AudioCircle
Audio/Video Gear and Systems => Open Baffle Speakers => Topic started by: TitaniumTroy on 25 Dec 2016, 05:18 am
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Any thoughts design wise on this dipole subwoofer, other than it's not cheap?
https://www.fernandroby.com/products/details/rockett-dipole-subwoofers
Our design features the stellar DC Gold Audio 10 inch driver. By having two drivers firing in opposition to each other, we increase efficiency and dampening in a balanced manner, allowing the experience to be dictated by the output rather than a resonant box’s characteristics (which is non-linear).
With only 17 grams of moving mass and no spider on the woofer, our drivers are incredibly fast, enabling them to keep up with a wide range of speakers like electro-stats and other loudspeakers that can typically be tough to keep pace with.
We designed the Rockett subwoofers to work as a summed single module, or in stereo as a pair, which is our favored approach. Each unit is powered by a 175 watt, Hypex DS 2.0 plate amp in the base with its own gain, crossover, phase, and eq controls. Bi-Amplification of the bass takes a heavy load off of the main power amp and lets it drive the main speakers to greater effect where it is most important, delivering greater nuance and detail in the mid and high range. The integrated power amp’s controls allow for the subs to be dialed in and tuned to the frequency response of the room and specs of y
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It must be designed to work in a vacuum if its going to keep up with electrostatics.
C.M
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At least you can buy the drivers at Walmart! :icon_twisted:
https://www.walmart.com/ip/The-Amazing-Quality-DC-GOLD-AUDIO-W10R-2-x-10-Subwoofers-Pair-White-10-OHM-Parallel/117888641
Seriously. If you are shopping anywhere near that price just go for the Rythmik/GR OB offerings, find a furniture craftsman and be done! :wink:
Happy Holidays :green:
Anand.
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At least you can buy the drivers at Walmart! :icon_twisted:
https://www.walmart.com/ip/The-Amazing-Quality-DC-GOLD-AUDIO-W10R-2-x-10-Subwoofers-Pair-White-10-OHM-Parallel/117888641
Seriously. If you are shopping anywhere near that price just go for the Rythmik/GR OB offerings, find a furniture craftsman and be done! :wink:
Happy Holidays :green:
Anand.
X2 :thumb: :thumb:
Merry Christmas!
Best,
Ed
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At least you can buy the drivers at Walmart! :icon_twisted:
That's a good thing, as the DC Gold Audio 10 inch driver (http://www.dcgold.com/home-audio/full-range-drivers/) link on the Rockett Subwoofer page is broken and the DC Gold website doesn't list any 10" subwoofer drivers, only 4" to 9.5" full-range drivers.
The drivers listed on Walmart are Sold and Shipped by K Sparkle (https://ksparkle.com/index.php/) :scratch:
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Better still, if you want a decent OB subwoofer get 8 of these Peerless 830669 's and wire them in series /parallel on a big baffle.
https://www.madisoundspeakerstore.com/approx-12-woofers/peerless-sls-830669-12-woofer-coated-paper-cone/
Plus a cheap subwoofer amp and you'll be laughing, all for around a $1000 bucks.
Mind you, you may crack a few windows and loosen the plaster at full volume but that's just part of getting the best bang for your buck. I did.
C.M
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Greetings to all As the designer of Surreal Sound's 5th row speaker and the Fern and Roby Rocket subs I feel I need to step in and make several clarifications. The search for a woofer that was fast enough to make with an electrostatic speaker began in earnest in 2001. I have tried thousands of dollars worth of woofers and ended up having DC gold build these woofers for us. A 10 inch Wall Mart woofer isn't worth mentioning because it simply will not work. The closest other 10 inch driver to the DC gold is the Morel 10 inch driver. Prices are very close with both costing in the $150 to $175 dollar range each. These are not Chinese made mass produced units. It you care to actually measure the driver parameters the variation's of the cheep drivers is all over the place. I would never base a design on there made up values. If you want to read more I have posted several articles on Facebook open baffle site. We have many electrostatic panel speaker owners who can attest to the speed of my design and yes they are the only woofers I have heard that integrate flawlessly. We have shown these subs at Capital Audio Fest and Rocky mount. Check out what the reviewers said. If you want cheep then buy Chinese. If you want good buy German Scandinavian (Morel is a Dynaudio based design) or USA made drivers remember you GET WHAT YOU PAY FOR. We do a demo at the shows where we have a good set of speakers the the manufacturer say go down to 30 hertz and we put our subs in the room with them. While the music is playing we turn off the Rocket dipole subs and everyone in the room has the same reaction. "What just happened" They are in disbelief. The DC gold 9.5 is similar to our 10. It is the same size. We use a custom ultra low inductance, longer excursion coil with the same neo magnet. I you actually check out people who have heard our bass check out the reviews by Scott Hull on the Surreal 5th row and Dagago. Until you have actually heard what these subs can do there is really no point writing and opinion about them as way to many people do. Again there is nothing like them that you can purchase anywhere else. We guarantee they will match the speed of any electrostatic. Hope to see you at an audio show.
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@hifiralph are you doing any shows in the Richmond area?
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@hifiralph - welcome to the forum, we always like to see manufacturers, designers and others from the audio community. Please do review the specifics of how a manufacturer should register and ID themselves.
Thanks!
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Please explain how this sub works. It's described as a dipole, but the two drivers are stated to be "firing in opposition to each other". Wouldn't that be a bipole design? And calling it an open baffle is obviously wrong from the images (and without a cabinet wouldn't the two bipole drivers cancel each other out)?
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It looks fairly simple to me. This is a force-cancelling configuration using a two-driver configuration arranged so the two cones are always moving in opposite directions.
The photographs are poor, so it's a bit difficult to envision the inner construction. If there was a cutaway view or a photo showing the internals with one of the sides/tops removed, it would be easy to see the dipole operation.
See Linkwitz for an example that dates back many years to the Audio Artistry speakers.
http://www.linkwitzlab.com/woofer.htm
I see nothing innovative with this fernandroby speaker at all.
Dave.
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I'm not sure the statement "moving in opposition to each other" means a Linkwitz type push/pull configuration... it could be interpreted as an opposing push/push configuration, as in a Ripol
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I'm not sure the statement "moving in opposition to each other" means a Linkwitz type push/pull configuration...
I didn't say it did. Whether it's "push/push" or "push/pull", the concept is the same. The cones always moving in exact opposite directions to create the force-cancellation configuration. The Linkwitz style "W"-frame construction (as it's been sorta labeled) is just an example.
The push/push and push/pull difference/distinction would have a contribution to even-order distortion cancellation, but the cones are still moving opposite to each other at all times.
This type of construction creates resonant cavities, which would need to be characterized.
Dave.
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I'm not sure the statement "moving in opposition to each other" means a Linkwitz type push/pull configuration... it could be interpreted as an opposing push/push configuration, as in a Ripol
A so called Ripol is simply a variation of the Linkwitz W frame, as Davey linked. The sub in this thread appears to be a W frame variant. The idea is dipolar radiation in some fashion.
cheers,
AJ
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Titanium: Do you will connect then in phase or out of phase?
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After having a closer look at the photos is appears that the woofers are facing the same direction ala Linkwitz, hence; push/pull if wired in phase. Whereas the woofers oppose in a Ripol, hence; push/push if wired in phase.
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In phase or out of phase ("polarity" is the proper term) connections can be somewhat confusing depending upon how the woofers are mounted. You connect simply so the woofer cones are always opposing each in their motion. You might have the woofers wired in series too. :)
Ripol is essentially the same thing except the construction creates much increased air-loading on the cones to alter their parameters significantly.
The woofers used in this FandR scheme are obviously small-motor types which have high-Q characteristics. The Hypex plate amplifiers support the required equalization to make this scheme work.
Dave.
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It looks fairly simple to me. This is a force-cancelling configuration using a two-driver configuration arranged so the two cones are always moving in opposite directions.
The photographs are poor, so it's a bit difficult to envision the inner construction. If there was a cutaway view or a photo showing the internals with one of the sides/tops removed, it would be easy to see the dipole operation.
See Linkwitz for an example that dates back many years to the Audio Artistry speakers.
http://www.linkwitzlab.com/woofer.htm
I see nothing innovative with this fernandroby speaker at all.
Dave.
Thanks Dave, and very true. You are obviously right this is an open baffle W frame. I figure that most of the cost born is because of the mixture of hardwoods and profits. That's fine, there's probably a market for that, so good luck to the company. The woofers used aren't expensive (in my book!), and neither is the Hypex plate amp. Implementation is what counts so Birch ply will do just fine for me.
Best,
Anand.
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After having a closer look at the photos is appears that the woofers are facing the same direction ala Linkwitz, hence; push/pull if wired in phase. Whereas the woofers oppose in a Ripol, hence; push/push if wired in phase.
Ok, lets try this again
(http://www.linkwitzlab.com/images/graphics/d_woof1.gif)
What direction do the "cone" arrows point in?
The only difference with a so called Ripol is the "H" woofer is mounted on the other side of wall "D". It "pushes" in the same direction in a "Ripol".
The Linkwitz W frame is a force cancelling dipole. The so called Ripol is simply a variant, with the woofer mounted on the other side of "D".
The sub in this thread appears to be a W, turned sideways if you will.
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Post deleted; wisdom of hindsight...(couldn't stop myself from being the grammar police!)
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I have a question? I have always heard that you need high qts woofers or subs for open baffle applications then why is that the woofers used by the Linkwitz Orion has a QTS of .27 still is one of the best sounding woofers for OB applications?????
https://www.madisoundspeakerstore.com/approx-10-sub-woofers/seas-l26ro4y-10-subwoofer-4-layer-vc-d1004-04/ (https://www.madisoundspeakerstore.com/approx-10-sub-woofers/seas-l26ro4y-10-subwoofer-4-layer-vc-d1004-04/)
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I have a question? I have always heard that you need high qts woofers or subs for open baffle applications then why is that the woofers used by the Linkwitz Orion has a QTS of .27 still is one of the best sounding woofers for OB applications?????
https://www.madisoundspeakerstore.com/approx-10-sub-woofers/seas-l26ro4y-10-subwoofer-4-layer-vc-d1004-04/ (https://www.madisoundspeakerstore.com/approx-10-sub-woofers/seas-l26ro4y-10-subwoofer-4-layer-vc-d1004-04/)
Low QTS woofers need EQ, the Linkwitz Xover should do it.
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Greetings to all As the designer of Surreal Sound's 5th row speaker and the Fern and Roby Rocket subs I feel I need to step in and make several clarifications. The search for a woofer that was fast enough to make with an electrostatic speaker began in earnest in 2001. I have tried thousands of dollars worth of woofers and ended up having DC gold build these woofers for us. A 10 inch Wall Mart woofer isn't worth mentioning because it simply will not work. The closest other 10 inch driver to the DC gold is the Morel 10 inch driver. Prices are very close with both costing in the $150 to $175 dollar range each. These are not Chinese made mass produced units. It you care to actually measure the driver parameters the variation's of the cheep drivers is all over the place. I would never base a design on there made up values. If you want to read more I have posted several articles on Facebook open baffle site. We have many electrostatic panel speaker owners who can attest to the speed of my design and yes they are the only woofers I have heard that integrate flawlessly. We have shown these subs at Capital Audio Fest and Rocky mount. Check out what the reviewers said. If you want cheep then buy Chinese. If you want good buy German Scandinavian (Morel is a Dynaudio based design) or USA made drivers remember you GET WHAT YOU PAY FOR. We do a demo at the shows where we have a good set of speakers the the manufacturer say go down to 30 hertz and we put our subs in the room with them. While the music is playing we turn off the Rocket dipole subs and everyone in the room has the same reaction. "What just happened" They are in disbelief. The DC gold 9.5 is similar to our 10. It is the same size. We use a custom ultra low inductance, longer excursion coil with the same neo magnet. I you actually check out people who have heard our bass check out the reviews by Scott Hull on the Surreal 5th row and Dagago. Until you have actually heard what these subs can do there is really no point writing and opinion about them as way to many people do. Again there is nothing like them that you can purchase anywhere else. We guarantee they will match the speed of any electrostatic. Hope to see you at an audio show.
Sir,
Your description of the woofer intrigues me greatly-- especially the "no spider" configuration. And I'm wanting to ask if the "17 grams moving mass" ascribed to this woofer in another post was a typo because I've never seen a number that low published for a woofer of that size (or even smaller, for that matter). I would assume a moving mass spec would have to include the spider's mass so perhaps the absence of a spider explains the low number (assuming it's not a typo). That coupled with low inductance would indeed give serious speed!
I would love to hear more about your woofer. I build ESL's and I'm a DIY guy and I confess ulterior motives for asking if your company or DC Gold offers that particular woofer for sale as a lone driver.
In any case I'm intrigued and would love to hear any additional details about that woofer you might care to offer (LOVELY cabinet too, BTW).
Regards,
Charlie (a.k.a Jazzman)
http://jazzman-esl-page.blogspot.com/
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I have always heard that you need high qts woofers or subs for open baffle applications then why is that the woofers used by the Linkwitz Orion has a QTS of .27 still is one of the best sounding woofers for OB applications?????
High Qts gives "free" EQ for passive systems. Linkwitz designs are active, so he can pick any driver and EQ it to the desired final response. The benefit there is the driver can then be chosen for specific attributes, like silent mechanically during very long strokes (rare!), low distortion, high Xmax, etc, etc., rather than Qts.
Those attributes are extremely rare or non-existent with high Qts drivers, which are often inexpensive weak motor units. The exceptions being drivers from companies like AE, custom made specifically for passive OB use, but with advanced low distortion motors and silent operation.
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FYI, with SL's thoughts on this topic.
http://www.linkwitzlab.com/faq.htm#Q34
Dave.
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Once the driver is EQ'ed, doesn't the group delay end up the same (regardless of its starting Q)?
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The mechanical parameters of two different drivers will not change, but electronic equalization can force different amplitude roll-off behaviour and the phase-response/group-delay characteristics along with it. So, within reason, yes.
The vast majority of speaker drivers (easily available to us today) are designed for some sort of box usage and are (generally) higher motor-strength (low Q) designs. Using said drivers in open-baffle (free-air) configurations means conforming the roll-off to a more suitable rate with EQ.
If typical drivers were used in a "W"-frame application like the Fern and Roby, it would require three different forms of equalization. A 6db/octave dipole correction, a driver Q-correction, and a resonant peak (notch) filter to account for the cavity resonance created by the enclosure.
These fellas seem to have selected a high-Q driver that (sort of) addresses the first two characteristics without the need for extensive equalization.
It seems an interesting design but, obviously, a good DIY'er can create something equivalent (or more likely superior) for much less money.
Dave.
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Sir,
Your description of the woofer intrigues me greatly-- especially the "no spider" configuration. And I'm wanting to ask if the "17 grams moving mass" ascribed to this woofer in another post was a typo because I've never seen a number that low published for a woofer of that size (or even smaller, for that matter). I would assume a moving mass spec would have to include the spider's mass so perhaps the absence of a spider explains the low number (assuming it's not a typo). That coupled with low inductance would indeed give serious speed!
I would love to hear more about your woofer. I build ESL's and I'm a DIY guy and I confess ulterior motives for asking if your company or DC Gold offers that particular woofer for sale as a lone driver.
In any case I'm intrigued and would love to hear any additional details about that woofer you might care to offer (LOVELY cabinet too, BTW).
Regards,
Charlie (a.k.a Jazzman)
http://jazzman-esl-page.blogspot.com/
Sorry for the late reply, we are the manufacturer of the driver. It is a high Q, fairly high resonance (55Hz) with a low Fs peak of 8-9 Ohms for a 4 Ohm driver. It has very low inductance (my stack of six drivers wired in series in my dipole is about 0.2mH. The actual MMs of the driver is 21 gms, out N7 has MMs of 17gms. They got that wrong.