Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Mark DeArman said:
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This weekend's garage project, is to decide whether it is realistic to design a three-way passive dual 8in box with a 1in exit driver. Anyone else ever try this? It actually worked well with dual 6in drivers with a higher crossover point. Pretty sure the components are going to get ridiculous at this size.
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What components are you using? And what horn flare is that?
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Tim Weaver said:
What components are you using? And what horn flare is that?
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Tim,
For this box I chose the Celestion NTR08 for the low mid, the B&C MDN51-16 for the mid, and the Celestion CDX1730-16 for the highs.
Horn is a CD 60x60 on this box. Kind of honky but doesn't have the large impedance bumps that a slot horn would have.

The crossovers are aprox. 900-1000Hz for the low, 1500Hz for the mid. Placing the All-pass component on the mid section is the hard choice.

The sub is a prototype McCauley dual 12in we haven't sold yet, but it really sounds great :-)
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Mark DeArman said:
What are you talking about?
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You asked if anyone had tried a three way passive with 8 inch drivers. Jason mentioned the fulcrums as a high end example but they aren't passive. I mentioned I have some Kustoms which are definately low end. I am also not certain if they are truely three way on the passive crossover. I think there is more overlap in the high mids.
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Jason Phair said:
To be honest, I'd rather see this in more of a frontfill-sized box, turned on end.
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If I was designing a dedicated front fill, I think i'd make it symmetric and forget about the three-way network ;-) Although, the overall sound quality is greatly improved by using a dedicated mid-range driver instead of a compromised "full range" speaker.
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Jay Barracato said:
You asked if anyone had tried a three way passive with 8 inch drivers. Jason mentioned the fulcrums as a high end example but they aren't passive. I mentioned I have some Kustoms which are definately low end. I am also not certain if they are truely three way on the passive crossover. I think there is more overlap in the high mids.
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Not sure, I didn't see any allusion to them on the Kustom website, which really takes the cake as far as bad sites.
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Jay Barracato said:
You asked if anyone had tried a three way passive with 8 inch drivers. Jason mentioned the fulcrums as a high end example but they aren't passive. I mentioned I have some Kustoms which are definately low end. I am also not certain if they are truely three way on the passive crossover. I think there is more overlap in the high mids.
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A fulcrum FA28 is passive in my book. It requires one amplifier channel (and DSP).
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Jason Raboin said:
A fulcrum FA28 is passive in my book. It requires one amplifier channel (and DSP).
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Yeah, I saw that, I was looking at the wrong spec sheet before. I'd love to see the insides of that one. I'd like to know how the two drivers are wired, and what compensation if any is done on the network. Based on it's dims it is probably not the same issue I'm playing with having the outer LF driver so far from the horn.
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Mark DeArman said:
Yeah, I saw that, I was looking at the wrong spec sheet before. I'd love to see the insides of that one. I'd like to know how the two drivers are wired, and what compensation if any is done on the network. Based on it's dims it is probably not the same issue I'm playing with having the outer LF driver so far from the horn.
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There is no padding happening in the Fulcrum crossover. It is a simple 2 (or 3) way dividing network. The magic happens in a DSP that allows FIR filters. They fix the levels and phase response via DSP. There is a standard setting for non-FIR capable processors as well, but from the reports that option is no better than any other mid-level box on the market. The magic is Gunness' FIR cookery....
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Tim Weaver said:
There is a standard setting for non-FIR capable processors as well, but from the reports that option is no better than any other mid-level box on the market. The magic is Gunness' FIR cookery....
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I'm not sure what reports you are hearing, but I have both level 1 and level 2 settings for FA boxes in my Powersoft K2's. Even in level 2 they hold their own against any box on the market.

Sorry to hijack the thread.
 
Re: Passive All-Passed Three-Way Dual 8in and 1in exit Driver Box

Tim Weaver said:
There is no padding happening in the Fulcrum crossover. It is a simple 2 (or 3) way dividing network. The magic happens in a DSP that allows FIR filters. They fix the levels and phase response via DSP. There is a standard setting for non-FIR capable processors as well, but from the reports that option is no better than any other mid-level box on the market. The magic is Gunness' FIR cookery....
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Well it's really hard from the published impedance response to tell whether it is three or two-way. Zmin ~= 5.5Ohm falls in that range where it could go either way. If it was higher I would assume it was two-way with the drivers in series. Probably an 8 Ohm LF and 16 Ohm MF driver wired in parallel or through some type of three-way/two-way network. For their design, with the driver spacing as it is, there is no need for full three-way passive, unless there are issues with the LF driver in the upper mid.

Anyway, I've built prototypes of boxes like the FA28 before. Although, when I made them I individually chambered and tuned the two 8 in. drivers. I find it kind of odd that the impedance shows that the drivers in the FA28 are significantly over damped, giving up a huge amount of low end sensitivity. Really, I've just never been happy with the way coaxial 8 in. drivers sound. I like having a properly designed horn loading the compression driver better than the compromise 8 in. coax solution. In larger speakers, like our McCauley S15, 15 in. coax, I have been pretty happy with the response. In fact there is a quite a bit of improvement due to the horn loading the 15 in. diaphragm.
 
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