Gravity Well Of A DarkStar

mcgsxr · « **Reply #280 on:** 16 Jun 2005, 08:23 pm »

I am very pleased that Vinnie has been able to find an affordable source for lexan baffles - I looked around locally here in Canada, and found the prices to hover around US$500+ for a set of what he describes... So, there are no pretty baffles in MY future!

Personally, I have been happy with the sound of the Visatons, especially with a little cheap EQ via the "executive" units I have paired them with, but I have been privately unimpressed with my unwillingness to cart those big baffles out, and start carving them up a little, and get my $33 worth out of that mdf! I went to HD today, and now have 4 36 inch piano hinge sections, some 5/8 screws (3/4 inch material you may recall), and a renewed willingness to get back out to the garage.

I might be able to slide out of work early tomorrow, so I will remove the drivers in the AM, in prep for this. Tonight I will plan where to make the vertical cuts, so that I can recreate these big flat monsters, as folded winged creatures.

Stay tuned!

Dmason · « **Reply #281 on:** 16 Jun 2005, 08:41 pm »

Mark

Piano hinge is your friend when time to fold the wings of the creature. You can make your cuts for a narrow static baffle, and you would be AMAZED at how little is left when it is folded square. You can double up on the bottom length of the static baffle, and attach it to a plate.

If you can find a headstone shop around you, they most likely will have some granite clinkers lying around that you can have. This way you can have granite footers which not only look cool, but are ultra steady. Use two 6 inch angle brackets tucked under the clinker and you are done.

tubeytubeamp · « **Reply #282 on:** 16 Jun 2005, 09:00 pm »

Guys,

This thread is facinating to say the least. It is amazing to see what direction the love of this hobby has taken some of you.

I am interested in building a pair of open baffle computer speakers. I know diddly about speaker building but have learned that drivers suitable for open baffle applications must have low qts. I am curious to see if the famous TANG BAND W4-1052SA 4" drivers are suitable for such an application. The speakers will be used at my desk at work driven by the famous Sonic impact. The specifications for the Tang Bands are;

Specifications: Power Handling: 45 watts RMS/90 watts max *VCdia: 1" *Znom: 4 ohms *Re: 3.80 ohms *Frequency range: 60-15,000 Hz *Fs: 63 Hz *SPL: 90 dB 2.83V/1m *Vas: .26 cu. ft. *Qms: 4.52 *Qes: .49 *Qts: .44 *Xmax: 4 mm *Dimensions: Overall Diameter: 4-9/16", Cutout Diameter: 3-3/4", Mounting Depth: 2-1/4".

Thanks in advance.

ooheadsoo · « **Reply #283 on:** 16 Jun 2005, 10:18 pm »

I think the qts is supposed to be high, not low. In fact, .5 or higher is the rule of thumb.

barfind · « **Reply #284 on:** 17 Jun 2005, 08:15 am »

Hi tubeytubeamp ( man that takes some typing) Yes you can that driver, in fact most drivers will work. HOWEVER, low QTS drivers have a bass rolloff higher up, and will not make strong bass in OB. If you have a small-driver sub, you could get away with using that driver, and crossing the sub over about 140-170hz. This would work, but as I have never played with this driver, some experimentation would be called for. OK. But hey, whats it going to cost you?

Nigel

mcgsxr · « **Reply #285 on:** 17 Jun 2005, 09:51 pm »

After 4.5 long hours in the garage, the baffles have been cut into 3, and two 36 inch piano hinges per baffle have been installed. For the record that is 38 screws for each hinge... having to predrill each hole... ouch. Oh, and MAN I hate using tiny screws... I had to use #5 5/8 screws due to the material thickness, wish I could have used some #8 3/4 inchers, those just fly into the material. Ah well, such is life trying to experiment I suppose.

I goofed trying to cut an appropriate angle onto the wings, to allow for the main section to lean back... and that took around 1 hour to think and cut my way out of! Thankfully, in the end, I simply lost about 4 inches of vertical H out of the whole setup, having to cut all parts down to the same, after the error. This now means that the drivers are closer to the ground, and more around seated ear height. They were around 28 inches off the floor, and are now 24.5 inches from the floor.

God I wish I had a friggin table saw! I am glad I invested in the B&D Workmate, so that I am no longer cutting on the ground with my circular saw... but I still hurt my back, wielding those immense panels around, in order to find a way to cut them down semi-accurately.

I will NOT be rounding egdes, sanding etc, I am simply going to reassemble, and start listening.

I am waiting for one section I glued up to get bonded well enough that I can drop the clamps, and take these now less visually massive panels to the basement, bolt in the drivers, and get back to listening. I added a horizontal section of "baffle" to the rear, over the driver, as I have read (and thanks to powerbench for reminding me!) that helps with the bass.

Pics to follow, after dinner, and reassembly.

Hope you all had a good one in the office!

Dmason · « **Reply #286 on:** 17 Jun 2005, 10:27 pm »

JohninCR

Thanks for the post and for sharing. I had seen that shot long ago on DIY, I believe. It reminds me abit of the housing architecture in the Town of Bedrock, and I bet they look even better in person. I like.

Could you tell us if that is an Eminence Coaxial, and abit about the 5" load etc. The final result is a very interesting one; please tell us about its sound. I am fascinated by the idea of using large calibre coaxials in the type of config. seen in your pix, with swept back wings, and saw a design recently of a tapered trapezoidal "H" baffle for a 15" PAS coaxial, a little bit like a minimalist Tannoy Westminster was how it looked. It's owner was very pleased with the result.

Thanks again for your input.

mcgsxr · « **Reply #287 on:** 18 Jun 2005, 12:21 am »

Here are the pics of the transformation. Hardly beautiful now, but Michelle likes them considerably more this way...

For those that forgot, here is the before.

And here is the after! Included is the Red Wine Sharp EX-111 that I am playing around with.

Quick shot of the backside of the baffle...

After a day of hard work, I would like nothing more than to plunk down and listen for a couple of hours... but I am off to see some friends.

I should have some time tomorrow, and will report on how it differs from the enormous flat panels.

barfind · « **Reply #288 on:** 18 Jun 2005, 01:21 am »

Mark, Hey nice work. They look heaps better in your room. My wife had a look and was impressed too. Looking forward to sonic impressions.

Nigel

barfind · « **Reply #289 on:** 18 Jun 2005, 01:22 am »

Hey John, great to have your imput here, ggod work.

Nigel

Dmason · « **Reply #290 on:** 18 Jun 2005, 01:42 am »

John

I discovered a very high quality pro audio Neodymium coaxial with a Q=.54, would that be high enough in your opinion to be worth ordering to try "on the rack?"

With a 12, one could go with a narrower baffle, 1st order XO a la Bastanis Prometheus, cept with Uber sonics and point source.

JohninCR · « **Reply #291 on:** 18 Jun 2005, 02:18 am »

Thanks Barfind,

I'm glad Nodiak posted a link to here. A lot of the questions remind me of where I was a year and a half ago and while there some great OB info out around, there's also alot of myths floating around that seem quite plausible especially when you can't say here are my driver parameters and punch them into a program and it tells you what to do.

Plus the OB experts who really know the math and physics behind what is going on are as tight lipped as horn designers. When you can get them involved in a discussion, they talk in riddles or so far over your head that you can't ask an intelligent question.

The lack of hard info or guidance is scary for someone who wants to try OB for the first time. The beauty is that almost anything can work. Shoot I ran my Selenium coax 15's with no baffle for months at my desk. I just propped the magnets up on a stack of paper egg crates and made the drivers so they wouldn't roll off the table. Plus since everything is open, you can get everywhere to change anything you want and you can make something with cardboard, a knife, and duct tape that is going to give a good approximation of the final result. What more can you ask for ?

Add to the fact that it's so easy and flexible the idea that no other speaker sounds as open and natural as even just a decently implemented OB speaker, then there's no reason not to give it a try.

JiffyBoob · « **Reply #292 on:** 18 Jun 2005, 02:47 am »

John

That is a very insightful anecdote of yours, and bodes well for the future.

Let me say that when I first heard Dr D's "DarkStar" rig in full livery at his place, I could not believe just HOW different things sounded. I actually thought that in his enthusiasm he might have been overstating the experience abit, but this was not the case, in fact, his assessment was conservative. When I had a chance to spin some tunes I knew well, I knew right away this type of set up with the B200 was for me. Hopefully mine will be done in the next two weeks.

Anyone sitting on the fence about this stuff, needs to jump in. I can't wait to hear those black beauties with my Art Audio tube amp. And one other thing. They can CRANK out the tunes, and no distortion. Just louder. The dynamics like speakers in boxes I have heard won't do, in my limited experience.

nodiak · « **Reply #293 on:** 18 Jun 2005, 03:16 am »

Hey John, glad you're adding to all this. Good down to earth experiences. For where I'm at the tip about angling the top piece really makes sense. I am building folding baffles for the B200 and will have the driver close to the top edge (keeping unit shorter) so was going to add a piece above it on the back, now definitely at an angle, thanks, those are the type of details in design that add up. Also it makes me wonder if part of what I like about my dual 107 ob is the top piece keeps things more coherent. My 167 ob doesn't have a top piece, I'll add one and see if that helps it's "spacey" sound, which could be excessive high frequencies output over the top, maybe ceiling reflections (but 12' ceiling so maybe less so).
Don

powerbench · « **Reply #294 on:** 18 Jun 2005, 10:44 am »

Hey Mark the alteration looks great!! Im sure you ll let us know how they sound...

Looking forward to it.

powerbench · « **Reply #295 on:** 18 Jun 2005, 10:45 am »

oops message duplicated..

maxwalrath · « **Reply #296 on:** 18 Jun 2005, 03:47 pm »

duplicate post

maxwalrath · « **Reply #297 on:** 18 Jun 2005, 03:55 pm »

DMason, are you planning on selling completed speakers or kits for the OB design any time soon? Just wondering... a lot of us city living music lovers don't have tools or the space to put 'em.

Dmason · « **Reply #298 on:** 18 Jun 2005, 04:59 pm »

John

Q=.18?

Now that is a statement on the "pliable" nature of the whole thing. I am assuming you are referring to the Selenium Coax?

I was thinking along the lines of the 12 or 15 BMS, with the best CD driver available these days, pure light, heard it, love it, crystalline highs. See how far out one can push the sound. It sounds soooo good Clair Bros. recently retrofitted their whole inventory with these things. I feel it could be worth the investment. You get a BIG sound in the mids and lower mids, upper bass, that is gorgeous. ....'DeathStar' open baffle.

I noticed there are some amendments and additions to the Linkwitz site, with the small dipole bass unit. IKEA has a lattice-frame box that makes this idea muy simple as a "V" baffle tucked into the box, with 2 X 12, I believe.

Max,

I am considering drawing up some final plans for two versions of DarkStar and selling them as a .pdf file for a nominal fee of say $25 once I decide on the bass drivers to be used for the smaller version. For the full-on versions about to be built, about 2K. These are full range, have hinged, folding, veneered baffles with 3/4 roundover-ed verticals, DEQ, delivered, set up and rocking in their new homes. I am hoping to take a pair up to visit Dr Linkwitz this summer if I rent his pad in H.M. Bay and he could help me tweak the concept abit.

mcgsxr · « **Reply #299 on:** 19 Jun 2005, 12:26 pm »

I agree that boxed bass does not, for me, seem to add up that well, with the OB Visatons. I have tried using my 12 inch sealed Fosgate, and am now playing with the ported Nak 12 inch - the Nak does a better job, due in part to having higher sensitivity, but is also slower than the b200's.

I do prefer some bass... well, OK, I prefer stupendous bass when it can be arranged!

I have noticed the Riple thing over on DIYAudio, but I also notice a corresponding lack of existing guidance on implementation, or math to use, to design such a creature.

I notice that you mention using push pull with a Riple - this is to say that you mount 2 of the 12's in a Ripole? Face to face perhaps, and in phase, such that they "fight" each other, as opposed to isobarically, where they "help" each other.

Interesting that you mention tall cabinets for the Ripoles, I had not noticed anyone else doing that - a little more info would be great. Also, sharing any info about higher QTS drivers (.8-1.2 for example) vs using lower QTS drivers and using EQ - I know Linkwitz's view on this, do you have any experience using the cheap EQ (ie using a 1.2 QTS driver with an FS of around 25Hz, to give a big boost to the response at 25Hz, with no external EQ)?

I would love to build a W or Ripole with a set of 18's I have found locally...

Yes, I am that sick.