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Bohlender Graebener RD40 Planar Transducer

Bohlender Graebener RD40 Planar Transducer

Brand:| Model: RD40
Specifications: • Power Handling: 50 watts RMS/200 watts max • Nominal Impedance: 5 ohms • Re: 5.0 ohms • Frequency range: 150-18,500 Hz • SPL: 88 dB 1W/1m • Net weight: 18.4 lbs. • Dimensions: 40" L x 4-11/16" W x 1-1/2" D.
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Weight: 20 lbs.  
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Product Details

Bohlender Graebener RD40 Planar Transducer

The RD series of loudspeaker drivers offer the systems designer the advantages of a thin-film, line-source transducer with very high performance potential for fixed installation sound reproduction. Unlike most exotic driver types, the RD Series models feature unmatched bandwidth, power handling and ruggedness, as well as the ease of an almost entirely resistive load to the amplifier. All models in the RD Series feature linear, push-pull Ceramic 8 motors linearly driving a polyester diaphragm whose moving mass is actually less than the air load. The bandwidth of the RD Series drivers is extraordinarily large, and is usable from as low as 150Hz to beyond audibility. Program power handling of the RD40 driver is 100 watts. The diaphragm is protected within a chassis made of three layers of heavy gauge, self-reinforced steel.

Specifications: • Power handling: 50 watts RMS/200 watts max • Nominal impedance: 5 ohms • Re: 5.0 ohms • Frequency range: 150-18,500 Hz • SPL: 88 dB 1W/1m • Net weight: 18.4 lbs. • Dimensions: 40" L x 4-11/16" W x 1-1/2" D.

Bohlender Graebener RD Series Planar Transducers cannot be shipped or sold to customers that live outside of the United States. There is no warranty extended to customers outside of the United States that purchase any of the Bohlender Graebener RD Series (including the RD75, RD50, and RD40) Planar Transducers from Parts Express.

Product Specifications
  • Tweeter TypePlanar
  • Impedance5 ohms
  • Power Handling (RMS)50 Watts
Bohlender Graebener RD40 Planar Transducer
  • BrandBohlender Graebener
  • ModelRD40
  • Part Number264-706
  • UPC844632053009
  • Product CategoryPlanar / Ribbon Transducers
  • Unit of MeasureEA
  • Product Rating
    (4 Reviews)
  • Weight20 lbs.
  • California Prop 65

    Warning: California residents only. Please note per Proposition 65 that this product may contain chemicals known to the State of California to cause cancer and birth defects or other reproductive harm.

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Bohlender Graebener RD40 Planar Transducer
Bohlender Graebener RD40 Planar Transducer is rated 4.5 out of 5 by 4.
Rated 5 out of 5 by from COMING ALIVE!This whole project to bring my hi-fi system up a notch began last summer, when I decided to switch out my aging Vandersteen Ones in favor of ribbons. I bought a couple of premium models on eBay, only to discover after inquiring about technical support, that they were stolen. I was able to return them, but by that time I was spoiled. The obvious alternatives were the Bohlender Graebener RD-40s, so I ordered them from Parts Express, only to be told that they were back ordered.They arrived in August and I hooked them up. After a couple of glitches that were dealt with graciously and rapidly by the BG tech support people, I finally got them working. In the meantime, I lucked onto two Carver AL-III Plus bass units including the drivers and cabinets on eBay, and snapped them right up. Now the system is driven by two Carver M1.0t power amps, with a Carver M0.5t driving a Yamaha YST-SW216 subwoofer. This whole thing is controlled by a Carver C-4000 preamp. In essence, the main speakers are biamped Carver AL-III plus, crossing over at 150Hz, except that the planar magnetic drivers are forty inches rather than forty-eight inches, with the subwoofer kicking in below 80Hz through a Carver DPL-33 Dolby Processor. Program source is the Carver PSD-36b 10 disk CD player.I have heard references to planar magnetic speakers “opening up,” or “coming alive.” That happened tonight during a recording of the Vivaldi Concerto No. 7 in F Major for Four Violins and Cello by L’estro Armonico. Suddenly the sound was glorious, the best that I have ever heard. Since the RD-40s are dipoles about two feet from the back wall and four from each side, the entire wall seemed suddenly to disappear in favor of the orchestra, placing the instruments exactly where one would expect them to be. For the first time, I was able to appreciate what the Sonic Holography and Peak Unlimiter features of the Carver preamp bring to music. I may never leave here!I live only a few blocks from Davies Hall, the home of the San Francisco Symphony Orchestra, and its great conductor, Maestro Michael Tilson Thomas. I have heard many performances there, but never one any better than what I now can hear from my home stereo system. The question now is whether the San Francisco Symphony Orchestra will ever be able to perform again to my satisfaction?
Date published: 2012-12-13
Rated 5 out of 5 by from Unique and pleasant sounding unit!Reasonably good efficiency. Minimal coloration. Nice bi-polar output giving a rich and spacious sound quality. Matches most types of amplifiers well. (impedance wise)
Date published: 2009-01-25
Rated 4 out of 5 by from I CANT COMPARE THEM WITH NOTHINGIF U WANT THEM U KNOW SOME!So i rate 5 for value not because im rich, they worth it for the money if we can pay several hundred $ for good tweeter! IT MAKES EASLY 20 TWEETER they need long burn in period.they need notch filter,they've tricky instalation (that's why I rate them 4, Not because any finish quality)U"ll need sealed woofer (cause they are very fast) I'm going to seal my 15"push pull Aura sub to!Dont waste them with passive xover go for active sysytem i've lots of experience with matin logan, acoustat speakers (former dealer) B&G more accurate then electrostaticsthey are very loud 88dB! good for line arraythey have smaller sweet spot then regular driverswich IF YOU ARE USEING THEM FOR SURROUND you are wasting them !! for music they are the bestif you see the response curve, u can scare litle bit about high end frq.response DONT PANIC AND DONT BUY ANOTHER TWEETER TO FIX HIGH END,ihave dynadio d260 & D330(1000$ pr) they were funny with BG , Buy behringer ultra drive pro or dbx drive rack pa like i did get everything u need for this driver. they advice 6"x6" sealed box i tried somany different box .ligtly stuffed round box made some noticeble diffrece at 150hz~600hz region. before build a box try them free air to find right higth for your ear??? it's makes magical sound.if u know how to deal with them.thanks to Parts Express.only Partsexpress faster than Bohlender Graebener
Date published: 2008-04-10
Rated 4 out of 5 by from Sound is amazing with uncolored clarity.I purchased two B&G RD 40's from Parts Express and built two 5-foot tall cabinets to house them. Each B&G is housed with three Dayton RSS265HO-4 10" Reference HO Subwoofers and one Aurum Cantus G2Si Ribbon Tweeter. For most listing levels I crossover the B&G s at 150Hz. For very loud levels, which are rare, I switch my electronic X-over to 400Hz. The Aurum Cantus ribbons are simply connected with a 2mf poly cap to help compensate my elderly hearing. I have been using B&G s 22 drivers (no longer made) in my front, center and surround speakers for nearly 12-years. The RD 40 s were purchase to upgrade my front speakers (stereo pair). I have been building speaker systems off and on for nearly 38-years and nothing can compare to these drivers. I can t imagine using any other driver for mid-range, yes their expensive but worth the price. For use in a stereo only system I prefer them best as a dipole setup but in a surround system I prefer them in a closed cabinet. Don t cripple them with a passive crossover bi-amping is a must and don t forget to use the required notch filter! I use an active notch filter in my front pair, center and rear I use the passive notch filter. Their build quality is top notch. Their sound is amazing with uncolored clarity and great imaging. You won't be disappointed.
Date published: 2008-04-02
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Product Q&A

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Bohlender Graebener RD40 Planar Transducer

Is this a difficult driver to pair? Because it is 5 ohms, what drivers would you recommend pairing it with? looking into building a 3 way speaker with this model hitting mids.

Asked by: djdaveastro09
The impedance generally is not an issue when pairing drivers as long as you are using active or custom crossover networks. These are usually used as mid-high drivers and are not normally paired with a tweeter, so the implementation may be interesting. Unfortunately this type of thing is basically all custom and the only way to get good results is with a lot of trial and error.
Answered by: MattP
Date published: 2014-08-14

What kind of crossover does BG recommend a passive or active ?

Asked by: Wildchild
The lowest recommended crossover for this is 150 Hz second order, it will work with active or passive networks.
Answered by: MattP
Date published: 2014-05-22

Notch filter design

BG recommends a notch filter for the RD line. Others say a notch flter is mandatory. Without resorting to an electronic filter (like the Behringer), does anyone have a design for an appropriate passive notch filter?
Asked by: old_bassist
BG has the recommended notch filters in their install guide below.
Answered by: MattP
Date published: 2014-02-15

B&G RD40 Vertical Dispersion question.

I'm thinking of using the RD40's (along with woofers) for the front three speakers in my home theater. Two questions come to mind:1) How important is it (if at all) to have the center of the RD40 at ear level?If the answer to the first question is that it is important, then I will need to do something special for my center speaker. I have an acoustically transparent screen and the center RD40 would sit on a stand (vertically) behind the screen . The bottom of the screen is about 35" off the floor, so the center of the RD40 would be about 55" high. This would leave about the bottom couple of inches of the RD40 at ear level, but most of it would be above ear level. So,question 2:2) Would it work well to angle the RD40 down slightly (about 10 degrees) so that it is aimed at ear level on the couch where we sit?Any suggestions would be greatly appreciated.Best wishes,Dave
Asked by: wookus
Creating a project with such an expensive driver demands good planning. It's not just the driver, it's the cabinet, crossover and amplifiers. The BG drivers gained notoriety with Arnie Nudel from Infinity and are still used in Genesis loudspeakers - which cost well over $10,000 a pair. If you are building a music and film system, you need to consider MANY things. Your viewing distance should be 1.5 to 2 times the distance from the screen width optimum. Read THX articles on this. Film sound is mixed at 1.5 in the studios. Now since you have an acoustically transparent screen - you can actually place the speakers correctly so the the left and right are not too far apart. If you are doing dipolar, the speakers should be 6 - 8 feet apart and 3 feet from side and rear walls... In a cabinet, forget about the rear clearance. In your situation, if you are sitting far enough away from the screen - say 12', I'd have all three speakers oriented identically for correct imaging and voicing. If the base of the RD40's are all at 35" - you will be fine. If you do not cross over the RD40 at 5000 hz to a tweeter, you will need an eq network to flatten the response above that. It get's a little dicey. The BG specs outline that. Also - the driver has a sweet spot operating area - 500 - 5000hz. Below you want a fast mid-woofer(s) and then to your sub, above - you should consider a quality tweeter - like the Aurum Cantus ribbons. Besides linear response - each driver is then optimized for horizontal dispersion. The RD40 begins to "beam" at higher frequencies. This is why drivers get smaller as the frequencies are higher - aperature size contributes to dispersion characteristics. (Save electrostats which are very different.) The neo3PDR's in line array are also a perfect and stunning match taking you up to 28,000 - plenty of headroom. have fun. Oh - Don't tilt down.
Answered by: MarkAJH
Date published: 2013-06-04
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