Econowave - Separate Horn vs Same face as woofer

loudsubz

Member
2007-12-19 3:45 am
Going to be embarking on an econowave deluxe model. I have all the parts (QSC Waveguide + 3012LF woofers).

Most of the builds I see incorporate the waveguide and woofer on the same sheet of wood that is the face of the speaker. I have also seen some horn builds where the woofer is in a separate enclosure, and the waveguide doesn't really have any enclosure around it (free air sort of speak) and is free to adjust its position (forward/back, side to side etc).

Any drawbacks from doing the second? I have read about having the HF driver flush mounted with the front of the baffle to reduce unwanted disturbances in the HF, so I'm not sure how it would play out to have the WG seperate from the rest of the system.

Basically this:

[IMGDEAD]https://i713.photobucket.com/albums/ww131/lennon_68/Speakers/IMG_8179.jpg[/IMGDEAD]

VS

this

(not exact but you get the idea)

janez02.jpg
 
Most waveguides are designed to be used on a baffle. Without a baffle, they tend to have a little more ripple down low, towards the bottom edge of their useful range.

You can put the wavegude in its own separate enclosure, but I wouldn't leave it in free air unless I tested it and saw that it was OK with the crossover point chosen.

I've done some speakers that had cradle mounted waveguides above the main box, just for appearances sake. It's cool, and I understand your attraction to that look. But the waveguides I used were designed for that purpose and were made a little larger to accomodate.

One last thing, if you are considering placing the waveguide in another enclosure, be sure to move the midwoofer all the way up to the top of its box. You want the waveguide and woofer pretty close together.

And don't forget to measure the midwoofer cabinet to make sure standing wave modes inside the box aren't making some ripple in the lower midrange. The larger cabinets needed for speakers like these tend to have standing waves in the lower midrange, so where you put the woofer and port is kind of important. It can make the speaker sound "throaty" or "boxy" sounding.
 
One last thing, if you are considering placing the waveguide in another enclosure, be sure to move the midwoofer all the way up to the top of its box. You want the waveguide and woofer pretty close together.

This would allow to use rubber band(s) to make a mechanical decoupling; it works best when the rubber is stretched at nearly max lenght :scratch1:
 

loudsubz

Member
2007-12-19 3:45 am
And don't forget to measure the midwoofer cabinet to make sure standing wave modes inside the box aren't making some ripple in the lower midrange. The larger cabinets needed for speakers like these tend to have standing waves in the lower midrange, so where you put the woofer and port is kind of important. It can make the speaker sound "throaty" or "boxy" sounding.

How do I go about this. I had never thought about speaker and port placement other than port on the front/side/back
 
One way is to build a box and measure it, looking for impedance and response blips in the lower midrange. Ultimately, that's what you must do.

But you can do some mathematical models to simulate the physical model, and that way you might not have to go through so many iterations of building a physical model, testing, perhaps rejecting, rebuilding and retesting.

A good way to do this is to go grab a copy of Martin King's spreadsheets. Check out this website:

Write the author there - Martin King - and tell him you want to model your cabinet with his spreadsheets. You are using cavity (Helmholtz) resonance as your primary tuning mechanism, so you'll probably want his vented box spreadsheets. I think he charges a nominal fee.

With those spreadsheets, you can enter the electro-mechanical parameters of your midwoofer, the dimensions of the cabinet and the size and positions of the port and midwoofer. It will simulate the response curve for you. Manipulate the positions of driver and port, and perhaps the cabinet dimensions until the response curve is nice and smooth.

Then line the cabinet inside with insulation. I find using a sheet that spans the cross-section is even more effective than just lining the cabinet walls. For large cabinets, I install sheets that span the cross-section in two places.