My new speakers - Orcus (mark 1)

[planet10]

You can get close enuff by doing a model (or getting someone to do so for you), I don't design ML-TLs (i don't have Windoz) so farm those out.

dave

[neebster]

Alright. Well thanks for the guidance, planet10!
I don't have windows either. I'm a linux guy. If anyone's with mathcad is interested in this, that'd be cool. Otherwise, these are still good-sounding speakers.

I think that I will alter my designs for the bookshelf model I want to build. It will still be a bass-reflex design, and still use PVC. But the driver I was looking at would require much less enclosure volume, which translates to a shorter pipe. Also, I may use pvc adapters to bump up the diameter even further, thus shortening the length further.

How deep can the chamber be, with a 3.5 inch driver, before getting a standing quarter wave?

[neebster]

OK, I've been reading hours worth of stuff on transmission lines. I think without buying the mathcad worksheets and using them on a friend's windows machine, I won't be able to perfectly model the speakers.

In addition, from the alignment tables, it looks like the minimum diameter for a ml-tl should be 6 inches for these drivers, so I don't think I will ever be able to get them to be optimum.

However, what about half-wave resonators? I've been googling them, and can't seem to find too much. I think if I add a T adapter to the base of the tubes, they will be just the right length if I stuff them with long-haired wool, to make a half-wave resonator tuned to the Fs of the speakers.

[Scottmoose]

There aren't any alignment tables for the MLTLs (at least, Martin hasn't done any TTBOMK). Rick Schultz did some simple ones, and a few of us have our own alignments / design routines we work to, but that's about it AFAIK.

I took a quick gander at your pipes the other day; FWIW, the basic alignment didn't look too bad all things considered; that said, there are things that software doesn't account for. If you like what they do, I'd be inclined to leave alone & if you want a new project, go for a new one rather than trying to change what you have, or pull it apart. We (as in everyone here) can help with that.

[Cal Weldon]

Any concern about dust in the coil?

[neebster]

Dust in the coil? I've thought about that. I think a weekly spritz of compressed air will do the trick, as long as I am careful.

And scottmoose, you're probably right -- I should just leave them alone. EQd theyre great. I don't think there are any clipping issues, or phase issues, so I should just count my blessings that it worked decently.

I've got my design for the Vanth bass-reflex speakers down, and I think it should eliminate the standing wave problem, while still using PVC fittings. I will post a new thread when I build them, in a month or two.

But I am still interested in half-wave resonators. If anyone's published an article outlining the theory I'd be interested.

[chrisb]

Originally Posted by neebster

Dust in the coil? I've thought about that. I think a weekly spritz of compressed air will do the trick, as long as I am careful.

And scottmoose, you're probably right -- I should just leave them alone. EQd theyre great. I don't think there are any clipping issues, or phase issues, so I should just count my blessings that it worked decently.

I've got my design for the Vanth bass-reflex speakers down, and I think it should eliminate the standing wave problem, while still using PVC fittings. I will post a new thread when I build them, in a month or two.

But I am still interested in half-wave resonators. If anyone's published an article outlining the theory I'd be interested.

go directly to MJK's QuarterWave site, do not pass go, do not spend $200 on any more projects still you've read everything there

twice

Quarter Wavelength Loudspeaker Design

[neebster]

Although I appreciate your concerns, chrisb, I still fully intend to build a second set of bass-reflex bookshelf speakers, which will not have the disproportionate length that is causing it to behave as a transmission line. They will then be closer to "true" bass reflex. In that case, the QW point will be moot.

And for that matter, I have read the whole MJK website. I just need to read it a few more times before I grasp all of it. And maybe buy the worksheets.

[chrisb]

Originally Posted by neebster

Although I appreciate your concerns, chrisb, I still fully intend to build a second set of bookshelf speakers, which will not have the disproportionate length that is causing it to behave as a transmission line. They will then be closer to "true" bass reflex. In that case, the QW point will be moot.

And for that matter, I have read the whole MJK website. I just need to read it a few more times before I grasp all of it. And maybe buy the worksheets.

Fair enough - my point was if you're planning on further exploration of this particular category of enclosures (i.e. the continuum of QW action bases designs from VP to TLs to "BLH") as mentioned, you could do far worse that to study Martin's work and build one of his projects, or one of many enclosures designed by others using his worksheets. It's always faster to follow a proven plan, but then I'm just too lazy to want to learn how to do the math - I'd just rather build stuff.

Just as with the aforementioned QW continuum, there is a wide range of vented enclosure designs, some of which straddle borders of simple categorization.

anyway - enjoy your next projects

[vinylkid58]

Originally Posted by neebster

Although I appreciate your concerns, chrisb, I still fully intend to build a second set of bass-reflex bookshelf speakers, which will not have the disproportionate length that is causing it to behave as a transmission line. They will then be closer to "true" bass reflex. In that case, the QW point will be moot.

Try WinISD, it might run in Linux.

LinearTeam

jeff