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Discussion Starter #1
I have a Denon AVR-2808CI and was wondering if it has enough output on the LFE channel, or will I need an Art Clean Box for more gain.

I'm looking at the EP1500 and Mackie M-1400i pro amplifiers. I will run it bridged to a Mach5 IXL 15.2.2 in about 5 or 6ft^3.

I like the Mackie because it has a built in adjustable high pass filter (0-170hz). Any reason not to try the Mackie?

James
 

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Why not get the EP2500 instead for few more $ and this will give you some headroom power wise when you will want an extra subwoofer :whistling:.
 

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The Mackie manual states there is a sub sonic filter at 30 hz that can be turned on or off.

http://www.mackie.com/pdf/FRSeries_OM.pdf
On the M-1400i the subsonic filter is vernier adjustable (knob control with some rough frequency markings). I use it with my DIY subwoofer.

http://www.mackie.com/products/m1400/
Two 2nd order, 12dB/octave, Bessel low-cut filters with variable frequency from Off to 170Hz
The Mackie amp does require full pro audio +4dBu line level input -- so the Art Clean Box is very helpful to boost the line level from consumer audio level of -10 dBv provided by most AVR's. Works for me. :T

The Clean Box needs the modification of its 0.047 uF input coupling capacitors to around 0.47 uF -- 1.0 uF to get the 30 Hz -3dB low freq rolloff changed to ~3 Hz or so.
 

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I have a modded cleanbox I will let go fairly cheap. It is missing one xlr output that I used in another project (i.e., for me, a better way!) but for a single channel sub output, it would be fine.

>>I do not like the cleanbox though.
 

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Discussion Starter #7
Hey Mike,

It looks like the newer Mackies have a selectable 30hz subsonic filter, but the m-1400,M-1400i and the M-2600 are adjustable from off, which gives a natural 10hz roll off from the amplifier circuitry, to 170hz.

Would a behringer feedback destroyer give me the gain I need and a subsonic(17-18hz) is what I will need for my design? It seems like this would eliminate the need for a Clean Box and I could use the Behringer amps which are a little cheaper = same out of pocket expense, with more flexiblity.

James
 

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Would a behringer feedback destroyer give me the gain I need and a subsonic(17-18hz) is what I will need for my design?
The BFD offers neither gain nor subsonic filtering. It is a unity gain device.

brucek
 

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Discussion Starter #9
Can I set one of the filters to act as a 17 or 18hz high pass?

I thought I remembered a post where a guy stated he longer needed the Clean Box after installing the BFD.

James
 

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Discussion Starter #13
Reckhorn's B-1 online instruction manual sucks. I usually don't post stuff like that, but I can't figure out much from the chopped up back and forth english-german text. I find several places where it says one thing and then later says something totally different.

It reminds me of instructions coming out of China when we first started shipping all our manufacturing jobs there. You would think the Germans would be on top of this.

Is the high pass 12db or 18db? I need to know this so I can input the correct filter slope when modeling my enclosure. Without much test equipment, how would I go about setting the high pass filter for 18hz before putting it in the system.

Sorry for the rant, I'm sure it's a great piece. I guess I need to spend some time in the forums to learn more from the others that had the same questions.

James
 

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Discussion Starter #14
OK, I just read the subsonic is 24db. I should have read more on their site before posting.

Does the range of the subsonic filter change to 15-35hz when the HIGH CUT ON button is pushed in? It appears to change the boost freq. to 20-40hz also.

I'm starting to make sense of this. When in doubt, I guess it's best to read before posting.

My bad.

James
 

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Does the range of the subsonic filter change to 15-35hz when the HIGH CUT ON button is pushed in? It appears to change the boost freq. to 20-40hz also.
It might but I am not sure.
I am using it with the high cut button off. I am letting the receiver do the high cut. Then, in theory, any adjustments that you make are just extensions of the graphs he has provided.

As a rule of thumb, I do not hear a big difference turning the subsonic filter in the down low end, say 12 to 50. I do hear a big difference turning the boost frequency knob. Therefore I like to boost a lot, but I am careful to boost away from the very low, say at 50Hz. In other words I am not boosting near where I want cut, at 18 or 16Hz. Other users are likely doing things a bit differently?
 
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