Volt radial woofer


Anyone on Audiogon have hands on experience with either the 12" or 15" Volt radial woofer? Thinking about a custom build, and looking for useful commentary.
askye
Askye i will be getting a state of the art mj acoustics reference 800 in the beginning of november

https://mjacoustics.co.uk/reference-800mk2/

https://mjacoustics.co.uk/reference-800mk2-sr-ff/ this is the one we are getting


Mj acousticsWh s the Only company using rhe radial driver  in a consumer producf pmc uses the radial for studio use

The radial is not used in most commercial subwoofers due to the drivers  extreme cost which is two to three times more expensive then the woofers used in competing products

Mj acoustics has a custom radial built for them they use the radial because of tts lack of compression Unde rheating conditions the radial cools betterrwhich reduces distortion compared with conventional bass drivers 

Hete is a nice disscusion on how unique the radial is designed and built

you can observe that the Volt Radial Technology consists of a front-mounted eight-spoke proprietary cast aluminum frame that is mechanically coupled to both the back plate and to the top of the pole structure/phase plug, in contrast to a normal rear frame that is only coupled to the motor front plate. This not only has greater mechanical coupling to the major heat conducting elements of the motor structure, but much of the heat produced by the motor is being radiated to the air outside the enclosure rather than heating the air within the enclosure.

Additional cooling to the front plate is provided by a rather substantial 72 fin heatsink that also includes 36 vents (5 mm × 9 mm) beneath the primary spider mounting shelf. As can also be seen, the Volt RV3143 has a dual-spider suspension system, with a smaller diameter spider attached from the cone to the front located frame, and a larger primary spider that is attached from the cone to the front plate heatsink system. Note that air from the top side of the pole piece is vented to the outside of the enclosure rather than venting into the enclosure as with most venting below the spider mounting shelf systems. The Volt Radial Technology provides a powerful heatsink to the outside of the enclosure and a convection cooling system that is coupled to the outside of the enclosure.

Heating of the air inside an enclosure contributes to power compression, and it would be incorrect to think there is a lot of thermal communication through a port tube, as that is not the case. In fact, Patrick Turnmire who does the Klippel testing for Test Bench, and his partner Enrique Stiles (two of the best transducer engineers I know of in the industry) have a patent titled “Thermal Chimney Equipped Audio Speaker” (Patent US 7181039 still available for licensing), which uses a device to transmit heat away from a motor structure to the air outside the enclosure, again to decrease power compression at high thermal levels.

After reviewing countless driver cooling systems in Voice Coil, and not an inconsequential number of car audio subwoofers cooling structures in the now defunct Car Audio and Electronics magazine, this appears to me to be one of the best configured driver cooling systems I have examined to date. What this means is that a driver will stay cooler with less dynamic changes over time, an important aspect to recording studio monitors or to live sound PA speakers. For this reason, Volt Radial Technology is utilized in a number of highly respected UK studio monitors and high-end home speakers from companies such as PMC, Quested, and Robson Acoustics.

In terms of the rest of its features, the RV3143 has a stiff curvilinear paper cone suspended by an inverted NBR surround and a dual-spider system. The top spider is a 5” diameter flat cloth spider and on the bottom spider is a 6” diameter elevated cloth type. The assembled motor is driven by a 75 mm (3”) diameter four-layer voice coil wound with copper wire on a non-conduction Kapton former. The motor structure consists of a single 155 mm diameter × 25 mm high ferrite magnet sandwiched between milled and polished friont and back plates. The plates are bolted together to the frame through the shaped pole piece by a large central bolt. Tinsel lead wires connect to color-coded push terminals on one side of the driver.

you can observe that the Volt Radial Technology consists of a front-mounted eight-spoke proprietary cast aluminum frame that is mechanically coupled to both the back plate and to the top of the pole structure/phase plug, in contrast to a normal rear frame that is only coupled to the motor front plate. This not only has greater mechanical coupling to the major heat conducting elements of the motor structure, but much of the heat produced by the motor is being radiated to the air outside the enclosure rather than heating the air within the enclosure.

Additional cooling to the front plate is provided by a rather substantial 72 fin heatsink that also includes 36 vents (5 mm × 9 mm) beneath the primary spider mounting shelf. As can also be seen, the Volt RV3143 has a dual-spider suspension system, with a smaller diameter spider attached from the cone to the front located frame, and a larger primary spider that is attached from the cone to the front plate heatsink system. Note that air from the top side of the pole piece is vented to the outside of the enclosure rather than venting into the enclosure as with most venting below the spider mounting shelf systems. The Volt Radial Technology provides a powerful heatsink to the outside of the enclosure and a convection cooling system that is coupled to the outside of the enclosure.

Heating of the air inside an enclosure contributes to power compression, and it would be incorrect to think there is a lot of thermal communication through a port tube, as that is not the case. In fact, Patrick Turnmire who does the Klippel testing for Test Bench, and his partner Enrique Stiles (two of the best transducer engineers I know of in the industry) have a patent titled “Thermal Chimney Equipped Audio Speaker” (Patent US 7181039 still available for licensing), which uses a device to transmit heat away from a motor structure to the air outside the enclosure, again to decrease power compression at high thermal levels.

After reviewing countless driver cooling systems in Voice Coil, and not an inconsequential number of car audio subwoofers cooling structures in the now defunct Car Audio and Electronics magazine, this appears to me to be one of the best configured driver cooling systems I have examined to date. What this means is that a driver will stay cooler with less dynamic changes over time, an important aspect to recording studio monitors or to live sound PA speakers. For this reason, Volt Radial Technology is utilized in a number of highly respected UK studio monitors and high-end home speakers from companies such as PMC, Quested, and Robson Acoustics.

In terms of the rest of its features, the RV3143 has a stiff curvilinear paper cone suspended by an inverted NBR surround and a dual-spider system. The top spider is a 5” diameter flat cloth spider and on the bottom spider is a 6” diameter elevated cloth type. The assembled motor is driven by a 75 mm (3”) diameter four-layer voice coil wound with copper wire on a non-conduction Kapton former. The motor structure consists of a single 155 mm diameter × 25 mm high ferrite magnet sandwiched between milled and polished front and back plates. The plates are bolted together to the frame through the shaped pole piece by a large central bolt. Tinsel lead wires connect to color-coded push terminals on one side of the driver.
Long story sport wereplaced our jl udiofathom f113with the mj  reference 800 which will go down to 10 hz in a relatively Compact form factor 

We cant wait till wr get ours so we can tell you in november

Dave and Troy
Audio.intelleact Nj

Us importers Mj Acoustics subwoofers 


The ref 800 are supposed to be amazing








Very well engineered driver with excellent reputation.
What is it you would like to know?

Years ago I had considered the 12" for an open bafflesubwoofer, 2 per side, but it was too costly and difficult to configure for a stark amateur such as myself. It has a reasonably powerful magnet, low compliance and low Q on one hand, but it easily handles high input power on the other. On paper you can get plenty of tight low bass from this unit, but actually designing the right enclosure is tricky.

The TS parametres are given on the site https://voltloudspeakers.co.uk/loudspeakers/rv3143-12/
gregm,
Actually, giving some consideration to a custom build. Am inspired by the Verity Lohengrin. Alas, I will never have $80K to invest in loudspeakers.
I like the non-square cabinets of the Lohengrin, and from an engineering perspective, understand the purpose they serve.

My idea is the Volt RV3143 (12") or RV3863 (15") woofer in the lower cabinet, coupled with Seas Exotic W8 X2-08 (8") woofer, the Volt VM752 (3") midrange dome, and Seas T29CF001 or Scan-Speak D2904/7100-03 tweeter in the upper cabinet.
Yes, I fully understand these are $$$ drivers. I can design the cabinets, and am thinking 30mm internally braced MDF with front baffle angled to maintain time alignment.
Probably have the cabinets cut/fabricated on CNC router. Definitely need assistance with crossover design.
Design goals are wide frequency response, excellent micro/macro dynamics, and relatively high efficiency. I will be using a SUMO Half Power for amplification, but prefer the load to be an easy one, so as to make maximal use of the amplifier.
Your thoughts/comments are appreciated!
Hi if it's any help to you I built a pair of speakers a couple of years ago using the RV3863, VM753 and Scanspeak D2904/710003. The cabinet was a Wilmslow Audio TL15 transmission line and the only change to it was to specify all panels (internal as well as external) in 25mm mdf. I followed their exact recommendations on line stuffing.
The sound quality is astonishingly realistic, I think mainly due to the RV3863's uncoloured lower midrange and the VM752's clarity. Distortion doesn't exceed -45dB across the range until the lowest frequencies. Bass is of course very extended but at first listeneing seems "dry" until you realise that there is no emphasis. Then an organ pedal or bass drum shakes the room! I'm a big fan of transmission lines.
I run all-Bryston electronics and am happy with the setup.
Some advice:
1. Buy Dayton Audio's Omnimic and Test System v2. You will need this to obtain the data for the crossover design.

2. Mount the drivers in the completed cabinet and measure the response of each individually to create FRD and ZMA files for each driver using the test CD provided. Take care with volume levels so as not to damage the mid and tweeter.

3. Install XSim on your PC. It's free, easy and intuitive to use and will give you hours of fun playing with different circuits and values.

4. When you are happy with the results you can order the components and build the crossovers. I used 2nd order designs for the bass low pass, the mid low pass and high pass and 3rd order for the tweeter. Don't be too ambitious and try to design 4th order circuits like PMC do. They are complicated and extremely difficult to get right. They use this design with its steep slopes to get very high power handling in commercial installations. You don't need that at home if you value your hearing.

5. Make sure you order the Volt drivers in 8 ohm spec. The Scanspeak D2904/710003 is a 4 ohm unit and is extremely sensitive so will need padding resistors. The bass and mid are perfectly matched and don't need any balancing.

6. For initial trials keep the crossover outboard. The system may measure flat but it may not sound right and you could have to make changes - especially adding resistors to balance the drivers. XSim will help with this as it is so interactive and you can see the results as you play with different values. It may be helpful to use switches to select alternative values at this stage. It took me two years of listeneing to be satisfied with the crossovers.

7. Don't be afraid to cross the bass to mid at 500-600Hz. The RV3863 is very clean up to higher than this and the VM752 needs to roll off below 500Hz if you want decent power handling. I chose 550Hz and 3.8kHz for my design.
I'm sorry if this is a bit long winded. I hope it helps.
Correction: The midrange unit which I used is the VM752, not VM753.
The VM752 matches the sensitivity of the 15" RV3863 at 94dB/w@1m

The 12" RV3143 is less sensitive and matches the VM753 at 91.5/92dB/w@1m. They both have smaller magnet assemblies than the above.