Will a helper tweeter kill me?

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So the the title may be a slight overstatement but...

I will soon be getting a ART 311 Stereo 2-Way Crossover with Sub Out from parts express and I just noticed something I overlooked.

There is no way to only run a subwoofer and a midrange without the 6kHz low pass filter on top. This is ok for my current system because I am going to put a helper tweeter on it anyway above around there.

But...
I will soon be making some Aiko's with the Fostex FE108Es for my main system and I am wondering if being required to use a helper tweeter at above 6kHz will kill the full range awesomeness. It will help with dispersion for sure but I don't know how this will effect the soundstage. That woofer doesnt really need the tipy top help so if you guys think it would sound better without the tweeter I could find someway to go without the active crossover for that system.
 
to address the issue of "killing the majik" of the FE108es with a helper tweeter - in short - not necessarily - particularly if you run let the sigma run wide open and gently roll in the tweeter - make/model which I don't think you mentioned yet

as to exactly how to go about implementing should you choose, there's more than one way to skin a cat (that's a joke PETA ), and if you don't need an active XO for other reasons, you could certainly save the bucks
 
That's still a stock filter. It's active, but it just applies the generic LR4 transfer function with no care for the actual acoustic response. However, that is somewhat better than what a passive stock filter would do.

Alright that totally went over my head. What is a stock filter? What's a lr4 transfer function? Why is this bad?

I don't know, but I wonder if you could combine the two halves of the XO with a Y cable into your amp. This would effectivelyby-passthe2 waypart but stil allow you to use the sub-out.

This sounds like it might work. Would that do anything weird to the signal?

Even if I couldn't bypass the top filter could would using a helper tweeter be such a bad thing?
 
If we ignore the knee of the filter (the part that rounds over) and only consider the straight portion of the slope, then the transfer function is 24db/octave. So if 6khz, it'll be -6db at 6khz and -30db at 12khz. Graphs work better. Here.

ONS6khzLR4nodesign.png


In the above, red is tweeter. Blue is woofer. This is a little dome and the HiVi B4N (iirc) from the overnight sensations. The black line is the summation. At 6khz they're actually fighting each other and the output is below the individual outputs. On top of that, they're out of phase. And all us full range guys have such a hard on for phase that this is very concerning.

Now I'll use acoustic output specific filters:

PCDrun1.png


Much better. In phase, flat summation, etc.

Even if I couldn't bypass the top filter could would using a helper tweeter be such a bad thing?

Yes. As you can see above, unless you can confirm somehow, you may end up with a worse response, a big hole right at 6khz.
 
I think I'm just going to keep it and play around with it for best response. Considering that my current system will actually benefit from a helper tweeter (ragged response about about 5k) worst case ill just leave it with that for a backup system and use a simple high pass filter on the aikos below about 80hz to improve power handling and let the sub handle below that.
 
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