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.
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.
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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Yes dipole
Here's from the other thread... and the build thread from 2007.. looks like the image files are broken tho...
and from another thread... 2006
http://www.diyaudio.com/forums/multi-way/95603-bg-75-atc-planar-dipole-construction.html
Here's from the other thread... and the build thread from 2007.. looks like the image files are broken tho...
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
Set-up flat... sounds too shrill
and from another thread... 2006
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
another pic earlier while building...
John L (auplater)
http://www.diyaudio.com/forums/multi-way/95603-bg-75-atc-planar-dipole-construction.html
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.
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.
not so complicated... and got results
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.
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.
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 ....
why did you treat the other wall with diffusers then?
thought the Haas effect wasn't limited to the early reflections, but, I may be wrong..
The Haas Effect is the effect of early reflections only (arriving up to 50 ms after the direct signal), and they make the direct sound become stronger and - depending of direction - make the direct sound "bigger" and more spacious, but without being heard as separate echoes or reverb.
The rear wall diffusor is there to avoid early reflections from the rear wall; no Haas effect.
The rear wall diffusor is there to avoid early reflections from the rear wall; no Haas effect.
I've seen your design before over in my own dipole thread. Nice build, but quite different from my own.
I have lifted the top end 12 dB at 20 kHz with EQ. Without EQ a super-tweeter would probably be needed.
Here is my solution to a baffle for a RD-75 - magneplanar bass panels either side. They fill in the bottom end nicely, same fast speed as the RD-75 (I could never put a panel with a cone) and make a handy baffle. Crossover is first order at 660Hz, achieved by a passive filter in the input of each amp - speakers are bi-amped so I have a dedicated amp for each driver - so each driver is direct coupled to the amplifier. I have a notch filter according to the BG recommendation. I an very happy but to tell the truth I have heard a better tweeter than the RD75. SOme crazy friends of mine have designed and built 65 inch ribbon tweeter to match their maggie panels. Sounds simply magnificent. That is next on the DIY list.
Attachments
Well spotted, its a SOTA sapphire, with a Souther linear tracking arm. I've had this combo for nearly 20 years and still ahppy with it. I've recently added a Win strain gauge cartridge which is best cartridge that I've ever heard.
Back on topic - yes I know that the RD-75 needs a bit of top-end lift. As much as I love what it can do matched to the Maggie panels, I have heard a true ribbon and it is a big improvement on the RD-75. Rather than build a super tweeter I have decided to build a ribbon tweeter. Pic.s to follow tomorrow night. Oh and I know that I can't even hear 15kHz, so maybe no point to a super tweeter!
Your question about LF extension - never measured the maggie panels. They are reputed to go down to 40Hz, not super low but it is the quality of the bass that counts. I can't stand listening to box speakers after using the planar bass panels. There is absolutely no boom or overhang with maggies, so I have become hyper sensitive to those when I listen to boxes. I have 3 other friends who have replaced the Tympani tweeter with ribbons in a layout the same as mine, we have a small cult on our hands. Amaing how good 40 year old bass panels sound (though one of the boys has replaced the wire on our bass panels - a very clever boy).
Given the dominance of room modes below ~ 400 hz, I've never experienced the "slow bass" problem implied about cone drivers used with planar drivers, at least when used inside a room of anything less than auditorium dimensions. As long as the "box" Q is near critical damping, "overhang" etc. is all a subjective observation...
My setup has profound deep bass, as well as appropriate "speed" when necessary. It's all in the implementation...
John L
My setup has profound deep bass, as well as appropriate "speed" when necessary. It's all in the implementation...
John L
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