Truncated baskets ----> OB line arrays. The best of All Worlds..That is exactly what I thought when I saw that. that and the Qts being .7, when everyone was shoehorning them into cabinets. Add a T90A or Fountek ribbon on top.
The icing on the cake was Tom's response. I should get them today. I am sure Bob Reimer would have a sharp pencil for 32 of em.
The icing on the cake was Tom's response. I should get them today. I am sure Bob Reimer would have a sharp pencil for 32 of em.
All it takes is 2 mid-high Q drivers. Put one in any box you want. You can even handicap the OB by putting it on anything that will support the driver. Then put one on the left channel and one on the right channel and start the music. You become an instant convert and that's before you even flatten the response and fill in the bass.
The numbers guys are against it because they can't plug specs in and have their computers tell them what to build, but that's what I like about it. You can be creative and the result is a nice blend of art and engineering that you can't buy in a store.
The numbers guys are against it because they can't plug specs in and have their computers tell them what to build, but that's what I like about it. You can be creative and the result is a nice blend of art and engineering that you can't buy in a store.
I should have mentioned also to those investigating the B200, that right out of the box and onto cardboard baffles as John suggests, and the original home to my first drivers for two months, the sound was so good that I was a convert. When you start using tools like DSP to contour in the digital, then it gets scary good. The mids and highs are so good that I didnt care too much about proper bass, and I like FULL range sound, always. The Behringer DEQ2496 works great in this role, and is another bargain in audio, allowing one to bring up the LF abit and tailoring the sound to taste, this simple combo yields spectacular results that simply cannot be found in any audio salon.
Nice reads from Audiocircles and Linkwitz Labs. They made me a believer. I ordered the FR125's last night. I will mount them in OB on MDF using something close to the Phoenix design, using wings. I'm initially thinking of a baffle main panel of 16"x 26" (ala Golden mean) with wings 3"x 26" and 4"x 26". I believe I can hinge the wings with a wood strap and dowel method, routing the edges to exhibit a nearly curved surface between the panels. Do these dimensions seem workable? I am willing to use trial and error but am open to any suggestions as to this scheme. Thanks for all of your posts regarding the OB methods. Lots of good stuff, there.dmason said:
Highly workable. If apparent width of baffle is an issue, you can consider narrower baffle and wider wings, etc.
The sets I made have roundovers on the main baffle so that when the wings fold back, the entire thing looks more like a typical monkey coffin floorstander speaker. Fold out the wings while CD's are loading, like some veneered dish antennae, and away you go. All that good wood with the big black driver embedded in the middle looks quite elegant, and all business.
The sets I made have roundovers on the main baffle so that when the wings fold back, the entire thing looks more like a typical monkey coffin floorstander speaker. Fold out the wings while CD's are loading, like some veneered dish antennae, and away you go. All that good wood with the big black driver embedded in the middle looks quite elegant, and all business.
I doubt you'll need to go half so big as planned. Presently, I've a 1 foot x 3 foot main panel with 11 inch wings on one side and only 3 inches on the other side, but this side is six inches from side walls of my smallish room. 4 feet from back wall. But I'll be playing further this week when I finish up a dedicated setup.
Truly the bass is outstandingly quick and clear.
Truly the bass is outstandingly quick and clear.
Thanks Tom for the dimension advice. I realized that I'll have a lot of ease in playing around with the panel dimensions as I can start the wings as a large size and cut my way down to an acceptable size. It's good to hear that you are getting a good bass response from these drivers. From my readings I understand that the size of the panel and the position of the driver in the panel effect bass frequency i.e. the lower the driver placement in the panel, the lower the frequency. Do I understand this correctly? Where do you have your driver placed in the 1'x3' panel? I look forward to your success on the dedicated setup this week.TomekZ said:
Presently, I've the center of the driver at 28 inches from the floor. This is mounted on plywood. In a couple days, I'll have my solid oak panels up, with the driver mounted at 25 inches. So low? I sit on the floor (futon) with my head near to the rear wall. Not the average manner of positioning, I know.
Regarding baffle shape- Something I had found is that if wings are used I prefer to fold them as close to the driver as possible and never at 90 degrees. Also with wings of at least 1" difference in length. It avoids cavity resonance except with very close (a few inches) rear wall placement.
I also believe that it has a couple of other benefits:
1. With the typical design you see with some distance from the driver to the wings, the rear wave starts to propagate and then strikes the wings causing reflections. My way, the rear wave just expands rearward with the wings acting as wave guides until it reaches the ends of the wings and propagates freely from their. I've yet to notice any horn loading type of effects, but I'm sure you need to stay away from a squarish horn shape in the back.
2. Folding close to the driver gives you the greatest front/rear wave difference differential using the same amount of wood and results in quite a compact form.
A narrow baffle front isn't without compromise, because baffle step influences come into play. Also, any time you fold wings back you get away from pure dipole radiation, but this isn't necessarily a bad thing. Also, if you take it too far you can lose some of the ground effect especially if you mount your driver up a ear height.
It also has advantages over a flat baffle in addition to size and stability. Placement much closer to rear walls can work while retaining much of the open OB sound. Also, I've found large baffles to cause a big blackhole in the audio image because they block a large area of rear wall reflections much like a monitor can do in a desktop sound setup.
Just my 2 cents.
I also believe that it has a couple of other benefits:
1. With the typical design you see with some distance from the driver to the wings, the rear wave starts to propagate and then strikes the wings causing reflections. My way, the rear wave just expands rearward with the wings acting as wave guides until it reaches the ends of the wings and propagates freely from their. I've yet to notice any horn loading type of effects, but I'm sure you need to stay away from a squarish horn shape in the back.
2. Folding close to the driver gives you the greatest front/rear wave difference differential using the same amount of wood and results in quite a compact form.
A narrow baffle front isn't without compromise, because baffle step influences come into play. Also, any time you fold wings back you get away from pure dipole radiation, but this isn't necessarily a bad thing. Also, if you take it too far you can lose some of the ground effect especially if you mount your driver up a ear height.
It also has advantages over a flat baffle in addition to size and stability. Placement much closer to rear walls can work while retaining much of the open OB sound. Also, I've found large baffles to cause a big blackhole in the audio image because they block a large area of rear wall reflections much like a monitor can do in a desktop sound setup.
Just my 2 cents.
Thanks for the post John. That is some really useful info. I've been searching on the net for more info about OB and the Audio Circle post you participated in and Linkwitz's site are about the most practical information I can find. Since I'll be experimenting with MDF for my first OB application the cost of panels will be insignifigant. Lots of wood to butcher, lol.
How would you compare the FR125's to the Vistaton in OB?
How would you compare the FR125's to the Vistaton in OB?
westend said:
Send me a pair of each and I'll be happy to compare them head to head. I buy everything used because the import duties on new stuff here essentially doubles my price and unfortunately no used pairs of either have shown up for sale.
I'd recommend cutting a MDF front baffle with something to support it. Then get out the cardboard and tape for experimenting. While cardboard wings can add a "papery" sound you get a good idea of FR and can quickly make changes in shape and size to evaluate differences.
Also, if you have amp power to spare, pick up a few pairs of resistors or a pair of Lpads. It's another way to do quick tuning changes because series resistance changes the Q. Using an Lpad, don't connect the bypass, just the variable resistance. Then if you like it using some resistance, just measure it and replace it with a resistor or keep the Lpad and leave it variable.
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