What's the best 'active servo' sub on the market for the money? (1 Viewer)

[Kevin*Harley]

Where do I sign up for the HGS credit voucher upgrade program?

 

[Mark Seaton]

Brett DiMichele wrote:

Servodrive is the company and I was just gonna mention that.

They are made for COMMERICAL applications though.

While our company's primary market, and majority of sales is indeed commercial, the ContraBass has found the majority of use in large home theaters, as well as organ augmentation in churches. In the past 3 years, I would say >80% of ContraBasses sold have gone into dedicated home theaters. The primary reason for my joining the company was to position us to better address the home theater market, specifically, the CEDIA/custom install mareket.

Just throwing in my experience for the original poster, for what it's worth, in casual observations, the Martin Logan subs produced the best resulting sound of those using correctional feedback systems to my ears, and I have achieved good results with Velodyne's HGS subs when kept well below their limits, typically used in multiples. I have only heard the Paradigm subs a couple times, not enough to comment on.

To Bruce Hall-

Kudos for bringing another integrated EQ solution to a larger market of Home Theater. The measurement capability will be a significant step past others presently on the market. Too many underestimate the benefits of appropriate EQ in the bass range.

Regards,

 

[Alex Prosak]

Kyle,

I'm not sure what your schedule is but there will be a new player in the servo sub market a bit later this year (Q3 or 4). Mark Schifter of Perpetual Technologies/Onix/AV123 will be introducing one for their Reference line of speakers, a step above the Rocket line. It will have dual 12" drivers, 1000 W amp, 5-band parametric equalizer to help tame in-room acoustics, and 5 memory settings for the equalizer. The equalizer will be computer programmable so you'll be able to store many more eq settings if you wish. I believe the sub will use technology similar to Genesis servo sub when Mark was still there. The price isn't set yet but they're shooting for the $1200 range.

Based on the products he's introduced so far it's definitely worth checking out if you're not in a hurry.

Alex

 

[Randy G]

Bruce,

So are the HGSX subs IDENTICAL to the HGS? Can you tell us what the differences, if any, are?

thanks

 

[Bruce Hall]

Randy,
The HGSX will be "entry level" servo subs, in 12" and 15" models. They will identical to the current HGS technology, except that they be finished in black ash vinyl and be less expensive than their HGS counterparts.

Bruce

 

[Steve_AS]

Check out the September issue of Sound & Vision for a subwoofer roundup of models costing

 

[SC Trojan]

Well I will put my genesis 928 into the mix. Dual 12" servo controlled with It has replaced my HGS18 due to it's smaller footprint and therefore higher WAF. In my application, I havent really missed a beat or thud- no pun intented! Didnt have any time to a/b the two since the HGS18 was sold to purchase the 928. Wasnt arnie at genesis one of the first servo guys or something like that (dont know because I must have been a little tyke back then).

 

[RichardHOS]

I'm glad Bruce Hall stopped by and cleaned up some of the technicalities of servo-feedback mechanisms.

It seems that a lot of people have the impression that all the servo-feedback in Velodyne subs does is act as a limiter. I think this is because of the rather understandable assumption that the only way to lower distortion at low frequencies and high volumes is to limit excursion... or in other words limit the volume.

That's just a bad assumption from which to start any consideration of the technology. Servo-feedback has another weapon at its disposal to limit distortion at high volumes - introduce distortion. This feedback loop is a staple of the engineering control systems community... has been for decades, and it works.

Here's the way I prefer to think about the situation (and, this is assuming that the servo feedback is working as well as it can).

Sub A uses servo-feedback, sub B does not. Both are in identical sealed enclosures, using identical drivers and amplifiers (apart from feedback control). At 70% output they will both perform nearly identically, with the servo model having marginally lower distortion. At 90% they will both be experiencing compression artifacts and distortion rises in the non-servo model, yet holds constant in the servo model. This difference could be one percent, or ten percent, depending on driver and enclosure. At 99% output the non-servo model is distorting fairly bad, with occasional bottoming. The servo model's limiting algorithm kicks in and prevents bottoming and further cone distortion. Neither case is really good, but I don't see how limiting can really be considered worse than the alternative, since it only affects that last few percent of the output capability.

Of course, this is all dependant on the drivers involved, as well as the design of the servo-feedback as well. And servo technology can be put to different uses as well... making inferior drivers sound pretty good, or making great drivers world class. What they do best, IMO, is make sub designs that target smaller enclosure sizes sound pretty damn good.

From a pragmatic and value viewpoint, there's nothing a servo design can do that can't be accomplished by simply using a better quality driver, larger driver, larger enclosure, and/or more powerful amplifier. When space is the primary consideration servo's have a lot to offer. When size isn't the restriction, then from this engineer's viewpoint there isn't a whole lot of need for a servo design. It's cheaper just to get a longer throw driver or multiple drivers in a larger enclosure to maintain low distortion levels... at the cost of space.

So, in theory servo-feedback can improve any sub design. In practice they serve a very useful purpose... wringing good (sometimes great) performance out of size challenged designs.

 

[Lewis Besze]

Lewis,
Sorry, I wasn't too clear there. All subs distort at least somewhat. By distortion products I meant the harmonic distortion products that are also created in addition to the original note by the woofer - I wasn't referring to other subwoofer products. For example, 30 Hz creates harmonics at 60 Hz, 90 Hz, 120 Hz, etc. In this case, our ears are more sensitive to the harmonic distortion products than they are to the original note, so a distorting sub can sound quite a bit louder.

I understood you well,perhaps I wasn't too clear here.
I know that there are plenty of bad subs[harmonics louder then fundamentals] out there,but if you look around in the DIY section,you'll find plenty of example for "clever and sensible" desingns that don't rely on electronic manipulations,but on high quality drivers,and the fact that one can't rewrite "Hoffman's Iron law".
Many of these will give the run for their money of the often prestiogious brands selling 5-6 times the cost of doing one of these DIY subs.

 

[Lewis Besze]

Sub A uses servo-feedback, sub B does not. Both are in identical sealed enclosures, using identical drivers and amplifiers (apart from feedback control). At 70% output they will both perform nearly identically, with the servo model having marginally lower distortion. At 90% they will both be experiencing compression artifacts and distortion rises in the non-servo model, yet holds constant in the servo model. This difference could be one percent, or ten percent, depending on driver and enclosure. At 99% output the non-servo model is distorting fairly bad, with occasional bottoming. The servo model's limiting algorithm kicks in and prevents bottoming and further cone distortion. Neither case is really good, but I don't see how limiting can really be considered worse than the alternative, since it only affects that last few percent of the output capability.

Yes This sounds good if both subs built the same and used identical parts,but,what if the non servo model use a better driver,or larger enlclosure or both? Would it have an edge over the servo sub's output and still manatain low distorsion simply because it's not even close to it's limit? Servo is a good "tool" but not the only "answer".

 

[Bill Law]

Yes, but assume you've installed the best driver available in the best enclosure available the only way to improve it is to servo control it. Right?

 

[Lewis Besze]

If that's what you call improvement?

but assume you've installed the best driver available in the best enclosure available

There is no such thing as best driver,as it will be "bettered" soon.

 

[Brian Bunge]

No, an Adire Audio Tumult will exhibit less than 3% distortion with 1000W applied to it all the way down to 10Hz. This is in an 18" external cube. There'd be no need to add a servo to it. The only way to really improve upon it, IMHO, is to add a Linkwitz Transform circuit to extend the low end response.

 

[Jack Gilvey]

In practice they serve a very useful purpose... wringing good (sometimes great) performance out of size challenged designs.

Yup...I'd prefer not to introduce that "challenge", though, and avoid such "band-aids". Still, you've got to consider interior decorating.