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post #331 of 4018 Old 03-17-2019, 08:38 PM - Thread Starter
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@carp I just cut holes in the back riser to mount the JBL's. That riser has been there for 20 years without any holes, then one day my wife walks in and finds 3 11" holes cut in it....lol. Below is a picture of what she witnessed....lol.

No holes needed for the BOSS isolators. The BOSS is all about floating the platform as softly as possible plus making it as stiff as possible. Carpet underneath the isolators won't effect it's performance....no holes needed.

It's totally the opposite of a Crowson setup because those linear actuators need something solid to push against to maximize the effect.

You won't believe the difference the isolators will make, it will be a night and day difference!


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post #332 of 4018 Old 03-17-2019, 09:04 PM
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What do you think about springs as the isolators? I just remembered i have some heavy duty springs, maybe 3 inch tall and 1.5 in diameter.
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post #333 of 4018 Old 03-17-2019, 09:25 PM - Thread Starter
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^^^^^ Good question. Unfortunately, springs alone have no damping and there is a ringing after an impulse bass note. The isolators not only provide a spring but also dampening. It would be something to try until the isolators get there. I didn't like them because of the ringing.
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post #334 of 4018 Old 03-18-2019, 03:56 AM
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Quote:
Originally Posted by trhought View Post
^^^^^ Good question. Unfortunately, springs alone have no damping and there is a ringing after an impulse bass note. The isolators not only provide a spring but also dampening. It would be something to try until the isolators get there. I didn't like them because of the ringing.

I am no expert but I am pretty sure something can't be a spring and a damper - you have to apply an external force to damp the natural oscillations of the spring.

So a spring could work just as well - someone needs to try one and report back.
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post #335 of 4018 Old 03-18-2019, 05:11 AM - Thread Starter
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^^^^^ niterida. Good question and one would think that naturally. Fortunately, viscoelastic polymers (like the silicone isolators) do indeed provide spring and dampening properties. Here's an excerpt from 3M on the subject "Viscoelastic Damping Polymers are designed to have both "Viscous" and "Elastic" characteristics; "Viscous" to damp vibrational energy by converting it to negligible heat and "Elastic" to allow it to recover after each vibration cycle repetitively. Vibration amplitudes and structure-borne noise, subsequently can be reduced. "

Having said that, if one is inclined to test more with springs, I won't discourage it. I personally didn't like the ringing effect.
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post #336 of 4018 Old 03-18-2019, 08:05 AM
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post #337 of 4018 Old 03-18-2019, 08:25 AM - Thread Starter
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^^^^^ LOL. Yeah, no reason to reinvent the age-old dashpot. These along with springs would get the job done for a BOSS platform, but much more expensive and cumbersome to work with.

Polymer isolators.....much easier and less expensive, spring and damper all in one!
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post #338 of 4018 Old 03-18-2019, 12:49 PM
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Ok, I feel like a dumbass. I deleted my previous video, when I attached my Iso's I had a temporary screw which cuts the TR in half. This starts at 5hz and goes to 10hz. At the 1 minute mark the noise is me trying to turn the signal down in REW so the coil doesn't bottom out. The platform was moving so much the keyboard was not responding.

The light reflection shows the movement of the platform. My reason for staying doubled is I can keep TR at low volumes, movies that need boost can get it and those with too much I can turn down the amp gain.

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post #339 of 4018 Old 03-18-2019, 01:53 PM - Thread Starter
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^^^^^ @Gorilla Killa That's more like the BOSS TR we know and love!

3 JBL's on a platform will do the same down to 3Hz with 240 watts of power (80 watts x 3).

Gotta love the power of a BOSS!

BTW, you probably already know, some movies just have the bass filtered when authored to Blu-ray. It can be restored with BEQ. However, I do like your mechanical solution to the filtered bass movies!

That's a great idea. I'm gonna give it a shot to see if I like it.

That would simplify my setup and make it easy for the family to enjoy the theater when I'm traveling and not have to fuss with BEQ.

Right now, I'm remuxing movies and music they like with BEQ so they don't have to worry about setting everything up when I'm gone.....don't think I would trust them anyway....lol.

Would be great if I didn't have to do that......interesting!

Great idea!

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post #340 of 4018 Old 03-18-2019, 05:57 PM
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Planning on building a full riser for my theatre. Will this design be strong enough and what thickness would you recommend of MDF or Plywood ?
And isolators on each corner of the whole thing or each corner of the sections ?

There will be extra corner bracing to mount the isolators - just haven't drawn them
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post #341 of 4018 Old 03-18-2019, 06:03 PM
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Big difference Gorilla!
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post #342 of 4018 Old 03-18-2019, 07:47 PM
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Quote:
Originally Posted by niterida View Post
Planning on building a full riser for my theatre. Will this design be strong enough and what thickness would you recommend of MDF or Plywood ?
And isolators on each corner of the whole thing or each corner of the sections ?

There will be extra corner bracing to mount the isolators - just haven't drawn them

Are you space limited and that's why you are going 3' 11" deep with the riser? Mine is 5' and I wouldn't want much less because people wouldn't have room to walk around the people that are sitting down.

Like you I'm wondering how many isolators I will need on mine. It's really heavy and I'm thinking it will take more than 4 but I could be wrong...
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post #343 of 4018 Old 03-18-2019, 09:00 PM - Thread Starter
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Quote:
Originally Posted by niterida View Post
Planning on building a full riser for my theatre. Will this design be strong enough and what thickness would you recommend of MDF or Plywood ?
And isolators on each corner of the whole thing or each corner of the sections ?

There will be extra corner bracing to mount the isolators - just haven't drawn them [IMG class=inlineimg]/forum/images/smilies/smile.gif[/IMG]
A good rule of thumb is about 200-250 lbs per isolator. So depending on how many chairs and people on the riser plus the weight of the platform will determine how many isos are needed.

I'm guessing you have 3 chairs on there at about 200 lbs per person plus the weight of the riser with 3/4" plywood will be around 1,000 lbs, so about 4 isolators will be OK. If you expect more weight back there, 6 would be fine. You're going to get incredible TR back there with that rigid platform with either 4 or 6. You won't be able to tell the difference if that's what you're wondering.

Regarding the size, if you have recliners, the depth of the platform may have to be deeper but I'm presuming you already have all that factored into your design.

Hope this helps.
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post #344 of 4018 Old 03-19-2019, 05:54 AM
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Yeah its the only row of seating and just 3 reclining seats so no need for movement room - just step off the front
Will this driver be OK since I am in Oz and can't get the JBL for a reasonable price : https://www.jaycar.com.au/woofer-spe...-inch/p/CW2199 ?
Or if the next time they come on sale can someone volunteer for me to have them sent to a US address for posting to me ?
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post #345 of 4018 Old 03-19-2019, 06:11 AM - Thread Starter
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Quote:
Originally Posted by niterida View Post
Yeah its the only row of seating and just 3 reclining seats so no need for movement room - just step off the front [IMG class=inlineimg]/forum/images/smilies/smile.gif[/IMG]
Will this driver be OK since I am in Oz and can't get the JBL for a reasonable price : https://www.jaycar.com.au/woofer-spe...-inch/p/CW2199 ?
Or if the next time they come on sale can someone volunteer for me to have them sent to a US address for posting to me ?
Niterida. Thanks. I'll model that driver tonight and let you know. Regarding procurement in US and shipping overseas, my guess is shipping costs and customs fees won't make that option very attractive.

I'm confident, there's a driver we can find as an alternative.

Also, forgot to mention, the joist spacing on your riser should be closer to 2 feet instead of 3 feet with the 3/4" plywood. This will make the platform more solid when walking on it plus allow the subs to transfer their energy to the platform better due to less bending of the plywood between joists.

Hope this makes sense.

Will provide some feedback on that driver soon.
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post #346 of 4018 Old 03-19-2019, 06:29 AM
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I have 3' spacing because our ply or MDF comes in 3' widths and I planned on doing 3 sheets and that is also the width of each seat roughly.


Maybe this would be better :
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post #347 of 4018 Old 03-19-2019, 06:51 AM
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Originally Posted by niterida View Post
Will this driver be OK since I am in Oz and can't get the JBL for a reasonable price
The most important spec is xmax, which is not listed on the data sheet. Maybe you can find out from the seller.
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post #348 of 4018 Old 03-19-2019, 09:45 AM
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@carp @SteveCallas when are your insulators due in?

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post #349 of 4018 Old 03-19-2019, 09:47 AM
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Getting mine tomorrow.
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post #350 of 4018 Old 03-19-2019, 03:09 PM - Thread Starter
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Quote:
Originally Posted by niterida View Post
I have 3' spacing because our ply or MDF comes in 3' widths and I planned on doing 3 sheets and that is also the width of each seat roughly.


Maybe this would be better :
Yes, looks better. That design will transfer the motion of the drivers to the platform better. 👍
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post #351 of 4018 Old 03-19-2019, 03:23 PM - Thread Starter
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Quote:
Originally Posted by niterida View Post
Yeah its the only row of seating and just 3 reclining seats so no need for movement room - just step off the front
Will this driver be OK since I am in Oz and can't get the JBL for a reasonable price : https://www.jaycar.com.au/woofer-spe...-inch/p/CW2199 ?
Or if the next time they come on sale can someone volunteer for me to have them sent to a US address for posting to me ?
niterida....just tried to find more details about that driver and didn't see the model number or anything else listed.

By chance, can you ask the seller if they have the Thiele/Small parameters for the woofer they are selling?

If they don't have them, are there any other 12" woofers you can find that have Thiele/Small parameters or T/S parameters.

Those parameters are usually located on the technical data sheet for each driver and are usually called out as Thiele/Small parameters or T/S parameters. Once I have those T/S parameters, I can model accordingly to see if they will be OK for a BOSS configuration.

Below is an example of what the T/S parameters should look like......these are for the JBL's.

Hope this helps.

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post #352 of 4018 Old 03-19-2019, 05:40 PM
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I think I'm sold on giving this a try. I've been planning to make a VNF array of 12s anyway so if it doesn't work I can repurpose them for it. My couch was made to create the Ultimate BOSS. I could theoretically put 24 subs in it. I'm not going to, but technically I could.

I'm going to be doing a mini-riser since I'm only one row for the room I'm in. No one sits with their legs to the ground but I don't want to go too high for people climbing on and off. I do have a few questions after reading all of the thread.

Has one been made yet with the 15" driver mentioned earlier in the thread? I think no one has it up and running yet. I'm curious to how it compares to the 12s since I can fit them in too. I could only fit 12 of them though... Also did anyone ever figure out the max power needed for them? With the size constraints I have I could even do a mix of 15" and 12" if it looked like there might be an advantage to it.

Has anyone looked at the optimal number of drivers per weight? I'm wondering when diminishing returns sets in. I was thinking of doing 8 of them but I'm not sure if that's overkill or even underkill if the weight requires more. I don't want to cut to many holes for rigidity but I also don't want to take it apart every week to cut more.

For the isolators, anyone found good ones that screw in? Stick on ones concern me a bit for coming a loose and the riser shifting under them.
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post #353 of 4018 Old 03-19-2019, 05:47 PM
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For the isolators, anyone found good ones that screw in? Stick on ones concern me a bit for coming a loose and the riser shifting under them.
You do not want to do this, it will cut the response down .Mine are stacked with velcro on the bottom one, they havent moved.



@SteveCallas is doing 15's, should be running any day I think he's just waiting on the Iso's.
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post #354 of 4018 Old 03-19-2019, 06:30 PM - Thread Starter
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^^^^^^ @DesertDog ....Thanks for stopping by and for all your excellent work on the BEQ thread....you'll be amazed with a BOSS especially sprinkled with some BEQ. It is truly an incredible experience as it feels you are attached to the suspension of the woofers as they are working their magic and providing single digit response.

I've found having no footrest isn't a big deal for movie watching. All our legs on up on the chairs/couch also...lol.

Steve Callas will be the first 15" BOSS to my knowledge and I think he's getting his isolators today so hopefully he'll report soon.

I did tons of work with different platforms, alignments, iso durometers, # of drivers and location of isos. All my work was with the JBL's since my goal was max TR for the money. I also think the JBL's can't be beat for single digit frequency response down to 2Hz with low power. They are so incredibly sensitive in an open baffle design like the BOSS.

And, the BOSS as designed in post 29, translates that motion to your butt starting at 3Hz!

If different drivers are desired, I would recommend doing a test of those woofers in open air to make sure your getting respectable excursion into the single digits like my video of the JBL's a few posts ago.

If you're getting single digit response from the woofer and good excursion with those single digit frequencies, it will work great in a BOSS. The other thing to look for is MMS (moving mass) in the T/S specs. Compare those to the JBL's to see what kind of ratios are possible and associated costs....i.e.; the JBL's have a moving mass of 179g so if the 15 has double that MMS, say 358g, then it will only take 1 15 to equal 2 JBL's if both are responding with the same excursion at single digit frequencies. WinISD can also be used to model how much excursion and power levels required for that single digit response also to help with driver selection.

My work shows that 3 JBL's are optimum on a 4x8 sheet of plywood for a mini-riser, the additional displacement was linear with each addition. Beyond 3, the effect tapers pretty quickly as the isos will only compressor so much before the provide too much resistance for the extra drivers to overcome.

For the full size riser, with the extra mass of the riser, I think more than 3 would benefit a BOSS, but I haven't done any more work back there since my initial concept build, so I think that's uncharted territory for exploring.

My recommendation would be to build your mini-riser BOSS with 3 JBL's as prescribed to get started. I think you will be very, very happy with that arrangement.

If, however, you want to experiment with more or larger drivers, that's easy enough to do since it's rather easy to cut more holes. As you said, each additional driver will reduce the rigidity of the platform so more isolators will be needed which starts to take away the TR when those start getting added to stabilize the platform. The loss of rigidity can be mitigated by making the platform thicker also. So many possibilities and dials to turn in a BOSS setup once you start thinking about all the possibilities.

That's why I thought it was important to prescribe a formula that is tested and delivers incredible single digit ULF and TR. I'd recommend starting with that as your baseline and you could always come back to that if the other experiments don't work out.

But, this is AVS, and I totally understand the need to experiment and desire to go bigger out of the gate so definitely not going to discourage that...lol.

Regarding isos, I haven't heard of anyone yet that has found anything better than the prescribed isos....quite the opposite, when the Crowson isolators are used, the reports haven't been good, but when they get the prescribed isos, their reaction is always......Holy Crap !

Hope some of this feedback helps as you're contemplating your BOSS.
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post #355 of 4018 Old 03-19-2019, 06:55 PM
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The isolators did not arrive today unfortunately, and the timing is such that my new Titan 15s and Marantz 8012 are both supposed to arrive tomorrow, so its going to be a bit of overload. I will definitely report back when i have it going.

Regarding the Dayton Classic 15 driver, if you only plan on using one driver per seat, based on specs, it seems like a great fit - free air response stays extremely linear.
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post #356 of 4018 Old 03-19-2019, 07:34 PM
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Was out of the country and missed the boat on the JBL sale price of $30 but found some for $50. I had to go ahead and get'm Ordered 3 of the JBLs and the Iso's. I think Amazon is having a hard to keeping up with the demand on these things probably form this forum LOL

I was going to do 3 across a single piece of plywood for my 3 seats, but measured today and am about 4" over and really need it to be about 100" instead of 96". Guess I could make 3 separate platforms, but I bet 3 drivers on one larger platform for all 3 seats would generate more power. What do you think Tim? I guess I could do what Chris Young did on his and extend it a little. 4" isn't much, but I'll need it.

Can't wait to try this thing out
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post #357 of 4018 Old 03-19-2019, 08:04 PM - Thread Starter
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^^^^ Hey Shelby....welcome back....great to see you back here again!

Sorry you missed the sale price but totally understand the desire to pull the trigger now.....lol. I would have done the same thing. Even at the low price of $50.....can't beat the performance you're going to get!

I think you may be right about Amazon keeping up with the isos. I was wondering the same thing. Hopefully it doesn't take too long.

Yes, one big platform with 3 JBL's does great! That's the direction I would go for sure. So, for the extra 2" on each side, does that mean, the chair legs will rest in that extra 2 inch region on both sides? If so, then yes, the extra 2" per side will be needed.

If the chair legs are resting inside the 96", then letting the chairs overhang beyond the legs won't hurt anything....actually preferable as it would help hide the platform even more.

If the legs land in that extra 2 inch region on both sides, I would then just add 4" in the middle and use a joining method like Chris Young did. That way the edges of the plywood where the chair legs land will be nice and sturdy as part of the original plywood sheet which is what you want.

I may not be understanding your setup totally though so could be way off. ¯\_(ツ)_/¯ Hopefully this gives a little insight to help with your plans.

You're going to enjoy your BOSS....can't wait to hear your impressions!
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post #358 of 4018 Old 03-19-2019, 08:04 PM
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post #359 of 4018 Old 03-19-2019, 08:15 PM
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Originally Posted by trhought View Post
My work shows that 3 JBL's are optimum on a 4x8 sheet of plywood for a mini-riser, the additional displacement was linear with each addition. Beyond 3, the effect tapers pretty quickly as the isos will only compressor so much before the provide too much resistance for the extra drivers to overcome.

My recommendation would be to build your mini-riser BOSS with 3 JBL's as prescribed to get started. I think you will be very, very happy with that arrangement.

If, however, you want to experiment with more or larger drivers, that's easy enough to do since it's rather easy to cut more holes. As you said, each additional driver will reduce the rigidity of the platform so more isolators will be needed which starts to take away the TR when those start getting added to stabilize the platform. The loss of rigidity can be mitigated by making the platform thicker also. So many possibilities and dials to turn in a BOSS setup once you start thinking about all the possibilities.
Thanks for all the info. I really hadn't been thinking about using another driver. It was mainly out of curiosity about the 15" that @SteveCallas was talking about. I was looking as 1 15" is about the same price as 2 12" and since I have the room I might as well check what's the better option.

For my riser I had been thinking of using 8 of the 12" but I might drop that down to 6 to start and then I can always add the other 2 if needed. I made a large "moon pit" couch that's about the size of 2 sheets of plywood. It's big and has a ton of open air underneath for the first 9" off the ground. (I wasn't joking with saying I could technically fit 24 of them under it.) So for the size of it I think I'm right in the ballpark of what you're suggesting.

I'm bummed that I missed last Friday's sale. I was out of commission all day and never saw the sales post. I think I'm going to order everything else and keep an eye out for the next week while waiting for all of the other supplies to come in. Hopefully you guys haven't bought out Amazon yet on the isolators.
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post #360 of 4018 Old 03-19-2019, 08:16 PM
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Originally Posted by SBuger View Post
Was out of the country and missed the boat on the JBL sale price of $30 but found some for $50. I had to go ahead and get'm Ordered 3 of the JBLs and the Iso's. I think Amazon is having a hard to keeping up with the demand on these things probably form this forum LOL

I was going to do 3 across a single piece of plywood for my 3 seats, but measured today and am about 4" over and really need it to be about 100" instead of 96". Guess I could make 3 separate platforms, but I bet 3 drivers on one larger platform for all 3 seats would generate more power. What do you think Tim? I guess I could do what Chris Young did on his and extend it a little. 4" isn't much, but I'll need it.

Can't wait to try this thing out
Sorry about the ISO’s I think I ordered the last 2 packs off amazon. They arrived today.
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