Econowaves in old Radio Shack cabs, and I liked that project. I just procured a pair of remarkably nice Pioneer cabs from the 70s. About 1.7 cu. ft., 3/4" particle board, they even have a brace and carpet padding inside. I will be ordering parts shortly.

I have a question for the experienced Econowavers. Do you leave these on the floor, or raise them up a bit, and tilt them back perhaps on stands?

I will post a few construction pics soon.

It depends on how you mount the woofer; behind a thick baffle, and the whole forward lobe position changes. You can take the files from any of the threads, plug in the acoustic offsets, and then run the min phase versions of the response files, and sim any axis you want. It was really interesting to see how well Zilch's data, fed into PCD, predicted what he was measuring. It worked so well, that it brought up a correction to the way PCD was calculating off axis behavior.

And in most cases, due to the depth of the waveguide, it puts the tweeter acoustic center behind the woofer. The example I posted above would be for a stand mount version, pointing straight ahead, but you sacrifice group delay at the crossover point, since the tweeter is actually 180 degrees out, for an in-phase summation at the crossover point, on that particular axis. It would be great to use a 15" woofer with such a deep guide, or figure some way to move the 12" woofer back, to better line up with the tweeter, so that you don't have to compensate for so much acoustic offset.

[djg]

Re: Flex Your PCD Mettle:

Thanks Pete. I will probably make a new baffle and rear mount the woofer as Zilch did his PA cab version of the original standard Econowave version.

[Pete Schumacher]

Re: Flex Your PCD Mettle:

That FRD and ZMA files are from econowave delite so we are talking about the design that is already done. Measurement provided by Zilch.

So it is not the question of what i want. It is more about what should we do in case that you can't change the speaker cabinet. What you see is what you get

Does this setup match the mounting configuration from the test data? That data shows an easily defined offset for the particular mounting conditions, and a mic position in between the woofer and tweeter. If you design for the tweeter being on axis, it will help push the woofer acoustic center farther back.

Just remember, all that will change is the listening axis, and not by that much, so you can adjust tweeter height to suit.

[Zvuchniak]

Re: Flex Your PCD Mettle:

Does this setup match the mounting configuration from the test data? That data shows an easily defined offset for the particular mounting conditions, and a mic position in between the woofer and tweeter. If you design for the tweeter being on axis, it will help push the woofer acoustic center farther back.

Just remember, all that will change is the listening axis, and not by that much, so you can adjust tweeter height to suit.

Everything is exactly as Zilch did it. Even the thickness of front baffle Midpoint between midbass and tweeter is in ear hight. Stands are custom made for it.

[voodoo2crue]

Re: Flex Your PCD Mettle:

Hey guys, long time lurker here first time post.Was wondering if there is any info on inwall econwaves that have been built. I did a few searches and couldn't find much. I built a pair of the mini 8 econowaves and have thought about converting them to inwall if possible.Would it be as simple as keeping the same cu.ft for the enclosure size or would crossover changes also need to be made.

[bkillen]

Re: Flex Your PCD Mettle:

an in-wall mounting could affect mid-bass a bit. With a mini-8 I don't think it will be of much concern. I would be more concerned in making sure your in-wall design includes adequate toe-in of the speakers. This pretty much means the best location for in-wall will be actually building the corners in at an angle. this toe-in is really important in a constant directivity design.

[dtruck]

Re: Flex Your PCD Mettle:

If anyone is interested in helping me use PCD for the first time (just pointing out mistakes, would be great), I've got a build started. Initial measurements and PCD attempts (with files) are posted here. More measurements and files will be coming. I'll post them here as well, if I haaaaave to.

It's a DE250, QSC HPR152i waveguide, and Lambda TD15M-4.

I could probably use a few tips on taking measurements, too.

[bwaslo]

Re: Flex Your PCD Mettle:

dtruck, that should be a phenomenal set of speakers.

[dtruck]

Re: Flex Your PCD Mettle:

I think they will be, someday. Btw, bwaslo, if you were to download my PCD files, you would find "TD15M_bwaslo_shifted_down.zma". I am using your impedance measurement divided by 2 as a stand-in until I get a real one.

[bwaslo]

Re: Flex Your PCD Mettle:

Well, you can blame me if there are problems, then!

Using a 4 ohm driver is what I wanted to do, but not what I had. It will give you about another 3dB in sensitivity (not efficiency, but if you use a class D amp, it comes to about the same thing). A little T-Amp would even do well.

I found that it all works best with the speakers up on stands, so the woofs are several ft off the floor and the tweeters are at ear level. And of course, toe-in. Plan to spend a lot of time listening to music when you get them done, and for your friends to tire of hearing about your speakers.

[Zvuchniak]

Re: Flex Your PCD Mettle:

I think they will be, someday. Btw, bwaslo, if you were to download my PCD files, you would find "TD15M_bwaslo_shifted_down.zma". I am using your impedance measurement divided by 2 as a stand-in until I get a real one.

If you tell me internal box volume and tuning frequency, i can calculate your speaker impedance based on that and TS parameters using Frequency Response Modeler.

If you want

Use Jeff Bagby's guide how to measure so we can use it in PCD knowing it will work. Download it from here:

http://www.box.net/shared/ouxjjsx0m8bs00cil5iq

[dtruck]

Re: Flex Your PCD Mettle:

Zvuchniak, thanks for the offer, but what I need is a precise impedance curve in the midrange, while the method I think you're describing is a fairly accurate simulation in bass impedance with an extrapolation based on Le into the midrange.

I already performed the measurement method that you linked to, and it matched physical measurements - that's in the AK thread linked in my post above. However, my frequency responses are still a little suspect, IMO, so the project is somewhat on-hold while I try a bunch of things to identify and reduce any flaws in my impulse measurements. I may have a post on here regarding that tonight if I don't get anywhere new..

[Zvuchniak]

Re: Flex Your PCD Mettle:

........... the method I think you're describing is a fairly accurate simulation in bass impedance with an extrapolation based on Le into the midrange.

Quite right. I thought that is what you're looking for.

Regards

[gmannel]

Re: Flex Your PCD Mettle:

Design recomendations

Using the B&C DE250-8 1" + QSC PL-000446GP Replacement Waveguide Horn for HPR152i (or different if you rec)
and bass is covered by 15" Dayton Titanic Tuba HT 24"
and the LR are MCLA w/ 16 each http://www.parts-express.com/pe/show...number=295-338
What would ur rec be for the woofer in a 2 way single center channel speaker and what crossover point - could do w/ biamped miniDSP as well as a passive
I like Dayton Ref drivers but pro OK if better.

[Pete Schumacher]

Re: Flex Your PCD Mettle:

Design recomendations

Using the B&C DE250-8 1" + QSC PL-000446GP Replacement Waveguide Horn for HPR152i (or different if you rec)
and bass is covered by 15" Dayton Titanic Tuba HT 24"
and the LR are MCLA w/ 16 each http://www.parts-express.com/pe/show...number=295-338
What would ur rec be for the woofer in a 2 way single center channel speaker and what crossover point - could do w/ biamped miniDSP as well as a passive
I like Dayton Ref drivers but pro OK if better.

That guide/tweeter combo is begging for the or Deltalite 2512 in a sealed, stuffed, 1cf enclosure.