Change my mind-Ported subs cant touch sealed - Page 3 - AVS Forum | Home Theater Discussions And Reviews
Forum Jump: 
 116Likes
Reply
 
Thread Tools
post #61 of 201 Old 07-26-2019, 10:51 PM
AVS Forum Addicted Member
 
notnyt's Avatar
 
Join Date: Dec 2008
Location: Long Island, NY
Posts: 10,264
Mentioned: 321 Post(s)
Tagged: 0 Thread(s)
Quoted: 3783 Post(s)
Liked: 3756
Quote:
Originally Posted by BassThatHz View Post
I partially disagree...

Internal-resonances can be damped with fill to an acceptable degree, and yes for extremely long enclosures the braces can act as barriers and do help break up those standing waves in that regard as well.
However: The remainder IS caused by box flex (which IS solved by stiffening the box via bracing).

The stiffer the box, the higher the resonant frequency. Push it up high-enough and it will shift outside the bandwidth of the cone and therefore cannot be induced by it.

re: still moving...
"Technically": Everything above 0 Kelvin is moving. Motion can NEVER be stopped.
(Unless... it is currently in-the-process of being converted to/from pure energy: i.e. black holes, antimatter and fission etc. )
I'm not talking about internal resonances, I'm talking about panel resonances. They're not the same, and damping will not stop panel resonances.
notnyt is offline  
Sponsored Links
Advertisement
 
post #62 of 201 Old 07-26-2019, 11:34 PM
AVS Forum Addicted Member
 
BassThatHz's Avatar
 
Join Date: Apr 2008
Location: Northern Okan range (NW Cascades region)
Posts: 10,775
Mentioned: 230 Post(s)
Tagged: 0 Thread(s)
Quoted: 3754 Post(s)
Liked: 4262
Quote:
Originally Posted by notnyt View Post
I'm not talking about internal resonances, I'm talking about panel resonances. They're not the same, and damping will not stop panel resonances.
I know you weren't talking about it, but I'm talking about both... and yes I know they aren't the same thing.

The conclusion is still the same. The thing has to flex, otherwise there won't be a panel resonance.

Not sure what you exactly meant by "it's not just flex, it's resonances."
Resonances ARE a flex, and flexes are gonna cause noise/sound by displacing air particles.
You speak like they are two disassociative things or something...

Resonances are just a special sub-type of flexing action.

If you significantly reduced all-flex, then all-resonance will also be significantly reduced.
I just wanted to be more clear, as it is already too confusing for most people as-is.

There is also a third force that is often noticed... Box "rocking" motion.
Which is caused by the cone momentum at high excursions (generally at low Hz) and from being off-centered (relative to the COG of the object). This occurs even WITH a perfectly stiff box with no resonances, because it is DUE to insufficient box-mass to offset those cone forces and/or not being dual-opposed (i.e. a counteractive force).

Most of us know this as well, I'm just saying it for those that don't the WHY of it.
Anyhow...
BassThatHz is offline  
post #63 of 201 Old 07-27-2019, 12:09 AM
AVS Forum Special Member
 
Join Date: Sep 2016
Posts: 1,157
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 437 Post(s)
Liked: 362
Quote:
Originally Posted by Remy.Alexander View Post
Just fired them up now- lightly stuffed HOF 20hz 12db and HS12 -2db, +2DB gan on bot to offset-- Whats thoughts on this?
Not sure what you are asking here, but if this means you gained +2 db on the 20hz you are most likely hitting port compression.
Trimlock is online now  
Sponsored Links
Advertisement
 
post #64 of 201 Old 07-27-2019, 12:50 AM
AVS Forum Addicted Member
 
BassThatHz's Avatar
 
Join Date: Apr 2008
Location: Northern Okan range (NW Cascades region)
Posts: 10,775
Mentioned: 230 Post(s)
Tagged: 0 Thread(s)
Quoted: 3754 Post(s)
Liked: 4262
If you stood on a panel, that would be a static displacement panel-flex. Which is an entirely different test condition BTW.

If a reciprocating acoustical pressure wave hits a panel (because of a cone pumping in a box), the panel-flex is coined a panel resonance. Its frequency will be a harmonic of the panel's length, based on a known speed-of-sound one can calculate all the applicable harmonic wavelengths, for both even and odd orders.

Both are flexes, but entirely different in nature and end-result.

That would be like standing on a floor in a house and then claiming "the house doesn't have any significant resonances", and then a 180db basshead cruises by your house and proves that an invalid-assertion as all your wife's collectors-edition china smashes. hehe!

Just because it can support a static load, doesn't mean it can resist reciprocating forces. Tesla understood this principle as well. Just ask the Tacoma narrows bridge or the apartment he lived in when testing his reciprocation-weapon. Recent China-Lake earthquake-generator test by chance?
BassThatHz is offline  
post #65 of 201 Old 07-27-2019, 04:35 AM
AVS Forum Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 5,626
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 607 Post(s)
Liked: 574
Damped resonance amplitude is less than undamped resonance, a little less while exciting driver is still applied, obviously a lot less when excitation is removed.

It isn't just about moving resonance out of passband either. You need raw stiffness, and better to be stiff with resonance in band than significantly less stiff with resonance out of band.

That's because the pressure differential and force generated can cause a panel to flex whether the driver is at panel resonance or not. It will move more at resonance, but still flex at other frequencies as it is reacting directly to an applied force.

Consider an extreme example. On one hand, an extremely lightweight large panel made of a single glass fiber layer skin on either side of a very lightweight foam. Let's make up numbers and imagine it's natural frequency is 200Hz and it's a 1/4" thick panel. Reasonably stiff for it's thickness but easily flexes with light hand pressure. Resonance driven up by it's absurd light weight. On the other hand is a thick 3/4" panel of lead. It's natural frequency is 80Hz, driven down by it's high weight. But it is both stiffer than the glass fiber sandwich and massively heavier.

Which one is going to move more a a side of a sub enclosure?

Moving resonance out of passband is worth thinking about, but honestly more so for full range enclosures. For subs, just do heavy and stiff (bracing significantly helps the stiff part) and reasonably well damped and let resonance fall where it may.
Bigus is offline  
post #66 of 201 Old 07-27-2019, 08:27 AM
Advanced Member
 
Russell Burrows's Avatar
 
Join Date: Oct 2007
Location: Tamaulipas Mexico
Posts: 600
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 79 Post(s)
Liked: 30
Smile

Pauses from pouring a concrete foundation for a future concrete 1240 cubic foot ib for 16 fi car audio ib318 v2 subwoofers.

Whats box flex?


Goes back to pouring concrete.
lknhomeaudio likes this.

Yamaha avr, diy l c r surround Behringer nx3000 dsp Fi car audio ib318 v2 310 cubic foot concrete ib lg pf 1500 projector.steren projector mount at diy 135 inch screen triple 15 boss build .
Pending buy fourty 6 inch drivers for some new mains new 4k projector 1240 cubic foot ib for 16 fi car audio ib318 v2 subwoofers 4 nx3000 dsp
Russell Burrows is offline  
post #67 of 201 Old 07-27-2019, 09:19 AM
AVS Forum Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 18,612
Mentioned: 135 Post(s)
Tagged: 0 Thread(s)
Quoted: 2490 Post(s)
Liked: 2544
Well, Sonotube is not in stock locally, would have to order, might just head to HD and get some plywood or MDF. Hate cutting MDF but like how smooth and even it is.

Nothing right now
MKtheater is online now  
post #68 of 201 Old 07-27-2019, 09:49 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by Trimlock View Post
Not sure what you are asking here, but if this means you gained +2 db on the 20hz you are most likely hitting port compression.



I mean I used the Inuke workaround trying to get a 18HZ HPF.
HPF set to 20HZ(Its lowest) HS12 at 20HZ set to -2DB and the "gains" set to +2DB to offset.



Not sure this is exactly 18HZ-
Remy.Alexander is offline  
post #69 of 201 Old 07-27-2019, 11:45 AM
Advanced Member
 
Russell Burrows's Avatar
 
Join Date: Oct 2007
Location: Tamaulipas Mexico
Posts: 600
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 79 Post(s)
Liked: 30
Thumbs up

Quote:
Originally Posted by MKtheater View Post
Well, Sonotube is not in stock locally, would have to order, might just head to HD and get some plywood or MDF. Hate cutting MDF but like how smooth and even it is.
Hmmm large diameter sonotube.Did you have a look at multilevel parking ramp support s use sixty inch diameter sonotube or larger comercial form column and twenty feet length

Yamaha avr, diy l c r surround Behringer nx3000 dsp Fi car audio ib318 v2 310 cubic foot concrete ib lg pf 1500 projector.steren projector mount at diy 135 inch screen triple 15 boss build .
Pending buy fourty 6 inch drivers for some new mains new 4k projector 1240 cubic foot ib for 16 fi car audio ib318 v2 subwoofers 4 nx3000 dsp
Russell Burrows is offline  
post #70 of 201 Old 07-27-2019, 11:49 AM
Advanced Member
 
lknhomeaudio's Avatar
 
Join Date: Jan 2012
Posts: 677
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 287 Post(s)
Liked: 146
Quote:
Originally Posted by BassThatHz View Post

There shouldn't be a huge separation of the SPL in the upper Hz like that.
They are at different power levels.
lknhomeaudio is offline  
post #71 of 201 Old 07-27-2019, 12:02 PM
AVS Forum Addicted Member
 
MKtheater's Avatar
 
Join Date: Jul 2006
Location: New Hartford, NY
Posts: 18,612
Mentioned: 135 Post(s)
Tagged: 0 Thread(s)
Quoted: 2490 Post(s)
Liked: 2544
Quote:
Originally Posted by Russell Burrows View Post
Hmmm large diameter sonotube.Did you have a look at multilevel parking ramp support s use sixty inch diameter sonotube or larger comercial form column and twenty feet length
Too big, won't fit in my vehicle.
Remy.Alexander likes this.

Nothing right now
MKtheater is online now  
post #72 of 201 Old 07-28-2019, 12:58 AM
Senior Member
 
VegaMan's Avatar
 
Join Date: Nov 2015
Location: Chicagoland
Posts: 270
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 103 Post(s)
Liked: 79
Quote:
Originally Posted by Bigus View Post
Damped resonance amplitude is less than undamped resonance, a little less while exciting driver is still applied, obviously a lot less when excitation is removed.

It isn't just about moving resonance out of passband either. You need raw stiffness, and better to be stiff with resonance in band than significantly less stiff with resonance out of band.

That's because the pressure differential and force generated can cause a panel to flex whether the driver is at panel resonance or not. It will move more at resonance, but still flex at other frequencies as it is reacting directly to an applied force.

Consider an extreme example. On one hand, an extremely lightweight large panel made of a single glass fiber layer skin on either side of a very lightweight foam. Let's make up numbers and imagine it's natural frequency is 200Hz and it's a 1/4" thick panel. Reasonably stiff for it's thickness but easily flexes with light hand pressure. Resonance driven up by it's absurd light weight. On the other hand is a thick 3/4" panel of lead. It's natural frequency is 80Hz, driven down by it's high weight. But it is both stiffer than the glass fiber sandwich and massively heavier.

Which one is going to move more a a side of a sub enclosure?

Moving resonance out of passband is worth thinking about, but honestly more so for full range enclosures. For subs, just do heavy and stiff (bracing significantly helps the stiff part) and reasonably well damped and let resonance fall where it may.
I only ask this because the quoted text is so well written...where should dampening be considered vs bracing
VegaMan is offline  
post #73 of 201 Old 07-28-2019, 01:30 PM
AVS Forum Special Member
 
Bigus's Avatar
 
Join Date: Feb 2003
Location: The South
Posts: 5,626
Mentioned: 13 Post(s)
Tagged: 0 Thread(s)
Quoted: 607 Post(s)
Liked: 574
Quote:
Originally Posted by VegaMan View Post
I only ask this because the quoted text is so well written...where should dampening be considered vs bracing
Stiffness is King in sub enclosures where passband is low. Well, stiffness and mass as I explained.

All are useful in full range enclosures. Driving frequency can easily be at panel resonance. With higher natural frequency it takes much lower panel excursion to be audible. And damping material is much more efficient at high frequency.

So for full range enclosures it is beneficial to damp panels with a dynamat or similar material internally. Subs not so much.
Bigus is offline  
post #74 of 201 Old 08-05-2019, 09:40 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
I think the Pros here would be disappointed - Here is measurement inside with HPF at port..I think im giving up on ported lol, Ignore the green one, i just added 3db Deq there for fun
Attached Thumbnails
Click image for larger version

Name:	67776433_1518182658321692_4827706535360593920_n.jpg
Views:	44
Size:	38.4 KB
ID:	2598858  
Remy.Alexander is offline  
post #75 of 201 Old 08-05-2019, 09:51 AM
Advanced Member
 
Jedi940's Avatar
 
Join Date: Dec 2009
Location: Northwest Ohio
Posts: 509
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked: 202
Quote:
Originally Posted by Remy.Alexander View Post
I think the Pros here would be disappointed - Here is measurement inside with HPF at port..I think im giving up on ported lol, Ignore the green one, i just added 3db Deq there for fun
Couple questions:
1. Is this measurement with both boxes?
2. Are the boxes in different location or stacked on top of each other?
3. Did you run Audyssey?

Aside from what could be sub-optimal placement That response looks about like what the models suggested. Roll off starting a little above 30Hz and falling off significantly after 17Hz. I would suggest measuring them separately as well. One could have a huge null between 20 and 30 Hz accounting for the steeper than expected drop there. That would mean you aren't getting reinforcement in that range.

Also, are they hooked up to the same sub out on the receiver or are you using 1 and 2? I can't remember if Audyssey EQs them separately but if it does, that could also help smooth out the response.
Jedi940 is offline  
post #76 of 201 Old 08-05-2019, 10:30 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by Jedi940 View Post
Couple questions:
1. Is this measurement with both boxes?
2. Are the boxes in different location or stacked on top of each other?
3. Did you run Audyssey?

Aside from what could be sub-optimal placement That response looks about like what the models suggested. Roll off starting a little above 30Hz and falling off significantly after 17Hz. I would suggest measuring them separately as well. One could have a huge null between 20 and 30 Hz accounting for the steeper than expected drop there. That would mean you aren't getting reinforcement in that range.

Also, are they hooked up to the same sub out on the receiver or are you using 1 and 2? I can't remember if Audyssey EQs them separately but if it does, that could also help smooth out the response.



I think this was after Audyssey, This is one sub by its self in its own location and on its own sub out. That roll off is garbage though so something is up. I made them 17/18Hz tune. I didnt measure the other location yet- its a pain in the A$$ as i have to use my 25' HDMI to connect laptop to avr yadda yadda.


Im off Wednesday so Ill try more locations then. Luckily the one smart thing i did was add large felt pads to the bottom of them so it'll be super easy to slide them around..


As for filling-- I had like 2-3lbs pollyfill in them, Is that not a good thing?
Remy.Alexander is offline  
post #77 of 201 Old 08-05-2019, 10:40 AM
Senior Member
 
CrusherW9's Avatar
 
Join Date: Apr 2016
Location: Central Iowa
Posts: 355
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 213 Post(s)
Liked: 127
So I can get caught up here, can you detail what enclosure this is in and what iNUKE settings you're using?

"Becoming educated is more than just acquiring knowledge. It involves the ability to see the world in ways never before conceived."
CrusherW9 is offline  
post #78 of 201 Old 08-05-2019, 11:26 AM
Advanced Member
 
Jedi940's Avatar
 
Join Date: Dec 2009
Location: Northwest Ohio
Posts: 509
Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 286 Post(s)
Liked: 202
Quote:
Originally Posted by Remy.Alexander View Post
I think this was after Audyssey, This is one sub by its self in its own location and on its own sub out. That roll off is garbage though so something is up. I made them 17/18Hz tune. I didnt measure the other location yet- its a pain in the A$$ as i have to use my 25' HDMI to connect laptop to avr yadda yadda.


Im off Wednesday so Ill try more locations then. Luckily the one smart thing i did was add large felt pads to the bottom of them so it'll be super easy to slide them around..


As for filling-- I had like 2-3lbs pollyfill in them, Is that not a good thing?
You made 2 boxes didn't you? I would add the second box in where its gonna go and see if the curve gets better. If you do have other placement options that is great and try that as well. Not all of us do.

Sent from my SM-G950U using Tapatalk
Jedi940 is offline  
post #79 of 201 Old 08-05-2019, 11:59 AM
Advanced Member
 
lknhomeaudio's Avatar
 
Join Date: Jan 2012
Posts: 677
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 287 Post(s)
Liked: 146
It's possible audyssey is detecting a dip or something at 38hz and setting that as your -3dB point, because it looks pretty evenly rolled off from that point.

Can you turn audyssey off and show us a comparison of the two?
lknhomeaudio is offline  
post #80 of 201 Old 08-05-2019, 01:38 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by CrusherW9 View Post
So I can get caught up here, can you detail what enclosure this is in and what iNUKE settings you're using?



Just 6.6FT with 1"X18"X20" slot port no eq just 18ish hz HPF
Remy.Alexander is offline  
post #81 of 201 Old 08-05-2019, 01:39 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by lknhomeaudio View Post
It's possible audyssey is detecting a dip or something at 38hz and setting that as your -3dB point, because it looks pretty evenly rolled off from that point.

Can you turn audyssey off and show us a comparison of the two?



Thatll be my next task.
Remy.Alexander is offline  
post #82 of 201 Old 08-05-2019, 02:52 PM
Senior Member
 
CrusherW9's Avatar
 
Join Date: Apr 2016
Location: Central Iowa
Posts: 355
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 213 Post(s)
Liked: 127
And here's how the model looks. As others have mentioned, I'd suspect modal issues are the cause of the slightly faster roll off in the 20-30hz range. I believe I mentioned it before but you have the wrong driver if you're trying to go for ULF at 6 cubic feet. You'll have to either swap the driver or go to a bigger cab to get the output you're looking for. I think your expectations are unrealistic for the current configuration you have and are leading you towards conclusions that I wouldn't say are accurate.
Attached Thumbnails
Click image for larger version

Name:	Screen Shot 2019-08-05 at 4.35.12 PM.png
Views:	35
Size:	52.7 KB
ID:	2598970  
Heide264 likes this.

"Becoming educated is more than just acquiring knowledge. It involves the ability to see the world in ways never before conceived."
CrusherW9 is offline  
post #83 of 201 Old 08-05-2019, 05:43 PM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by CrusherW9 View Post
And here's how the model looks. As others have mentioned, I'd suspect modal issues are the cause of the slightly faster roll off in the 20-30hz range. I believe I mentioned it before but you have the wrong driver if you're trying to go for ULF at 6 cubic feet. You'll have to either swap the driver or go to a bigger cab to get the output you're looking for. I think your expectations are unrealistic for the current configuration you have and are leading you towards conclusions that I wouldn't say are accurate.



Damn! that's $80 down the drain. I'll just have to turn them into a kids toy play thing lol. My sealed did pretty darn good job of ULF so I assumed I can get similar but with more authority.



As for driver choices- I don't make a lot of money and i support my wife and three kids, so bigger ticket woofers are generally out of the question. The UM15-22 while having a bit more excursion, I haven't noticed any other gains to go to them over the HF. I do want to give ported a fighting chance. Im not out to just bash on them- As mentioned I bought the plans for the THTLP monsters but was advised against it because no ulf and the cost of materiel's is crazy high.


I watch the classifieds here but every time there is something decent im broke, and no offense to easily a offended people but lot diy guys on there are dumb. Trying to sell used woofers no warranty for same price they paid new with warranty.


As of now these woofers are my "budget" and i do want the very best box I can get for them...Hell for two seconds i thought- Heck ill just build sanded plywood cabs 6Ft tall like 20" W and 20"D and make monsters and being sanded plywood it wont cost me a fortune and i can move them, But i remeber a lot of people saying sanded play cant work and to use plywood costing as much as damn woofers almost lol

Last edited by Remy.Alexander; 08-05-2019 at 05:55 PM.
Remy.Alexander is offline  
post #84 of 201 Old 08-05-2019, 06:19 PM
AVS Forum Special Member
 
asarose247's Avatar
 
Join Date: Mar 2010
Location: DIY enabled in SoCal / OC
Posts: 4,404
Mentioned: 104 Post(s)
Tagged: 2 Thread(s)
Quoted: 1234 Post(s)
Liked: 1079
"But i remeber a lot of people saying sanded play cant work"
So . . . .
WTF!?!
NOW you tell me?

maybe you mean Sander Ply, usually HD ,

tho a current search doesn't show that brand (?) specifically

iirc, about +/- $45 sheet, .709 thickness

in 6 years - subs built with sander ply

3 full Marty's
marty cube,
Submaximus v2 and a V3,
2 x LOWARHORN TH subs
VBSS MBM tuned dual driver

and in the 1/2" random ply, some was free

3 x THTLP's.

so . . .

it won't work for some . . . .
maybe
maybe not
might be an overdose of "member berries"
as a worse case scenario.

SAD
Remy.Alexander likes this.

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
asarose247 is online now  
post #85 of 201 Old 08-05-2019, 08:49 PM
AVS Forum Addicted Member
 
noah katz's Avatar
 
Join Date: Apr 1999
Location: Mountain View, CA USA
Posts: 22,790
Mentioned: 14 Post(s)
Tagged: 0 Thread(s)
Quoted: 1925 Post(s)
Liked: 686
BTH,

I'm impressed at your much improved batting average on technicals, however...


Quote:
Originally Posted by BassThatHz View Post
Sealed and IB tends to suffer from a lack of 15-30hz, and bottoming and overheating. The increased excursion per watt increases distortion for a given SPL.

Increased excursion per watt = higher SPL and efficiency, and less power compression.

Of course, distortion increases with cone excursion for all enclosure types.



Quote:
Originally Posted by BassThatHz View Post
Sealed doesn't take advantage of the back side of the driver, ported does (focusing all that extra energy at the tuning frequency). In fact the back side on a sealed drivers fights the cone motion in every possible regard, leading to the inefficiency it is known for.


Ported doesn't use the back of the driver any more than sealed; the increased efficiency comes from the port resonance, at which freq the cone isn't contributing much.

And the box air fights the driver just as much in ported, even moreso at Fb.


Quote:
Originally Posted by BassThatHz View Post
If a reciprocating acoustical pressure wave hits a panel (because of a cone pumping in a box), the panel-flex is coined a panel resonance.

Only around the resonant freq.


Quote:
Originally Posted by BassThatHz View Post
Its frequency will be a harmonic of the panel's length, based on a known speed-of-sound one can calculate all the applicable harmonic wavelengths, for both even and odd orders.

The freq of panel resonance has nothing to do with the speed of sound in either air or the panel; it depends on the panel's mass and bending stiffness.

The speed of sound in the panel would affect traveling waves, not oil-canning type modes.

Noah
noah katz is online now  
post #86 of 201 Old 08-06-2019, 06:54 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by asarose247 View Post
"But i remeber a lot of people saying sanded play cant work"
So . . . .
WTF!?!
NOW you tell me?

maybe you mean Sander Ply, usually HD ,

tho a current search doesn't show that brand (?) specifically

iirc, about +/- $45 sheet, .709 thickness

in 6 years - subs built with sander ply

3 full Marty's
marty cube,
Submaximus v2 and a V3,
2 x LOWARHORN TH subs
VBSS MBM tuned dual driver

and in the 1/2" random ply, some was free

3 x THTLP's.

so . . .

it won't work for some . . . .
maybe
maybe not
might be an overdose of "member berries"
as a worse case scenario.

SAD

Hmm- If thats the same as this stuff- Then hell Id rather use this then 3/4MDF. Tired of using MDF lol nasty crap.

https://www.homedepot.com/p/23-32-in...1428/100061386
Remy.Alexander is offline  
post #87 of 201 Old 08-06-2019, 07:13 AM
AVS Forum Special Member
 
Join Date: Sep 2016
Posts: 1,157
Mentioned: 20 Post(s)
Tagged: 0 Thread(s)
Quoted: 437 Post(s)
Liked: 362
Most ply will work adequately, just make sure not to use stuff with a foam core or a type of quark center to it. Although that stuff is awesome in walls and sometimes flooring.


A friend of mine found some odd thickness ply at HD, it was under 3/16th's but it was also greater than a 1/4" and it wasn't very uniformly ... formed lol. But it was $11 a sheet and squaring it up was easier than I thought since they all did have one squared off corner (imagine that for $11!). We doubled up some and use the other as backers and over all the ply performed excellent!


Long story short, don't judge Ply by the price alone or the fact its not BB or Birch.
Remy.Alexander likes this.
Trimlock is online now  
post #88 of 201 Old 08-06-2019, 10:31 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52



Did some figures in WinISD- and to get what I was hoping for im looking at 350W- 20HZ HPF, 18FT3 cab. I don't have a WAF I can build what ever I want, but that's nuts lol- Oddly i said to my self, What would happen if that same cab i put both woofers like the JTR stuff...Yeah said worse results.
Remy.Alexander is offline  
post #89 of 201 Old 08-06-2019, 10:41 AM
AVS Forum Special Member
 
asarose247's Avatar
 
Join Date: Mar 2010
Location: DIY enabled in SoCal / OC
Posts: 4,404
Mentioned: 104 Post(s)
Tagged: 2 Thread(s)
Quoted: 1234 Post(s)
Liked: 1079
currently on hold awaiting other room improvements . .

NO! WAF?

keep modeling . . .
Attached Thumbnails
Click image for larger version

Name:	20190127_142414.jpg
Views:	28
Size:	2.58 MB
ID:	2599378   Click image for larger version

Name:	201902 7 pillows.jpg
Views:	32
Size:	1.98 MB
ID:	2599380   Click image for larger version

Name:	20190125_120811 - Copy.jpg
Views:	33
Size:	2.24 MB
ID:	2599382   Click image for larger version

Name:	20190129_135103.jpg
Views:	30
Size:	2.06 MB
ID:	2599384  

DIY FAN Denon X4400 , ATI A 2000 for 7.4.6 SCATMOS Sammy 82" 4K/HDR
L/R: Fusion 15 V2 , C: 88 Special , SL/SR: 88 Special(V2) , RL/RR: F-3, TF/TR: Volt 6's TM: SLX, FH: F4Q4
SUBMAXIMUS V2, ,Submaximus V3,LOWARHORNCustom Dual Driver VBSS,2 x 6000DSP
asarose247 is online now  
post #90 of 201 Old 08-06-2019, 11:22 AM - Thread Starter
Senior Member
 
Join Date: Aug 2018
Posts: 369
Mentioned: 4 Post(s)
Tagged: 0 Thread(s)
Quoted: 172 Post(s)
Liked: 52
Quote:
Originally Posted by asarose247 View Post
currently on hold awaiting other room improvements . .

NO! WAF?

keep modeling . . .



HAHA NICE that stuff is nuts. And YUP 0 WAF- I gots me a healthy relationship. I am limited by size and money though. ceiling i think are 7'-8' and i hate really deep cabs so im trying to keep it 20" and under. ITs not a large room either, I think its 13'X11' .


I'll keep modeling, but I think im at the max i can do, 20"X20"X96"(if its not to tall, I have to remeasure)
lknhomeaudio likes this.
Remy.Alexander is offline  
Sponsored Links
Advertisement
 
Reply DIY Speakers and Subs

Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page


Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off