Buttkicker BKA300-4 external high pass cutoff filter - AVS Forum
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post #1 of 21 Old 05-28-2011, 08:14 PM - Thread Starter
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So I got the Wireless Buttkicker Kit, but my YSP-1100 Yamaha receiver only has the lowest LFE cutoff of 80hz, so when I watch movies I end up feeling a lot of shakes on moments that I don´t want and I find it distracting.

So since the amplifier that comes with this buttkicker does not have a high fq. cutoff option, I would like to get a cheap and simple high cutoff filter that can bring the Buttkicker down to 40hz and lower.

I found this:

http://store.hlabs.com/pk4/store.pl?view_product=9

It´s just that I don´t know if it is what I need. I surely don´t want to spend more than $50 to do this nor I´m tech savvy to DIY one.

Does anybody have any suggestions or ideas? I would really appreciate them.

Thanks!
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post #2 of 21 Old 05-28-2011, 08:46 PM - Thread Starter
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I did more research and found that the 50hz FMOD (Filter Module) Low Pass RCA Level Crossover is the one to go. Thank you cause I found most of the info in this forum anyway.

Just one more question, if the Fmod only cuts -3db from the higher frequencies, do these cuts occur exponentially? (let´s say 100hz is at -3bd, then 200hz would be at -6db?)

Or what about this crazy idea? I get a pair of the 50hz and connect them together. That way I cutoff the high frequencies to double (-6db). Would this work well?

What do you think?
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post #3 of 21 Old 05-29-2011, 05:27 AM
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Quote:
Originally Posted by bahsura View Post

I did more research and found that the 50hz FMOD (Filter Module) Low Pass RCA Level Crossover is the one to go. Thank you cause I found most of the info in this forum anyway.

Just one more question, if the Fmod only cuts -3db from the higher frequencies, do these cuts occur exponentially? (let´s say 100hz is at -3bd, then 200hz would be at -6db?)

Yes, its -3dB every octave but you have to know the impedance of your load to know the true -3dB point.

Quote:


Or what about this crazy idea? I get a pair of the 50hz and connect them together. That way I cutoff the high frequencies to double (-6db). Would this work well?

What do you think?

Does it work that way with passive line filters? No reason not to just try it.

It is not "open-minded" to reject knowledge - Bob Lee
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post #4 of 21 Old 05-29-2011, 10:20 AM
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Either way that's way too shallow a slope to be effective.

Dunno how that thing works, but using the subwoofer out on your AVR is a good start.

Noah
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post #5 of 21 Old 05-29-2011, 11:33 AM
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the slope is 12db per octave. that is different from the -3db point.
http://store.hlabs.com/pk4/store.pl?view_product=9

here is the frequency response with the standard 80hz 4th order crossover.

then adding 1 2nd order at 50hz. then adding a second one.


LL

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post #6 of 21 Old 05-29-2011, 11:42 AM
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also "Keep in mind that two equal value FMOD low pass modules will increase the slope to 24db per octave and the crossover point will be 1/2 the FMOD value. Two 100 low pass FMODs with the 3db attenuator between them will become a 50 low pass 24db per octave crossover."

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post #7 of 21 Old 05-29-2011, 11:47 AM
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if you buy two 50hz versions, you are going to end up with a 25hz low pass filter at 24db per octave.

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post #8 of 21 Old 05-29-2011, 11:48 AM
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it sounds like this is your solution:

"Two 100 low pass FMODs with the 3db attenuator between them will become a 50 low pass 24db per octave crossover"

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post #9 of 21 Old 05-29-2011, 11:49 AM
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either that or the dual 70's with 3db attenuator.

give them a call. tell them what you are trying to accomplish and i'm sure they will fix you up.

sorry for so many posts.

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post #10 of 21 Old 05-29-2011, 01:56 PM - Thread Starter
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Yes! That´s exactly what I wanted. Thanks. So I´ll get two 70hz and the 3db attenuator. So it´s a 35hz low pass 24db per octave crossover. That should do it.
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post #11 of 21 Old 05-29-2011, 02:10 PM
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i'd give them a quick call/email just to confirm though. definitely report back, as you can't be only person with this experience. nice find btw.

you might even ask them if your order both can your return the one that isn't optimal. not sure if they will go for that, but why not ask?

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post #12 of 21 Old 05-29-2011, 03:02 PM - Thread Starter
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I did. Thanks!

Just one question, where did you get that graph? Did you make it? I can´t seem to find it on the FMOD site.

That and what would happen if I use a pair of 70hz with the 6db or 12db attenuators and not with the 3db as the manufacture´s page example says? Which added values instead of the 24db per octaves would I be getting?
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post #13 of 21 Old 05-29-2011, 11:01 PM - Thread Starter
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Just got my answer from the FMOD Engineering Dept.

"If you are looking for 24 db per octave slope, a 70 hz low pass and a 100 low pass (plus isolation attenuator) would be around 40 to 45 hz."

So yes! I should try this!

I just have some questions:

Should not the FMODS crossovers paired together be like this:
70 hz LP + 100 hz LP = 85 hz LP?
Is it the extra attenuator that brings it down to 40 hz to 45 hz?

On the other hand, these attenuators, what do they do? If you pair two LP filters it seems that you already got the 24 db per octave slope isn´t? So attenuating the signal should bring them even lower, isn´t? But it seems they stay at 24db.

LP filter (12db) + LP filter (12db) = LP filter (24db) + Attenuator (3db version) = (27db) ???
I got lost.

Why do I need these attenuators for?

Sorry for the amateurish questions. I just really want to understand how this works.
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post #14 of 21 Old 05-30-2011, 09:19 AM - Thread Starter
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So after some thought I think I got something:

70 hz LP + 100 hz LP = 42 hz LP (40 hz to 45 hz) if you add the half of 70hz LP to the half of the difference between the two (which is 15hz)

So if we take the lower low pass crossover and add up the half of the difference with the higher low pass one ends up being something like this:

70 hz LP + 100 hz LP = 35 hz LP + 7 hz LP (1/2 of 50 hz - 35 hz) = 42.5hz

So in this case when you add both filtered signals they only add up half of the frequencies of between them. They stay at the middle of their halves.

So 50 hz LP - 35 hz LP = 15 hz x 1/2 = 7.5 hz

Another theory is that they could be like this:

For 70hz LP is 35hz(1/2) = 17.5hz
+
For 100hz LP is 50hz(1/2)= 25hz
___________
42.5hz

To illustrate it better you just have to image the middle point between the halves of the two low pass filters crossovers you are pairing (since you are pairing them and they are Low Pass, they subtract each other).

Maybe I´m wrong but in some weird way I cannot explain it makes sense.
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post #15 of 21 Old 05-30-2011, 11:12 AM - Thread Starter
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So I got a pair of FMODS on ebay. They sell them in singles there and not in pairs like on the official page or parts-express.

I got the 70hz LP and the 100hz LP for $36.79 shipped.

I don´t think I´ll be getting the 3db attenuator since my receiver has the ability to control the LFE channel level (Low-frequency effect level) Choices: –20 to 0 dB

I´ll be posting back here with my results. I should be getting them around mid june.

Cheers.
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post #16 of 21 Old 06-17-2011, 11:26 AM - Thread Starter
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So as I follow up, I just got my pair of the 70hz and 100hz LP crossovers and I connected them to the Yamaha Amplifier.

The difference is VERY noticeable. I tested them with the scene when the helicopter crashes in The Matrix blu ray. With the crossovers the wooshes of the helix and the explosion afterwards FEEL very nice and controlled. Like a good bass. And I don´t mean "mellow" but contained, polished.

Without them is just like the Buttkicker is in "wild" mode. You feel everything and that distracts you a lot more and pulls you out of the experience, which is the opposite of what is supposed to do. It feels "raw" and unpolished, berserker and out of control. I didn´t like it that way.

This feeling, is not something you can address or control with the amplifier the buttkicker comes with. It´s not a matter of lowering the "volume" of the shakiness, it´s not intensity, it´s frequency modulation. And since you cannot control the frequencies with the amplifier it comes with, then it´s flawed IMHO.
You´ll need a crossover and this item is just perfect for that.

I´m very happy with this purchase. I haven´t gotten the 3db attenuator yet, but by next week I should have it and I would post again my results. I really want to see if the 24db slopes make a real difference and a nice addition.

I truly believe these items are a must have if you have the Wireless Buttkicker Kit.
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post #17 of 21 Old 06-24-2011, 08:42 PM
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asides from using a fmod, is there anything else you can use to get a useable lowpass for buttkickers?
like a no0b i set up my buttkickers with a 50hz highpass that is built into my behringer ep4000.
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post #18 of 21 Old 06-24-2011, 08:54 PM
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I use one 50 hertz low pass fmod on my bass shakers, works great, I have no complaints at all.
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post #19 of 21 Old 06-24-2011, 11:44 PM
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Quote:
Originally Posted by ufokillerz View Post

asides from using a fmod, is there anything else you can use to get a useable lowpass for buttkickers?
like a no0b i set up my buttkickers with a 50hz highpass that is built into my behringer ep4000.

An external x-over like this one:

http://www.zzounds.com/item--BEHCX2310
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post #20 of 21 Old 06-25-2011, 09:42 PM - Thread Starter
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So I got my -3db attenuator. I tried it and... I didn´t like it when used with the 70hz and 100hz LP FMODs. The buttkicker was too mellow IMHO.

I noticed thought that if I put my hand on the shaker, the feeling was really good, the shaking was smooth and nice. But unfortunately if I sat on the couch, even when I turned it´s volume up to 11 it was always missing something more than the "punch" and "wow" factor of the buttkicker.

I guess it´s the mass of the couch that makes it feel almost unnoticeable. With the attenuator on it the kick felt soft and as if the bass sound coming from the woofer was slightly shaking the sofa. But then again, it was missing part of the shaky fun.

So I would consider returning them, since they only come in pairs and are not cheap (like $30+shipping for a pair). And I´m pretty happy with having the 70hz/100hz LP fmods combo that equals 45.2"ish" hz LP.

So there you have it, cause they are only sold in pairs too get one of each on ebay.

Cheers.
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post #21 of 21 Old 06-25-2011, 09:53 PM
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Quote:
Originally Posted by Manic1! View Post

An external x-over like this one:

http://www.zzounds.com/item--BEHCX2310

thanks, that seems decently priced, picked one up!
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