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Old 1st June 2012, 07:28 PM   #61
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Yeah well, I might have exaggerated my point a little bit.... Even with a lot of reflections, good dipoles (the RD-75 included) have better resolution that any boxed speakers I have heard. But strong enough room refections WILL mask low-level early reflections on the recording. Thats a fact.
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Old 2nd June 2012, 06:39 AM   #62
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I take your point! Dipoles DO need room treatment, the fact the they interact less with the room especially in the bass is not an excuse. I have not started to treat mine yet, and it's my lounge so not an easy task to accomodate my wife deco taste either!
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Old 2nd June 2012, 09:07 AM   #63
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An other fact is that dipoles have less radiation off-axis than typical boxed speakers, so they create less room reflection. They give more direct sound, so to speak. But I agree that it's not an excuse for not treating the room! I have treated my dedicated room quite extensively, far above any level of wife acceptance ......

I have set up a system similar to my own for a friend of mine. It's scaled down on the woofer side, but it's still the big RD-75. The room is treated very gently, just some absorbers on the front wall and not much else. Much of the qualities of the RD-75 comes through, but because of the higher level of room reflection, minor details in the music are lost, and the imaging is not as knife-sharp as I have in my own room.
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Old 2nd June 2012, 10:17 PM   #64
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Default BG RD75 on/off axis

Here's my setup @ 0, 15, 30, 45, and 60 degrees off axis (top to bottom)

Click the image to open in full size.
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Old 3rd June 2012, 07:23 AM   #65
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Incredible.. in an ideal world the response would be within +/-5db, but this is really CD! do you run them dipole too?
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Old 3rd June 2012, 08:49 AM   #66
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That looks really good. We would like to know more about baffle width and so on!
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Old 3rd June 2012, 01:36 PM   #67
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Default Yes dipole

Quote:
Originally Posted by lolo View Post
Incredible.. in an ideal world the response would be within +/-5db, but this is really CD! do you run them dipole too?
Here's from the other thread... and the build thread from 2007.. looks like the image files are broken tho...

Quote:
Originally Posted by auplater View Post
While I built my Rd 75 Dipoles baffled 5 yrs. ago, and don't much hear any great advantage in "CD" in practice, I certainly don't have any dynamic range issues with them...xover @ 600 Hz

slight downward tilt from ~ 1Khz up is personal preference... these will measure flat, but that sounds too brite to me...

2nd plot is off axis @15, 30, 45, & 60 degrees @ 3 meters

Click the image to open in full size.

Click the image to open in full size.

Set-up flat... sounds too shrill

Click the image to open in full size.
and from another thread... 2006

Quote:
Originally Posted by auplater View Post
Hi folks...

The BG's run free from ~600 hz up....with Peerless HDS
mid-woofers for 600 Hz to 50 Hz range, Peerless silk tweeters (one firing forward, one backwards) from 3500Hz up, EAS-400 leaf-tweeter as super tweeter from 7000Hz up. The bottom end is augmented by a Titanic 12" sub in a 5 ft^3 sonotube, pretty much from 100 Hz to < 20 Hz. all @ 2nd order

RD 75 has the notch filter... dipole baffle roll off compensated and levels matched for all drivers...

I'm still tweaking (does it ever end?) The baffles are 1" cherry and the mid woofers are housed in mdf enclosures tuned to ~48 hz.

another pic earlier while building...

John L (auplater)
BG-75 / ATC planar dipole construction
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Old 3rd June 2012, 07:43 PM   #68
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wow.. this is a complicated case! a 5 way speaker..

Stig Erik. It seems to me your room is built on a studio principle, reflexion free zone, do I have to assume you spent too much time in these?
given the size of the room the Haas effect is still there I guess, but you must gain the clarity from the absence of comb filtering from the early reflections. Anyway, acoustic black hole must be, in front or behind the speakers.
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Old 3rd June 2012, 08:43 PM   #69
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Well there isnt much Haas effect since all early reflections are inaudible with music signal. To call it an "acoustic black hole" might be appropriate I guess ....
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Old 3rd June 2012, 10:21 PM   #70
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Default not so complicated... and got results

Quote:
Originally Posted by lolo View Post
wow.. this is a complicated case! a 5 way speaker..

.
Actually, it started out as a 2 way at most (BG-75 plus 2x6.5 peerless woofers)... baffle width 21"... if I recall, the BSC starts around 270 hz or so

I added the additional speakers to improve the sound and power handling, but the original RD75 + 2 woofers sounded pretty good on its own. The high end super-tweeter addresses the beaming and dropoff of the BG's > 12 Khz quite nicely, uses a simple 1st order xover.... no high end xover for the RD75's... the bass bin is xover 2nd order LR.... and the baffle step helps the transition zone at the low end

I may rebuild them using Lucite baffles (see thru).... still debating on that...

cheers

John L.
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