Seeking advice for new 12" sub design

[Spearmint]

Reading Kramskoi's thread about his Tumult experience using a sealed enclosure (great read BTW) I am seeking some advice on the best setup for a couple of new subs.

Currently I have 2x 15in subs in ported enclosures tuned to around 15Hz, and these perform magically for both 2ch & HT. My trouble is now that I have a 2ch pre with HT bypass, and my HT both in the same setup, I am going to add 2x more subs to fill in the bottom end of my mains for 2ch duties only.

Currently the M&K sub is doing the 2ch duties (very well I might add it is just I want stereo subs) and will be replaced by the 2x new subs which I will probably locate behind the mains.

I have on order 2x 12” Tumults and 2x ADA1200 plate amps. These are still a couple of weeks away from being delivered.

What is a preferred design i.e. sealed/ported and suitable enclosure size for these subs bearing in mind that their primary duties are as stereo subs to extend my mains, although who knows what they may get used for around the corner.

[Jack Gilvey]

If all you're doing is extending the depth of your mains for stereo listening (as opposed to LFE reproduction), why not build some small sealed boxes and use the ADA1200's built-in LT circuit?

On the surface, a pair of those amps seems an expensive way to go about it, though. Why that route, instead of a something like a stereo pro amp and a DEQ2496?

[Spearmint]

Hi Jack,

Thanks for the response.

I realise the amps are expensive, but I couldn’t find a reasonable priced quiet pro amp that could deliver enough power unless I went for two amps and used them in bridged mode, and some of the cheaper ones don’t like low impedance when in bridged mode.

Anyway the thing is both drivers & amps are on order, and was just wondering what type & size of box to install them in.

And if in a sealed box what the LT circuit would need to be?

[Jack Gilvey]

And if in a sealed box what the LT circuit would need to be?

All depends on the FR/Qtc/F3 you're looking for. I'd choose a box appropriate to provide excursion protection at the lowest frequencies and go from there as far as LT is concerned. I'd bet DanW could suggest a nice config for the combo for a stereo music setup.

[Spearmint]

Thanks Jack!

I thought these drivers and amps would have been popular on here with a few designs already in the system.

I'll send Dan an Email.

[ThomasW]

The 15" Tumults have always been popular with the 'cost-is-no-object' folks. The 12's are brand new, you're the first person I'm aware of who's ordered any.

Although the Adire' are probably the best plate amps made, for that amount of money you could grab a Crown K2. 800+ watts/channel is more than enough to drive a couple of 12"s. Since the Tumults are closer to a 3 ohm load, the K2 power would be virtually 1000 watts/channel

[Spearmint]

Thanks Thomas,

I thought about the Crown K2 but at $4495 Aus retail I can get the 2x 12D2 drivers, ada1200 amps and cabinets for less than the cost of the K2 alone.

I realise I could get some discount off the K2, although how much I'm not sure.

[ThomasW]

Oops, forgot the Australia part.... ops:

[Jack Gilvey]

A quick Unibox sim shows you don't need a very large box at all, 1-1.5ft^3 looks great as far as excursion, and the natural unassisted f3/fc under 40Hz might be perfect for your room even before taking the LT into account.

[Spearmint]

That’s okay Thomas, something’s are reasonably priced downunder and others well you just look to alternatives.

Thanks Jack, I appreciate you taking the time to run the numbers. :T