Help with buttkicker bottoming out?!?!? - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 34 Old 09-16-2014, 06:23 PM - Thread Starter
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Help with buttkicker bottoming out?!?!?

Hey all. So I recently picked up a Buttkicker LFE and a BK1000 amp. I put a 2x6 board across the entire length of the bottom of the couch and mounted the Buttkicker in an upright position. Its low enough where its not going to hit the seat even with sitting which worked out well.

Anyways my concern is that adjusting the amp settings to make it NOT bottom out means I have to severely limit this thing. I have a Denon 1911 receiver, and playing the movie Constatine through a recording my Directv DVR. I set the volume to -10 which is what I might typically watch a movie at.

There is a scene (for anyone familiar) where Keanu Reeves and the girl are in an alley, and it gets dark and he lights up his lighter and there are a **** ton of demons around. Anyways it has a lot of bass. Well to get it to NOT bottom out I had to set the following settings

Volume = -10
High pass filter = ON, at 60Hz
Low pass filter = ON, (not adj, set to 25Hz)
Volume = 30%


So I guess the part Im most upset about is that I had to lower the amp volume (gain) to 30%. I dont know if that equates directly to being 30% of the power (so 30% of the 1000watts) but I was really wanted to put more power. I find that most of the film is fine at 50 or 60%, but a few scenes have so much bass that it bottoms out and makes a loud thump. Obviously Im not going to sit there playing with the dial throughout the movie...

So with this all said, are my settings the best its going to get? Am I missing something? Or is it possible this isnt normal and my LFE unit is not working right? My mounting is pretty straight forward but maybe I did something in that regard that isnt ideal?

Anyways, any help is greatly appreciated

Thanks!
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post #2 of 34 Old 09-16-2014, 07:02 PM
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A highpass filter chokes the low end. You are choking it from 60Hz and down. Those things are rated to 5Hz. You shouldn't need a highpass filter.


Lowpass chokes highs. Try setting that to about 70Hz.

When amps clip it can mimic drivers bottoming. Make sure your level isn't too high that feeds your amp's input.
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post #3 of 34 Old 09-16-2014, 07:13 PM - Thread Starter
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Quote:
Originally Posted by Shreds View Post
A highpass filter chokes the low end. You are choking it from 60Hz and down. Those things are rated to 5Hz. You shouldn't need a highpass filter.


Lowpass chokes highs. Try setting that to about 70Hz.

When amps clip it can mimic drivers bottoming. Make sure your level isn't too high that feeds your amp's input.
My apologies but I dont quite understand the lingo.


Are you suggesting that I example the levels of my sub channel on my receiver? Just checked and its set to +4.0db for the sub channel. I had run Audesey before hooking up the Buttkicker. I likely DID increase the channel level some though.

Regarding the LPF and HPF, from my understanding the amp can only be adjusted on the HPF side. So the dial I can change it from 40-160. On the LPF side, if its on, its going to cut around 25hz (there is a rolloff I was told). So are you suggesting I turn the HPF off completely and leave the LPF on? My originally thinking was the opposite, since I wanted the lower freqs to play, but recently I turned the LPF off as it seemed it was bottoming out when it got super low.

Anyways if you could try to clarify I would appreciate. Thanks!
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post #4 of 34 Old 09-16-2014, 07:20 PM
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BKA1000 settings -
- Low Cutoff Filter: Off
- High Cutoff Filter: On
- High Cutoff Frequency: 60 Hz
- Volume: Set to the highest comfortable setting that doesn't cause the transducer to bottom out.

If the settings above don't provide enough tactile response, install a second Buttkicker LFE transducer under your sofa.

Don't worry about what level the Buttkicker amp's Volume control is set at. As long as it's between Min and Max and the transducer is operating properly, the volume setting is fine.
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post #5 of 34 Old 09-16-2014, 07:24 PM - Thread Starter
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Thanks. The settings you described are almost precisely what i had set it to (less the LPF piece) prior to posting here.

Im thinking now of lowering my sub channel setting a few db. Should this, in theory, allow the Buttkicker Amp volume to be increased? I realize you said not to worry about it, but if my volume is only set to 30% on between Min and Max, doesnt that mean the amp is feeding it WAY LESS than the rated 1000watts?

Also I was debating getting a 2nd unit anyway but figured that there is a lot of wasted power on the table here. I mean, if Im at 30% its almost like Im missing out on 70% of the shaking power? Maybe Im just expecting too much though

Thanks all!
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post #6 of 34 Old 09-16-2014, 07:33 PM
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If you've caused your transducer to bottom out, that's the max power it can handle. Don't try to feed it more. If you can't get enough tactile response with one transducer operating at it's limits, add a second.
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post #7 of 34 Old 09-16-2014, 07:37 PM
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Lowpass set to 60-80 (whatever).
Highpass off.

If your gain is at +4 and you have Audesey on it is possible that the level to your amp is very high at certain frequencies when listening at reference level. In my experience Audesey boosts huge amounts down low which might double the already hot voltage to your amp. Proper gain structure is very important.

I would use REW and do a loop back to see where audesey is boosting and spectrograph the movie scene in question and see where the bass hit is centered. In my experience, bass shakers are best left without eq.
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post #8 of 34 Old 09-17-2014, 04:34 AM - Thread Starter
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Thanks guys.

Heres a dumb question. In the car audio world (or at least 10 years ago when i set up some JL subs in my previous car), there was a calculator and a test to determine the wattage of the amp. Something like you would play a test tone, turn volume to 3/4 and then measure the voltage after using the calculator to determine what X volts would be in watts. Is there something like this I can do in this scenario?

It sounds like my bassshaker is capable of 1000w and I want to maximize the power, however its hitting its peak before that point (my perception anyways based on the fact I have the amps gain at only 30% of the max). But from what you are both saying, that Audessey and my sub channel settings, could in fact be boosting this signal. So even at 30% its still getting close to the full 1000w of power. Am I understanding you guys correctly?

I would also turn down the Channel settings more but I still have a standard sub in the mix and that will lower that subs output which is no bueno.

Lastly you mentioned about NOT using the eq for the bassshaker. How might I go about using Audessey for the standard sub, and not for the bassshaker? My understanding is they are tied together since I am simply splitting the signal with a T.

Thanks!
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post #9 of 34 Old 09-17-2014, 08:06 AM
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My Denon 5308a AVR has 3 subwoofer out jacks and one of them can be configured as a transducer, so that output is not EQ'ed. Most receivers don't have that flexibility however, including your 1911. Unless you want to live without Audyssey room correction you're stuck running your Buttkicker on the EQ'ed sub out. That will result in less accurate transducer action (some frequencies will be over-emphasized while others may be too weak), but again, that's what you're stuck with.

The BKA1000 amp has sufficient power to drive 4 LFE transducers. As you've discovered, if you turn up it's volume control too high the piston in your transducer will hit the limits and you'll hear loud knocking. That can damage the transducer. If you just follow the recommendations in post 4 then your amp's volume control is correct. If that setting doesn't give you enough tactile response, add another transducer:
http://www.thebuttkicker.com/configu..._2LFE-1000.gif

If you're not satisfied with this advice and still want to "maximize the power", then go ahead and turn up the amp's volume control to the max. Turn up the volume on your AVR to maximize it's power too. Play the pod emergence scene from War of the Worlds. Watch your transducer explode. Test complete. Buy a new transducer...
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post #10 of 34 Old 09-17-2014, 08:20 AM - Thread Starter
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Haha. In no way am I trying to say your advice isnt sound so I hope you dont take offense. I know just enough about audio to be dangerous so I value your opinion and will stick by it. I can look into another transducer if this is really the max I can get out of the existing one. Also I did plan to get a new receiver anyhow so now I will be sure to look with ones with independent sub configurations. Do you happen to know if the x4100 offers this? That is the one I was eyeing. Im not sure if there is a 'special term' they use to identify this on the receiver.

Thanks!
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post #11 of 34 Old 09-17-2014, 08:46 AM
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Search the AVR Owner's Manual for the word "transducer". Neither the X4000 or 4520 AVRs include that feature as far as I can tell, so the X4100 probably doesn't have it either. It's not a feature that many customers would ask for so you're probably out of luck unless you find an old 5308.

You should still be able to get good output from your Buttkicker using the Audyssey EQ'ed subwoofer out. If the transducer hits it's limits a little sooner due to an Audyssey boost at some frequencies, just nudge the BKA1000 volume down a bit until you can play the offending passage without issues.

Alternately, you could feed the BKA1000 input from the sub out on your Blu-ray player if it has one. That would eliminate Audyssey from the picture, but then the transducer amp's input isn't tied to the AVR's volume and you won't have shaker action for other sources like your DVR. Your current configuration is probably the best compromise.
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post #12 of 34 Old 09-17-2014, 09:13 AM - Thread Starter
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ok thanks. I ended up calling Denon to see what options their receivers had. They mentioned that something like the 4520 which has independent sub configurations could be used, but that both would use Audyssey at the same time (or not at all). The gentleman mentioned I could run Audyssey, record the settings, then set it up manually without Audyssey and then I could configure the two independently (basically one with Audyssey settings and one without).

It sounded odd when he mentioned but shrug, maybe that work work?


Also does a device exist that I could put between the Denon and the transducer that would flatten the EQ?

Thanks!!!
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post #13 of 34 Old 09-17-2014, 09:44 AM
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The tech's advice sounds poor. The only independent sub configuration parameters in that model are distance & level AFAIK. I don't believe that you could do what you want with that AVR (EQ all speakers except the second sub out). I also don't believe that there's any easy way to use an external device to reverse the EQ on the second sub out to negate Audyssey's correction.

It seems like you're over-analyzing the shaker optimization task. A single transducer obviously isn't doing it for you. Just bolt on a second, adjust the amp's volume so that they don't hit their limits, sit back & enjoy...
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post #14 of 34 Old 09-17-2014, 09:48 AM - Thread Starter
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yeh I think youre right! By the way, wanted to post pics of how I mounted. Just to be sure I did this the proper way. At first I mounted just between the crossmembers but then I went back and used one single board across the entire couch. I figured this would be more solid as its connected to the cross members AND the frame. The instructions with the buttkicker on very light in this regard. Thanks
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post #15 of 34 Old 09-17-2014, 11:04 AM
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Your installation looks good to me.

Rubber isolators attached to your sofa's feet might help to increase the tactile response. You might want to try that before ordering another transducer:
http://www.thebuttkicker.com/ri-4
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post #16 of 34 Old 09-17-2014, 11:11 AM - Thread Starter
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yeh good idea. The isolators have nothing to do with the bottom out though right? It might just give me more of the 'feeling' than without it? Plus I am on tile which is in general not so great


On a related note, for my other sub (traditional), should I add some isolators to it as well since Im on tile? its a Polk PSW505

Thanks a lot for all your help on this. I know my questions are very basic so I appreciate it
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post #17 of 34 Old 09-17-2014, 11:24 AM
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I'm someone who has experience with these.

First, you DEFINITELY want to install rubber isolation feet. No question.
Personally, I leave the high cutoff at 40. I think it doesn't feel natural to have the BKs engaged at that high a frequency, but that's up to you.
I also leave the low cutoff OFF. The whole point of the transducer is to provide tactile feedback where your subs may not be able to. Why would you limit that?
I have my amp set at a hair above 9 o'clock on the knob now. The knob is for gain, not volume, regardless of what it's called. If you have your subs trim on the AVR set to +4, you're already sending a strong signal to it. And that doesn't even account for what Audyssey is doing.
Lastly, I added a second BK unit to my reclining sofa. 1 was great, but I just wanted that little extra oomph without pushing the one too hard.
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post #18 of 34 Old 09-17-2014, 11:28 AM - Thread Starter
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wth
Its safe to assume that your sub channel is lower than +4? Like a bunch lower? On the rubber isolaters, the 2 front legs of my couch sit on a rug, the back two on the tile. In this scenario would only the back two need the rubber isolators? Thx
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post #19 of 34 Old 09-17-2014, 11:28 AM
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Quote:
Originally Posted by Roachforlife View Post
yeh I think youre right! By the way, wanted to post pics of how I mounted. Just to be sure I did this the proper way. At first I mounted just between the crossmembers but then I went back and used one single board across the entire couch. I figured this would be more solid as its connected to the cross members AND the frame. The instructions with the buttkicker on very light in this regard. Thanks

Does the piece of wood that you added sit directly on the floor? If so, those bolt heads are probably making some noise against the tile floor. You definitely want to lift that and use some isolators.

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post #20 of 34 Old 09-17-2014, 11:32 AM - Thread Starter
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No, there is at least a 2" gap between that board and the floor due to the legs of the unit. When I redid the board (to the one long board), i moved the BK unit further back into the couch because before it was more in the center. Because I have to do this upright I thought I might accidently hit it if I sat in the middle of my couch. Now its literally 1/2" forward of the frame (aka as far back as I can go) plus with the one big board, its now an inch or two lower than it was in the previous set up with just the cross member board.

To mount I used 6mm bolts, 65mm long with 1" washers so it didnt dig into the wood. The board size was 2x6, and like 77inches long IIRC

Thanks
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post #21 of 34 Old 09-17-2014, 12:16 PM
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The floor damps the Buttkicker's vibration. Isolating the sofa from the floor may help.

I wouldn't bother putting isolators on your sub unless you need rubber feet to keep it from walking across the floor.

Good luck with your shaker tweaks!
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post #22 of 34 Old 09-17-2014, 12:24 PM
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Quote:
Originally Posted by Roachforlife View Post
wth
Its safe to assume that your sub channel is lower than +4? Like a bunch lower? On the rubber isolaters, the 2 front legs of my couch sit on a rug, the back two on the tile. In this scenario would only the back two need the rubber isolators? Thx
Yes, preferably you'd want isolators on each foot of the sofa. I think the FAQs on their site specifically mention that being on carpet doesn't suffice for dampening purposes. As the BK isolators are pretty pricey, I found and have been using these with good results:

http://www.ebay.com/itm/MOUNTABLE-RU...item3a660bff65

Also, my sub trim is -2. General rule of thumb is you want to be in the negative territory and as close to zero as possible. Easiest fix if you don't want to mess with the subs is to just turn the BK amp down.
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post #23 of 34 Old 09-17-2014, 03:06 PM
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You could also try these for cheap isolation http://www.parts-express.com/penn-el...x-1-h--260-772

Shake in the infrasonic region I find may also vary significantly depending on the weight seated upon the couch in the absence of isolators to both limit/ keep dampening uniform by decoupling your couch from the floor.

Interestingly, I find sensitivity in the audible frequencies is increased with a more rigid mounting. You could perhaps play that to your advantage though making your buttkicker mount as springy as possible to enhance low frequency flex if your not as interested in the higher octaves. Perhaps by unfastening those two wood blocks on either side of the couch's two central supports may enhance deep flex but severely limit top end sensitivity in terms of shake by not being directly attached to those junctures. you could also perhaps purchase a board of wood just large enough to be used as a platform for your couch, attach the buttkicker to that, have isolators placed underneathe the board to decouple it from the floor, (and perhaps some cloth atop the board for aesthetic reasons though that might slightly dampen vibration) and place the couch on top of that.
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post #24 of 34 Old 09-17-2014, 10:21 PM
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Your installation looks to be the culprit to me. My couches have more structural supports, but because of my installation I am able to shake my two couches with just one Aura Pro transducer per couch (I know that I'm giving up the really low frequencies but I'm happy for now) I actually have to turn my transducer amplifier down in order to not be obnoxious (and I'm a real bass head). The reason that I am able to do this is that there is a central support that is only about 3/4"to 1" thick that I mounted my Aura Pro transducer to. Your installation is way too beefy to get any shake out of the wood that the transducer is mounted to, its rock solid with the addition of such thick wood. I see this all of the time where good meaning folks mount there transducers to a super tight framework. In my opinion you will probably get plenty of shake out of the one buttkicker transducer if you remove the 2x4 addition and mount the transducer sideways to one of the two couch supports that are currently on either side of the transducer. These supports are thinner and will shake more easily which will transfer more energy to the rest of the frame of the couch. There are so many bass shaker installations that are simply putting the bass shaker in a really difficult position where the super thick wood that the transducer is mounted to will quite obviously not transfer "shake" so folks then have to add another and then throw tons of power at the situation or they are left with little to no shake. Working with physics instead of fighting it is the key.
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post #25 of 34 Old 09-18-2014, 04:53 AM - Thread Starter
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The reason I used the size wood I did was the small paragraph in the BK LFE manual specifically mentioned using a 2x4 or 2x6 piece of wood. So in this case the 2" being the thickness. Also when I called BK they told me never to mount the BK sideways. I could, however, get a 1x6 board for the bottom and mount it like that???
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post #26 of 34 Old 09-18-2014, 05:52 AM
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Check out my old thread a comparison of three transducers.

I had the same concern with the buttkicker minis (one per seat)

My recommendations:

Turn the gain on your polk sub up and rerun audyssey (try to have sub channel trim negative on the avr to avoid potential amp clipping.)

Don't worry about 30% amp gain. It isnt volume knob. Its an input signal attenuator. This is a common misperception. You can still get full voltage out of the amp at lowest gain settings if your signal is high on the subwoofer out preout. Again this isn't a volume knob - it matches input voltage from your AVR to the amp. If your amp put out a weak signal you'd turn up the input attenuation to allow the incomming input signal to pass more voltage. Sounds like that isn't your problem. Discard your concern. You are still able to get full power at 30%.

Use the high pass filter (aka low cut filter). The filter isn't a brick wall filter, its a slope. You aren't cutting off the low frequencies, you are lowering them to prevent bottoming of the transducer. The transducers are more sensitive at lower frequencies and so don't need a boosted signal down low. (Which as others said, Audyssey may be trying to do in your room). The hpf may help eliminate your issue.

I agree with about a 60hz range LPF (aka high cut filter). The transducers start feeling fake above that general frequency range to me.

Consider buying a new AVR. A 7.2 or 9.2 or 11.2 receiver. Having the second subwoofer out allows you to adjust volume and distance settings independantly of your actual subwoofer. That is HUGE in my experience. I like my transducers set to about 4.2 feet distance and my front subs are about 12 feet away. Adjusting them each individually allows for a much more realistic feel. With one sub setting the timing is off and feels so in my experience.

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post #27 of 34 Old 09-18-2014, 06:02 AM
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I wasn't aware that you couldn't mount the bk transducers sideways, so that limits you. Regarding the 2x4 you have mounted, can you make it so that it is only attached to the couch on the very ends of the 2x4 and detach it from the two supports that are right near the center of the couch? Decoupling the couch from the floor by using rubber feet on the couch is also good. These ideas may be your only option to loosen up what the bk is mounted to.

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post #28 of 34 Old 09-18-2014, 09:56 AM - Thread Starter
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Thanks again guys.

I was looking to upgrade AVRs anyway (ran out of HDMI ports on my 1911). I was looking at the X4100 from Denon but even though its a .2 AVR I believe its just internally split so no real advantage from what I have now in that regard. Also I completely forgot to look at the distance side of the subwoofer. FWIW I previously had my Polk PSW505 next to my couch. I realize this IS NOT ideal but I was able to get more of the shake since the port pointed directly onto the side of my couch, mimicing the bass shaker sorta. Anyways so the sub distance (without looking) is likely set to the proper distance for the transducer as well, lets say like 12ft. I have yet to rerun Audyssey since I didnt have a spare Dig Coax cable for the Polk sub. I expect that cable to arrive today and plan to put it closer to the TV itself rather than by the couch.

Also I do have some rubber isolators which I will install and see how it affects things. I actually bought the couch mounting kit but realized after I got it, it was for the BK Advance, not the LFE. So I can, at least for the moment, use the isolators from the kit and see how that works.

Regarding the board, it sounds as though you are saying that I dont want the BK to touch the cross beams at all and only the outer frame? If you look in the pics with the large board, there actually was a gap of 1/2" between the long board and the 2 cross beams. To purposely stiffen this I added 2 extra small pieces that were screwed into both the cross beam and the long board. But are you saying I should remove this and leave the gap? I guess my only concern is Im not sure how much flex there might be and if 1/2" gap would suffice to ensure it doesnt shake to the point of hitting the cross beam. The sound of two boards hitting clearly wouldnt be good. My guess is it would be fine but just mentioning.

Back on the amp for a moment, with both a traditional sub and a transducer what would be the preferred channel setting in the AVR for the sub? 0? Or something more like -4? As you mentioned I can increase the gain on the Polk sub to compensate but I dont know if I will have similar problems by having the gain too high on that unit as well. Im not home now to look at it but I would guess my gain is probably around the 12oclock mark on the Polk. Of course, now that I moved the Sub this could all change again I suppose.

Thanks all
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post #29 of 34 Old 09-18-2014, 11:27 AM
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Quote:
Originally Posted by Roachforlife View Post
Thanks again guys.


Regarding the board, it sounds as though you are saying that I dont want the BK to touch the cross beams at all and only the outer frame? If you look in the pics with the large board, there actually was a gap of 1/2" between the long board and the 2 cross beams. To purposely stiffen this I added 2 extra small pieces that were screwed into both the cross beam and the long board. But are you saying I should remove this and leave the gap? I guess my only concern is Im not sure how much flex there might be and if 1/2" gap would suffice to ensure it doesnt shake to the point of hitting the cross beam. The sound of two boards hitting clearly wouldnt be good. My guess is it would be fine but just mentioning.


Thanks all
Its not so much that you don't want the BK touching the cross beams, its more about the fact that the BK is able to shake the longer stretch of 2x4 much more easily without the attachment to the cross beams. I would think that a half inch of gap is enough between the cross beams and the 2x4 since I doubt that the BK can shake the 2x4 enough to close that gap.
Your install was too good I believe that by adding the rubber feet and "loosening up" the install that you will get more shake. Whether it is enough shake is yet to be seen, but these are steps in the right direction.
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post #30 of 34 Old 09-18-2014, 01:54 PM - Thread Starter
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Great, thanks. And fwiw I called BK on my lunch break and ran it by them. They mentioned that 3/4" inch thick plywood is preferred. Interestingly enough the manual mentions a 2x4 (in this case 2 would be like 1.5" thick) but maybe real world suggestions differ from the manual.

I am considering if its worth swapping out a new board. I suppose Ill try those other options first (isolators, adjust other sub, rerun adyssey, adjust volume on BK amp, and maybe loosen middle boards) and see where that takes me.

One minor thing but the guy mentioned using plywood. I believe the wood I got was called Whiteboard (or maybe it was whitewood). Is this the same? Sorry Im definitely not a lumber expert
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