New Home for the BG Ribbons - Part 27

[fjhuerta]

That. Is. Huge.

[JonMarsh]

Yeah, I think ET is going to get an inferiority complex about this vs. his "DeathStar" project- the "DeathStar" may weigh more, but it won't be "bigger". :W

[chasw98]

Jeez! You guys act like this is something new around here. Has no one ever seen a 4 way floor to ceiling Acoustat, RD75, Leaf Tweeter, IB rig before? Any of you?

Or one of these?

[Bear]

More Peerless 6.5" woofers are on buyout at PE, though not in the HDS line with the truncated frames. $27.66 again in 4+ quantities:

http://www.parts-express.com/pe/showdetl.cfm?Partnumber=299-260

Anyone have any thoughts on how these will compare? Is this just the 830875, but with a "full" faceplate?

[JonMarsh]

It looks like it, but it is a "funny" part number, having trouble crossing it elsewhere, including Peerless site and Madisound. Does claim to have shorting rings, so HD should be decent.

[kingpin]

Jeez! You guys act like this is something new around here. Has no one ever seen a 4 way floor to ceiling Acoustat, RD75, Leaf Tweeter, IB rig before? Any of you?

Or one of these?

Hmm. I've seen, built, heard, enjoyed and then sold something a wee bit larger than that. LOL

Ahh! Good Times.

Looks good chuck.

Mike

[chasw98]

Here is the weekend update. I got all of the routing done on the laminated MDF body and came up with the beginnings of a method to make this guy stand up straight. Lots of pictures.

I have not used more than 2 screws per woofer, I haven't put the aluminum bars in to stiffen the panel up yet, I haven't done a roundover on the backs of the woofers, and most of all, I didn't put the scallops in yet (Jon)!

But what I gained from this almost complete mock up was the ability to hear 2 of these behemoths in the room in stereo! Put you hearts at ease. The imaging and soundstaging is great. Off axis response is quite good. Now all of this is done with my poor old ears so take that into account because I have not taken any measurements at all. Just listened to them. So far, it seems, they can only get better.



Note the spacing between the woofers. Krutke would be proud!



Closeup of the Neo's.









Yes, that is a 40 pound steel plate laying there.

[---k---]

Impressive. :T

One questions I have for you about line arrays. Some of this is theoretician. Sorry, I haven't read Griffin's paper yet, but I'm making my way through Toole's book, and he says quite a few positive things able line array's. But, one point he has made a few times is that the line of drivers HAVE to be from floor to ceiling, or it doesn't form a cylindrical wave front. (I guess some power tapering or curving the baffle will also work for shorter line array's) You're basically there with the woofers. Is that good enough? Should the mids and tweeters floor to ceiling also for theoretic perfection?

[chasw98]

Impressive. :T

One questions I have for you about line arrays. Some of this is theoretician. Sorry, I haven't read Griffin's paper yet, but I'm making my way through Toole's book, and he says quite a few positive things able line array's. But, one point he has made a few times is that the line of drivers HAVE to be from floor to ceiling, or it doesn't form a cylindrical wave front. (I guess some power tapering or curving the baffle will also work for shorter line array's) You're basically there with the woofers. Is that good enough? Should the mids and tweeters floor to ceiling also for theoretic perfection?

Ryan:
Let me state that I am approximately one page ahead of you in line array theory (OK, maybe 2 pages ) Everything I have read states that for a line array to work on paper, yes, it should be floor to ceiling. In real life it almost never happens, even with 3 mile long sounding arrays in oceanic science. And in high frequency antenna arrays that do not reach the sun? Then you get into what are known as truncated line arrays and that is a whole other study in itself. You are right that it all concerns what happens to any factor at the ends of the array. Any factor could be phase shifting, frequency response, off axis response, cylindrical wavefront forming, etc. You get the picture. From what I have read and what I have heard in my testing is that unless Shaquille O'neal or some other close to 8 foot tall person comes to visit me, they will not lose any of the good part of an array. The floor to ceiling 'sweet spot' appears to be from approx 2 feet off the floor to above 6 feet off the floor. I haven't climbed on a ladder or laid on the floor yet but all my listening and measuring at diffferent heights bear that out so far. The left to right window between those heights appears to be quite adequate also, maybe 6 to 8 feet wide as a rough guess. In the end I should have a 5 foot tall by 8 foot wide listening 'stike zone' that will have even response and power for a depth of 6 to 10 feet starting about 6 feet away from the speakers. HTH.

[ThomasW]

he has made a few times is that the line of drivers HAVE to be from floor to ceiling, or it doesn't form a cylindrical wave front. (I guess some power tapering or curving the baffle will also work for shorter line array's) You're basically there with the woofers. Is that good enough? Should the mids and tweeters floor to ceiling also for theoretic perfection?

It's important for the low frequency drivers to be floor to ceiling. The idea is to have symmetrical boundary loading for the top and bottom woofers.

Floor to ceiling mids and tweets would be ideal, but there's a decreasing performance benefit for the amount of $$$$ invested. So we're happy to compromise and use what you see Chuck building..

[---k---]

There is always a difference between theory and practice. Sort of the answers I was expecting. :T One of these days, I'm going to have to find an excuse to make a trip to Miami.

[chasw98]

One of these days, I'm going to have to find an excuse to make a trip to Miami.

Just get close. I will come and get you!

[---k---]

I've made 4 trips to Tampa this year for work. Is that close enough. It's Florida.

[Hank]

I've got a ~20 foot high cathedral ceiling, so no way am I going to build a floor-to-ceiling line array. All the more reason to stick to RD50 and ~10 mid-woofs per speaker.

[Amphiprion]

All those pro sound setups that use line arrays outdoors should probably be told they're not doing it right

[cjd]

No kidding. Maybe if they used quality systems we'd not have people craving harsh hashy systems with no dynamic range or resolution, just loud....

[JonMarsh]

JBL has well documented the effects of line length on frequency response and frequency response versus distance from the line.

Useful in Pro sound.... even "short" flying lines.

I really have to wonder at all the interest in Pro Sound oriented systems for the home- waveguides, high efficiency woofers, compression drivers- etc. I don't need 115 dB in the home, and don't like the short comings of those kinds of systems. They have far too much of a signature to pull any kind of disappearing act with music.

If I was King or Emperor, I would have EVERY budding speaker designer and 98% of the so called speaker designers exhibiting at CES to spend a week listening to a pair of Orions with decent recordings before they're allowed to make sawdust or even paper plans again. At least, there's a small chance they'll remember what some notion of neutrality and low coloration sounds like.

[Dennis H]

I really have to wonder at all the interest in Pro Sound oriented systems for the home- waveguides, high efficiency woofers, compression drivers- etc. I don't need 115 dB in the home, and don't like the short comings of those kinds of systems. They have far too much of a signature to pull any kind of disappearing act with music.

If I was King or Emperor, I would have EVERY budding speaker designer and 98% of the so called speaker designers exhibiting at CES to spend a week listening to a pair of Orions with decent recordings before they're allowed to make sawdust or even paper plans again. At least, there's a small chance they'll remember what some notion of neutrality and low coloration sounds like.

Ouch!

FWIW, at least one person sold his Orions after he built a Geddes kit. I don't think there's universal agreement that pro drivers and waveguides necessarily have to equal bad sound. That said, I've heard Orions and loved 'em but I haven't heard a Geddes kit.

[ThomasW]

That said, I've heard Orions and loved 'em but I haven't heard a Geddes kit.

I've heard both. From a distance (the hallway at the RMAF) the Summas sounded like very high quality PA speakers. It was impossible to do a serious listen because Earl was flogging them (as he is want to do) and I wasn't in the mood for permanent hearing damage.

[cjd]

There is a line most of these folks wander well beyond - it's about finding a particular flavor that they like (for whatever reason) - if that means the warm tickle of blood seeping from the ears, they're welcome to listen to pro systems at 110dB.

Lack of coloration is often NOT the intent.

These days it seems like some "music" only needs to reproduce 50Hz. They'd have it made in Europe - no amp needed, just feed line voltage to the system!

[Johnloudb]

All those pro sound setups that use line arrays outdoors should probably be told they're not doing it right

I just thought Mark was saying that to build a line array from floor to ceiling outdoors would one looonnngggg line array. Not touting the wonders of most pro speakers.

Our main speakers, the Nelson/Reed 804B, use high sensitivity pro drivers. They were designed to used as a recording monitors. And they have a very natural and uncolored sound. Probably not the last word in resolution, but I don't feel I'm missing anything.

I've always really liked Sound Lab Loudspeakers. That's one reason I'm building this line array with the RD50. I think a dipole line array would work well in our room. The ceiling is fairly low with the wood cross beams exposed, and is kind of dead sounding. More drivers with more radiating area might make it more open sounding?

Actually, I'm a bit worried. I've got our main speakers sounding really good since I took them off their stands and positioned better. What if my dad likes the old speakers better? 8O I've heard the RD50 does have gorgeous midrange, so I hope I can do this right and get some neutral and open sounding speakers.

[JonMarsh]

If a line array is built floor to ceiling, then the woofer array is "mirrored" by the floor and ceiling and the acoustic throw behaves accordingly. Otherwise, what happens is that at some LF point the system no longer follows the 3 db drop off with distance doubling, but goes to 6 dB in the lower frequencies.

Listening to a Griffin LA clone in MarkK's large family room high lighted that kind of behavior; at a distance, they became "shouty" because the bass fell off in level but the midrange didn't.

[JonMarsh]

I just thought Mark was saying that to build a line array from floor to ceiling outdoors would one looonnngggg line array. Not touting the wonders of most pro speakers.

Our main speakers, the Nelson/Reed 804B, use high sensitivity pro drivers. They were designed to used as a recording monitors. And they have a very natural and uncolored sound. Probably not the last word in resolution, but I don't feel I'm missing anything.

I've always really liked Sound Lab Loudspeakers. That's one reason I'm building this line array with the RD50. I think a dipole line array would work well in our room. The ceiling is fairly low with the wood cross beams exposed, and is kind of dead sounding. More drivers with more radiating area might make it more open sounding?

Actually, I'm a bit worried. I've got our main speakers sounding really good since I took them off their stands and positioned better. What if my dad likes the old speakers better? 8O I've heard the RD50 does have gorgeous midrange, so I hope I can do this right and get some neutral and open sounding speakers.

Compared to many other solutions, the RD50/RD76 set have far lower linear distortion in the midrange (500 Hz to 3 kHz) than most cone type drivers; less energy storage and hangover (think shaped sine testing like SL and Mark K do) and more resolution. Other drivers work well in this regard, too, such as domes like the RS52, or very small cones (W4-1337, RS100-4). So there is good potential for combining a pleasing tonal balance and high resolution.

[Johnloudb]

Good to hear that and I see what you mean. We have our speakers positioned along the long wall and can't sit more than 10 - 12 feet from the speakers, with them positioned 2.0-3.0ft from the back wall. Hopefully this will work well, or I might be selling drivers in by the end of summer. Probably work out great, just me worrying.

[---k---]

It was impossible to do a serious listen because Earl was flogging them (as he is want to do) and I wasn't in the mood for permanent hearing damage.

He isn't alone in this. I've been to DIY meets where Tom from SVS was demoing their new at the time SVS-1 speaker and another meet where Jeff from JTR Speakers was demoing his Triple 8 speakers. Both tended to turn them up to '11' to show off any chance they could get. The Triple 8s and a sub had the dinning room lights flickering. Chased me from the room. The saddest thing to me was that at reasonable volumes, they were decent speakers for the price, but at the demo levels, they were sounding pretty ragged. Maybe normal people (and the seller) don't notice this?

I'm not sure I've ever turned my Khans up to those levels. I'm going to have to tr it sometime and see how they sound...

BTW, is there a topic to this thread?

[cjd]

Get earplugs out and listen for popping from the tweeters. I doubt you'll push anything else in the system to the limits before your amp runs out of steam. At least not the Khans.

C

[JonMarsh]

Hello? Hello? Anybody home? Kind a quiet around here all of a sudden... :W

[chasw98]

Don't worry, just recouping from an influx of parts and electronics (amplifiers, inductors, bassis unit, etc.). I took all the test units apart, packed away the drivers, cleaned up the work area, and disassembled the one good one so that I can start building the second one to match it. Just a short lull. You know how when you have done something once for the first time, you say to yourself "If I do that again, I would do it this way" now that you have done it and experienced the little pitfalls inherent in doing something like this. Well, I am refining my technique and am having a hard time finding 1/4" hardboard (masonite to you old timers). Have to check out a lumberyard tomorrow afternoon. NO, the box stores don't have it around. But, guess what? I just noticed that one of the big orange places has finally started to carry 'birch hardwood plywood' in 4' X 8' sheets for $50/sheet. I doubt if it is baltic or russian birch, but it appeared to be void free! They have never carried it before. Must buy a few sheets.

[Dennis H]

But, guess what? I just noticed that one of the big orange places has finally started to carry 'birch hardwood plywood' in 4' X 8' sheets for $50/sheet. I doubt if it is baltic or russian birch, but it appeared to be void free! They have never carried it before. Must buy a few sheets.

That's a really good price if it's real appleply, what they usually call US-made baltic birch in 4x8 sheets.

[ThomasW]

The stuff at HD is likely from China. I used it in the Isiris and Black Whispers, seems fine but for the occasional thick spot in the laminations

[cjd]

Yup. I use that stuff from HD as well. Good 'nuff for me, i'm cheap and lazy. :P

[chasw98]

Need to get this back on the first page before I lose track of it. I am almost finished constructing the second mirror image baffle. Waiting on 15 10-32 X 3/8" flat head screws.



Once I get the drivers screwed in place I will have two complete baffles with drivers mounted and ready for bracing and bases. I am going to laminate 2 pieces of 1 X 4 red oak for a single rear diagonal brace going from 5 feet up the baffle to the rear of the base which will be 24 inches deep. Once I laminate the oak I am going to route a channel down the piece that will hold the cables that feed the arrays. The brace will bolt into the array with flat head 1/4-20 bolts and hurricane nuts. The base will be sort of pentagonal and bolt onto the rear of the baffle at approx. floor height. This will allow me to break down the array into 4 pieces for transportation or moving it. Base, brace, baffle with woofers, and plexiglass mid/hi section.

Just getting the baflles ready is only part of this procedure. Constructing the base and the brace will allow me to stand these guys up and listen to them while I sort out crossover issues and such. And at some point I will tear them down again and make them look pretty with a nice finish.

[Johnloudb]

Just one brace? Screws & T-nuts? No Glue? That's it? :E What happened to the aluminum angle and spine? Are you crazy ... what if there's an earthquake. :B Oh, I forgot you're in Florida ...

[Mazeroth]

what if there's an earthquake. :B Oh, I forgot you're in Florida ...

Even worse! :B

[PhilDSP]

I don't know if the old B&G whitepaper is still on the PE website, it had recommended listening distances for the various height planars. The shorter the planar the shorter the listening distance.

That was an initial concern for me as the preferred listening position in my living room is about 12 foot from the front plane of each speaker. But I've lived with a a pair of RD75's standing straight up off the floor with no baffle what-so-ever for the past few months and find that they definitely sound much better and more balanced up close.

Then again my room seems to kill high frequency signals. To flatten the FR for the RD75 with a 31 band DEQ I needed to boost everything above 12K by about 12db. I'm also testing a Foundtek NeoCD2.0 and it's output looks exactly like the published specs until 20K and then it rolls off extremely quickly.

I'm in the process of building a 4-way array: a 10" Scanspeak isobaric pair, [8] SB15 5" mid-woofers, the RD75 and [8] NeoCD2.0's

In the process of testing I've found that a single SB15 paired with a single NeoCD2.0 at ear level crossed over at 1800 Hz actually compares nicely to a single RD75. I might slightly prefer the tonality of the SB15/NeoCD2.0 as the treble is quite a bit nicer and lower mids punchier. (The NeoCD2.0 has less mass and reacts even more quickly to the signal than the RD75) But of course distortion and cone breakup sets in at higher SPL's with denser audio material with that crossover. That shouldn't be a problem at all in an 8 element array.

The SB15 with NeoCD2.0 setup is just a test of course. I haven't heard all of the intended components together yet but what I've heard is already amazing. The RD75 brings an enormous sound stage to the table.

115 db SPL's without audible distortion? No problem whatsoever for these puppies in full configuration I'm sure. But now one has to worry about hearing loss...

[JonMarsh]

You'll get a cleaner response out of those RD75's with a baffle to support the lower mids; even then, my preference is about a 600 Hz crossover.

[ThomasW]

To flatten the FR for the RD75 with a 31 band DEQ I needed to boost everything above 12K by about 12db.

Yeap most planars have a soft top end

I'm in the process of building a 4-way array: a 10" Scanspeak isobaric pair, [8] SB15 5" mid-woofers, the RD75 and [8] NeoCD2.0's

Should sound pretty good... :T

115 db SPL's without audible distortion? No problem whatsoever for these puppies in full configuration I'm sure. But now one has to worry about hearing loss...

+1

It's easy to toast one's ears with a big array. Our brain tells us to turn things down when the distortion reaches a certain level, that keeps most people from damaging their hearing. With a big array distortion isn't audible until the output is at the major ear damage level.

[PhilDSP]

You'll get a cleaner response out of those RD75's with a baffle to support the lower mids; even then, my preference is about a 600 Hz crossover.

That sounds good, they're just standing there now for test purposes. Since I like the top end with the Fountek's the crossover values I plan are 125 Hz, 600 Hz & 4000 Hz.

[PhilDSP]

It's easy to toast one's ears with a big array. Our brain tells us to turn things down when the distortion reaches a certain level, that keeps most people from damaging their hearing. With a big array distortion isn't audible until the output is at the major ear damage level.

It's especially problematic with very dynamic material. This weekend I was listening to the DVD Audio release of the Verdi Requiem recorded in St. Petersburg, Russia. It's often fairly quiet and of course I like to turn up a bit to revel in the low level details. But double sfortzando (sp.?) with the entire choir and brass blaring that comes on suddenly in places is truly frightening :E

[lilypotter]

Looks awesome.

[chasw98]

Here you go. Another weekend update. I have completed both frames and the method of supporting them upright. They are built and ready to load the drivers into.





I have both plexiglas panels finished and wired and ready to bolt in. I also have the wiring harness for one set of woofers ready to go. Tomorrow I will get the other set of woofers wired up and ready, then install everything, turn 'em on, and listen for a while.

Note that no attempts to make them stylish, pretty, or any other looks enhancing techniques have taken place yet. I am only at the stage where I now have a pair that I can A/B against the other, test and measure different xover configurations, and move them about fairly easily. The real work is yet to come.

[JonMarsh]

The real work is yet to come.

Man, that always seems to be the case no matter how far along you are!

[CraigJ]

I see you dressed up for our picture. You're going to love the dynamics of your upcoming array!


Cj

[Dennis H]

I see you dressed up for our picture.

Hah! Chuck busted with a bare belly in the reflection. Man, I don't know how you southern guys get anything done. 106 today here in the NW and I stayed inside with the AC and didn't do diddly.

[chasw98]

Hah! Chuck busted with a bare belly in the reflection. Man, I don't know how you southern guys get anything done. 106 today here in the NW and I stayed inside with the AC and didn't do diddly.

How many ways can I spell EMBARASSED!!!!!!!!! ops: ops: ops:

Dennis:
I moved to Florida in 1993 and I am still NOT USED TO THE HEAT! Before that I lived for 20 years in Woody Creek, Colorado at 8,000 feet altitude. Why did I ever leave?????