The Open Baffle Project

[richidoo]

I built some open baffles for the Feastrex drivers. They sound great in them with no box coloration, extended highs, crystal clear mids, but no bass - zip, nada. Simulation says knee is at ~200Hz, 12-18dB/octave below that. So I ordered some killer woofers from Peerless, model 830845. The trick with the feastrex drivers mating to woofer is the fast speed of the Feastrex gets bogged down by any other normal bass driver. I picked the fastest tightest woofer I could get that will also play down to 30 Hz with enough juice applied. I don;t know if I still need a 8" "mid" driver as peacemaker. I hope I don't need that because if I do it will be expensive to keep up with Feastrex. 

I will use Didden modified Behringer DCX2496 Xover, and active amps. Then I can boost the bass as much as I want with the woofers' 13mm excursion and ultra low distortion. I will need a powerful amp for them, I think Hypex UcD will do it well for reasonable bucks. With the xover I can contour the bass EQ to force it to play down to resonance 21Hz, and adjust delay and level.  To go that low I will probably need another woofer and H frame around them, plus boost. What fun!!

I haven't played the woofers yet, I am waiting to get some hardware to bolt them to the baffle, then I will play the woofers to see how they do, I don;t expect the combo without crossover to be anything special, but might show promise..... Baffle is just MDF for now, but if I can get it to sound 1/2way decent in this then I will make something more musical to hold the drivers.
Pics
Rich

[miklorsmith]

Way cool, Rich.  Are you planning to run the Feastrex drivers full boat, no XO out of one preamp output and just EQ the bass drivers?  That's what I'd try hard to do - maintain the grains of the mains.

[bpape]

Hey Rich.

If you try some angled 'wings' on the back side of the Feastrex, you can probably get the response to smooth out considerably better considerably lower.  Have you read any of Martin King's stuff?

Bryan

[richidoo]

Mike, I will try running the Feastrex naked and have been doing that before I put the woofers in, but I don't wanna over excursionate it  when the woofers start inspiring higher volume settings.   I will be using the 100w Snappers on them, so there will be no mercy. Probably end up with a 2nd order at 175Hz. mgalusha has convinced me that the Didden modded Behringer xover will not be a weak link. He uses Revelator tweeters which reveal any nasties. We'll see.

Bryan, I used Martin's mathCAD sheet to design it. That's why the driver off center so far. It sounds amazing like that. The sheet I'm using can't model wings. Of course he can simulate H and U frames with other sheets, so I can try that approach. I will just email him to ask about simulating wings, He is very helpful to newbies. Great idea thanks Bryan.

Here is a simulated FR with two woofers, the eventual goal. I will have to boost 30Hz by 16dB for flat, this already has 3dB figured in. I'm hoping a lot less boost in a more optimized open cabinet like horizontal H on the floor. This simulation is 1M on Feastrex axis, floating in space no walls or floor, so it looks smoother than reality. I don't know how to tweak for flat response with floor - yet.



Rich

[miklorsmith]

Check these guys out:

http://www.hlabs.com/technical/crossovers/page2.html

Way cheap, purely analog, and darn transparent.  I was using these with my Def. Pros for over a year with no complaints.  The 2s don't need them.  I would try these before going with any DSP.

I went pretty far with the TacT thing for over two years, which starts out life as a premium audiophile piece.  Even using the Lessloss DAC (another $4k) at the native TacT frequency the results were nowhere near where I've gotten now.

In the mids and treble, DSP may not be *obviously* flawed unless you can truly compare without it.  It can do so many cool things that people I think jump ahead.  Eventually this may be the end-all but I wouldn't put it back in my setup at this stage of the game.

Now, going room correction with SB/Inguz/Acourate is another matter . . .

[richidoo]

Yeah, I agree, I have not heard it myself, and am very picky. I'll just hacve to see. But I wouldn't have fallen for it had Mike not assured me it was decent. They are on fire on AC so it would sell easily if it doesn't work out.

I think the processing part is easy, 32 bit is perfectly inaudible. But once to go to convert it back, then you find the trouble, x 6 channels in this case  Like I said "We'll see!"

I might still use some Inguz on the bass EQ because the DCX filters aren't very sophisticated. But it doesn't really have to be flat as long as it's smooth...

Thanks for the link, that looks really intersting. I may ask you about that more later.
Rich