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Lilmike's Cinema F-20 - Page 50

post #1471 of 1699
The original seal on the woofer works fine. I took the weatherstripping off and just tightened the woofer down on the woofers seal. There are no leaks that I could find so tomorrow I'm going to swap in another woofer and see what happens. The sound that I'm hearing is coming from inside the enclosure. Here is a second listen.

http://s596.beta.photobucket.com/user/louisdamani/media/20121219_0103001_zps0eb33493.mp4.html
post #1472 of 1699
Quote:
Originally Posted by louisdamani View Post

The original seal on the woofer works fine. I took the weatherstripping off and just tightened the woofer down on the woofers seal. There are no leaks that I could find so tomorrow I'm going to swap in another woofer and see what happens. The sound that I'm hearing is coming from inside the enclosure. Here is a second listen.
http://s596.beta.photobucket.com/user/louisdamani/media/20121219_0103001_zps0eb33493.mp4.html

It is hard to say what that sound is, but it very well could be the spider landing spacer "tapping" against the speaker frame (if it came loose.) You would have to pull the speaker to take a look

JP
post #1473 of 1699
IMG_1474.JPG

I recommend installing the extra bracing.




*note: no children were harmed in the making of this F-20
post #1474 of 1699
FWIW, running mine with an EP2500 does not seem as dangerous as one would think, due to the EP's relatively low input sensitivity. Currently using it for music, CD/MP3 to receiver to BFD to EP2500, monitoring the voltage I would have to have everything near maxxed to worry about that 32V max we discussed. Of course if one were boosting the input signal that would change things.

I am leaning towards getting an INUKE DSP3000, only thing holding me back is I still wouldn't have the ability to high pass at 20 Hz, right? So if I end up needing a mini-DSP anyway. I'm hoping the limiting feature of the INUKE could be helpful in keeping that power in check for HT use.
post #1475 of 1699
Thread Starter 
Quote:
Originally Posted by vitaminbass View Post

...I am leaning towards getting an INUKE DSP3000, only thing holding me back is I still wouldn't have the ability to high pass at 20 Hz, right? So if I end up needing a mini-DSP anyway. I'm hoping the limiting feature of the INUKE could be helpful in keeping that power in check for HT use.

The iNuke DSP implementation works great to 20 Hz, that is just the lowest it will go. Should work fine for you.

As far as the limiters? They look like they might help a LOT, I hope that I have something to test them out with soon. Need to make some room to work in my shop and get some lights hung up, so I can see what I am doing.
post #1476 of 1699
When my wife and I moved the F-20 from sitting on the sawhorses, to verticle on the floor....we lost control and the sub actually crushed/bent one of the sawhorses (and it's pretty sturdy). A few tense moments but no one got hurt and the sub didn't even get a scratch amazingly....and we got a good laugh about it.

It's not THAT heavy but other than the mouth, no good place to grab ahold.
post #1477 of 1699
I have just finished reading this entire post. WOW. I am going to build this as my first diy sub. I'm torn between good plywood and MDF. Any thoughts?
post #1478 of 1699
plywood. MDF is nasty. Messy. And heavy.
post #1479 of 1699
MDF is very solid, has no voids, doesn't resonate as much as plywood and doesn't have the issue of delamination that veneered plywood does. Once the box is built, I prefer MDF. But as the builder, I hate it. What I didn't understand prior to experiencing it, is when you cut MDF, bad fumes are released (and it's dusty to boot) so you can wear a standard dust mask or hook up your shopvac but those fumes are still there. Maybe this isn't the case with all MDF but it sure was with the stuff that I had.

If you were just buying flat packs, MDF would be great.
post #1480 of 1699
Thread Starter 
I recommend using good plywood.

I've built with both, and hands down, I recommend using good ply.

Plywood and OSB smell like wood when you cut it, not chemicals.

They also make sawdust, not the super-fine haze of fibers that MDF does.

Honestly - I'd use proper commercial grade particle board over MDF, but before I picked that I'd use OSB, and I'd only use OSB if I couldn't get ply.
post #1481 of 1699
i'm a happy MDF'er, but I also had the sub built for me so the construction mess wasn't an issue. Heavy, yes, but I'm not moving it 10 times a year (or up/down stairs).
post #1482 of 1699
Quote:
Originally Posted by vitaminbass View Post

MDF is very solid, has no voids, doesn't resonate as much as plywood and doesn't have the issue of delamination that veneered plywood does. Once the box is built, I prefer MDF.

MDF is neither as rigid nor as stable as ply. The frequencies where a TH (or any subwoofer) resonates are FAR below the panel resonances of ply. For tapped horn subs, rigidity is much more important than a dead (above 300hz) panel.
Quote:
Originally Posted by lilmike View Post

I recommend using good plywood.

There is a reason you will not find a single commercial cinema horn sub-woofer built with MDF. Ply is what you want.. Listen to Mike. And ask him about the importance of enclosure rigidity with horns..... (He's learning smile.gifsmile.gif )
Edited by dB-Kicker - 1/1/13 at 1:55am
post #1483 of 1699
Quote:
Originally Posted by dB-Kicker View Post

And ask him about the importance of enclosure rigidity with horns..... (He's learning smile.gifsmile.gif )

So am I wink.gif

Plywood and proper bracing, all the way. Even if I could use MDF, I wouldn't.
post #1484 of 1699
Yes, plywood all the way especially with horns. Sealed boxes are the better MDF candidate.
post #1485 of 1699
these statements are based on...... ? Mine has been assembled and exercised for nearly a year with absolutely no issues. With proper bracing, how is MDF supposedly inferior?
post #1486 of 1699
It's not inferior per se, but with horns that are braced as part of their design...the weight and fragility of MDF are not worth it when 3/8 or 3/4 ply is plenty strong.

MDF certainly helps with deadening and can be more easily routed for rounded edges etc, but also can be damaged easier. Ply has the advantage of better mechanical fastener holds and can be stained or finished like MDF.

Often there are many solutions to the same problem or in the case, build. Some just work slightly better for the given demand.
post #1487 of 1699
Thread Starter 
Table 12-1 of this document shows that MDF has a Modulus of Elasticity that is lower than OSB, which is in turn lower than plywood, yet MDF has a density that is higher than either.

Whether that matters or not? Dunno, I'm not an engineer. As I understand it, a material with a low modulus of elasticity means that it bends more easily.

Weighs more and bends more easily....not a win-win in my eyes.

In my experience, MDF does not take glue as well, and splits far too easily when driving screws into the edge. I've taken apart plenty of cabinets over the years (they take up a lot less space in the truck when you haul them to the wood-waste recycler). MDF cabinets tend to come apart more easily, all else being equal (design, glue, and assembly techniques).

I also know from my firsthand experience making speaker cabinets for the last 25+ years or so now that the dust, weight, and other issues associated with working with MDF in my shop preclude its use more often than not.

I use and recommend plywood. MDF may be just fine for some, but I prefer and recommend plywood.

To each their own.
post #1488 of 1699
Quote:
Originally Posted by lilmike View Post

Table 12-1 of this document shows that MDF has a Modulus of Elasticity that is lower than OSB, which is in turn lower than plywood, yet MDF has a density that is higher than either.
Whether that matters or not? Dunno, I'm not an engineer. As I understand it, a material with a low modulus of elasticity means that it bends more easily.
Weighs more and bends more easily....not a win-win in my eyes.
In my experience, MDF does not take glue as well, and splits far too easily when driving screws into the edge. I've taken apart plenty of cabinets over the years (they take up a lot less space in the truck when you haul them to the wood-waste recycler). MDF cabinets tend to come apart more easily, all else being equal (design, glue, and assembly techniques).
I also know from my firsthand experience making speaker cabinets for the last 25+ years or so now that the dust, weight, and other issues associated with working with MDF in my shop preclude its use more often than not.
I use and recommend plywood. MDF may be just fine for some, but I prefer and recommend plywood.
To each their own.

perfect, thank you. i just want people reading this thread to make decisions based on fact and not personal opinion. good and solid insight.
post #1489 of 1699
lilmike seems to know what he's talking about based on all the other threads I have read. Thanks for the info.
post #1490 of 1699
Quote:
Originally Posted by lovearkansas View Post

lilmike seems to know what he's talking about based on all the other threads I have read.

Absolutely!
post #1491 of 1699
which material is used for most commercial sealed and ported subs? I thought a lot of them were MDF. If so, why is this...cost?

One more advantage to ply is if it ever gets temporarily wet, it will likely be ok where MDF degrades quickly with moisture.
post #1492 of 1699
Yes, most commercial offerings are MDF. One reason is that MDF easily routable for recesses, rounded corners, etc.
post #1493 of 1699
Thread Starter 
I'm thinking that it primarily comes down to cost.

A sheet of 3/4" MDF costs me between 1/3 and 1/2 of a sheet of 3/4" ply does.

Profit is a powerful motivator.

Consider though - pro-grade horn cabinets (Danley and the like) are not made of MDF.
post #1494 of 1699
Forgive me if this question has already been addressed here or elsewhere...

I'm going to place my sub standing up in a corner with my opening cut out of the top of the enclosure, instead of one of the 3 sides. Is this OK so long as the opening area is the same?
post #1495 of 1699
Hey guys, Lilmike,

I have had my F20 running for an awesome year now but have made some changes and would like your advice. Up until recently I was feeding my F20 via a Pioneer VSX-21 through the Dayton 240 amp http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-804.

With this setup I had the Sub level in the AVR at 0 and the volume on the Dayton at the 10-11 O'clock position. Now I just replaced my AVR with a Denon 4311 and man I can already tell the difference with Audyssey's better sub EQ correction! However When running Audyssey I had to put the volume knob down at the 6-7 O'clock position to get it down to the 75 db that Audyssey wanted. This sounded good but did not have any of the huge hitting that I know the F20 is good for. Following traditional advice I listened to it like this for a week before deciding that although cleaner (due to the EQ I assume) the punch was missing. So I turned the sub level up in the AVR from -5 to +2.5 and I like that much better but something was still not there. So I turned up the Volume on the Dayton to about the 9 O'Clock position and I am happier with the output. My concern is why I feel I need to do it this way when everyone seems to say set the amp were Audyssey wants and then adjust in the AVR not the AMP, but that was not getting the result I wanted. Is it maybe partly the Dayton amp needing to be up higher to properly output? I guess what I am asking is as the F20 designer and also owners what do you Recommend as far as how to dial in these settings. Obviously I like the Bass on the Hot side.

Thanks in advance!
post #1496 of 1699
Hey Cheez...

I am not sure how my application might compare to yours, but I am running four F20s off two Crown XLS1000s fed by an Onkyo 709 with Audyssey MULTEQ® XT. I have my amps turned all the way up to the max on all four channels, and my AVR sub settings at -12dB. The volume on the Onkyo goes from 0 - 100 and I watch movies somewhere between 72 and 78. This gives the F20s the kick I want. One of the reasons I have my setup this way is to ensure the bass can never be turned up loud enough to damage the drivers. I find it far more likely that someone might accidentally or purposefully turn the amps up than the same thing happening to the sub's settings on the AVR.

That said, I have not actually used the Audyssey to calibrate any EQ up to this point.
post #1497 of 1699
Thread Starter 
Quote:
Originally Posted by Stumbo View Post

Forgive me if this question has already been addressed here or elsewhere...

I'm going to place my sub standing up in a corner with my opening cut out of the top of the enclosure, instead of one of the 3 sides. Is this OK so long as the opening area is the same?

Not sure I follow where you're going here - you want to stand it upside down in a corner and open the mouth through the top?

If the area is the same, it should work OK.
post #1498 of 1699
Thread Starter 
Quote:
Originally Posted by cheezit73 View Post

Hey guys, Lilmike,

I have had my F20 running for an awesome year now but have made some changes and would like your advice. Up until recently I was feeding my F20 via a Pioneer VSX-21 through the Dayton 240 amp http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-804.

With this setup I had the Sub level in the AVR at 0 and the volume on the Dayton at the 10-11 O'clock position. Now I just replaced my AVR with a Denon 4311 and man I can already tell the difference with Audyssey's better sub EQ correction! However When running Audyssey I had to put the volume knob down at the 6-7 O'clock position to get it down to the 75 db that Audyssey wanted. This sounded good but did not have any of the huge hitting that I know the F20 is good for. Following traditional advice I listened to it like this for a week before deciding that although cleaner (due to the EQ I assume) the punch was missing. So I turned the sub level up in the AVR from -5 to +2.5 and I like that much better but something was still not there. So I turned up the Volume on the Dayton to about the 9 O'Clock position and I am happier with the output. My concern is why I feel I need to do it this way when everyone seems to say set the amp were Audyssey wants and then adjust in the AVR not the AMP, but that was not getting the result I wanted. Is it maybe partly the Dayton amp needing to be up higher to properly output? I guess what I am asking is as the F20 designer and also owners what do you Recommend as far as how to dial in these settings. Obviously I like the Bass on the Hot side.

Thanks in advance!

Bass on the hot side? I can relate...that's why the F-20 exists...

Make sure that Audyssey is not applying any crazy boost down low before twisting the knob. With that Dayton, you shouldn't hurt the driver, but the amp may clip and distort. If it sounds alright to you, you're probably OK. Without measurements, it is hard to tell what's really going on.

I can't add too much - cause well, though I have Audyssey in my 3312 and a BFD, a MiniDSP, and DSP in my iNuke 3000 for EQ, I'm not using any of it right now....

Yup - the cobbler's still barefoot.... Well, not exactly. My T-6s sound good enough so that I haven't really focused on replacing them until a couple weeks ago.



The new cabinet has made some noise and measured pretty well. I am still refining things and working on the bracing, but for a proof of concept, I'm pleased.

Edit: Fixed the pic.
Edited by lilmike - 1/10/13 at 9:39am
post #1499 of 1699
After building a few subs in my time I would have to agree that ply is 10x's better. Working with, smelling, cleaning up and rigidity. But to each there own. I love MDF for mockups but would never buy anything built with it commercially. Secondly I hate working with it any more. Just a pain really.

Mike is this a TH?
post #1500 of 1699
Quote:
Originally Posted by chrapladm View Post

After building a few subs in my time I would have to agree that ply is 10x's better. Working with, smelling, cleaning up and rigidity. But to each there own. I love MDF for mockups but would never buy anything built with it commercially. Secondly I hate working with it any more. Just a pain really.

Mike is this a TH?

Hi,

yes it is TH (Tapped Horn) and it looks very nice. It looks more for the 18-inch driver than for 15-inch driver?
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