Axiom Home Page Forums General Discussion Technical Questions Subwoofer Servo Technology

Hey, thanks for the plug, Tom! What a guy.

Yeah, Dave, post away. Here's the link.

Okay guys, I'm on it...

just as soon as I figure out what Peter is saying

Yeah, Dave, Peter(buko)is tossin' around some lawyer-like talk(although I'll raise his a posteriori with an ex post facto)for the simple fact that Axioms are in a class by themselves, as determined by experience, not speculation.

Now that's a post I can agree with!

The last time I heard "a priori" was in philosophy class in college. AFAIK, peterb used it correctly here. Too bad he didn't follow up his other assertions as well.

He and Stone__Man are right about the vigorous Axiom defenders, to a degree. As expected, there's a range of tact/diplomacy in our responses to a challenge, with people such as Jack and tomtuttle on one end of the spectrum and BrenR on the other. Wasn't it tom who said God loves diversity?

Well, I guess whether he was a troll or not, we circled the wagons and scared 'im away good, huh?!

This is my first post to this forum. Please be easy on me but I have to chime in here. I am in a debate with some gentlemen on the audio circle forum about the Rythmic sub. To me the Rythmic sub is hype. They claim to "achieve lower extension and flatter response in a small enclosure" - from the Rythmik website using their patented servo technology. For starters, servo tech has been around for years High Gain Servo™ Technology Patent by Velodyne in 1984 just to name one.

They claim their subs work in a 2 cubic foot enclosure to me this is not a small enclosure.

Here is the website… http://www.rythmikaudio.com/

I can see how the axiom sub using DSP is using new technology but the Rythimic sub uses old technology and claims it as their own. Or this is how I perceive it after reading their website.

I am of base here or am I on the right track?

Well let me add my voice to the chorus that Brian Ding is a terrific sub designer. While it's true that servo technology has been around for some time, Brian has spent six years tweaking and researching it in order to get better linearity, low distortion and deeper response than what one would normally have from a servo controlled sub. He has developed some propretary techniques to achieve these objectives which is why he suggests his technology DirectServo requires a special driver and a dedicated amp.

I've always had a keen appreciation for how a well designed sealed sub can perform and with that in mind I spent a week or so last summer conversing with him about the upcoming 15" version. He was very open about his ideas. From what I gather he started tweaking the servo sealed box 6 years ago with a 15" NCA driver. He preferred that driver because of its low inductance so that the zero phase crossover in the impedance curve was in the order of 150hz. Because that driver was expensive to make he later used a modified 12"TC Sounds driver which used a propretary short circuit ring in the servo mechanism to help achieve his design goals.

For the amp he likes using his own designed A370SE which is now shipped with a torrodial transformer, instead of the EI type. I don't know what else he has done to the amp except that it seems to match well with the enclosure and driver. The dedicated amp is critical to achieving low distortion levels in his subs. The extra SPL gain is mainly from high BL value and the larger enclosure.

While I do not suggest I know all the intricacies in his ideas or design, there is no doubt he has developed modifications which push the servo technology to the next level. It has been targeted at the DIY market but I believe its only a matter of time before he starts mass producing those subs. Judging by the many positive comments he has a strong following. It would be a mistake to dismiss the Rythmic subs as using old technology which he is calling his own.

I was afraid.

But that was actually quite civil, illuminating and interesting. Bravo!

Wow that was very interesting and enlightening! That was just the information I was looking for! 
Sounds like a good concept but with today’s crop of super woofers is the servo control really necessary?

Matt