Riser Subwoofer - ideas please! - AVS Forum
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Old 05-05-2014, 05:54 PM - Thread Starter
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After investigating home theater seating, i have been advised that placing a second row on a riser would be a good option.

What would be the pro's and cons of doing an actual pair of subwoofer drivers in the riser with a grill to cover them?

The recommended riser height is 8" and I will likely have a step in front of the seating that is around 4".

I have outlets and speaker terminals for my current seating where I actually have tactile transducers hooked up to my 3 current couches.

My current 4 sealed subs that are corner loaded are working out great but what do you guys think about a ported enclosure riser where the tuning frequency is around 15hz and then do away with the tactile transducers?

Is this whole idea crazy or what? Opinions?

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Old 05-05-2014, 06:28 PM
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You'd be better off building the riser to be a bass trap (for smoother response) and adding some more subs ( don't mix ported and sealed ) in the rear. Four subs in four locations with a bass trap should sound better IMO.

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Old 05-05-2014, 06:40 PM
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I really like mine, you cant even tell it is there, visually.
My riser is 14" tall if that will work for you.
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Old 05-05-2014, 06:52 PM - Thread Starter
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So fill the riser with oc703 with an acoustically transparent side or some slits in it? Building a resonator is something I am clueless about designing correctly...

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Old 05-05-2014, 07:07 PM - Thread Starter
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Originally Posted by FUN4ME View Post

I really like mine, you cant even tell it is there, visually.
My riser is 14" tall if that will work for you.
Link is in sig below

Reviewed your work which is pretty cool... Thats a lot bigger than I can do.

I have about 150" in length with another 24" of depth available. The height cant be more than the minimum useful height possible (around 8") because it will be visible from the back of the room and probably wont look good any taller.

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Old 05-05-2014, 08:39 PM
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Originally Posted by Mfusick View Post

You'd be better off building the riser to be a bass trap (for smoother response) and adding some more subs ( don't mix ported and sealed ) in the rear. Four subs in four locations with a bass trap should sound better IMO.

Maybe, or maybe not.

Subs in the riser puts them in the nearfield and their SPL will be louder relative to modes than subs placed farther away.

Also the location away from walls means they will excite modes less to begin with.

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Old 05-05-2014, 09:55 PM - Thread Starter
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well I calculate upwards of 16 cubic feet of space in a riser made for my space with enough space for easily around 4 drivers facing straight up into the couches... maybe covered by a metal grill for protection?

Perhaps 2 drivers is enough to get the desired effect...

Should i keep the tactile transducers or get rid of them altogether at that point?

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Old 05-05-2014, 10:18 PM
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I'd see how the subs do on tactile before deciding, as you can't adjust the tactile level independently of the sound.

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Old 05-05-2014, 10:24 PM
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Quote:
Originally Posted by blazar View Post

well I calculate upwards of 16 cubic feet of space in a riser made for my space with enough space for easily around 4 drivers facing straight up into the couches... maybe covered by a metal grill for protection?

Perhaps 2 drivers is enough to get the desired effect...

Should i keep the tactile transducers or get rid of them altogether at that point?

16cuft would be perfect for one SI24, though it may bounce you around in your seat😁
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Old 05-06-2014, 12:18 AM - Thread Starter
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16cuft would be perfect for one SI24, though it may bounce you around in your seat😁

I thought of that level of awesomeness but I think anything bigger than 15" Ultimax will require a greater depth than I have.

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Old 05-06-2014, 06:20 AM
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I have been considering building a sub into my riser as well. From what I understand, this may not be all that practical or useful. I am, however, still very curious and would love to see someone try this and post the results!

I have been reading a lot about risers , and I intend on building one for my dedicated theater room (room currently 27ft by 14ft, I am planning to put a wall up in the middle to make two separate rooms, the theater room being 17ft by 14ft.).

From all that I have read, you would likely get better sound quality by building the riser as a bass trap, assuming that your riser runs side wall to side wall and connects to the rear wall. It is my understanding that all you have to do is cut some holes or slots in the corners where the riser corner meets the wall corners, and then cut some similar shots or holes in the sides close to the wall.

Does that sound like the proper way to construct a bass trap in a riser??
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Old 05-06-2014, 06:27 AM
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You can use a grate too.

A grate along the back or side walls makes it more broad band than smaller ports with grates

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Old 05-06-2014, 10:23 AM
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Quote:
Originally Posted by Martycool007 View Post

I have been considering building a sub into my riser as well. From what I understand, this may not be all that practical or useful. I am, however, still very curious and would love to see someone try this and post the results!

I have been reading a lot about risers , and I intend on building one for my dedicated theater room (room currently 27ft by 14ft, I am planning to put a wall up in the middle to make two separate rooms, the theater room being 17ft by 14ft.).

From all that I have read, you would likely get better sound quality by building the riser as a bass trap, assuming that your riser runs side wall to side wall and connects to the rear wall. It is my understanding that all you have to do is cut some holes or slots in the corners where the riser corner meets the wall corners, and then cut some similar shots or holes in the sides close to the wall.

Does that sound like the proper way to construct a bass trap in a riser??

Dgage is building one to incorporate drivers into/under his couch. Unsure about his progress so far since I haven't heard much about it lately.

http://www.avsforum.com/t/1529081/couch-sub-orientation-question#post_24650877

FYI, electrodynamic designs the SI24 and could answer any questions you may have about mounting depth, box vol etc.
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Old 05-06-2014, 03:37 PM
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If you crave tactile feedback, building your subs into a riser is a fantastic idea!. Mark Seaton did one lately on a professional scale - can't remember in which thread I saw the pics, but he did his dual opposed design, but used the riser as airspace. I personally would do an enormous ported sub with as low a tune as I could, or perhaps four smaller sealed subs underneath four chairs with some DSP applied to fire directly up into the seats! A choice high quality 10 or 12" sub might be shallow enough to fit in a 8" high riser. The vibration from the sub I would actually want, rather than dual opposed design which has limited vibration. I'm a fan of tactile feedback. I've been playing with some nearfield subs lately myself, and if I had a tall ceiling I would be building a riser for sure... I may still try it with my ceilings anyway.
http://www.avsforum.com/t/1438696/a-comparison-of-three-tactile-transducers-buttkicker-mini-lfe-vs-clark-synthesis-tst209-vs-aura-bass-shaker-pro/120#post_24641545


One thing I'd always wished I could try was a riser built out of two DTS-10s laying flat.

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Old 05-06-2014, 04:15 PM
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I personally would do an enormous ported sub with as low a tune as I could...

There might be uneven tactile response because of the driver's lower excursion near Fb.

OTOH maybe the reaction force of the lighter but much higher velocity port air would replace it.

Noah
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Old 05-07-2014, 05:53 AM
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What about instead of building subs into the riser, how about adding some types of springs between the riser and floor so to allow the 4 full sized MartySubs of mine to be able to actually give a REAL tactical sensation?? I remember reading something from someone else who did something similar. I wonder how tall the riser would need to be with the springs incorporated? What type of springs and where to find them? Also, should the riser not be attached to the rear and side walls in this situation?
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Old 05-07-2014, 06:01 AM
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I'd just buy a transducer if that's your thing

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Old 05-07-2014, 06:18 AM
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Originally Posted by Mfusick View Post

I'd just buy a transducer if that's your thing

I just don't like the idea of using a transducer. In my opinion bass sounds & feels best when your room is on a crawl space foundation, and being that my room is concrete on all 4 walls and the floor, I would really like to recreate the same visceral sensation that I got in my old home. I wish that someone knew more about the floating floor with springs idea that I am considering, although, building a conventional riser that has slots cut at the rear, corners on the rear wall and sides in order to function as a bass trap, sounds pretty awesome as well!
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Old 05-07-2014, 06:47 AM - Thread Starter
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The springs would be more likely resonate at specific frequencies. You want the riser to absorb at a wide variety of frequencies i imagine so you dont get "one note" effect?

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Old 05-07-2014, 08:04 AM
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Valvetrain springs from an engine could be one consideration. They are short/stout and inexpensive.



I have a set of lightly used GM 3.8 liter valvetrain springs right now and couldn't even sell the set for $10 on ebay when I was trying to upgrade the valvetrain as part of a performance package.

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Old 05-07-2014, 09:05 AM
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Originally Posted by Martycool007 View Post

I just don't like the idea of using a transducer. In my opinion bass sounds & feels best when your room is on a crawl space foundation, and being that my room is concrete on all 4 walls and the floor, I would really like to recreate the same visceral sensation that I got in my old home. I wish that someone knew more about the floating floor with springs idea that I am considering, although, building a conventional riser that has slots cut at the rear, corners on the rear wall and sides in order to function as a bass trap, sounds pretty awesome as well!

I guess I disagree. Every experience I ever had with an unsolid foundation with regard to bass performance was highly undesirable for me. It's very hard (almost impossible) to get a room or riser to move with the bass perfectly but not resonate, add unwanted noises, or pollute your sound quality. As soon as you design a riser to do such a thing it's likely to resonate like a drum. I hate that. I have a guitar amp stack and drum kit at my house and when I would play the guitar through the cab the bass freqencies would vibrate the drum kit and the drums and they would resonate and make a very annoying noise- different freqencies specific to each drum and size of it. The snare drum was the most annoying because the snare band of springs would make terrible noise from it, I would have to go and take off the tension anytime I wanted to play guitar alone without that annoying sound. This is what happens when you get loud sound waves in a tight space - they interact with different things. Personally I hate it.

My fear is that any riser that is not properly damped will resonate like a drum head at whatever frequency excites it and totally ruin your sound quality, noise floor and otherwise smooth response. A proper riser should be IMO stuffed with pink fluffy insulation or sand to prevent resonating - and it should be built solid. There is a reason why professional theater builders and experienced builders (think amateurs on their second or third build revision) use 3 layers of plywood on the riser, with green glue and 30lb roofing felt. Roofing felt under the boards and joists and in between layers of wood. It's because they do not want the undesirables associated with otherwise (or what you are thinking of doing).

I too love the tactile feel. I want the bass to hit me in the face and chest, make it hard to breath at times and shake the sh!t out my chair, myself and my room for that ultra impressive experience. But my opinion on getting that isn't from building a resonating riser. Transducers are way cheaper and easier and can be mounted on your chair - they can provide even more "tactile feel" directly to where you want it and most importantly they can also be turned off if you don't want it or don't like it. It's cheaper and easier and can easily be undone. Very hard to undo a bad riser design and result. I'm not saying you can't do it or should not do it- I am just cautioning you that if you do decide to do it- you should take great care to make sure you do it right.

I've been researching theaters, and build process for a while now. I don't think many more have done as much as I am in this regard that are not professionals or have not already build a theater and completed the process by living through it.
It seems like most of the people that are trying to do what you want to do, or desire it - they tend to be uninformed and beginners. <-I hate to say that and I say it with as much respect as I can, I am not calling you or anyone else a beginner and I am a beginner as well. I just want to highlight that it seems like it's a beginner thing and more often than not it's not executed very well. My hope in saying this all is not to persuade you from your dreams, but help you realize them but making sure you don't fall into the same trap. If you do it, then execute it well.

My dream bass response is the same as your's I think. I just have a different approach. I want to build the room solid as can be (double walls, double sheet rock with GG, putty on box outlets, double doors for entrance with weatherstrip seal, no windows, and everything bolted down and nailed down tight including riser with 2 or three layers of plywood to make it very solid and stuffed with pink insulation to make it quiet) - but I still want to shake the sh!t out of myself and guests when the content is there. So focus on low response, and high SPL in the 5hz to 35hz region. This means a bass system with overhead and headroom and enough power and driver surface area to make enough output to rattle my tight room. It's going to feel way better if your riser is still moving because you have enough bass to move that solid three layer riser stuffed with insulation- or you have enough power to move the entire floor (which can be double floored with the upper level "floating") or best yet shake the entire room.

If you want direct tactile feel use a transducer system (even directly on your chair if you wanted) or just employ a bass solution that will shake the entire room including a solid and otherwise quiet riser.

I have a suggestion: Could you build an 18" ported sub that has a tune like 10hz and place it near field to your seat ? It should work well with your other ported subs but get you that response you are missing with the higher tune on the others. You really should not mix ported and sealed, and ported has a steep roll off lower than port tune so you lose a lot of output at 5-15hz with typical ported enclosures. You could add a near field sub ported even lower than your other subs for that extra brutality you seem to want. It might be easier to do that than risk messing up a riser.
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Old 05-07-2014, 10:08 AM
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Quote:
Originally Posted by Martycool007 View Post

What about instead of building subs into the riser, how about adding some types of springs between the riser and floor so to allow the 4 full sized MartySubs of mine to be able to actually give a REAL tactical sensation??

Those aren't mutually exclusive.
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The springs would be more likely resonate at specific frequencies. You want the riser to absorb at a wide variety of frequencies i imagine so you dont get "one note" effect?
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Originally Posted by Mfusick View Post

It's very hard (almost impossible) to get a room or riser to move with the bass perfectly but not resonate,

The riser's resonant freq should be below the desired operating band so it responds linearly in-band.

So if you want tactile response down to 10 Hz, make the riser res freq 7 Hz or below.

I wouldn't recommend metal springs as when people climb on it will oscillate for awhile; use rubber/neoprene isolators which are self-damping.

Noah
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Old 05-07-2014, 01:30 PM - Thread Starter
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I have a solid stone on slab floor now and I like the way the room is. I am worried about creating distracting creaking or vibrations with a wood riser that might resonate.

I think i learned enough about bracing from building subs to use bracing/pink fluffy to create either an actual subwoofer or maybe a rudimentary attempt at a bass trap.

The tactile transducers i have in my couches now (clark synthesis platinum) work quite well for 20-40hz range and dont feel abnormal. I would likely put these in the actual couch and not in the riser though... Im not sure the riser would transmit the vibrations as evenly? The transducers work well at night when i cant do earth shattering bass but i still get some effect of perceived higher volume/intensity.

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Old 05-07-2014, 01:54 PM
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What's wrong with mixing ported and sealed? I was tinkering with the idea of 2 martycubes in the front, and 2 sealed flatpacks in the rear on the riser and behind second row. Front and back would each be on its own channel of inuke dsp.
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Old 05-07-2014, 02:02 PM
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I myself am trying to get some more feel from the low end on a concrete slab and am installing one as I do some more changes to the room. For one thing I like the additional tactile sensation, and now with a 2 year old and another on the way, would like more feel at lower levels at night. I am trying out the earthquake riser as I have low ceilings and don't want a tall riser.

http://earthquakeeurope.com/Products/Home-Audio/BassShakerAndAccesories/Q10B/Pdf/US/Q10B_mountingInfo_US.pdf

I am using two 23/32 sheathing plywood, 2x3's (actual 1.5x2.5) with #30 roofing felt between all the wood layers. Also using four of the buttkicker rdb 220 rubber isolators.





I might try adding a rubber skirt around it like FoLLgoTT did to his really cool riser here.

http://www.avsforum.com/t/1507428/follgotts-build-18-x-peerless-xxls12/60

I also may try adding additional 2x3 supports or another plywood layer to tune it after a while. Any ideas on how this will affect its resonance frequency?

I hope this works without a shaker, but will probably add an earthquake q10b with an S shaped bracket for late night viewing. Hope to have the theater back together by the end of the month to test out and see where I am at. cool.gif
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Old 05-07-2014, 03:13 PM
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Quote:
Originally Posted by blazar View Post

I am worried about creating distracting creaking or vibrations with a wood riser that might resonate.

Why would you worry about this for a riser more than your walls?

Plus the transducer doesn't have excitations at as a high a freq.
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I think i learned enough about bracing from building subs to use bracing/pink fluffy to create either an actual subwoofer or maybe a rudimentary attempt at a bass trap.

Now that I think about it, I'm not sure what the point of a bass trap would be away from the walls.

You might just be attenuating bass you want to hear, and I believe the proper place for traps is near walls where reflections create the modes.

I guess it could help with floor/ceiling modes though.

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Old 05-07-2014, 04:05 PM
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Another thing I was wondering on the discussion of a riser resonating like a drum, is the threshold of hearing. If we are targeting resonance down low, it would have to be adding a pretty decent level to be audible.

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Old 05-07-2014, 05:51 PM
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What's wrong with mixing ported and sealed? I was tinkering with the idea of 2 martycubes in the front, and 2 sealed flatpacks in the rear on the riser and behind second row. Front and back would each be on its own channel of inuke dsp.

The waves don't play nice with each other so it's better to stick with all sealed or all ported. There's been plenty of threads explaining more if you are interested.

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Old 05-07-2014, 08:30 PM
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The waves don't play nice with each other so it's better to stick with all sealed or all ported. There's been plenty of threads explaining more if you are interested.

Like-type subs *may* be the safest starting point, but it's also possible that the differing phase responses could help rather than hurt.

Are the explanations you mentioned backed up by actual experiences and/or measurements?

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Old 05-07-2014, 08:47 PM
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Like-type subs *may* be the safest starting point, but it's also possible that the differing phase responses could help rather than hurt.

Are the explanations you mentioned backed up by actual experiences and/or measurements?

I am no expert I just know what I have read, and it could be wrong. Do you know differently ? I would love a solid explanation.

My understanding is that the main problem is the phase problems introduced between a sealed and ported sub playing the same frequencies in the same room. I know that there was some significant explanations about this based on theory, but I don't to my knowledge recall if this has ever been tested. I also remember it being explained that very mixed and complicated results will happen in the room tuning, set up and EQ process if you mix ported with sealed for the same frequencies and that can make proper set up and smooth response at the LP not impossible, but very likely almost impossible. My understanding was it was not worth it, and the trouble was more than it would be worth. My audio understanding is noob- perhaps just a tad above noob. I am not an expert by any means but I understood that at certain frequencies, the port of a ported sub is 180 degrees out of phase of the driver and that this also means it is also out of phase with the sealed sub too. I think if you complicate things by factoring in the subs in different locations, each having different frequency responses, and the entire thing becomes a super crazy effort in futility if your goal is proper sound, proper set up, and proper smooth response at the LP. It seems like it might work, or make sense but the result is different.

I kind of took all the info I have seen on it at face value though- so I have no clue if any of it is scientifically proven or validated or not. I would also like to see such data or a better explanation like you are asking. Perhaps someone can help out that knows more than me ?

I was just trying to be helpful with advising not mixing them. Everything I have ever read or seen suggested this was how things should be.

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"Too much is almost enough. Anything in life worth doing is worth overdoing. Moderation is for cowards."
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