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Lilmike's Cinema F-20 - Page 15

post #421 of 1698
Quote:
Originally Posted by t6902wf View Post

Sorry MK I must have missed it. Are you replacing the sealed subs or adding to them.

Replacing.
post #422 of 1698
Thread Starter 
Quote:
Originally Posted by diaz View Post

Are there any graphs with in-room corner loading?

Also, I would be interested in a comparison between my current 7.1 cf 23hz ported box vs the F20..

I have the F20 graph in hornresp, but I am not sure how to graph my ported box on there too..

No corner-loaded graphs that I am aware of. Some in-room measurement comments were posted here. Even so - since we all have different corners in different rooms, someone else's graph may not be applicable to your situation anyhow.

You can model a ported box in Hornresp. See note 12 in the Hornresp help file.

I sort of covered that here and here though.
post #423 of 1698
Quote:
Originally Posted by lilmike View Post

No corner-loaded graphs that I am aware of. Some in-room measurement comments were posted here. Even so - since we all have different corners in different rooms, someone else's graph may not be applicable to your situation anyhow.

You can model a ported box in Hornresp. See note 12 in the Hornresp help file.

I sort of covered that here and here though.

Thanks!

Is there a reason why hornresp give a different spl response curve as winisd?
post #424 of 1698
Ok so I managed to get placement and phase issues sorted out I THINK. One big thing, when measuring at the mouth of each enclosure, the mfw box is averaging about 2-3 db more than the tempest, can this be right? perhaps the tempest needs more juice than the 650 watts im throwing to it?
post #425 of 1698
Yes, the MFW-15 has higher sensitivity than the Tempest. If you have more power for the Tempest go for it.
post #426 of 1698
so making good progress on the f-20s. I put veneer on each of the edges that show and am countersinking all the screws and bondo'ing over them to get a nice clean look. I figured if I was going through the effort of making it, I might as well spend a bit more time and make it look good. Probably going to black lacquer all of it. I'll post some pics after it's done
post #427 of 1698
well didn't quite finish things tonight but will get it all done tomorrow. Got started late again today. Here are some pictures of the two f-20s being built. Both my father and I are perfectionists so they are taking a lot more time than they have to.

http://imageshack.us/g/12/imag0242n.jpg/
post #428 of 1698
Quote:
Originally Posted by blackoper View Post
well didn't quite finish things tonight but will get it all done tomorrow. Got started late again today. Here are some pictures of the two f-20s being built. Both my father and I are perfectionists so they are taking a lot more time than they have to.

http://imageshack.us/g/12/imag0242n.jpg/
Good progress! It must be nice to have access to a wood shop. Also, are you using PL as you assemble? If so, you are the neatest PL applier I have ever seen.

BTW, I see that you....... Got Clamps?



Uploaded with ImageShack.us
post #429 of 1698
Quote:
Originally Posted by turdlepoker View Post
Good progress! It must be nice to have access to a wood shop. Also, are you using PL as you assemble? If so, you are the neatest PL applier I have ever seen.

BTW, I see that you....... Got Clamps?
Yeah PL is being applied. I've used a lot of it in the past and put on a really nice bead plus everything is fitting together without any seams so we are not having to slather it on much. All edges have been cut for square so other than the plywood being warped and having to use clamps to get it perfectly aligned, we have not had too much trouble.

It is nice having a full wood shop but I have to drive down from Louisville to use it (90 miles). Those pictures probably only show about 1/4th of the place. There is a full spray booth on the other side and a large 4ft x8ft cnc router on the other end as well. My next speaker project the econowave sr compacts, I'm just going to use the cnc to cut everything and save myself some hassle. I hate dealing with the table saw.

P.S. Those are just the pipe clamps. You should see the barrels and boxes of other clamps
post #430 of 1698
wow, lilmike. After spending a month building 2 THT's with a buddy I'm sooooooooooooooo wishing I had built the F-20 instead. looks so much simpler and using 5x5 baltic birch cutting the long panel would have been a breeze
post #431 of 1698
Quote:
Originally Posted by blackoper View Post

Yeah PL is being applied. I've used a lot of it in the past and put on a really nice bead plus everything is fitting together without any seams so we are not having to slather it on much. All edges have been cut for square so other than the plywood being warped and having to use clamps to get it perfectly aligned, we have not had too much trouble.

It is nice having a full wood shop but I have to drive down from Louisville to use it (90 miles). Those pictures probably only show about 1/4th of the place. There is a full spray booth on the other side and a large 4ft x8ft cnc router on the other end as well. My next speaker project the econowave sr compacts, I'm just going to use the cnc to cut everything and save myself some hassle. I hate dealing with the table saw.

P.S. Those are just the pipe clamps. You should see the barrels and boxes of other clamps

Beautiul work! I envy you the CNC machine.

I would not want you to inspect mine. The bigger the glob the better the job. I figure I can always go back and cut the excess out with a box knife and a chisel if I think I used too much. Plus I like to work pretty fast so I am not too concerned with what the inside looks like. Or the outside for that matter. I just painted mine flat black latex since it will sit below the screen. My wife is talking about putting black velvet on it now to make it disappear if possible.

Mike, I have been considering standing them up and firing them into the corners on each side of the screen with about 18 inches from the screen wall and tight on the side wall. Any thoughts on this? As it is now my other choices are side by side below with the exits on the outer edges firing forward, or in the same orientation but split apart and moved to the edges of the wall so that my center channel can be placed between them. As it is now the center channel is standing in front of the subs forcing me to move the mains out near it to try to keep some continuity with the LCR. I am starting a build project for some Ewaves (you have already seen that) and was thinking they could be mounted to the wall or stand on the subs if I split them out to the corners. I am tight for space on the front and searching for answers. In the end, I will have to measure it all and jostle it around to get the best setup but any thoughts on this would be welcome.
post #432 of 1698
Thread Starter 
Wow - busy day....

@ all

I attached a cut-sheet for the 5X5 panel option. Takes a little more than 2.5 sheets. I can maybe tuck it into a zip file with the others, but I am out of room for attachments on the first post.

@ Rob

That's how I'd position them to start. Slide them into or out of the corner till you get the sound you want.

@blackoper

Very nice looking work.

@ beastaudio

Like the others said - balance the gains, I'd suggest that you give the MFW a little less power, but feed the Tempest all you've got on tap.

@ diaz

As I understand it, the differences between Hornresp and WinISD primarily comes down to how each program deals with box losses. I believe that Hornresp models a lossless, non-resonant box. WinISD does account for box losses. As both are free, we don't have to choose, we can use the tool best suited to the task at hand.

 

Cinema F-20 5X5 sheets.pdf 6.017578125k . file
post #433 of 1698
home for lunch. Test fit the final pieces and got some pics. Also some pics of the shop i'm working in (messy right now)


http://imageshack.us/g/839/imag0248v.jpg/
post #434 of 1698
nice! the cutsheet will definitely help folks.

lilmike, you can link to files stored on avs directly no problem. just use the direct link and put it in your first post. if you aren't sure what the direct link is, right click on the attachment and choose 'properties', then right click again on the url and 'copy' it to your first post. (sorry if any of this is redundant or if you know already) here is the link for the cutsheet just mentioned:

http://www.avsforum.com/avs-vb/attac...1&d=1306689609

you can spruce it up as always:

5' x 5' Cut Sheet (2.5 Sheets required)

if you need some help with this, feel free to pm to me. you have too much good stuff going on here to lit a little technology get in the way.
post #435 of 1698
Ok two questions for OP:

1. Is it worth me buying baltic birch for this? Would getting a cheaper plywood do the job?

2. Does it make a difference in the sound if I add small amounts of bracing at key locations?

Thanks
post #436 of 1698
I was also thinking of a rear speaker access panel, which would also move the speaker closer to center of mass.. but I'm not sure if that design would work right. (proportions are not accurate, just a quick drawing lol)

Edit: I prefer the original, simple and to the point.
LL
post #437 of 1698
Well transported the f-20s home in the truck. It is definitely a manly sized sub. Bondo and painting tomorrow morning.

post #438 of 1698
Thread Starter 
Quote:
Originally Posted by diaz View Post

Ok two questions for OP:

1. Is it worth me buying baltic birch for this? Would getting a cheaper plywood do the job?

2. Does it make a difference in the sound if I add small amounts of bracing at key locations?

Thanks

I did not use baltic birch with mine, but I did use a 13-ply hardwood plywood. In my opinion, it worked fine. The shop-grade birch I can get at my local lumberyard is even better than the stuff I used, and only costs $34/sheet. Arauco would probably require bracing.

Small braces should have no effect. Large ones that completely divide the horn passage might. Placement was discussed a couple of pages ago.
post #439 of 1698
Thread Starter 
Quote:
Originally Posted by diaz View Post

I was also thinking of a rear speaker access panel, which would also move the speaker closer to center of mass.. but I'm not sure if that design would work right. (proportions are not accurate, just a quick drawing lol)

Edit: I prefer the original, simple and to the point.

5-board folds for the win! I like simple too.
post #440 of 1698
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

nice! the cutsheet will definitely help folks.

lilmike, you can link to files stored on avs directly no problem. just use the direct link and put it in your first post. if you aren't sure what the direct link is, right click on the attachment and choose 'properties', then right click again on the url and 'copy' it to your first post. (sorry if any of this is redundant or if you know already) here is the link for the cutsheet just mentioned:

http://www.avsforum.com/avs-vb/attac...1&d=1306689609

you can spruce it up as always:

5' x 5' Cut Sheet (2.5 Sheets required)

if you need some help with this, feel free to pm to me. you have too much good stuff going on here to lit a little technology get in the way.

Thanks. Linked in the first post.
post #441 of 1698
if someone wants to go with good 4x8 ply, is there a cutsheet for them?
post #442 of 1698
Quote:
Originally Posted by LTD02 View Post

if someone wants to go with good 4x8 ply, is there a cutsheet for them?

the original plans were for 4x8 ply. That's what I just used to build two.


Minidsp question:
What kind of roll-off do I need to use with on the minidsp with the High pass? Options are like BW of 6,12,24,48 an octave, LR of 6,12,24,48 an octave and a Bessel option.
post #443 of 1698
probably go for the 24, dont think the 48 is necessary

I used auruco with no bracing and dont get much vibration of the box...

after reinstalling the MFW, i think it is still more placement than driver difference causing the cab to perform a little less. driving the mfw vs the tempest, the MFW does perform a little better with the power i am feeding it, but it seems that using the limiter knobs of the xls 2000 bears no effect on either, they both clip at about the same setting, regardless of driver. not sure if this is supposed to happen or not, any ideas? I am hitting both gain knobs at about 75% on.
post #444 of 1698
Thread Starter 
Quote:
Originally Posted by blackoper View Post

the original plans were for 4x8 ply. That's what I just used to build two.


Minidsp question:
What kind of roll-off do I need to use with on the minidsp with the High pass? Options are like BW of 6,12,24,48 an octave, LR of 6,12,24,48 an octave and a Bessel option.

Anything > 12 dB/octave is fine. I'd suggest 24 dB. LR vs Butterworth is not a big deal - try both, pick the one that sounds best.

There really isn't an excursion issue, the primary reason I suggest a highpass with amps less than 300 watts is for the reduction of distortion. As I have stated in the past - I like to match amplifier bandwidth to what the speaker can accurately reproduce.
post #445 of 1698
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

if someone wants to go with good 4x8 ply, is there a cutsheet for them?

The 4X8 cutsheet is attached to post 1.
post #446 of 1698
roger. how do you create the cut sheets/optimize the design? they look nice.
post #447 of 1698
Thread Starter 
Quote:
Originally Posted by LTD02 View Post

roger. how do you create the cut sheets/optimize the design? they look nice.

I use Cut List, available at delphiforfun.org. I print it to a PDF with PDF Creator. It works very well, especially for the cost.
post #448 of 1698
post #449 of 1698
Quote:
Originally Posted by lilmike View Post
There really isn't an excursion issue, the primary reason I suggest a highpass with amps less than 300 watts is for the reduction of distortion. As I have stated in the past - I like to match amplifier bandwidth to what the speaker can accurately reproduce.
I'm using a 400 watt amp - Crown 402D so will that change anything?
post #450 of 1698
Quote:
Originally Posted by blackoper View Post
I'm using a 400 watt amp - Crown 402D so will that change anything?
The highpass will still be good for you, with that you actually get 450@4 ohm stereo so that will pair up with a set of f-20's almost perfectly. with that amount of power, just dial down the knobs on the 402 a tad bit and you will be in business
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