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Open Baffle Epiphany!

thankee!

the more i listen to them the more i like them. the visatons are amazing drivers and i wasn't using them. would love to try them in a better room.

i'm thinking of putting some sort of a grill cover over them so they don't look quite so hideous. then i might move them up to my (small) listening room where my OBs are right now. would need to redo the EQ set into my miniDSP in that rig...
 
I've got my little hitachi's hanging from some speaker wire underneath my desk to save space...and surprisingly they sound pretty good like that. (I am cheap and couldn't find any wire so I used speaker wire.)
 
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my trek into the ob

thanks to all the ob posts and you fine folks sharing your stories i decided it was time to get busy. had a pair of sonotone WR-8BH drivers i thought would make good candidates. found a few old 1/2 mdf skids for cisco routers lying around, 33" x 24", close enough i thought. initial reports are it was time well spent, enjoying the heck out of some stan getz right now. this has merit, more later. and thanks for getting me off my duff!

4-14-2014
we finally have had some good weather, and i finally got a few extra square feet of shop space, i knocked out the stands and mounted the panels, im just enjoying the heck out of getting back into audio again and im hearing things in a new light, lots more work to do but having the time of my life, thanks again!
 

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I finally, just a few minutes ago, got my drivers mounted into the baffles. I'm just listening to the FRs at the moment but will get the wiring done very soon.

cubdog
 
born2tech said:
thanks to all the ob posts and you fine folks sharing your stories i decided it was time to get busy. had a pair of sonotone WR-8BH drivers i thought would make good candidates. found a few old 1/2 mdf skids for cisco routers lying around, 33" x 24", close enough i thought. initial reports are it was time well spent, enjoying the heck out of some stan getz right now. this has merit, more later. and thanks for getting me off my duff!

4-14-2014
we finally have had some good weather, and i finally got a few extra square feet of shop space, i knocked out the stands and mounted the panels, im just enjoying the heck out of getting back into audio again and im hearing things in a new light, lots more work to do but having the time of my life, thanks again!
Click to expand...

Very well done! :thmbsp:
 
beautiful work cubdog, i dont have access to nice drivers like those so im sure mine will end up being a hybrid system of some sort. mine need some serious help with the last couple of octaves.
 
So I've been doing quite a bit of tweaking and critical listening over the past week. I even went on a 110db excursion, but that didn't last very long! I've discovered several things, first of which is that this nondescript 3" FR driver is the real deal, the cat's pajamas, the BOMB. They look so similar to Fostex drivers that I wonder if they were the OEM. :dunno: The EIA code is 205, but I've never found a reference to that number. Good thing they have high excursion for a small driver, as they were bouncing pretty good at 105db sustained, 110db peaks. Then again, the entire room was vibrating...

Also I have an appreciation for OB bass. It's there, but needs a little massaging to get the most out of it. Once it's been released from captivity, it sounds really good. :D DSP would be a good way to go, or some sort of EQ like the Linkwitz setup. Right now I'm utilizing a combination of tone control on the preamp, and active crossover points. Unfortunately my crossovers lowest point is 80 Hz; I could really use lower. Maybe mod the crossover? In my dreams!

For everything these speakers get right, and for their efficiency, the are incredibly good. More tweaking to come shortly, in this never-ending quest!

I'm also super jazzed about PG's other "discovery", the TPA3116 amp. The combo is amazingly good, with a neutrality, immediacy, and clarity that is so right. Nothing artificial or superficial, just music. :music:
 
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I should mention too that baffle vibration seems to be something of an issue. Even at moderate volume I can physically feel the baffle vibrating with the drivers, even the FR'er. I'm thinking this is causing a peak at about 320 Hz. Maybe that's the resonant frequency of the baffle itself? I'm not sure I want to keep screwing wood braces to the back side of the baffle, but I'm not sure how else to address this. I just love the tone and high-frequency extension of the FR driver so much that I don't want to mess with it, by "modding" it. And, MDF seems to be a pretty springy material. If I redo these down the road I'll use good birch ply. I'm thinking the springiness is not a good trait for big baffles. :no:
 
jhoyt: Are they sitting on carpet or hard surface? I may have a couple of suggestions based on my experiments....Spooker
 
jhoyt said:
I should mention too that baffle vibration seems to be something of an issue. Even at moderate volume I can physically feel the baffle vibrating with the drivers, even the FR'er. I'm thinking this is causing a peak at about 320 Hz. Maybe that's the resonant frequency of the baffle itself? I'm not sure I want to keep screwing wood braces to the back side of the baffle, but I'm not sure how else to address this. I just love the tone and high-frequency extension of the FR driver so much that I don't want to mess with it, by "modding" it. And, MDF seems to be a pretty springy material. If I redo these down the road I'll use good birch ply. I'm thinking the springiness is not a good trait for big baffles. :no:
Click to expand...



You may end up just adding splines to the rear of the baffle to add stiffness. If wood doesn't work, perhaps metal bar, square stock, or L stock?

Or you could get ahold of a sheet of solid surfacing and cut that with an angle grinder. ????

Have you tried spraying the back side with an acoustic sealer/ insulation?


Sent from my iPhone using Tapatalk
 
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The reason I asked is I would suspect the interaction of the bottom of the baffle and the support "leg" with the floor. My OB's are tabletop-sitters, but the concept is the same. I found remarkable improvement when I elevated them 2".

Mine use two pine "legs" with thick felt disks on the bottom. My 10" Goldwoods really thump yet vibration is minimal. They are 3/4" laminated pine.

I got carried away with sides and reinforcements on prototype #1 to the point where I believe the back wave was really affected. I've since gone with a plain baffle, no sides, etc. Imaging is much better. Sound stage is amazing.

Yep, MDF is a wet noodle. Keep on it. It's a proof-of-concept anyway. I would recommend using your round-over bit on the front edge of all four sides. The difference is amazing. Stay with it.....Spooker
 
I still have some trim work to do, including rounding over the edges, re-doing the rear support setup, and adding provisions for spike feet. I'm also going to try to smooth out the rear bracing, acoustically speaking. The speakers will also be painted black. Just waiting for the convergence of good weather, enough time, and no "family projects"!
 
I use small rubber feet under the baffle and crutch tips under the rear L brackets.

I primarily listen to small group jazz so there's no audible baffle vibration/resonance at the low levels this type of music requires.
 
For those that might be thinking of building a dual woofer OB, even a quad woofer OB, this Technics Plate Amp might be a good alternative. There is even a less expensive version. Be advised that the power rating is @ 1 Ohm.
 
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