No love for Tannoy Definition subs

Hey, so lets get into the physics a little.

The surface area of 1 12" driver = 116" squared

The surface area of two 12" subs = 232" squared

A single 18" sub = 255" squared

So you have a box with a surface area between a single 15" and single 18" driver. That’s good.

Because the drivers are co-located you don’t get the frequency response smoothing capabilities of multiple subwoofers.  Ideally you could locate them so they smooth each other's peaks and valleys. So that’s not quite as good, but a single sub, with EQ and room treatment can be magical if properly done.

To integrate this well, start by using the room simulator here.

https://amcoustics.com/tools/amroc

Try to put the sub and listening location OUTSIDE the first few room modes.

Measurements are really going to be your friend. The next two tools are EQ and room treatments.

Thanks for the good news. EQ and room treatment just happened to be my two highest priorities, so will accelerate the timetable on those and meanwhile learn more about measurement & download the room simulator tool right away.

Actually I have a little more driver surface -- dual 15" in this model, so that can't hurt.

Here's my quick / dirty advice:

• Cross the speakers high (80Hz) not low (40Hz)
• EQ for a descending slope from 20 Hz to 80 Hz.  Between 1.25 and 1.5 dB/decibel.
• Clip peaks before setting subwoofer level.

Legacy tech guru advised me to let the towers run full-range with no high pass. They have a peak at 35Hz and fall off steeply below 32Hz. So I set the sub cross at 31Hz with -24db/oct descent above that point. Basically sub is just picking up octave 0. 

Now, sub can be fine-tuned and I was planning to experiment after getting advice on how to go about it. Given current setting, and allowing towers to run full range, how would you proceed (pending EQ device and room treatment)?

And thanks for sharing expertise with an ignoramus in audio acoustics.

I'm not doubting you @hickamore but I thought the Definition subs were equipped with dual 12" drivers not 15" as mentioned. If the dual 12" model retailed for over $7k, I'd assume the dual 15" model would cost even more. ($9k?)

At that price you'd have to drive past a lot of proven designs from the likes of REL, JL Audio, and Rythmik.  That's probably the main reason you don't see a lot of discussion on the Tannoy sub, not that it's not worthy of discussion.

Best of luck with the integration in your system!

@yakbob You're right; I had a spell of the ditzies. Drivers are only 12" after all. Just knew they were bigger than my mains, which I mistakenly remembered as 12" rather than their actual 10". 
 
So at least they're not ill-regarded, just rare. Seems the right design for my constrained setup, once I've done the fine-tuning. Knowing now where the peaks are, thanks to @erik_squires, I can see the path forward.