Anyone use Bohlender Graebener RD50 Planar Transducer?

I use the RD50s with a line of 6 RS180s actively xo'd @ 500Hz. Sounds incredible with my sub doing LF duties.



See my sig for the transition from dipole to sealed.

PMAZZ,
Nice work. Love the craftsmanship. Also like how well thought out it seems.

The 50" B&G and an array of mid-basses. Seems like an excellent approach. Must sound great.

How is the center channel mix with the arrays? This is alway the problematic challenge with the large array in a home theater approach.

wow awesome ! not quite sure on your crossover though...

Does your Sub play UP to 500 hz ? or are you lowpassing your RS180's at 500hz ?

Hey Stealthlude,
as someone who set his mind, time, and pocketbook towards the smaller planar approach, I can say that I think PMazz's approach would sound better.

Not that the small ribbon approach sounds bad, or that I have any regrets. However in truth the drivers are cheap, and there is a certain amount of distortion that cannot be eliminated entirely. This is most evident is complex music where the tweeters cannot keep up. Also the crossover is very tricky, the tweeters completely distort under around 2700hz. Any signal below this level is just nasty.

I am pretty sure PMazz is high passing the rm180s at 500hz. Out of the sensitive midrange area, yet able to use the full power of the array for midbass punch. Again this is a very good choice on his part. (Complements PMazz.)

Frankly if you were considering building speakers like mine or his, I would recommend his.

James

James has it right. Active xover (Marchand) is set to 500 Hz for the transition from the 180s to the B&G. 4th order LR to be specific. The RS180s are a near perfect blend for the xover to the sub handled by my HT processor (2nd order HP, 4th order LP). Here's a 2 meter freq response. Green is after tweaking.

Sounds fine to me. Nothing is ever perfect, even using the same drivers, due to the room's influence. I gave up trying to do everything "by the book" years ago and just trust my measuring equipment, ears and common sense. I'm also not as critical about surround sound as I am with 2 channel, as I only listen to music in 2 channel.

I'm toying with the move to Jon's Neo CC design but only for "scratching the itch" reasons.

Pete

Hail.

I have seen your website a long time ago on the line
array project. Pretty nice. I really do think the small planar
approach is better than the BG approach if you execute
the small planar design well.

I use the PT2B planars in my budget line array
and I have exploited alot of potential from these tweeters.

I not sure if your Stryke Audio RTW2 are the same as
PT2 version B tweeters. I believe that maybe your tweeters
are the original design like Yag-20? RT2?. Point is, PT2
ver B or greater has a new magnet structure and better
dampening, these improvement didn't really jack up the costs. Now they offer PT2 ver. C ,
I don't know the difference as I haven't look at it in detail. Essentially, $30 for the small planar is pretty good.
If for some reason the Stryke are the older models, then I would say the improved
planar would allow more room for optimizations of the sound.

To get more line array performance I use the LR 8th order digital crossover, plus EQ, etc. I can easily tolerate a 1700hz crossover point, for high SPL, perhaps 1900hz is better. For mad SPL I'll take it over 2khz. Just like any other speaker/driver, if you push them hard enough distortion manifests. I'm case, the average listener rarely wants to listen to the budget arrays at 1/2 of potential as the SPL is more
than enough. /hehehehe ... there is no problems for the normal person as no crazy audible distortion manifests.

To minimize distortion, the PT2B or greater is nice, I prefer a lower impedance line array wiring, and the use of bridged proaudio amps to
give me crazy clipping headroom, line array sensitivity is the highest in this mode, steep crossover slope. The perception is a more life-like
audio experience. I use ten PT2 per channel, eight to tweleve is a nice number to keep performance up,
but I wouldn't choose the $30 planar for a small speaker design with only one tweeter per speaker cabinet, I'd rather use a good dome
tweeter in the same price range, but for a line array, it does rule if you expliot the tweeters more. The BG solution cost 2.5x more than the
small planar approach. With the savings of not buying the big BG planar, you can use the money to go active.

If you do have the old tweeters, I don't know if there is an audible 'great' reward by upgrading the tweeters. Maybe a better
reward is trying a very steep crossover slope. I don't know why 2700hz crossover point would sound bad to you. I haven't
use the Stryke planars and 4th order crossover isn't too shabby, but maybe you can look into 8th order?

Interesting thread.

When I constructed my line arrays about 4 years ago, I used 6 8" B&G Neo8PDR transducers on each side.
They are Active Xovered (DCX2496) to 8 7" Vifa PL190W09-8ohm mid woofers.
Each 2-way array is xovered to a 15" sealed subwoofer for bass duties.

Would I do it again?
You bet!
I'm actually thinking of building another pair (even bigger!) to put in the front and "retire" the old pair in the back...
I wonder if the Dayton RS series is in the same league as the Vifa PLs. From the reviews I've read they seem to be very nice drivers but I haven't heard them yet...
Any opinions out there?

Regarding the Colossi...

I think it is a great project.

However personally I think putting the subwoofers in the same enclosure as the arrays makes very little sense. There would be a lot more flexibility of subwoofer design and placement to have the subwoofers separate, and geez-man wouldn't they be big enough.

Aside from that, a very nice project.

James

What is really dissapointing in regards to line array design is that the market really does lack a variety of good tweeter
candidates in the lower price range. There is nothing
really wrong with the BG products for making a line array,
but their lineup doesn't offer anything really amazing that
can show people what a really good line array can do.

People who build these array won't realize the full potential
of a line array unless they migrate to the more expensive tweeters. That is the problem as I see it right now.

The Neo8 isn't a great tweeter, in spite that line arrays
have been built using them and people love the results.
They love it, maybe because there is no other speaker used
for comparison. If you love Taco Bell but never went to Mexico for food, then you will be missing out too.


I maintain a certain position on line arrays, the tweeter
is the most important variable because the market lacks
choices, therefore redirect the big money towards this first,
the remaining of the funds use it for midwoofers, even if
they are low in cost. The reason for this is; If you build a
massive project like this, one should go with active electronics and multichannels of amplification. Second,
in an array, even cheap midwoofers can do amazing things
in large numbers, but the ribbon/planar tweeters pose
more of a bottleneck in performance. If money is no object,
then spend the extra money on expensive midwoofers if
you want, but it's not mandatory.

Dayton RS or Vifa PL, using that DCX with 8th order
crossover, it wouldn't matter much to me on which one
to use, I would look for a better tweeter solution first
then analyze the midwoofers later. If your tweeter array
can be crossed over lower, lets say in the 1500hz - 2000hz
range, 4th - 8th order, practically any brand of decent midwoofer can do the job. If this was a 1st - 2nd order
crossover, passive or active, then I probably would avoid
exotic cone materials [metal, etc] as the ringing may annoy you.

PMazz,
tell us about your experience with dipole and monopole. Why the move? What changes in the sound?

James

I have been testing with the PT2C's for nearly a year now, I have tried several tweeters out and nothing quite compares, these drivers sound great in an array and are better than the ones in zaph's tests after two revisions. You can REALLY thrash them and they just keep on playing.

X2...I have been thinking about doing an OB experiment to see if I like the sound. What's the benefit of Line arrays besides high sensitivity and high SPL's? Do they have a wide dispersion or are they really detailed and warm? I imagine with that many mids/woofers you can get some "live concert" effect (viceral kick bass etc.)?

At $36 a pop!

I thought technological obsolescence is not supposed to happen in the DIY arena.

Oh well, on the other hand, it is nice to have a straight forward upgrade path.

I guess I would have plenty of tweeters for those surround channel and rear channel stubby arrays I've been day dreaming about. (Curved down and back like concert arrays...)

I have been learning a lot from this thread.

james

You are starting to use hard to define terminology. They do have very wide dispersion and yes, plenty of visceral impact to keep you enthralled. How warm and detailed they are depends on how you design them, I don't like warm much myself, I like things a little on the bright side, but yes, they are quite detailed and despite what many of the people here will tell you(because they read a test of an identical tweeter by zaph a while back( they are rather low in distortion, what they don't remember is that these have been through two revisions since then and these tweeters sound sweet in an array.

Just my preliminary reading on them it seems that:

A) It would be a great DiY project
B) It would need active crossovers
C) I would need a few pro amps (or monoblocks)
D) It would be somewhat easy to do smaller versions for the center and surrounds

Please correct me if I am wrong on any of these. It seems like these would provide the broad soundstage I am looking for instead of going with a OB setup while yeilding the impact I want?

Forums are great! My wife thinks they encourage me to spend more? Go figure...

Subjective... you be the judge.


False: Line arrays will work with passive crossovers. Active crossovers are better of course, but that is true of ALL mulit-way speakers.


False: Follows the answer to B.


False: If your idea is a perfectly matched Left - Center - Right, line arrays provide special challenges, unless you place all three behind a sound transparent front projection screen. Think about it. You will go from a full length array to what... above the screen? Below the screen? A point source speaker?


True!

My wife thinks they encourage me to spend more?

oh no.....

http://firstrung.co.uk/dbimgs/iStock...of%20worms.jpg

Hehe...much to learn. No time right now. Need to go home and get things ready for delivery of my Pioneer 6010!!

Loved the dipoles! Open, spacious sound. I changed them to sealed enclosures to facilitate the media center project and have them built in. I also realized I do very little critical listening and the large sealed enclosures sound fine.

Pete