DIY Open Baffle Full Range Speakers from Wal-Mart . . .

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Have to share a photo of my very first DIY Speaker Project.

Visaton B200's arrived today (Thank you Solen!).

I just could not wait until the weekend to buy a sheet of plywood & get to someone's shop (we live in an apartment) to build some nice baffles.

So this evening I ran down to Wal-Mart, searching all over the store for anything that might work, at least temporarily anyway. Lo and behold, I ended up bring home a pair of 22x34 cork bulletin boards with some nice oak trim (I know, not the best for diffraction) for all of $13 each!

I did some "Golden Mean" calculations for speaker hole placement. Whipped out the jigsaw and cut out the holes in the kitchen - No problem!. The holes for the bolts were a little more tricky as the drill bit would break off some cork as it exitted the backside. No worrys. The speakers bolted in fine.

Hooked them up and WOW! Open Baffle sure is what everyone says it is! Very open, clean & natural. Sure notice the lack of that "Box Sound"

The B200's are very quick and smooth - and they have some breaking in to do yet. Bass is a bit shy of course, but still is more than I expected. Treble extends nicely. This is going to be a late one!

Thanks everyone here for the inspiration & motivation and also for letting me live vicariously (up until now anyway) through your experiences.

Don't worry, I'll get those B200's in a nice set of baffles soon enough, probably with a sub of some type in the bottom of each.

I'm calling these the "Corky's". Incredible sound for less than $350!

Now I'm thinking about a decent SET amplifier. And maybe the Fertin voice coils one day as well.

Fun stuff.

PS: Yep, that's a towel over the TV (to avoid the camera flash issue)
 

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For future use, I'd go with two of them, dipolar, mouted either on a flat baffle or an H frame with EQ, preferably active unless you've got 200W available from your amp to pump into them, in which case passive is possible (though not as good). Should give you decent lows, but maintain the dipolar benefits, which are at their most pronounced in my experience in the bass and lower-mid regions (ironic, as this is the most difficult thing to do with dipoles) in preventing or reducing the influence of the room.

I like the idea of the cork boards -novel, and attractive too. Wish I could find somewhere in the UK that makes decent ones for a reasonable price. Looks great to me!

Best
 
Thanks Guys!

@Ropie:
Yep, my partner suggested taking the picture with a bunch of paper & notes pinned to the boards but I thought that would be a bit too "tacky".

@adason:
I have always been intrigued by the Basszilla. I think I may go a little different route though. I'm hoping to have a seperate amp/Eq for the Bass and try to do it with 10" or 12" drivers. I think the B200's go lower than the Lowthers and Fostex do in OB, so hopefully I can get away with a fast sub of sorts (probably in a sealed enclosure) like the Rythmik or maybe using a TCSounds driver. I'd be happy with response down to somewhere around 30hz.

@TomekZ
"Satisfying" is fairly relative. I listened to these guys for a few hours last night no problem. It is warm & natural bass and is not "one-note" resonant which i hear in so many systems. I have to admit though, it could use a boost (for my tastes) in the lower registers. I need to play with some wings and come up with a good plan to integrate a pair of subs.


One other note I'll have to add is that these are my first full-range drivers so I am getting the double benefit of both no-crossover and open-baffle. I think what else has bothered me with a lot of speakers (we listened to 50 or so pairs when buying our last set) is suboptimal driver integration. Having no crossover in the "presence" range is so alluring (preaching to the choir here!).
 
@Scottmoose

I'd love to keep the added bass drivers dipolar!
I come up to two issues. I want to get the baffle width down to 16" so large "pro" drivers are out.

Then, I have been modelling a bunch of drivers (subs and woofers) in Thorsten's xbaffle.xls and have not found anything that is going to give me a significant boost in bass using one driver in an OB. I see why a lot of dipolar bass implementations use multiple woofers. The B200 actually gives better OB bass response than most 10" and 12" drivers I have modelled so your idea of using another one may not be so bad!

H or U baffles are a definite consideration as well. I wonder how a couple of EQed 6.8extremis's in an H baffle on each side would work?

Lot's of planning left to do on this one . . .

PS: the cork boards I used are not actually cork all the way through. There is a thin layer of cork on the surfaces and the middle is some sort of tightly packed fibre. I double stacked a small and large washer on the speaker bolts to make sure I had enough surface area against the baffle, otherwise the smaller washers would sink right into the material.
 
I did some more experimenting with the Corkys tonight. I flipped the speakers over and changed sides. More weight now and a better balance overall, even with the drivers down that low.

This also gets the drivers away from radiating directly back into the blinds (which are made of metal).

Very educational.

Another idea I had today was that if I were to use cork board again, I would put a block of wood behind them when I was drilling the speaker bolt holes. This would probably prevent the cork layer at the back from breaking off when the drill punched through.

Also, Sixmoons just posted a review of the Omega A8's which use the Visaton B200 where Louis of Omega explained:

"I chose to modify the back wave of the B200. It's basically damping of the cast frame of the driver. I heard a need for this in listening. The damping reduces peakiness in the critical midrange. I try to response-shape by mechanical methods only. I have tried electronic components in the past but they always took the life out of the sound."

Hmmmm, I'm wondering exactly what he did there. Anyone have any ideas?
 

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Aha you put the drivers closer to the floor.

If you haven't read JEL's open baffle page, check it out:
http://members.myactv.net/~je2a3/open.htm

There are two basket mods with which I am aware. The first is putting "rope caulk" or similar on frame to damp any vibrations. Popular with stamped frame speakers. The second is wool or felt on inside of basket, to dampen reflections off of the frame.
 
@Dumbass,

Thanks for the tip. Yep, I've read that site over a couple times. Lots of good stuff there.


Well, I rotated the speakers back to their original position with the drivers up higher. I just could not get used to the image being so low.

BUT, what I also did was hang bath towels over the back of the speakers (I did not have any felt around). This had an incredible effect of absolutely locking down and nailing the imaging. Wow! Everything became more focused and all sounds were now distinct in their own space and vocals gained a level of coherence. It got downright spooky at times. Bass also improved and I could actually now feel a bit of vibration through the floor.

Unfreaken unbelievable this tweaking business I tell you.
 
Hi loudandclear. I have been using the B200's in OB for nearly a year. I have changed the baffle several times, and what I have now is an awsome speaker. You will not believe the sound as the driver breaks in. All that has heard mine say it is the best speaker they have heard. You are in for some very speacil times. I drive mine with a 6 watt "Charlize". amazing setup, and the bass is great.
Have fun

Nigel
 
I'd suggest a re-read of Siegfried Linkwitz site too (no way you can abosrb all that stuff in one sitting. Or even a couple of dozen.) Or evena read, if you haven't already. Plenty of useful spreadsheets there too, and Linkwitz is The Man for dipoles. No-one else really comes close. Going for an H or U frame should also solve the baffle-width problems -I see no reason why, if you use EQ, you shouldn't get it down to around 12" or less.

One suggestion, as you mentioned problems with tearing the cork when you mounted these things, straight from Linkwitz: mount the drivers via bracing the magnet from the rear, and don't bolt / screw them into the baffle at all. Not as easy to do, but much better, and will preserve the cork.

If you used another one in future in full-range, then of course, you'd run into lobing problems, so you'd have to introduce a filter to roll one of them off quite quickly, but this can occasionally be a better option than trying to match two dissimilar drivers.
 
@barfind,

Yep. I'm really getting a new appreciation for the music experience "playing" with the B200's. I don't know if it's just me, but the bass is improving the more they are run in.

Can you let us know (with pictures if possible) what you found to work best as far as baffles go?

@scottmoose
Lot's of great stuff on the Linkwitz site. Gotta read it several times to get the jist. I don't want to EQ the "main" B200, but will do what it takes (EQ/XO/Slope/Enclosure/Baffle) for the bass driver to get the low end right

The cork bulletin boards are temporary and a quick way to get listening to my new speakers. I don't think I fully trust them to stand up in the long term, as they are a touch fragile. I may do what several people have done though and that is attach a layer of cork to my permanent MDF or plywood baffles.

I will certainly consider magnet mounting for the "final" version as well.
 
Parts of my OBs in my PC rig are from WalMart. Parts from OfficeMax, parts from Michael's, parts from Loew's and the drivers from Best Buy. Maybe $60 total for the pair.

I used the stretcher bars from a pair of cheap 16"x20" canvases from Michaels, that I mounted sheets of black foam-core (black paper and foam, so really quite attractive) to with 2" OfficeMax binder clips (you take the silver arms out of them once you've got them in position). I made sure that I had all the clips oriented to where the engraved OfficeMax logo is visible on the front. No one ever seems to notice, so I guess its just a private little joke for me. Anyway, hinge mounted the stretchers to lengths of 1"x2" that were cut just so they would wedge frimly between the desk and top shelf of my PC desk so they're fully adjustible from 90 degrees straight out to how ever far in they can swing without hitting my gear (variable).

The drivers are Kenwood KFC-6949s which are 6"x9" bicone fullrangers so I don't have the crossover either. I'm driving them with a Sonic Impact T-Amp that I picked up for about $23 shipped that I leave set at 50% (connected with 3' lengths of CAT5 using bare wire on the amp side and gold AutoZone slip on connectors on the speaker side). My source is a EMu 0404 sound card which is very good for doing detailed EQ. In-between, I've got a Presonus HP4 headphone amp that also has monitor out volume/mute control that I use as preamp (I leave software volume controls turned off to keep my players from bit-shaving). The Kenwoods sound surprisingly good (I can chalk alot of that up to my quality source and the insanely high performance of the cheap little T-Amp). They're rated down to 28Hz by the manufacturer (and we all know how much weight those specs carry), but with minimal EQ, I'm getting flat to about 45Hz (though response drops off a cliff around 38-40Hz). On the way up its fairly smooth with a small peak around 2KHz and a large one around 9KHz (both of which have become less pronounced with break in). They seem to roll off around 16Khz, but I doubt that's the case since every speaker I've ever used in this set up, including ones that used BG Neo3PDRs as mid/tweeters seemed to roll off at the same point. It could be the source gear, but most likely its my ears, and I think Kenwood rates them up to like 22KHz.

This is near field listening, and with 94dB sensitivity and 4Ohm load, the T-Amp never breaks a sweat. The drivers are mounted approximately ear height and as far to the outside as possible. All it takes is a bit of tweak to the baffle angle to get an enormous sound stage, at least in width. I'm thinking to try your trick of hanging a towel or whatnot behind to try to tighten the imaging up. The desk is backed into a corner, so they get some fairly immediate reflections from the walls.

Anyway, I feel that OB used with single, fullrange drivers is the only way to go, and definitely the best way to go on a budget if you can find the right drivers (there are a few decent car audio drivers like the Kenwoods, some Pioneers, and then others like what you guys are working with, maybe some Fostex, an interesting set of Goldwood bicones (8008, I think is the model number) that I've been eyeing for awhile (drop in replacements on the big bookshelves I'm using in the living room, though probably experimental OB fodder first).

Go OfficeMax OBs!

Kensai
 
Dumbass said:
Beyond his obvious technical knowledge, I covet Linkwitz's handwriting and drawing skills. :mad:


You'll survive... ;)

The plan sounds sensible to me. Leave the main alone, EQ the bass, and roll it off if it's a full-ranger to prevent lobing. Good way forward in my view.

I know this is contentious, but for the final system, I'd heavily advise going for dipole bass, and I'm also less-than convinced about the merits of low mounting to get some gain from the floor. Plenty of people do both with decent, even excellent resusts -fair enough. But to me, a low-mounted driver, angled up throws away a large amount of a dipoles principle benefit -far less excitation of room-resonant-modes than a regular monopole. Ditto using a sealed box, BR or TL for the low-range (say from 200Hz down to about 40Hz or lower.) Dipoles, exciting less room-modes (which in the average room occur somewhere between these two figures) provide cleaner performance in this region. Below around 40Hz, unless you're in a giant room, you can go back to monopole, which is I believe what Linkwitz does with his Orions, which go to around 40Hz, then his Thor sealed box subs for the 25Hz requirements.
 
Kensai said:
Parts of my OBs in my PC rig are from WalMart. Parts from OfficeMax, parts from Michael's, parts from Loew's and the drivers from Best Buy. Maybe $60 total for the pair.
*snip*
Go OfficeMax OBs!

Sounds intriguing to me (like my "Bride of Son of Zen Goes to IKEA", in a way, but more McGuyver at the same time).

Got any pix?
 
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