A new "top dog"?

[Immacomputer 10+ year member]

GTi is a standard split gap iirc.

But it has coils wired out of phase so that when one coil leaves its own gap, it starts to enter the second gap and that actually begins to force the coil in the opposite direction. That way, you can keep adding power and you won't be continually throwing the coil out of the linear range. The more power you add, the more acceleration you get from the opposing coil which will limit excursion.

I'm guessing this works in the same way?

 

[sundownz Pro Seller]

The counter coil is fixed and, in this case, placed inside the XBL^2 rebate. It is fixed but is actively powered so it's effect scales with the power applied to the voice coil.

 

[80INCHES 5,000+ posts]

interesting sub

i will wait and see as more info comes about

80

 

[tommyk90 5,000+ posts]

Too bad I would never see myself spending that much on a single sub. //content.invisioncic.com/y282845/emoticons/crap.gif.7f4dd41e3e9b23fbd170a1ee6f65cecc.gif

Sounds pretty bomb diggity though.

 

[Electrodynamic 10+ year member]

Very cool indeed. XBL^2 big-boy with 14" spiders, custom surround, counter coil, oh yeaahhhh! That should bring an end to the ultra-woofer, sub-sonic monster war in the home realm.

PS: For those wondering what a counter coil does - it can lower inductance to 0.00 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif That's right, zero. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

 

[mrogowski 5,000+ posts]

I wish him luck with his project.

 

[newusername 10+ year member]

Very cool indeed. XBL^2 big-boy with 14" spiders, custom surround, counter coil, oh yeaahhhh! That should bring an end to the ultra-woofer, sub-sonic monster war in the home realm.
PS: For those wondering what a counter coil does - it can lower inductance to 0.00 //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif That's right, zero. //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif

Slower than the speed of sound? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

There is a lot of engineering to be done and I don't know how quickly they can turn this around, especially with the tooling to be done. But we'll see how things progress.

 

[ngsm13 5,000+ posts]

INdeed. Quite an undertaking... I imagine LOTS of prototyping too...

nG

 

[Electrodynamic 10+ year member]

Slower than the speed of sound? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

Yep, exactly what I meant. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif//content.invisioncic.com/y282845/emoticons/tongue.gif.6130eb82179565f6db8d26d6001dcd24.gif

 

[Parker G 10+ year member]

Hopefully with more companies interested in making Linear output subs it will help drive the prices down some so everybody can afford them.

 

[azbass 5,000+ posts]

ill take 5

 

[squeak9798 5,000+ posts]

The use of counter coils is intriguing.....not just in their abilities to reduce and linearize inductance....but from the simple fact that hardly anyone does use them ?? In that thread over on DIYMA Dan appeared to be hyping them pretty good while Mowry's opinion of them seemed to be "meh". You'd think they'd be particularly useful in wide-band midranges (hell, mids in general) yet you never really hear about their use. Shorting rings seem to be far more prevalent. Even if one were to play the cost card (i.e. counter coils are more expensive), you'd still expect to see them on the high end offerings from companies like Seas and Tymphany. Yet a quick glance at the Le and Impedance Plots shows this not to be the case.

 

[newusername 10+ year member]

The good thing about adding copper (or aluminum, if you prefer shorting rings of that nature) is that they improve passive cooling. Of course, saturation is a problem...

I don't know why counter-coils aren't more predominant either, aside from the fact that few seem to understand them. Dan says you want to put the counter-coil in the rebate in pole or on the pole piece...Kevin says you want to put it on the former. So two people working on the same driver have different answers on which location is better.

 

[Electrodynamic 10+ year member]

The use of counter coils is intriguing.....not just in their abilities to reduce and linearize inductance....but from the simple fact that hardly anyone does use them ?? In that thread over on DIYMA Dan appeared to be hyping them pretty good while Mowry's opinion of them seemed to be "meh". You'd think they'd be particularly useful in wide-band midranges (hell, mids in general) yet you never really hear about their use. Shorting rings seem to be far more prevalent. Even if one were to play the cost card (i.e. counter coils are more expensive), you'd still expect to see them on the high end offerings from companies like Seas and Tymphany. Yet a quick glance at the Le and Impedance Plots shows this not to be the case.

The thing to note about Dan's post is that the XBL^2 counter-coil is placed in the rebate of the pole piece. Any other topology has to put the counter-coil somewhere else besides one of the rebates. Placing it somewhere else besides the rebates (like Neil stated early in the DIYMA discussion) is typically on the VC former, which adds weight. In many circumstances, a lot of weight...especially when using copper to wind the coil(s). So with XBL^2 you're allowed the benefits of a counter-coil without the major drawbacks (see the DIYMA discussion for further clarification on the pros and cons of the counter coil here. It's an interesting read for those of you not well versed on topics over a DIYMA. With typical topology there are too many negative variables to using a counter coil (loss of flux, wide gaps, etc). Albeit efficiency is down a bit, but you end up with the potential for absolutely zero inductance.

 

[newusername 10+ year member]

And I am still quite sure that placing copper in the rebate is not the best solution...improved bandwidth at the cost of increased Le(x) distortion. Mind you, it accounts for ~10% of distortion so it may be a worthwhile sacrifice if you really need that bandwidth without making the gap wider and losing B.