Driver acceleration

[bhg41088]

I read a thing on Adire's website that says inductance, and not moving mass makes a quick driver, one with good transiet responce. But what is a good inductance level? Im looking at a Tempest versus a shiva.

[GM]

Correct. It depends on the app, so what is it?

GM

[bhg41088]

well, the app. is home theatre. Probably go the the mid q sealed design provided my adire if i go tempest, or the ported design for the shiva, to make up for the output loss.

Edit: I forgot to mention, that this will also double as my music system as well. So, this is why i chose these two allignments.

[johninCR]

The sealed tempest would be better for music and make sure the VC's are connected in parallel. Series wiring quadruples the Le.

[GM]

OK, then inductance WRT HF BW is a non-issue since you'll be XOing at/below the inductance peak, so all that matters WRT transient response is the roll off Q of the sub and the amount of added group delay if vented.

A 0.5 Qtc sealed or similar EBS vented alignment will yield the best transient response of the two types, with the EBS having more output above Fb than the sealed, so is my preference. Since some movies have <20Hz output and some organ CDs have 16Hz output, 16-18Hz tuned EBS is the no-brainer choice IMO, but the cost goes up if you need dual PRs due to excessive vent pipe length.

In this case, some prefer to build the largest acceptable sealed cab and use a L-R transform ckt. to get the desired Qtc/Fb. This limits output compared to the other options, though if your SPL requirements are <DD/DTS reference, then is probably the best way to go.

Note that WRT SPL requirements, if the mains/surrounds are set to 'small', then an additional ~7dB of output is demanded from the LFE sub to make up the difference.

The Maelstrom looks great on paper, but for a given Vb, dual Shiva's can match it down low where it counts, cost less, and can be mounted in a bipole layout for vibration cancellation.

Adding dual PRs allows the cab to be stuffed, reducing Vb requirements ~20% and insures no audible vent organ pipe resonances, so IMO, the best bang/buck sub short of an multiple driver IB is a dual Shiva/PR in a ~8ft^3 net cab. I built one, dubbing it the 'mini-contrabass' on the old basslist threads, using the then new Shiva/15" PRs and it had no problems meeting the 115dB/listening position required by DD/DTS in an open layout ~16ft x 27ft x 8ft room/14ft listening distance.

16Hz organ notes popped drywall nails out and the joint compound covering drywall screws of the newer addition, but then I have an old stick built G.I. tract home built in the early '50s, so the basic structure is poorly constructed.

Note that all this assumes the processor has an 80Hz/L-R 4th order XO. If not, then I recommend using an outboard one. Since room modes/gain dominate the FR, a digital LF EQ to flatten the response is required for best performance.

GM