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Lilmike's Cinema F-20 - Page 2

post #31 of 1695
Quote:
Originally Posted by lilmike View Post

Not all horns have to be tapped....

This particular driver performs much better in a front-loaded horn, so I conjured up one for it.

Ok, I didnt know if there was any particular reason for going this route as far as performance goes.

can't wait to see the finished insubnia!
post #32 of 1695
Cool...

Whats the RE on that driver? Either way it looks like 92-94ish efficiency 20-100hz gp. That is not too bad for a cab this size. Also the response looks like it is about +/-6.5db 20-120hz. Also not bad at all. Nice and simple build too.

Simulation data?
post #33 of 1695
Quote:


Look what happens at 21 Hz, same drive level...3% THD, and 107.6 dB

These are impressive numbers considering the $$$ invested!!!

Well Done!
post #34 of 1695
Quote:
Originally Posted by lilmike View Post

I have a complete set of dimensioned plans and cutlists done already (currently only in 2D - not spiffy like radman12 did with the Anarchy).

PM me if you still need drawings done (2D or 3D) and I'll be happy to help out.

Also could the 2 large side pieces be rabbeted for outside panels and slots cut for the inside panels and then ship only those two or would they still be cost prohibitive?
post #35 of 1695
Quote:
Originally Posted by lilmike View Post

It can also get stretched a bit without running out of driver capability, but that's for another thread.

I look forward to reading what it can do with more length. I think one of these in my basement would be fantastic.
post #36 of 1695
Pretty cool build, Lilmike. Looks like about the easiest horn build yet. I'm sure it'll become a staple suggestion for all newbs henceforth. Will an "F16" or whatever you call the lower F3 design, be a simple widening of the 20" side, or will it be much more different?
post #37 of 1695
Thread Starter 
Quote:
Originally Posted by CZ Eddie View Post

Pretty cool build, Lilmike. Looks like about the easiest horn build yet. I'm sure it'll become a staple suggestion for all newbs henceforth. Will an "F16" or whatever you call the lower F3 design, be a simple widening of the 20" side, or will it be much more different?

Thanks. I was definitely after easy, and this is the easiest horn I've come up with yet, at least when it comes to something that will do reference levels at 20 Hz in room with a little left in the tank. Though the fold looks simple enough - it isn't a single flare rate, there are actually three separate flare rates there. Sometimes simple isn't.

As far as the name - F= Front Loaded, the 20 is the cabinet volume in cubic feet.

22.5" wide internally looks nice in the model, but is not nearly as material friendly as 18.5" internally. At 18.5" internal width, you can get a side and an internal strip out of each sheet, with next to nothing but sawdust left, then cut the scrap into two of the three remaining pieces required. I cut the last piece out of a 2'X4' handy panel, cause I did not want to carve into another full sheet of ply and I was not driving the truck that day (can't fit a 4X8 in the Jeep). I only have two sheets of 3/4" ply left, and I have plans for those, namely the T-12 .
post #38 of 1695
I assumed "F20" stood for front loaded 20hz model.
post #39 of 1695
Nice work Lilmike... let me ask you something is the MFW 15 a better driver than the Classic Tempest...? I got another 2 hanging around...

I looked at the specs and it seems the Classic tempests also has 2 1/2 " voice coils and rated at 700 watts..
post #40 of 1695
Thread Starter 
Got specs for them? I don't think I do.

Model will be posted up in a few.

Edit:

Just looked - nope. The current Tempest X2 works well though. Models and design attached to post 1.
post #41 of 1695
Thread Starter 
Quote:
Originally Posted by Ricci View Post

Cool...

Whats the RE on that driver? Either way it looks like 92-94ish efficiency 20-100hz gp. That is not too bad for a cab this size. Also the response looks like it is about +/-6.5db 20-120hz. Also not bad at all. Nice and simple build too.

Simulation data?

3.04 according to specs, mine was a couple hundredths higher.

Model, sketchup and cutlists, as well as lot more data are attached to post one.

Working on some instructions and plotting up the impedance.
post #42 of 1695
Very nice, it is an impressive sub; best bang for buck I have seen yet!

JSS
post #43 of 1695
What are the specs for the MFW-15? Maybe I missed them... I don't see them on the opening post.
post #44 of 1695
Quote:
Originally Posted by Kanaris View Post

What are the specs for the MFW-15? Maybe I missed them... I don't see them on the opening post.

its pretty close to the dayton 15" dvc
http://www.diysoundgroup.com/MFW_15.htm
just a little less xmax
post #45 of 1695
Quote:
Originally Posted by stgdz View Post

its pretty close to the dayton 15" dvc
http://www.diysoundgroup.com/MFW_15.htm
just a little less xmax

Thats a pretty mild driver... I think my Adire Tempests are better.
post #46 of 1695
Thread Starter 
Quote:
Originally Posted by Kanaris View Post
Thats a pretty mild driver... I think my Adire Tempests are better.
Mild? Maybe.

Inexpensive? Yes. ~1/4 the cost of a Tempest X2, or ~1/2 the cost of your Tempest or the Dayton DVC.

As far as bang for the buck? Remember, it did manage 114 dB at 20 Hz in a groundplane setting, and I ran out of amp.

Thanks to the Google, I've found some specs for your Tempest. It might work in this cabinet, I'll check tonight.
post #47 of 1695
Adire Tempest specs attached.

 

TempestWhitePaper.zip 428.1376953125k . file
post #48 of 1695
Thread Starter 
Quote:
Originally Posted by CZ Eddie View Post
Adire Tempest specs attached.
Thanks CZ Eddie. Far better than what I found.

That driver will work fine in this horn. 500 watts should be safe, but it would not be a bad idea to run a 20 Hz highpass.
post #49 of 1695
I am considering 2 of these, what are some amp options to either run both or one per amp? PE isn't too far away but would consider other options. Any ideas? This would be my first build and I am excited to join the DIY crowd.
post #50 of 1695
Thread Starter 
Amp requirements are pretty modest. 300 watts into 4 ohms is all you need (for each cabinet). Wired in series, you'd want an amp that could deliver 600 watts into an 8-ohm load. Parallel wiring would be a 2 ohm nominal load, and looking at the impedance chart I posted, there are a few ranges where impedance will be below 2 ohms, which may cause issues with some amps.

I'd wire a pair in stereo for 2 4 ohm loads. Much more flexibility this way. As far as an amp, the Behringer A500 would do fine, and has no fan. According to the propaganda, it delivers 300 watts into a 4 ohm load, but a closer look suggests that the real RMS rating for 4 ohm stereo operation is 185 watts. At over 400 watts per channel, the Peavey IPR-1600 would be overkill, but I like overkill. The Crown XLS-1000 delivers 350 watts per channel, and has a built-in limiter, but the rest of the DSP fuctions are of limited value. Any of these amps will need a separate highpass, something like a MiniDSP can do that as well as loads of EQ to correct the room response issues.

Plate amps? There are a few options. I ran the test mule with a BASH 300 and had no problems at all. The Dayton 240 might also be a good option, but I don't have any experience with those. You would probably want one amp per cabinet. Most plate amps will need a filter modification for the highpass. This is usually as simple as swapping a pair of resistors.
post #51 of 1695
I plan on running mine with an OAudio 500W Bash Amp. It has a high pass filter built in and has sounded very clean with the smaller horns I have hooked to it right now. I am going to make some sawdust this weekend and hope for the best.
post #52 of 1695
Quote:
Originally Posted by Rob Flanery View Post

I plan on running mine with an OAudio 500W Bash Amp. It has a high pass filter built in and has sounded very clean with the smaller horns I have hooked to it right now. I am going to make some sawdust this weekend and hope for the best.

Make sure you do a build thread... I'm sure some of us would love to see yours come together.
post #53 of 1695
lilmike,

How do you think 4 of the F-20's being powered from an EP4000.... 2 per channel wired in series?
post #54 of 1695
Thread Starter 
Quote:
Originally Posted by turdlepoker View Post

lilmike,

How do you think 4 of the F-20's being powered from an EP4000.... 2 per channel wired in series?

Ohhhh, if I had the room.....

Reference levels plus at least 10 dB at a meter, in a 2pi setting, easily 10 dB more than that inside....

All four in one room? You'll break stuff.

The test mule was flexing all the windows on the side of my house visibly while we were doing the distortion measurements. There was 10 dB left in it at that point, and the sub was 4 M away from the house, facing the opposite direction....
post #55 of 1695
Quote:
Originally Posted by lilmike View Post

Ohhhh, if I had the room.....

Reference levels plus at least 10 dB at a meter, in a 2pi setting, easily 10 dB more than that inside....

All four in one room? You'll break stuff.

The test mule was flexing all the windows on the side of my house visibly while we were doing the distortion measurements. There was 10 dB left in it at that point, and the sub was 4 M away from the house, facing the opposite direction....


HAHAHA, this sounds just up my alley.

Yes, all in the same room. 2 on each side of the screen just for sheets and giggles. I'll make sure I do a build thread.

Do you think they will extend any lower due to the extra headroom?
post #56 of 1695
lilmike,

Thanks for your continued contributions to our community.

In the opening statement you indicate this unit is one in what is to become your cinema series of designs. Do you have any ~20Hz TH designs under consideration?

I'm tempted to try this guy, but I'd really like to experience a 15" TH in a similar footprint.
post #57 of 1695
Quote:
Originally Posted by turdlepoker View Post

Make sure you do a build thread... I'm sure some of us would love to see yours come together.

I've decided to hold out for the stretch limo version. I have a lot of other projects to attend to at the moment so I will content myself with doing "chores" for the house rather than building something fun.

I will try to get some pictures as I go along if for no other reason than to show how a caveman cuts wood. It is pretty pathetic.
post #58 of 1695
Thread Starter 
Quote:
Originally Posted by 04FLHRCI View Post

lilmike,

Thanks for your continued contributions to our community.

In the opening statement you indicate this unit is one in what is to become your cinema series of designs. Do you have any ~20Hz TH designs under consideration?

I'm tempted to try this guy, but I'd really like to experience a 15" TH in a similar footprint.

You're welcome.

As it looks currently, I'll have 4 designs in my Cinema series, each with a variation or two. I have models and ideas for folds for a large tapped horn with a single 15" driver, and an F3 below 20 Hz, but I don't have a dimensioned fold yet, nor do I have a driver to work with.

Here's the remainder of the Cinema Series (as I see things now):

Cinema F-20 (this thread) with a stretched variant that's in the works. The stretched one (F-24) will play a little lower, but might need a more capable driver.

Cinema T-6 (coming very soon - fold is done, plans are done, multiple suitable drivers in hand, my initial beta was a fail, but the current refold's beta results are great) Tapped horn with an 8" or 10" driver, cabinet is 6 cubic feet, F3 of ~28 Hz, single 4X8 sheet of 1/2" plywood. Widths will vary based on the driver used, 11.75" internally is about the limit for an unbraced cabinet, no point in going wider, the aspect ratio of the throat (width/depth) gets too large IMO.

Cinema T-12 (coming soon, model is done, fold is sketched, scaled plans are started, drivers are in hand and need a proper home) Tapped horn, 12 cubic feet, F3 of 20 Hz, 10" or 12" drivers, two sheets of ply. Widths will also be varied on this one, and it might get a stretch, all of this depends on the results of the beta build.

Cinema T-16 (a little further out, model is done, fold is sketched, but I currently have no suitable drivers to test with, though I am working on that too...)
Tapped Horn, 16 cubic feet, F3 ~17 Hz, 15" drivers, less than 3 4X8 sheets of ply. As with the T-12, widths will be varied on this one, and it might also get a stretch, this all depends on the results.

My design goals for these?
Capable of at least 115 dB in a groundplane setting within 1/2 octave of F3.
No more than a 6 dB drop from 2 octaves above F3 to F3.
post #59 of 1695
Thread Starter 
Quote:
Originally Posted by turdlepoker View Post

....

Do you think they will extend any lower due to the extra headroom?

Not significantly.

Horn length sets the corner.

Placement and boundary loading might give you a Hz or two, but that is it. Horn length is the variable that drives the bus here.

Lower requires a longer horn. To go from 20 Hz to 10 Hz means doubling the length of the horn. That's the easy part. The hard part is finding a driver that can handle the added demands. There are not any single-driver solutions that I'm aware of.

That being said - I am working on a 1-foot stretch to this cabinet that should get the F3 down a few Hz lower by adding approximately 3 feet to the horn path, but since nothing is free, it will cost a dB or two. The MFW might be able to handle the demands. If not, I know of several more capable drivers that will do just fine.
post #60 of 1695
Lilmike, if you can get someone to draw this out like the Anarchy, I'll post all the info on my site to keep it in one place.

Actually, it might be better at this point to give your horn designs their own page or two on the site. That way it's all in one place......and one nice big fat donation button if people feel the need to show they like your designs.

Let me know, and I'll start working on it.


After today I'll be caught up on all the Anarchy flat packs and MFW orders. So things will slow down a little bit and give me more time to get things rolling on the site and have it all laid out better.
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