[NoahH]

I am preparing to order the parts for a sub stack to go with NX-tremes. Current plan is a pair of 3 driver stacks, but I can't stop thinking about going all out and doing  6 driver stacks.

Has anyone on here done 4, 5 or 6 in a stack? Any comments on how they turned out?

[mlundy57]

Rich Hollis did dual six driver subs. I think one or two others have as well. Dual quads have also been done.

[Endo2112]

I have 4 stacks and love them, should have done 6's in hind sight and if you look at the cost difference between Danny's & ours(RNA'S) and say GT Audio's it becomes a no brainer it if you have the space. I can say that as you add more drivers (I've had duals and triples as well) the more effortless the lower octaves become. I'm sure Rich can provide 6 stack intel as well.

Cheers,

Don

[NoahH]

Thanks for the names to ping.

Related topic - does anyone know where Danny's subwoofers.start rolling off at the bottom? I see 20 hz kinda implied a few places but it is never explicit.

[mlundy57]

It depends on where you have the extension and damping controls set at. You can get them flat to 20Hz with -3dB around 14Hz. You can also have them -3dB at 20Hz or 28Hz depending on the way you configure the controls.

[NoahH]

That is what I was looking for. Thanks!

[HAL]

I have two 6x12 OB H-Frame servo sub stacks.  Mine are the modular style as they are very heavy.  Captainhemo sells that style of sub cabinets at this time.  Much easier to build and move than a single 6x12 cabinet per side.

Used a pair of HX300-12OB servo amps per side.  They give me more flexibility than the HX800-12OB that I original had for each side.  I use the balanced inputs on the amps for long interconnects and short cables to the sub drivers.  Only tried the A370's when I had the Super-V's and I like the lower heat output of the HX amps.  Brian is working on a replacement version for the HX300's, but have not seen it on his website.

The dspMusik 2x8 is used to do the DSP crossovers and time delays to match up the subs to my main speakers.   That will be upgraded to the new dspNexus 2x8 once it is in production.

It really depends on room size as to what size servo sub stack makes sense.  Danny can guide you in that process.

Hope that helps.

[NoahH]

Appreciate it, Hal. I am surprised to hear you needed to time delay though. Is that because you are using dsp on your main speakers as well?

I assume your cone travel is pretty minimal even at volume with the stack? Also, any chance you have comments on how different these are than 3x stacks? Note that I am not too worried about volume, I am entirely motivated by resolution for the decreased settling time, and the scale one gets from more vertical coverage.

Thanks!

[HAL]

The servo subs and line arrays are 8' apart for better room integration.  Time delay is easy to set to correct for the distance offset in DSP.  It means the wavefront from both speakers are time aligned since it is 7.1mS of time difference. 

At low frequencies cone travel is still a good amount of displacement.  At 16Hz in room response takes some cone motion.  I measure pretty flat to 10Hz.  As reference my room is 10'H x 16'W x 25.2'L. 

Going from a 3x12 stack to 6x12 stack helps with better LF response, only if the room works with it.  If an 8' ceiling probably not really needed and may cause other room interactions as you are exciting more room modes that may or may not help overall response.  Might even be better to have 4-3x12 stacks instead of 2-6x12 stacks to work with room acoustics.  That is where having 4 servo amp instead of 2 servo amps are better and why I like the modular 1x12 style H-Frames for the subs.

I have switched from 6x12 to 3x12 setups and sense of scale is not as big a change as you might expect.   That maybe the fact that the subs are 16' from my listening chair.