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No love for Tannoy Definition subs

I bought the big (& beautiful) Tannoy Definition dual-firing sub when they discontinued and went on closeout pricing. Because it has two active drivers firing in opposite directions, I figured this was this was designed as equivalent to two subs -- very useful for me as sub placement is a major limitation in my listening room.

Okay, I'm not dissatisfied, but this product is never discussed or even mentioned so far as I can tell. Does everyone just "know" it's junk and unworthy of mention? And is there any validity to my supposition that this should equal two subs (albeit both drivers are powered by the same 1k class D amp)? Really doesn't seem so, although comparison with two RELs is not really a feasible experiment for me. (Also, black boxes look ugly in my room).

hickamore
erik_squires
16,124 posts
 

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.

hickamore OP
670 posts
 

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.

erik_squires
16,124 posts
 

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.
hickamore OP
670 posts
 

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.

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