[jcotner]

So you can almost make them do anything you want and play to where ever you want them to play.

Don't know what almost means, but assume this has to be somewhat dependent on the mass
in the driver you have to move around and the amount of current available in the servo
amp to move it. So practically I would assume there is some sort of amplitude vs frequency
curve that really defines the limits of the sub response?

[Danny Richie]

Don't know what almost means, but assume this has to be somewhat dependent on the mass
in the driver you have to move around and the amount of current available in the servo
amp to move it. So practically I would assume there is some sort of amplitude vs frequency
curve that really defines the limits of the sub response?

The control system on the servo amp will allow you to select the extension and the roll off curve and the amount of damping (control). It has variable phase, variable crossover point, variable gain, and even a variable EQ. So you can alter the response any way you want to play anyway you want.

[Marbles]

If you were going to build woofer stands for monitor speakers, would you build them with one 12" servo, or two 8" ones?
Lets say fr will be up to 80hz
Music only system
I guess the question is will one 12" or two 8" servos sound more musical?

[jcotner]

The control system on the servo amp will allow you to select the extension and the roll off curve and the amount of damping (control). It has variable phase, variable crossover point, variable gain, and even a variable EQ. So you can alter the response any way you want to play anyway you want.

I was referring to frequency response range, which I thought was what
the question about you doing a frequency response curve was about.
I kind of assumed all that other stuff was a given in this kind of amp.

[Danny Richie]

I was referring to frequency response range, which I thought was what
the question about you doing a frequency response curve was about.
I kind of assumed all that other stuff was a given in this kind of amp.

The frequency response of the servo subs directly reflect the settings on the amp. And I have taken some near field measurements with the controls in various positions to confirm.

[jcotner]

I dug back through the posts and I think near DC to 125Hz or so is the
the range of the sub and amp? That's what I was asking about
in response plot form. Sounds like you measured it but haven't posted
the plots yet.

[Danny Richie]

Here are near field measurements of the SW-12-04 servo sub in a sealed box.



Just for accuracy I took two measurements back to back at each setting. The changes are simply from turning the dial on the crossover setting.

[jcotner]

Those do look good, but that's the accuracy of a servo I'm sure.
The orange line is probably with the low pass cutoff set at it's
highest setting (125Hz)?
Is the ouput at 300Hz really enough to be useful?
I think I remember you saying you start having directional
issues above about 80Hz anyway.

[emailtim]

I have a new project in the works that involves adding our open baffle servo subs to the Maggies. I will be adding a pair of the 8's below the new 1.7's and a pair of our 12's below the 3.7's. This may also involve a frame support and crossover upgrades. I am just waiting for the new speakers to arrive.

Any update on the Magnepan projects?

TIA

[Danny Richie]

Any update on the Magnepan projects?

TIA

I had a guy that wanted to move forward with doing this as a business venture and offer their newest models with the built in servo subs. He even had a blessing from the owner of the Magnepan. But it just hasn't happened yet.

I may push forward with the project myself if I have some interested Maggie owners that would like to give it a shot.

[emailtim]

I had a guy that wanted to move forward with doing this as a business venture and offer their newest models with the built in servo subs. He even had a blessing from the owner of the Magnepan. But it just hasn't happened yet.

I may push forward with the project myself if I have some interested Maggie owners that would like to give it a shot.

Hi Danny,

I have several Magnepan systems(MiniMags, MC2's, 3.6's, 20.1's) and am looking for seamless sub-extensions.  I am not interested in re-packaging the Maggies.  Keep us posted.

Thanks,
Tim

[Danny Richie]

Hi Danny,

I have several Magnepan systems(MiniMags, MC2's, 3.6's, 20.1's) and am looking for seamless sub-extensions.  I am not interested in re-packaging the Maggies.  Keep us posted.

Thanks,
Tim

All of my current Maggie customers use the pair of SW-12-16FR's in an H frame or W frame configuration standing next to their Maggies. I also sell a lot of crossover parts upgrades to the Maggie owners. Apparently they don't leave the factory with the best crossover parts that they could have.

[Hank]

Danny, for this application and others, including other panel types, as well as OB line arrays, what is your opinion of U-frame, as opposed to H and W frame configurations for servo subs?

[Danny Richie]

Danny, for this application and others, including other panel types, as well as OB line arrays, what is your opinion of U-frame, as opposed to H and W frame configurations for servo subs?

I think what most people don't realize is how much pressure is created inside these frame types. H frames and W frames break up the panel area creating much smaller areas. This really minimizes the resonance issues. The U frame leaves a very large panel area and it is extremely difficult to control the resonances created by the pressures in that space. And braces restrict air flow and load the driver so they would have to be taken into account if used. Un-braced side panels for a U frame will have to be three to four times as thick to get you back into the same range as the H frame with panel resonance (lengths being equal).

[Hank]

I know there's lotsa pressure, but 3 to 4 times wall thickness?  Wowzers. How about one cross brace - say 1" dia oak dowel?

[Danny Richie]

I know there's lotsa pressure, but 3 to 4 times wall thickness?  Wowzers. How about one cross brace - say 1" dia oak dowel?

You could do something like the braces found in our servo subs where you have a brace that hits all four walls with a large circle cut out of the center of it, and space them about 3" apart. Even still I'd double up the outside wall thickness.

[Hank]

That seems reasonable.

[jn316]

Danny,

Sorry to dig up an old thread, but is there an update on the use of these drivers in a new design? Still waiting on the 8" servo amp? 

Thanks!

Okay, new 8 ohm and 16 ohm samples have arrived. I will be testing these shortly.

These have been over a year in development. Nothing on the market like these currently exists. These were designed to be used as mid-bass drivers in open baffle applications and can also be used in sealed or ported cabinets.

These new woofers have a push pull motor design that uses a Neodymium magnet on the pole piece and a ceramic magnet on the top plate. They have Copper shorting rings and an Aluminum phase plug. And phase plug, back plate, and top plate are all Copper anodized. The voice coil is a large 44mm. The cones are paper of coarse and play smoothly into the upper ranges with no break up or ringing. And non-resonant polymer frames of coarse. There is no better frame.











8 ohm version T/S parameters:

Fs - 51.7Hz
Re - 5.49
Qms - 11.07
Qes - .58
Qts - .55
L1 - .12 mH
L2 - .50 mH
Vas - 19.07 liters
Mms - 13.1 grams
Cms - .723 mm/N
Bl - 6.35
Spl - 88.4db

16 ohm version:

Fs - 57.0Hz
Re - 12.70
Qms - 8.96
Qes - .72
Qts - .67
L1 - .17 mH
L2 - .83 mH
Vas - 16.48 liters
Mms - 12.36 grams
Cms - .624 mm/N
Bl - 8.86
Spl - 88.2db

Cool things are coming....

[Danny Richie]

Waiting on the new AMT tweeter from Hawthorne Audio. If that works out then we will be releasing some incredibly good kits with them.

[bdp24]

Danny,

Sorry to dig up an old thread, but is there an update on the use of these drivers in a new design? Still waiting on the 8" servo amp? 

Thanks!

JN- The new amps are offered on the Rythmik Audio site. Go to the Amplifiers section, click on Compact Size Amplifiers, and you'll see the HX300 and HX580 with pics, specs, and prices. I assume you can buy them from Danny as well as Brian.