Couple Questions About The FI BTL Options....

[Bumpin_Focus]

The base price for an 18" BTL is 409 shipped.  But you can get other stuff on it for more.   I understand the cooling option you can add,   but exactly what are the benefits of the other options (i.e. triple magnet)

[TechSys]

I'm gonna pull this off TeamSSAudio forum. Hope this doesn't cause any problems. This is from DevilDriver over there.

P Chamfer - This is usually putting a chamfer on the top of the pole piece. This has a two pronged effect:

1. Keeps back pressure behind the dustcap to a minimum to keep the dustcap from blowing off in any high SPL application.

2. Helps force air through the gap and around the gap, helping cooling of the voice coil.

Cooling - Not sure what Scott's plans are for this, but I would guess some sort of machining a couple extra vents to increase cooling.

3rdMagnet - This also has a two pronged effect. Not only will it allow more clearance if you go with the longer voice coil (should increase Xmech regardless), it will also help keep BL compression down as you reach the outward ends of the + and - sides of the stroke. The actual amount this helps depends on the interaction of the existing gap and coil geometry. Not sure how much it helps this particular design myself, but I'm sure Scott can you fill in on this one.

HiXmCoil - This one should be pretty obvious: it's a longer voice coil, potentially increasing Xmax. Again, the amount that increases depends on the design and Scott would need to answer how much it changes. There are a couple safe assumptions to make though:

1. Use of a longer voice coil will keep BL compression down (should extend BL curve further + and -)

2. Aside from the BL compression, this is a lot less useful to an SPL competitor than it is to a guy looking for a daily install. Xmech would really remain the same; although, if one were competing in something like Bass Race, this would likely be a very valuable addition.

Teflon - I wasn't aware that anyone has tried this idea yet, although I had heard that some companies were in development. The idea behind the Teflon coated pole piece is that it will decrease any rubbing in an application where there is a very tight gap. The advantage of a tight gap is a potentially stronger BL field, so this could be a great option if it suits the application (again, this is something only Scott could answer).

Inner H Sink - Not sure, but I will guess there is some sort of copper Faraday rings at play here, which would likely help with inductance and heat transfer. If it is a Faraday, I don't know how much it will help with inductance unless it is a fairly thick ring, which would likely require magnets with a larger inner diameter and, thus, a larger gap, and, thus, potentially less flux.

This is from Scott.

Cooling: Axial cooling channels machined into both the pole and top plate. The full cooling option for the BTLs already has the pole chamfer option included. Depending on application it can significantly increase the coils thermal power handling. For applications where you are not seeing much overall cone movement and high power, it wont do squat other than the small reduction in motor strength.

3rd magnet doesnt add much overall motor strength, but it does help reduce power compression due to the coils field in high power/current applications. Acts as a spacer for the longer coils.

High Xmax coil option nets you a 10-11 mm gain of Xmag. This has proved to be a considerable increase in daily and Bassrace applications. I will probably add a "Daily" option to the BTL list that has larger gaps to keep rocking down for daily applications. Yes this will reduce the motor strength some... but you wont notice it compared to the overall increase due to the gains in Xmax. If you dont care about coil rubbing for Bassrace and simply want the extra couple of tenths you might see... NP... Tight it is.

Teflon... Been trying out two different versions of this. One is a standard teflong coated pole similar to what you have on your cookwear. Works well, but still suffers from coil "ping" when it hits the pole. Second is a much thicker coating that softens the blows and "ping". I prefer the second for daily, and the first for SPL. Yes, I can tighten things up even more and increase motor strength... but Im not sure if I really want to. Ive got WAY more interesting ways of increasing motor strength that will show up in a few months smile.gif Only issue I have with Teflon coating is that I can not do it in house and the coater takes from 2-10 days... not acceptable at this point so I am looking at in house solutions.

Inner heatsink is like described above... It is a 10mm thick extruded aluminum ring that has fins on the inside of it. This both reduces inductance as well as transfers heat from the coil into the cooling air stream if the cooling option is added. Again, I have found this to add a decent amount of thermal power handling to the coil depending on application and other options used. This is a good option for the daily guys or some of the bassrace people. While I do have to swap magnets to one with a larger ID, and this does lower your motor strength, many daily applications wont mind the Qts increase from "very low" to simply "low"

Hope that helps.

[Bumpin_Focus]

Thank you!  :^