Brinkmann Bardo

Thank you for your explanation on the Dual EDS motor, Wjsamx. It's fascinating. I have a Dual motor like that as parts but unfortunately it has scraping noise and I don't have the complete power supply. I would love to be able to make it work and have a listen. After reading your post, even more so.

On Brinkmann's technical white paper, which provides interesting reading, in discussing the drive mechanism, it does mention the arrangement of the stator:

The motor’s stator consists of four specially designed field coils, which are mounted concentrically with high precision around the platter bearing. Based on listening and tuning sessions, we decided to forgo the typical 90-degree mounting angle in favour of a non-standard 22.5-degree raster, which, due to the magnetic fields overlapping, further reduced cogging. The motor’s rotor also acts as the sub-platter and carries a magnetic ring with 8 poles on its underside.

The drive mechanism, based around Hall sensors and an encoder disk, is designed in such a way that there is just enough power to bring the 10 kg heavy platter up to 33 ! e rpm in about 12 seconds. Conversely, only a minimal amount of energy is actually necessary to keep the rotational speed at a constant. While the drive mechanism is indeed direct, power is actually transferred without any contact.This soft coupling via a low power magnetic field translates into a silent drive, which reduces cogging further. One of the main attributes behind the sound quality of the “Oasis” has to do with our proprietary motor control. It works proportionally, i.e. it transfers just enough energy to the motor for it to remain at constant speed. Conversely, due to our ultra low-friction bearing, only a small amount of energy is actually necessary to keep the motor at constant speed. Previously available regulators typically work disproportional and rather abruptly: they speed up and slow down the motor very rapidly when necessary.

During the development phase of the “Oasis” turntable, we spent many long hours auditioning several different regulator designs; it became quite evident that utilizing our concept of proportional regulation always resulted in better sound: typical “harder” motor control concepts produced a sound significantly lower in quality, with less color and drive.

I do believe the Brinkmann motor is quite different from Technics. Many Japanese manufacturers switched to coreless motors in the late 70's to early 80's such as Sony BSL motor, Pioneer in the later SHR motors, Kenwood in their KD-770D and KD-990, almost all JVC QL series tables. Technics, however, stayed with core motor through that era. Reportedly coreless motors sacrifice torque for smooth rotation and less cogging. I am not an engineer so these are all based on visual observations of the physical motors that I have open apart.

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Hiho, That stuff could have come directly from literature on the Kenwood L07D. The speed control works the same way, using "proportional regulation". There are an optional platter ring and central weight to add mass to the L07D platter. When those are in use, you have to "tell" the power supply, and it alters the speed correction algorithm accordingly. Speed stability depends in part upon platter mass, rather than on super-high torque, in contrast to the Technics dd turntables. There is nothing new under the sun. The Bardo looks to be a great turntable. What does it cost?

"power is transferred without any contact" - that could be said of any direct-drive turntable wherein the magnet (or rotor) is part of the platter and the stator is mounted around the bearing assembly.

The cost is about 7-8000 dollars.

Lewn: "There is nothing new under the sun. The Bardo looks to be a great turntable. What does it cost?"

According this site, the retail is $7,990.00 USD so each coil is about 2 grands. :)

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Dear Lewm, There are 2 different motor designs for the K07D. The initial Kenwood motor that looks similar to the Brinkmann (and the Dual) but with 6 red coils was a patent infringement on the earlier Dual design. This is why Kenwood had to later change the design to the green star shaped coils, which you can see are not asymmetrical. Kenwood and other Japanese manufacturers thought they could get around the patent issue by using a different number of coils, placing them asymmetrical, compensating with electronics, and changing the specs. It was very common practice, and still is today, for manufacturers to purchase competitors products, completely disassemble them, study the design, and attempt to deviate enough in their own design to try and beat any patents. The Dual EDS motor had 8 double field coils in symmetry with a special conductor plate below it. The magnet was made of barium ferrite and had 8 pole symmetrical magnetization. The electronics in this system were so minimal compared to others that it fit on a round circuit board the same diameter as the bottom of the motor (5 inches). The motor was one complete assembly including the electronics. The platter just fit on top of it. In regards to the Brinkmann motor, I can't understand the reason for the odd placement of the coils. One would think there is a dead spot of power in its rotation which is why I believe its concept is to push and brake. The motor seems by design to only pulse power to the rotation as needed. Once the heavy platter is at speed, the energy within its mass is creating the needed centrifugal force for rotation. The tach feedback will sense speed deviation and only micro-pulse the "motor" as necessary to keep the platter steady at speed, like cruise control. Judging by the size of the motor, it's not meant to "direct drive", it is just too small and weak. It's really a "soft drive" system. Weak micro-pulses of "magnetic" power to the platter would certainly not create a large impact on such a heavy platter, thus eliminating any cogging effect. I do like it's simplicity, and it must obviously work, although they don't advertise any specific specs other than it takes 12 seconds for the platter to reach speed. The white pages on the Brinkmann motor suggest they are using a non-standard 22.5 degree angle on the coils with an 8 pole magnet, claiming that the overlapping magnetic fields reduce cogging. Isn't it strange that this Brinkman motor is very similar to the Dual EDS motor, which has 8 coils instead of 4, both use the coils at a 22.5 degree angle, both have hall sensors, and both have 8 pole magnets. I guess the Dual EDS motor patent has long expired. Essentially, one can get a Dual EDS motor, drop it in a plith, and have a Brinkmann for about $200 + tonearm. It might be ugly, but it won't cost 8 grand. Honestly, and with sarcasm aside, if I were looking for a new TT, I'd consider the Bardos, but only after having a demo.

Have a look at Dual EDS motor:
http://dual.pytalhost.eu/701/dual701-04.jpg
http://dual.pytalhost.eu/701/dual701-38.jpg

Brinkmann white pages:
http://www.brinkmann-audio.de/inhalt/en/whitepaper/oasis.pdf

Best Regards